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Toscano E, Cimmino E, Boccia A, Sepe L, Paolella G. Cell populations simulated in silico within SimulCell accurately reproduce the behaviour of experimental cell cultures. NPJ Syst Biol Appl 2025; 11:48. [PMID: 40379622 DOI: 10.1038/s41540-025-00518-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2024] [Accepted: 04/08/2025] [Indexed: 05/19/2025] Open
Abstract
In silico simulations are used to understand cell behaviour by means of different approaches and tools, which range from reproducing average population trends to building lattice-based models to, more recently, creating populations of individual cell agents whose mass, volume and morphology behave according to more or less precise rules and models. In this work, a new agent-based simulator, SimulCell, was conceived, developed and used to predict the behaviour of eukaryotic cell cultures while growing attached to a flat surface. The system, starting from time-lapse microscopy experiments, uses growth, proliferation and migration models to create synthetic populations closely resembling original cultures. Support for cell-cell and cell-environment interaction makes cell agents able to react to changes in medium composition and other events, such as physical damage or chemical modifications occurring in the culture plate. The simulator is accessible through a web application and generates data that can be shown as tables and graphs or exported for further analyses.
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Affiliation(s)
- Elvira Toscano
- CEINGE Biotecnologie Avanzate Franco Salvatore, Naples, Italy
- Department of Molecular Medicine and Medical Biotechnology, Università Degli Studi di Napoli "Federico II", Naples, Italy
| | - Elena Cimmino
- Department of Molecular Medicine and Medical Biotechnology, Università Degli Studi di Napoli "Federico II", Naples, Italy
| | - Angelo Boccia
- CEINGE Biotecnologie Avanzate Franco Salvatore, Naples, Italy
| | - Leandra Sepe
- Department of Molecular Medicine and Medical Biotechnology, Università Degli Studi di Napoli "Federico II", Naples, Italy
| | - Giovanni Paolella
- CEINGE Biotecnologie Avanzate Franco Salvatore, Naples, Italy.
- Department of Molecular Medicine and Medical Biotechnology, Università Degli Studi di Napoli "Federico II", Naples, Italy.
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2
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Pashos ARS, Meyer AR, Bussey-Sutton C, O'Connor ES, Coradin M, Coulombe M, Riemondy KA, Potlapelly S, Strahl BD, Hansson GC, Dempsey PJ, Brumbaugh J. H3K36 methylation regulates cell plasticity and regeneration in the intestinal epithelium. Nat Cell Biol 2025; 27:202-217. [PMID: 39779942 DOI: 10.1038/s41556-024-01580-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 11/20/2024] [Indexed: 01/11/2025]
Abstract
Plasticity is needed during development and homeostasis to generate diverse cell types from stem and progenitor cells. Following differentiation, plasticity must be restricted in specialized cells to maintain tissue integrity and function. For this reason, specialized cell identity is stable under homeostatic conditions; however, cells in some tissues regain plasticity during injury-induced regeneration. While precise gene expression controls these processes, the regulatory mechanisms that restrict or promote cell plasticity are poorly understood. Here we use the mouse small intestine as a model system to study cell plasticity. We find that H3K36 methylation reinforces expression of cell-type-associated genes to maintain specialized cell identity in intestinal epithelial cells. Depleting H3K36 methylation disrupts lineage commitment and activates regenerative gene expression. Correspondingly, we observe rapid and reversible remodelling of H3K36 methylation following injury-induced regeneration. These data suggest a fundamental role for H3K36 methylation in reinforcing specialized lineages and regulating cell plasticity and regeneration.
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Affiliation(s)
- Alison R S Pashos
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
- University of Colorado Cancer Center, Anschutz Medical Campus, Aurora, CO, USA
- Charles C. Gates Center for Regenerative Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Anne R Meyer
- University of Colorado Cancer Center, Anschutz Medical Campus, Aurora, CO, USA
- Charles C. Gates Center for Regenerative Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Cameron Bussey-Sutton
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Erin S O'Connor
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
- University of Colorado Cancer Center, Anschutz Medical Campus, Aurora, CO, USA
- Charles C. Gates Center for Regenerative Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Mariel Coradin
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
- University of Colorado Cancer Center, Anschutz Medical Campus, Aurora, CO, USA
- Charles C. Gates Center for Regenerative Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Marilyne Coulombe
- University of Colorado Cancer Center, Anschutz Medical Campus, Aurora, CO, USA
- Charles C. Gates Center for Regenerative Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Kent A Riemondy
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Sanjana Potlapelly
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
- University of Colorado Cancer Center, Anschutz Medical Campus, Aurora, CO, USA
- Charles C. Gates Center for Regenerative Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Brian D Strahl
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Gunnar C Hansson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Peter J Dempsey
- University of Colorado Cancer Center, Anschutz Medical Campus, Aurora, CO, USA.
- Charles C. Gates Center for Regenerative Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
| | - Justin Brumbaugh
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO, USA.
- University of Colorado Cancer Center, Anschutz Medical Campus, Aurora, CO, USA.
- Charles C. Gates Center for Regenerative Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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3
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Mamis K, Zhang R, Bozic I. Stochastic model for cell population dynamics quantifies homeostasis in colonic crypts and its disruption in early tumorigenesis. Proc Biol Sci 2023; 290:20231020. [PMID: 37848058 PMCID: PMC10581771 DOI: 10.1098/rspb.2023.1020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 09/22/2023] [Indexed: 10/19/2023] Open
Abstract
The questions of how healthy colonic crypts maintain their size, and how homeostasis is disrupted by driver mutations, are central to understanding colorectal tumorigenesis. We propose a three-type stochastic branching process, which accounts for stem, transit-amplifying (TA) and fully differentiated (FD) cells, to model the dynamics of cell populations residing in colonic crypts. Our model is simple in its formulation, allowing us to estimate all but one of the model parameters from the literature. Fitting the single remaining parameter, we find that model results agree well with data from healthy human colonic crypts, capturing the considerable variance in population sizes observed experimentally. Importantly, our model predicts a steady-state population in healthy colonic crypts for relevant parameter values. We show that APC and KRAS mutations, the most significant early alterations leading to colorectal cancer, result in increased steady-state populations in mutated crypts, in agreement with experimental results. Finally, our model predicts a simple condition for unbounded growth of cells in a crypt, corresponding to colorectal malignancy. This is predicted to occur when the division rate of TA cells exceeds their differentiation rate, with implications for therapeutic cancer prevention strategies.
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Affiliation(s)
- Konstantinos Mamis
- Department of Applied Mathematics, University of Washington, Seattle, WA 98195, USA
| | - Ruibo Zhang
- Department of Applied Mathematics, University of Washington, Seattle, WA 98195, USA
| | - Ivana Bozic
- Department of Applied Mathematics, University of Washington, Seattle, WA 98195, USA
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4
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Gall L, Jardi F, Lammens L, Piñero J, Souza TM, Rodrigues D, Jennen DGJ, de Kok TM, Coyle L, Chung S, Ferreira S, Jo H, Beattie KA, Kelly C, Duckworth CA, Pritchard DM, Pin C. A dynamic model of the intestinal epithelium integrates multiple sources of preclinical data and enables clinical translation of drug-induced toxicity. CPT Pharmacometrics Syst Pharmacol 2023; 12:1511-1528. [PMID: 37621010 PMCID: PMC10583244 DOI: 10.1002/psp4.13029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 07/13/2023] [Accepted: 07/17/2023] [Indexed: 08/26/2023] Open
Abstract
We have built a quantitative systems toxicology modeling framework focused on the early prediction of oncotherapeutic-induced clinical intestinal adverse effects. The model describes stem and progenitor cell dynamics in the small intestinal epithelium and integrates heterogeneous epithelial-related processes, such as transcriptional profiles, citrulline kinetics, and probability of diarrhea. We fitted a mouse-specific version of the model to quantify doxorubicin and 5-fluorouracil (5-FU)-induced toxicity, which included pharmacokinetics and 5-FU metabolism and assumed that both drugs led to cell cycle arrest and apoptosis in stem cells and proliferative progenitors. The model successfully recapitulated observations in mice regarding dose-dependent disruption of proliferation which could lead to villus shortening, decrease of circulating citrulline, increased diarrhea risk, and transcriptional induction of the p53 pathway. Using a human-specific epithelial model, we translated the cytotoxic activity of doxorubicin and 5-FU quantified in mice into human intestinal injury and predicted with accuracy clinical diarrhea incidence. However, for gefitinib, a specific-molecularly targeted therapy, the mice failed to reproduce epithelial toxicity at exposures much higher than those associated with clinical diarrhea. This indicates that, regardless of the translational modeling approach, preclinical experimental settings have to be suitable to quantify drug-induced clinical toxicity with precision at the structural scale of the model. Our work demonstrates the usefulness of translational models at early stages of the drug development pipeline to predict clinical toxicity and highlights the importance of understanding cross-settings differences in toxicity when building these approaches.
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Affiliation(s)
- Louis Gall
- Clinical Pharmacology and Quantitative Pharmacology, Clinical Pharmacology and Safety Sciences, R&DAstraZenecaCambridgeUK
| | - Ferran Jardi
- Preclinical Sciences & Translational SafetyJanssen Pharmaceutica NVBeerseBelgium
| | - Lieve Lammens
- Preclinical Sciences & Translational SafetyJanssen Pharmaceutica NVBeerseBelgium
| | - Janet Piñero
- Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Medical Research Institute (IMIM)UPFBarcelonaSpain
| | - Terezinha M. Souza
- Department of Toxicogenomics, GROW School for Oncology and Developmental BiologyMaastricht UniversityMaastrichtThe Netherlands
| | - Daniela Rodrigues
- Department of Toxicogenomics, GROW School for Oncology and Developmental BiologyMaastricht UniversityMaastrichtThe Netherlands
| | - Danyel G. J. Jennen
- Department of Toxicogenomics, GROW School for Oncology and Developmental BiologyMaastricht UniversityMaastrichtThe Netherlands
| | - Theo M. de Kok
- Department of Toxicogenomics, GROW School for Oncology and Developmental BiologyMaastricht UniversityMaastrichtThe Netherlands
| | - Luke Coyle
- Boehringer Ingelheim International GmbHRidgefieldConnecticutUSA
| | | | | | - Heeseung Jo
- Simcyp DivisionCertara UK LimitedSheffieldUK
| | - Kylie A. Beattie
- Target and Systems Safety, Non‐Clinical Safety, In Vivo/In Vitro TranslationGSKStevenageUK
| | - Colette Kelly
- Institute of Systems, Molecular and Integrative BiologyUniversity of LiverpoolLiverpoolUK
| | - Carrie A. Duckworth
- Institute of Systems, Molecular and Integrative BiologyUniversity of LiverpoolLiverpoolUK
| | - D. Mark Pritchard
- Institute of Systems, Molecular and Integrative BiologyUniversity of LiverpoolLiverpoolUK
| | - Carmen Pin
- Clinical Pharmacology and Quantitative Pharmacology, Clinical Pharmacology and Safety Sciences, R&DAstraZenecaCambridgeUK
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5
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Boman BM, Dinh TN, Decker K, Emerick B, Modarai S, Opdenaker L, Fields JZ, Raymond C, Schleiniger G. Beyond the Genetic Code: A Tissue Code?. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023. [PMID: 36945600 PMCID: PMC10028806 DOI: 10.1101/2023.03.05.531161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/10/2023]
Abstract
The genetic code determines how the precise amino acid sequence of proteins is specified by genomic information in cells. But what specifies the precise histologic organization of cells in plant and animal tissues is unclear. We now hypothesize that another code, the tissue code , exists at an even higher level of complexity which determines how tissue organization is dynamically maintained. Accordingly, we modeled spatial and temporal asymmetries of cell division and established that five simple mathematical laws ("the tissue code") convey a set of biological rules that maintain the specific organization and continuous self-renewal dynamics of cells in tissues. These laws might even help us understand wound healing, and how tissue disorganization leads to birth defects and tissue pathology like cancer.
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6
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Corominas-Murtra B, Hannezo E. Modelling the dynamics of mammalian gut homeostasis. Semin Cell Dev Biol 2022:S1084-9521(22)00317-2. [DOI: 10.1016/j.semcdb.2022.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 10/26/2022] [Accepted: 11/16/2022] [Indexed: 12/03/2022]
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7
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Biswas P, Datta C, Rathi P, Bhattacharjee A. Fatty acids and their lipid mediators in the induction of cellular apoptosis in cancer cells. Prostaglandins Other Lipid Mediat 2022; 160:106637. [PMID: 35341977 DOI: 10.1016/j.prostaglandins.2022.106637] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 02/28/2022] [Accepted: 03/18/2022] [Indexed: 01/06/2023]
Abstract
The oxygenation of polyunsaturated fatty acids such as arachidonic and linoleic acid through enzymes like lipoxygenases (LOXs) are common and often leads to the production of various bioactive lipids that are important both in acute inflammation and its resolution and thus in disease progression. Amongst the several isoforms of LOX that are expressed in mammals, 15-lipoxygenase (15-LOX) has shown to be crucial in the context of inflammation. Moreover, being expressed in cells of the immune system, as well as in epithelial cells; the enzyme has been shown to crosstalk with a number of important signalling pathways. Mounting evidences from recent reports suggest that 15-LOX has anti-cancer activities which are dependent or independent of its metabolites, and is executed through several downstream pathways like cGMP, PPAR, p53, p21 and NAG-1. However, it is still unclear whether the up-regulation of 15-LOX is associated with cancer cell apoptosis. Monoamine oxidase A (MAO-A), on the other hand, is a mitochondrial flavoenzyme which is believed to be involved in the pathogenesis of atherosclerosis and inflammation and in many other neurological disorders. MAO-A has also been reported as a potential therapeutic target in different types of cancers like prostate cancer, lung cancer etc. In this review, we discussed about the role of fatty acids and their lipid mediators in cancer cell apoptosis. Here we particularly focused on the contribution of oxidative enzymes like 15-LOX and MAO-A in mediating apoptosis in lung cancer cell after fatty acid induction.
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Affiliation(s)
- Pritam Biswas
- Department of Biotechnology, National Institute of Technology, Durgapur 713209, West Bengal, India
| | - Chandreyee Datta
- Department of Biotechnology, National Institute of Technology, Durgapur 713209, West Bengal, India
| | - Parul Rathi
- Department of Biotechnology, National Institute of Technology, Durgapur 713209, West Bengal, India
| | - Ashish Bhattacharjee
- Department of Biotechnology, National Institute of Technology, Durgapur 713209, West Bengal, India.
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8
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Dabelow S, LeHanka A, Jilkine A. Distinguishing between multiple mathematical models of neural stem cell quiescence and activation during age-related neural stem cell decline in neurogenesis. Math Biosci 2022; 346:108807. [PMID: 35304227 DOI: 10.1016/j.mbs.2022.108807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 02/16/2022] [Accepted: 03/05/2022] [Indexed: 10/18/2022]
Abstract
Stem cells are required for tissue maintenance and homeostasis during an organism's lifetime. Neural stem cells (NSCs) can be in an actively dividing state or in a quiescent state. The balance between stem cell quiescence and cycling activity determines the rate of neurogenesis. With age, more NSCs enter the quiescent state, while the total number of NSCs decreases. Here we reconsider an existing mathematical model of how neural stem cells switch between active and quiescent states from the point of view of control theory by considering the activation rate, self-renewal probability, and division rate as control parameters rather than as pre-defined functions. Our goal is to test whether those modifications to the basic model could explain the observed decline of neural stem cells with age better than Gomerzian time-dependent parameters, and compare the output from different model variants to experimental data from mice using AIC. We find that time-dependent activation rate provides the best fit to the activated cell fraction (ACF) of NSCs over time, but that other model variants with constant parameter values can better fit the total number of NSCs over time. We also consider an alternate model for NSCs with nonlinear feedback from progenitor cells that affect NSC parameters, and compare all models to experimental stem cell and progenitor data. However, all of the feedback models considered provide a worse fit to the experimental data. This suggests that when switching between active and quiescent stem cells is considered, a time-dependent linear model outperforms the integral feedback mechanism considered by other models of stem cell lineages. Fitting progenitor data for both the time varying models and feedback models indicates that four or five intermediate transit amplifying progenitor states are necessary. Our modeling suggests that in order to determine whether an increase in age-related neural stem cell quiescence is determined by by a decreasing stem cell activation rate or an increased stem cell depletion rate, additional experiments should be designed to explore whether or not depletion of the stem cell pool is occurring, and that a higher resolution time series for activated cell fraction (ACF) would be best to resolve this issue.
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9
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Pin C, Collins T, Gibbs M, Kimko H. Systems Modeling to Quantify Safety Risks in Early Drug Development: Using Bifurcation Analysis and Agent-Based Modeling as Examples. AAPS JOURNAL 2021; 23:77. [PMID: 34018069 PMCID: PMC8137611 DOI: 10.1208/s12248-021-00580-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Accepted: 03/09/2021] [Indexed: 11/30/2022]
Abstract
Quantitative Systems Toxicology (QST) models, recapitulating pharmacokinetics and mechanism of action together with the organic response at multiple levels of biological organization, can provide predictions on the magnitude of injury and recovery dynamics to support study design and decision-making during drug development. Here, we highlight the application of QST models to predict toxicities of cancer treatments, such as cytopenia(s) and gastrointestinal adverse effects, where narrow therapeutic indexes need to be actively managed. The importance of bifurcation analysis is demonstrated in QST models of hematologic toxicity to understand how different regions of the parameter space generate different behaviors following cancer treatment, which results in asymptotically stable predictions, yet highly irregular for specific schedules, or oscillating predictions of blood cell levels. In addition, an agent-based model of the intestinal crypt was used to simulate how the spatial location of the injury within the crypt affects the villus disruption severity. We discuss the value of QST modeling approaches to support drug development and how they align with technological advances impacting trial design including patient selection, dose/regimen selection, and ultimately patient safety.
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Affiliation(s)
- Carmen Pin
- Clinical Pharmacology and Quantitative Pharmacology, Clinical Pharmacology and Safety Sciences, R&D, AstraZeneca, Cambridge Science Park, Milton Road, Cambridge, UK
| | - Teresa Collins
- Clinical Pharmacology and Quantitative Pharmacology, Clinical Pharmacology and Safety Sciences, R&D, AstraZeneca, Cambridge Science Park, Milton Road, Cambridge, UK
| | - Megan Gibbs
- Clinical Pharmacology and Quantitative Pharmacology, Clinical Pharmacology and Safety Sciences, R&D, AstraZeneca, Gaithersburg, Maryland, USA
| | - Holly Kimko
- Clinical Pharmacology and Quantitative Pharmacology, Clinical Pharmacology and Safety Sciences, R&D, AstraZeneca, Gaithersburg, Maryland, USA.
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10
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Charlebois DA, Balázsi G. Modeling cell population dynamics. In Silico Biol 2019; 13:21-39. [PMID: 30562900 PMCID: PMC6598210 DOI: 10.3233/isb-180470] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 09/13/2018] [Accepted: 10/16/2018] [Indexed: 12/27/2022]
Abstract
Quantitative modeling is quickly becoming an integral part of biology, due to the ability of mathematical models and computer simulations to generate insights and predict the behavior of living systems. Single-cell models can be incapable or misleading for inferring population dynamics, as they do not consider the interactions between cells via metabolites or physical contact, nor do they consider competition for limited resources such as nutrients or space. Here we examine methods that are commonly used to model and simulate cell populations. First, we cover simple models where analytic solutions are available, and then move on to more complex scenarios where computational methods are required. Overall, we present a summary of mathematical models used to describe cell population dynamics, which may aid future model development and highlights the importance of population modeling in biology.
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Affiliation(s)
- Daniel A. Charlebois
- The Louis and Beatrice Laufer Center for Physical and Quantitative Biology, Stony Brook University, NY, USA
- Department of Physics, University of Alberta, Edmonton, AB, Canada
| | - Gábor Balázsi
- The Louis and Beatrice Laufer Center for Physical and Quantitative Biology, Stony Brook University, NY, USA
- Department of Biomedical Engineering, Stony Brook University, NY, USA
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11
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Abstract
Quantitative modeling is quickly becoming an integral part of biology, due to the ability of mathematical models and computer simulations to generate insights and predict the behavior of living systems. Single-cell models can be incapable or misleading for inferring population dynamics, as they do not consider the interactions between cells via metabolites or physical contact, nor do they consider competition for limited resources such as nutrients or space. Here we examine methods that are commonly used to model and simulate cell populations. First, we cover simple models where analytic solutions are available, and then move on to more complex scenarios where computational methods are required. Overall, we present a summary of mathematical models used to describe cell population dynamics, which may aid future model development and highlights the importance of population modeling in biology.
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Affiliation(s)
- Daniel A Charlebois
- The Louis and Beatrice Laufer Center for Physical and Quantitative Biology, Stony Brook University, NY, USA.,Department of Physics, University of Alberta, Edmonton, AB, Canada
| | - Gábor Balázsi
- The Louis and Beatrice Laufer Center for Physical and Quantitative Biology, Stony Brook University, NY, USA.,Department of Biomedical Engineering, Stony Brook University, NY, USA
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12
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Hyperprolactinemia-inducing antipsychotics increase breast cancer risk by activating JAK-STAT5 in precancerous lesions. Breast Cancer Res 2018; 20:42. [PMID: 29778097 PMCID: PMC5960176 DOI: 10.1186/s13058-018-0969-z] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 04/11/2018] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Psychiatric medications are widely prescribed in the USA. Many antipsychotics cause serum hyperprolactinemia as an adverse side effect; prolactin-Janus kinase 2 (JAK2)-signal transducer and activator of transcription 5 (STAT5) signaling both induces cell differentiation and suppresses apoptosis. It is controversial whether these antipsychotics increase breast cancer risk. METHODS We investigated the impact of several antipsychotics on mammary tumorigenesis initiated by retrovirus-mediated delivery of either ErbB2 or HRas or by transgenic expression of Wnt-1. RESULTS We found that the two hyperprolactinemia-inducing antipsychotics, risperidone and pimozide, prompted precancerous lesions to progress to cancer while aripiprazole, which did not cause hyperprolactinemia, did not. We observed that risperidone and pimozide (but not aripiprazole) caused precancerous cells to activate STAT5 and suppress apoptosis while exerting no impact on proliferation. Importantly, we demonstrated that these effects of antipsychotics on early lesions required the STAT5 gene function. Furthermore, we showed that only two-week treatment of mice with ruxolitinib, a JAK1/2 inhibitor, blocked STAT5 activation, restored apoptosis, and prevented early lesion progression. CONCLUSIONS Hyperprolactinemia-inducing antipsychotics instigate precancerous cells to progress to cancer via JAK/STAT5 to suppress the apoptosis anticancer barrier, and these cancer-promoting effects can be prevented by prophylactic anti-JAK/STAT5 treatment. This preclinical work exposes a potential breast cancer risk from hyperprolactinemia-inducing antipsychotics in certain patients and suggests a chemoprevention regime that is relatively easy to implement compared to the standard 5-year anti-estrogenic treatment in women who have or likely have already developed precancerous lesions while also requiring hyperprolactinemia-inducing antipsychotics.
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13
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Quantitative translational modeling to facilitate preclinical to clinical efficacy & toxicity translation in oncology. Future Sci OA 2018; 4:FSO306. [PMID: 29796306 PMCID: PMC5961452 DOI: 10.4155/fsoa-2017-0152] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/12/2018] [Indexed: 12/12/2022] Open
Abstract
Significant scientific advances in biomedical research have expanded our knowledge of the molecular basis of carcinogenesis, mechanisms of cancer growth, and the importance of the cancer immunity cycle. However, despite scientific advances in the understanding of cancer biology, the success rate of oncology drug development remains the lowest among all therapeutic areas. In this review, some of the key translational drug development objectives in oncology will be outlined. The literature evidence of how mathematical modeling could be used to build a unifying framework to answer these questions will be summarized with recommendations on the strategies for building such a mathematical framework to facilitate the prediction of clinical efficacy and toxicity of investigational antineoplastic agents. Together, the literature evidence suggests that a rigorous and unifying preclinical to clinical translational framework based on mathematical models is extremely valuable for making go/no-go decisions in preclinical development, and for planning early clinical studies.
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14
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Dufour A, Gontran E, Deroulers C, Varlet P, Pallud J, Grammaticos B, Badoual M. Modeling the dynamics of oligodendrocyte precursor cells and the genesis of gliomas. PLoS Comput Biol 2018; 14:e1005977. [PMID: 29590097 PMCID: PMC5903643 DOI: 10.1371/journal.pcbi.1005977] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 04/17/2018] [Accepted: 01/10/2018] [Indexed: 11/24/2022] Open
Abstract
Oligodendrocyte precursor cells (OPCs) have remarkable properties: they represent the most abundant cycling cell population in the adult normal brain and they manage to achieve a uniform and constant density throughout the adult brain. This equilibrium is obtained by the interplay of four processes: division, differentiation or death, migration and active self-repulsion. They are also strongly suspected to be at the origin of gliomas, when their equilibrium is disrupted. In this article, we present a model of the dynamics of OPCs, first in a normal tissue. This model is based on a cellular automaton and its rules are mimicking the ones that regulate the dynamics of real OPCs. The model is able to reproduce the homeostasis of the cell population, with the maintenance of a constant and uniform cell density and the healing of a lesion. We show that there exists a fair quantitative agreement between the simulated and experimental parameters, such as the cell velocity, the time taken to close a lesion, and the duration of the cell cycle. We present three possible scenarios of disruption of the equilibrium: the appearance of an over-proliferating cell, of a deadless/non-differentiating cell, or of a cell that lost any contact-inhibition. We show that the appearance of an over-proliferating cell is sufficient to trigger the growth of a tumor that has low-grade glioma features: an invasive behaviour, a linear radial growth of the tumor with a corresponding growth velocity of less than 2 mm per year, as well a cell density at the center which exceeds the one in normal tissue by a factor of less than two. The loss of contact inhibition leads to a more high-grade-like glioma. The results of our model contribute to the body of evidence that identify OPCs as possible cells of origin of gliomas. Gliomas are the most common brain tumors and result in more years of life lost than any other tumor. Standard treatments only confer a limited improvement in overall survival, underscoring the need for new therapies. Finding the type of cells at the origin of these tumors could lead to the development of new drugs, specifically targeted towards these cells. The oligodendrocyte precursor cells are suspected to be these cells of origin, because they continue to proliferate through all the adult life. In this article, we present a model of the dynamics of these cells, first in the normal brain, and then we extrapolate our model to the pathological situation. We study several scenarios where, from the normal situation, a cell appears with one property different from those of the normal cells. We show that the alteration of only one of the properties of these cells in the model can lead to the formation of gliomas with different aggressiveness and very similar to real gliomas, reinforcing the suspicion that the precursor cells are at the origin of gliomas.
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Affiliation(s)
- Aloys Dufour
- IMNC Laboratory, CNRS, Univ Paris Saclay, Univ Paris-Sud, Univ Paris Diderot, France
| | - Emilie Gontran
- IMNC Laboratory, CNRS, Univ Paris Saclay, Univ Paris-Sud, Univ Paris Diderot, France
| | - Christophe Deroulers
- IMNC Laboratory, CNRS, Univ Paris Saclay, Univ Paris-Sud, Univ Paris Diderot, France
| | - Pascale Varlet
- Department of Neuropathology, Sainte-Anne Hospital, IMA-Brain, INSERM U894, Univ Paris Descartes, Paris, France
| | - Johan Pallud
- Department of Neurosurgery, Sainte-Anne Hospital, IMA-Brain, INSERM U894, Univ Paris Descartes, Paris, France
| | - Basile Grammaticos
- IMNC Laboratory, CNRS, Univ Paris Saclay, Univ Paris-Sud, Univ Paris Diderot, France
| | - Mathilde Badoual
- IMNC Laboratory, CNRS, Univ Paris Saclay, Univ Paris-Sud, Univ Paris Diderot, France
- * E-mail:
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15
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Renardy M, Jilkine A, Shahriyari L, Chou CS. Control of cell fraction and population recovery during tissue regeneration in stem cell lineages. J Theor Biol 2018; 445:33-50. [PMID: 29470992 DOI: 10.1016/j.jtbi.2018.02.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 01/24/2018] [Accepted: 02/19/2018] [Indexed: 12/20/2022]
Abstract
Multicellular tissues are continually turning over, and homeostasis is maintained through regulated proliferation and differentiation of stem cells and progenitors. Following tissue injury, a dramatic increase in cell proliferation is commonly observed, resulting in rapid restoration of tissue size. This regulation is thought to occur via multiple feedback loops acting on cell self-renewal or differentiation. Models of ordinary differential equations have been widely used to study the cell lineage system. Prior modeling studies have suggested that loss of homeostasis and initiation of tumorigenesis can be contributed to the loss of control of these processes, and the rate of symmetric versus asymmetric division of the stem cells may also be altered. While most of the previous works focused on analysis of stability, existence and uniqueness of steady states of multistage cell lineage models, in this work we attempt to understand the cell lineage model from a different perspective. We compare three variants of hierarchical stem cell lineage tissue models with different combinations of negative feedbacks and use sensitivity analysis to examine the possible strategies for the cells to achieve certain performance objectives. Our results suggest that multiple negative feedback loops must be present in the stem cell lineage to keep the fractions of stem cells to differentiated cells in the total population as robust as possible to variations in cell division parameters, and to minimize the time for tissue recovery in a non-oscillatory manner.
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Affiliation(s)
- Marissa Renardy
- Department of Mathematics, Ohio State University, Columbus, OH, USA
| | - Alexandra Jilkine
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, Notre Dame, IN, USA
| | - Leili Shahriyari
- Mathematical Biosciences Institute, Ohio State University, Columbus, OH, USA
| | - Ching-Shan Chou
- Department of Mathematics, Ohio State University, Columbus, OH, USA; Mathematical Biosciences Institute, Ohio State University, Columbus, OH, USA.
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16
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Nikolov S, Santos G, Wolkenhauer O, Vera J. Model-Based Phenotypic Signatures Governing the Dynamics of the Stem and Semi-differentiated Cell Populations in Dysplastic Colonic Crypts. Bull Math Biol 2017; 80:360-384. [PMID: 29218591 DOI: 10.1007/s11538-017-0378-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 12/01/2017] [Indexed: 01/09/2023]
Abstract
Mathematical modeling of cell differentiated in colonic crypts can contribute to a better understanding of basic mechanisms underlying colonic tissue organization, but also its deregulation during carcinogenesis and tumor progression. Here, we combined bifurcation analysis to assess the effect that time delay has in the complex interplay of stem cells and semi-differentiated cells at the niche of colonic crypts, and systematic model perturbation and simulation to find model-based phenotypes linked to cancer progression. The models suggest that stem cell and semi-differentiated cell population dynamics in colonic crypts can display chaotic behavior. In addition, we found that clinical profiling of colorectal cancer correlates with the in silico phenotypes proposed by the mathematical model. Further, potential therapeutic targets for chemotherapy resistant phenotypes are proposed, which in any case will require experimental validation.
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Affiliation(s)
- Svetoslav Nikolov
- Department of Systems Biology and Bioinformatics, University of Rostock, 18051, Rostock, Germany. .,Institute of Mechanics and Biomechanics-BAS, Acad. G. Bonchev Str., Bl. 4, 1113, Sofia, Bulgaria. .,University of Transport, Geo Milev Str., 158, 1574, Sofia, Bulgaria. .,Laboratory of Systems Tumor Immunology, Department of Dermatology, University Hospital Erlangen, Erlangen, Germany.
| | - Guido Santos
- Laboratory of Systems Tumor Immunology, Department of Dermatology, University Hospital Erlangen, Erlangen, Germany.,Systems Biology and Mathematical Modelling Group, Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Instituto de Tecnología Biomédica, CIBICAN, Universidad de La Laguna, Campus Ciencias de La Salud, 38071, La Laguna (Tenerife), Spain
| | - Olaf Wolkenhauer
- Department of Systems Biology and Bioinformatics, University of Rostock, 18051, Rostock, Germany.,Stellenbosch Institute for Advanced Study (STIAS), Wallenberg Research Centre at Stellenbosch University, Stellenbosch, South Africa
| | - Julio Vera
- Laboratory of Systems Tumor Immunology, Department of Dermatology, University Hospital Erlangen, Erlangen, Germany.
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17
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Zhao Y, Shen L, Huang X, Jing D, Huang D, Fu J, Li Z, Zhang G, Shen L. High expression of Ki-67 acts a poor prognosis indicator in locally advanced nasopharyngeal carcinoma. Biochem Biophys Res Commun 2017; 494:390-396. [PMID: 28947213 DOI: 10.1016/j.bbrc.2017.09.118] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 09/20/2017] [Indexed: 11/28/2022]
Abstract
Nasopharyngeal carcinoma (NPC) is a common head and neck malignancy in Southern China and Southeast Asia compared with Western countries. The standard treatment for NPC is radiotherapy. However, radioresistance remains a serious obstacle to satisfactory treatment, it can cause local recurrence and distant metastases in some patients after treatment by radiation. We retrospectively reviewed 108 NPC patients (7th AJCC Ⅲ-Ⅳa) who have received intensity modulated radiation therapy (IMRT) between August 2008 and January 2012 at Xiangya Hospital of Central South University. Ninety-eight patients with >60% reduction of tumor size after radiation treatment were regarded as radiation sensitive, Ten patients with <40% reduction of tumor size after radiation treatment were regarded as radiation resistant. Using immunohistochemistry, we found that the high expression rate of Ki-67 in radiation resistant and radiation sensitive patients was 80.0% and 42.6%, respectively, and the difference was statistically significant (p = 0.025). The 5-year progress free survival rates in patients with low and high expression of Ki-67 was 70.7% and 48.0%, respectively, and the difference was statistically significant (p = 0.0008). Multivariate Cox regression analysis identified that high expression of Ki-67 was an independent negative prognostic factor in nasopharyngeal carcinoma patients [Hazard ratio (95% CI), 2.098(1.101, 3.996); p = 0.024]. These results demonstrate that high expression of Ki-67 contributes to radiation resistance and acts a poor prognosis indicator in patients with locally advanced nasopharyngeal carcinoma.
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Affiliation(s)
- Yajie Zhao
- Department of Oncology, Xiangya Hospital, Central South University, Hunan Province, PR China
| | - Lin Shen
- Department of Oncology, Xiangya Hospital, Central South University, Hunan Province, PR China
| | - Xinqiong Huang
- Department of Oncology, Xiangya Hospital, Central South University, Hunan Province, PR China
| | - Di Jing
- Department of Oncology, Xiangya Hospital, Central South University, Hunan Province, PR China
| | - David Huang
- Physics Graduate Program Duke Kunshan University, Shanghai, PR China
| | - Jun Fu
- Department of Oncology, Xiangya Hospital, Central South University, Hunan Province, PR China
| | - Zhanzhan Li
- Department of Oncology, Xiangya Hospital, Central South University, Hunan Province, PR China
| | - Guangying Zhang
- Department of Oncology, Xiangya Hospital, Central South University, Hunan Province, PR China
| | - Liangfang Shen
- Department of Oncology, Xiangya Hospital, Central South University, Hunan Province, PR China.
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18
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Shankaran H, Cronin A, Barnes J, Sharma P, Tolsma J, Jasper P, Mettetal JT. Systems Pharmacology Model of Gastrointestinal Damage Predicts Species Differences and Optimizes Clinical Dosing Schedules. CPT-PHARMACOMETRICS & SYSTEMS PHARMACOLOGY 2017; 7:26-33. [PMID: 28941225 PMCID: PMC5784737 DOI: 10.1002/psp4.12255] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 08/08/2017] [Accepted: 09/18/2017] [Indexed: 12/14/2022]
Abstract
Gastrointestinal (GI) adverse events (AEs) are frequently dose limiting for oncology agents, requiring extensive clinical testing of alternative schedules to identify optimal dosing regimens. Here, we develop a translational mathematical model to predict these clinical AEs starting from preclinical GI toxicity data. The model structure incorporates known biology and includes stem cells, daughter cells, and enterocytes. Published data, including cellular numbers and division times, informed the system parameters for humans and rats. The drug‐specific parameters were informed with preclinical histopathology data from rats treated with irinotecan. The model fit the rodent irinotecan‐induced pathology changes well. The predicted time course of enterocyte loss in patients treated with weekly doses matched observed AE profiles. The model also correctly predicts a lower level of AEs for every 3 weeks (Q3W), as compared to the weekly schedule.
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Affiliation(s)
- Harish Shankaran
- Drug Safety and MetabolismIMED Biotech Unit, AstraZenecaWalthamMassachusettsUSA
| | - Anna Cronin
- Drug Safety and MetabolismIMED Biotech UnityAstraZenecaCambridgeUK
| | - Jen Barnes
- Drug Safety and MetabolismIMED Biotech UnityAstraZenecaCambridgeUK
| | - Pradeep Sharma
- Drug Safety and MetabolismIMED Biotech UnityAstraZenecaCambridgeUK
| | | | | | - Jerome T. Mettetal
- Drug Safety and MetabolismIMED Biotech Unit, AstraZenecaWalthamMassachusettsUSA
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19
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Levine HA, Smiley MW, Tucker AL, Nilsen-Hamilton M. A Mathematical Model for the Onset of Avascular Tumor Growth in Response to the Loss of P53 Function. Cancer Inform 2017. [DOI: 10.1177/117693510600200022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
We present a mathematical model for the formation of an avascular tumor based on the loss by gene mutation of the tumor suppressor function of p53. The wild type p53 protein regulates apoptosis, cell expression of growth factor and matrix metalloproteinase, which are regulatory functions that many mutant p53 proteins do not possess. The focus is on a description of cell movement as the transport of cell population density rather than as the movement of individual cells. In contrast to earlier works on solid tumor growth, a model is proposed for the initiation of tumor growth. The central idea, taken from the mathematical theory of dynamical systems, is to view the loss of p53 function in a few cells as a small instability in a rest state for an appropriate system of differential equations describing cell movement. This instability is shown (numerically) to lead to a second, spatially inhomogeneous, solution that can be thought of as a solid tumor whose growth is nutrient diffusion limited. In this formulation, one is led to a system of nine partial differential equations. We show computationally that there can be tumor states that coexist with benign states and that are highly unstable in the sense that a slight increase in tumor size results in the tumor occupying the sample region while a slight decrease in tumor size results in its ultimate disappearance.
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Affiliation(s)
- Howard A. Levine
- Department of Mathematics, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, 50011
| | - Michael W. Smiley
- Department of Mathematics, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, 50011
| | - Anna L. Tucker
- Department of Mathematics, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, 50011
| | - Marit Nilsen-Hamilton
- Department of Mathematics, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, 50011
- Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, 50011
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20
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Mahdipour-Shirayeh A, Darooneh AH, Long AD, Komarova NL, Kohandel M. Genotype by random environmental interactions gives an advantage to non-favored minor alleles. Sci Rep 2017; 7:5193. [PMID: 28701726 PMCID: PMC5507875 DOI: 10.1038/s41598-017-05375-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 05/30/2017] [Indexed: 12/11/2022] Open
Abstract
Fixation probability, the probability that the frequency of a newly arising mutation in a population will eventually reach unity, is a fundamental quantity in evolutionary genetics. Here we use a number of models (several versions of the Moran model and the haploid Wright-Fisher model) to examine fixation probabilities for a constant size population where the fitness is a random function of both allelic state and spatial position, despite neither allele being favored on average. The concept of fitness varying with respect to both genotype and environment is important in models of cancer initiation and progression, bacterial dynamics, and drug resistance. Under our model spatial heterogeneity redefines the notion of neutrality for a newly arising mutation, as such mutations fix at a higher rate than that predicted under neutrality. The increased fixation probability appears to be due to rare alleles having an advantage. The magnitude of this effect can be large, and is an increasing function of the spatial variance and skew in fitness. The effect is largest when the fitness values of the mutants and wild types are anti-correlated across environments. We discuss results for both a spatial ring geometry of cells (such as that of a colonic crypt), a 2D lattice and a mass-action (complete graph) arrangement.
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Affiliation(s)
- A Mahdipour-Shirayeh
- Department of Applied Mathematics, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - A H Darooneh
- Department of Physics, University of Zanjan, P.O. Box 45196-313, Zanjan, Iran
| | - A D Long
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, 92697, USA
| | - N L Komarova
- Department of Mathematics, University of California, Irvine, CA, 92697, USA.
| | - M Kohandel
- Department of Applied Mathematics, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
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21
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Stability of Control Networks in Autonomous Homeostatic Regulation of Stem Cell Lineages. Bull Math Biol 2017; 80:1345-1365. [PMID: 28508298 DOI: 10.1007/s11538-017-0283-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 04/07/2017] [Indexed: 01/02/2023]
Abstract
Design principles of biological networks have been studied extensively in the context of protein-protein interaction networks, metabolic networks, and regulatory (transcriptional) networks. Here we consider regulation networks that occur on larger scales, namely the cell-to-cell signaling networks that connect groups of cells in multicellular organisms. These are the feedback loops that orchestrate the complex dynamics of cell fate decisions and are necessary for the maintenance of homeostasis in stem cell lineages. We focus on "minimal" networks that are those that have the smallest possible numbers of controls. For such minimal networks, the number of controls must be equal to the number of compartments, and the reducibility/irreducibility of the network (whether or not it can be split into smaller independent sub-networks) is defined by a matrix comprised of the cell number increments induced by each of the controlled processes in each of the compartments. Using the formalism of digraphs, we show that in two-compartment lineages, reducible systems must contain two 1-cycles, and irreducible systems one 1-cycle and one 2-cycle; stability follows from the signs of the controls and does not require magnitude restrictions. In three-compartment systems, irreducible digraphs have a tree structure or have one 3-cycle and at least two more shorter cycles, at least one of which is a 1-cycle. With further work and proper biological validation, our results may serve as a first step toward an understanding of ways in which these networks become dysregulated in cancer.
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22
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Ingham-Dempster T, Walker DC, Corfe BM. An agent-based model of anoikis in the colon crypt displays novel emergent behaviour consistent with biological observations. ROYAL SOCIETY OPEN SCIENCE 2017; 4:160858. [PMID: 28484606 PMCID: PMC5414243 DOI: 10.1098/rsos.160858] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 03/14/2017] [Indexed: 05/07/2023]
Abstract
Colorectal cancer (CRC) is a major cause of cancer mortality. Colon crypts are multi-cellular flask-shaped invaginations of the colonic epithelium, with stem cells at their base which support the continual turnover of the epithelium with loss of cells by anoikis from the flat mucosa. Mutations in these stem cells can become embedded in the crypts, a process that is strongly implicated in CRC initiation. We describe a computational model which includes novel features, including an accurate representation of the geometry of the crypt mouth. Model simulations yield previously unseen emergent phenomena, such as localization of cell death to a small region of the crypt mouth which corresponds with that observed in vivo. A mechanism emerges in the model for regulation of crypt cellularity in response to changes in either cell proliferation rates or membrane adhesion strengths. We show that cell shape assumptions influence this behaviour, with cylinders recapitulating biology better than spheres. Potential applications of the model include determination of roles of mutations in neoplasia and exploring factors for altered crypt morphodynamics.
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Affiliation(s)
- Tim Ingham-Dempster
- Insigneo Institute for in silico medicine, Pam Liversedge Building, University of Sheffield, Sir Frederick Mappin Building, Mappin Street, Sheffield S1 3JD, UK
- Department of Oncology and Metabolism, The Medical School, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Dawn C. Walker
- Insigneo Institute for in silico medicine, Pam Liversedge Building, University of Sheffield, Sir Frederick Mappin Building, Mappin Street, Sheffield S1 3JD, UK
- Department of Computer Science, University of Sheffield, 211 Portobello, Sheffield S1 4DP, UK
| | - Bernard M. Corfe
- Insigneo Institute for in silico medicine, Pam Liversedge Building, University of Sheffield, Sir Frederick Mappin Building, Mappin Street, Sheffield S1 3JD, UK
- Department of Oncology and Metabolism, The Medical School, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
- e-mail:
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23
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Shahriyari L, Mahdipour-Shirayeh A. Modeling dynamics of mutants in heterogeneous stem cell niche. Phys Biol 2017; 14:016004. [PMID: 28102174 DOI: 10.1088/1478-3975/aa5a61] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Studying the stem cell (SC) niche architecture is a crucial step for investigating the process of oncogenesis and obtaining an effective stem cell therapy for various cancers. Recently, it has been observed that there are two groups of SCs in the SC niche collaborating with each other to maintain tissue homeostasis: border stem cells (BSCs), which are responsible in controlling the number of non-stem cells as well as stem cells, and central stem cells (CeSCs), which regulate the SC niche. Here, we develop a bi-compartmental stochastic model for the SC niche to study the spread of mutants within the niche. The analytic calculations and numeric simulations, which are in perfect agreement, reveal that in order to delay the spread of mutants in the SC niche, a small but non-zero number of SC proliferations must occur in the CeSC compartment. Moreover, the migration of BSCs to CeSCs delays the spread of mutants. Furthermore, the fixation probability of mutants in the SC niche is independent of types of SC division as long as all SCs do not divide fully asymmetrically. Additionally, the progeny of CeSCs have a much higher chance than the progeny of BSCs to take over the entire niche.
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Affiliation(s)
- L Shahriyari
- Mathematical Biosciences Institute, The Ohio State University, OH, United States of America
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24
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Qiu K, Wang LF, Shen J, Yousif AAM, He P, Shao DD, Zhang XM, Kirunda JB, Jia Y. A van der Waals-like Transition Between Normal and Cancerous Phases in Cell Populations Dynamics of Colorectal Cancer. Sci Rep 2016; 6:36620. [PMID: 27857154 PMCID: PMC5114675 DOI: 10.1038/srep36620] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 10/17/2016] [Indexed: 12/03/2022] Open
Abstract
Based on a deterministic continuous model of cell populations dynamics in the colonic crypt and in colorectal cancer, we propose four combinations of feedback mechanisms in the differentiations from stem cells (SCs) to transit cells (TCs) and then to differentiated cells (DCs), the four combinations include the double linear (LL), the linear and saturating (LS), the saturating and linear (SL), and the double saturating (SS) feedbacks, respectively. The relative fluctuations of the population of SCs, TCs, and DCs around equilibrium states with four feedback mechanisms are studied by using the Langevin method. With the increasing of net growth rate of TCs, it is found that the Fano factors of TCs and DCs go to a peak in a transient phase, and then increase again to infinity in the cases of LS and SS feedbacks. The “up-down-up” characteristic on the Fano factor (like the van der Waals loop) demonstrates that there exists a transient phase between the normal and cancerous phases, our novel findings suggest that the mathematical model with LS or SS feedback might be better to elucidate the dynamics of a normal and abnormal (cancerous) phases.
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Affiliation(s)
- Kang Qiu
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan 430079, China.,Department of Mathematics and Physics, Xuzhou Medical University, Xuzhou 221004, China
| | - Li-Fang Wang
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan 430079, China
| | - Jian Shen
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan 430079, China
| | - Alssadig A M Yousif
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan 430079, China
| | - Peng He
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan 430079, China
| | - Dan-Dan Shao
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan 430079, China
| | - Xiao-Min Zhang
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan 430079, China
| | - John B Kirunda
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan 430079, China
| | - Ya Jia
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan 430079, China
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25
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Pearson AT, Jackson TL, Nör JE. Modeling head and neck cancer stem cell-mediated tumorigenesis. Cell Mol Life Sci 2016; 73:3279-89. [PMID: 27151511 PMCID: PMC5312795 DOI: 10.1007/s00018-016-2226-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 03/29/2016] [Accepted: 04/12/2016] [Indexed: 12/22/2022]
Abstract
A large body of literature has emerged supporting the importance of cancer stem cells (CSCs) in the pathogenesis of head and neck cancers. CSCs are a subpopulation of cells within a tumor that share the properties of self-renewal and multipotency with stem cells from normal tissue. Their functional relevance to the pathobiology of cancer arises from the unique properties of tumorigenicity, chemotherapy resistance, and their ability to metastasize and invade distant tissues. Several molecular profiles have been used to discriminate a stem cell from a non-stem cell. CSCs can be grown for study and further enriched using a number of in vitro techniques. An evolving option for translational research is the use of mathematical and computational models to describe the role of CSCs in complex tumor environments. This review is focused discussing the evidence emerging from modeling approaches that have clarified the impact of CSCs to the biology of cancer.
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Affiliation(s)
- Alexander T Pearson
- Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan School of Medicine, 1500 E. Medical Center Dr., SPC 5848, Ann Arbor, MI, 48109-5848, USA.
| | - Trachette L Jackson
- Department of Mathematics, University of Michigan School of Literature, Sciences, and the Arts, Ann Arbor, MI, USA
| | - Jacques E Nör
- Department of Restorative Sciences, University of Michigan School of Dentistry, 1011 N. University Rm. 2309, Ann Arbor, MI, 48109-1078, USA.
- Department of Otolaryngology, University of Michigan School of Medicine, Ann Arbor, MI, USA.
- Department of Biomedical Engineering, University of Michigan College of Engineering, Ann Arbor, MI, USA.
- Comprehensive Cancer Center, University of Michigan, Ann Arbor, MI, USA.
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26
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Sun Z, Plikus MV, Komarova NL. Near Equilibrium Calculus of Stem Cells in Application to the Airway Epithelium Lineage. PLoS Comput Biol 2016; 12:e1004990. [PMID: 27427948 PMCID: PMC4948767 DOI: 10.1371/journal.pcbi.1004990] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 05/18/2016] [Indexed: 01/16/2023] Open
Abstract
Homeostatic maintenance of tissues is orchestrated by well tuned networks of cellular signaling. Such networks regulate, in a stochastic manner, fates of all cells within the respective lineages. Processes such as symmetric and asymmetric divisions, differentiation, de-differentiation, and death have to be controlled in a dynamic fashion, such that the cell population is maintained at a stable equilibrium, has a sufficiently low level of stochastic variation, and is capable of responding efficiently to external damage. Cellular lineages in real tissues may consist of a number of different cell types, connected by hierarchical relationships, albeit not necessarily linear, and engaged in a number of different processes. Here we develop a general mathematical methodology for near equilibrium studies of arbitrarily complex hierarchical cell populations, under regulation by a control network. This methodology allows us to (1) determine stability properties of the network, (2) calculate the stochastic variance, and (3) predict how different control mechanisms affect stability and robustness of the system. We demonstrate the versatility of this tool by using the example of the airway epithelium lineage. Recent research shows that airway epithelium stem cells divide mostly asymmetrically, while the so-called secretory cells divide predominantly symmetrically. It further provides quantitative data on the recovery dynamics of the airway epithelium, which can include secretory cell de-differentiation. Using our new methodology, we demonstrate that while a number of regulatory networks can be compatible with the observed recovery behavior, the observed division patterns of cells are the most optimal from the viewpoint of homeostatic lineage stability and minimizing the variation of the cell population size. This not only explains the observed yet poorly understood features of airway tissue architecture, but also helps to deduce the information on the still largely hypothetical regulatory mechanisms governing tissue turnover, and lends insight into how different control loops influence the stability and variance properties of cell populations. Tissue stability is the basic property of healthy organs, and yet the mechanisms governing the stable, long-term maintenance of cell numbers in tissues are poorly understood. While more and more signaling pathways are being discovered, for the most part it remains unknown how they are being put together by different cell types into complex, nonlinear, hierarchical control networks that, on the one hand, reliably maintain constant cell numbers, and on the other hand, quickly adjust to oversee the robust response to tissue damage. Theoretical approaches can fill the gap by being able to reconstruct the underlying control network, based on the observations about the aspects of cellular dynamics. We argue that while many hypothetical networks may be capable of basic cell lineage maintenance, some are much more efficient from the viewpoint of variance minimization. Thus, we developed a new methodology that can test various control networks for stability, variance, and robustness. In the example of the airway epithelium that we highlight, it turns out that the evolutionary selected, actual architecture coincides with the mathematically optimal solution that minimizes the fluctuations of cell numbers at homeostasis.
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Affiliation(s)
- Zheng Sun
- Department of Mathematics, University of California, Irvine, Irvine, California, United States of America
| | - Maksim V. Plikus
- Department of Developmental and Cell Biology, Sue and Bill Gross Stem Cell Research Center and Center for Complex Biological Systems, University of California, Irvine, Irvine, California, United States of America
| | - Natalia L. Komarova
- Department of Mathematics, University of California, Irvine, Irvine, California, United States of America
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, California, United States of America
- * E-mail:
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Min KW, Kim DH, Do SI, Pyo JS, Chae SW, Sohn JH, Kim K, Lee HJ, Kim DH, Oh S, Choi SH, Park YL, Park CH, Kwon MJ, Moon KM. High Ki67/BCL2 index is associated with worse outcome in early stage breast cancer. Postgrad Med J 2016; 92:707-714. [DOI: 10.1136/postgradmedj-2015-133531] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 04/26/2016] [Accepted: 05/02/2016] [Indexed: 11/04/2022]
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Yang J, Plikus MV, Komarova NL. The Role of Symmetric Stem Cell Divisions in Tissue Homeostasis. PLoS Comput Biol 2015; 11:e1004629. [PMID: 26700130 PMCID: PMC4689538 DOI: 10.1371/journal.pcbi.1004629] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 10/27/2015] [Indexed: 11/18/2022] Open
Abstract
Successful maintenance of cellular lineages critically depends on the fate decision dynamics of stem cells (SCs) upon division. There are three possible strategies with respect to SC fate decision symmetry: (a) asymmetric mode, when each and every SC division produces one SC and one non-SC progeny; (b) symmetric mode, when 50% of all divisions produce two SCs and another 50%-two non-SC progeny; (c) mixed mode, when both the asymmetric and two types of symmetric SC divisions co-exist and are partitioned so that long-term net balance of the lineage output stays constant. Theoretically, either of these strategies can achieve lineage homeostasis. However, it remains unclear which strategy(s) are more advantageous and under what specific circumstances, and what minimal control mechanisms are required to operate them. Here we used stochastic modeling to analyze and quantify the ability of different types of divisions to maintain long-term lineage homeostasis, in the context of different control networks. Using the example of a two-component lineage, consisting of SCs and one type of non-SC progeny, we show that its tight homeostatic control is not necessarily associated with purely asymmetric divisions. Through stochastic analysis and simulations we show that asymmetric divisions can either stabilize or destabilize the lineage system, depending on the underlying control network. We further apply our computational model to biological observations in the context of a two-component lineage of mouse epidermis, where autonomous lineage control has been proposed and notable regional differences, in terms of symmetric division ratio, have been noted-higher in thickened epidermis of the paw skin as compared to ear and tail skin. By using our model we propose a possible explanation for the regional differences in epidermal lineage control strategies. We demonstrate how symmetric divisions can work to stabilize paw epidermis lineage, which experiences high level of micro-injuries and a lack of hair follicles as a back-up source of SCs.
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Affiliation(s)
- Jienian Yang
- Department of Mathematics, University of California, Irvine, Irvine, California, United States of America
| | - Maksim V. Plikus
- Department of Developmental and Cell Biology, Sue and Bill Gross Stem Cell Research Center and Center for Complex Biological Systems, University of California, Irvine, Irvine, California, United States of America
| | - Natalia L. Komarova
- Department of Mathematics, University of California, Irvine, Irvine, California, United States of America
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, California, United States of America
- * E-mail:
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29
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Osborne JM. Multiscale Model of Colorectal Cancer Using the Cellular Potts Framework. Cancer Inform 2015; 14:83-93. [PMID: 26461973 PMCID: PMC4598229 DOI: 10.4137/cin.s19332] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 08/09/2015] [Accepted: 08/12/2015] [Indexed: 12/17/2022] Open
Abstract
Colorectal cancer (CRC) is one of the major causes of death in the developed world and forms a canonical example of tumorigenesis. CRC arises from a string of mutations of individual cells in the colorectal crypt, making it particularly suited for multiscale multicellular modeling, where mutations of individual cells can be clearly represented and their effects readily tracked. In this paper, we present a multicellular model of the onset of colorectal cancer, utilizing the cellular Potts model (CPM). We use the model to investigate how, through the modification of their mechanical properties, mutant cells colonize the crypt. Moreover, we study the influence of mutations on the shape of cells in the crypt, suggesting possible cell- and tissue-level indicators for identifying early-stage cancerous crypts. Crucially, we discuss the effect that the motility parameters of the model (key factors in the behavior of the CPM) have on the distribution of cells within a homeostatic crypt, resulting in an optimal parameter regime that accurately reflects biological assumptions. In summary, the key results of this paper are 1) how to couple the CPM with processes occurring on other spatial scales, using the example of the crypt to motivate suitable motility parameters; 2) modeling mutant cells with the CPM; 3) and investigating how mutations influence the shape of cells in the crypt.
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Affiliation(s)
- James M Osborne
- School of Mathematics and Statistics, University of Melbourne, Victoria, Australia. ; Department of Computer Science, University of Oxford, Oxford, UK. ; Microsoft Research UK, Cambridge, UK
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30
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Rodriguez-Brenes IA, Wodarz D, Komarova NL. Characterizing inhibited tumor growth in stem-cell-driven non-spatial cancers. Math Biosci 2015; 270:135-41. [PMID: 26344137 DOI: 10.1016/j.mbs.2015.08.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 08/20/2015] [Indexed: 11/29/2022]
Abstract
Healthy human tissue is highly regulated to maintain homeostasis. Secreted negative feedback factors that inhibit stem cell division and stem cell self-renewal play a fundamental role in establishing this control. The appearance of abnormal cancerous growth requires an escape from these regulatory mechanisms. In a previous study we found that for non-solid tumors if feedback inhibition on stem cell self-renewal is lost, but the feedback on the division rate is still intact, then the tumor dynamics are characterized by a relatively slow sub-exponential growth that we called inhibited growth. Here we characterize the cell dynamics of inhibited cancer growth by modeling feedback inhibition using Hill equations. We find asymptotic approximations for the growth rates of the stem cell and differentiated cell populations in terms of the strength of the inhibitory signal: stem cells grow as a power law t(1/k+1),and the differentiated cells grow as t(1/k), where k is the Hill coefficient in the feedback law regulating cell divisions. It follows that as the tumor grows, undifferentiated cells take up an increasingly large fraction of the population. Implications of these results for specific cancers including CML are discussed. Understanding how the regulatory mechanisms that continue to operate in cancer affect the rate of disease progression can provide important insights relevant to chronic or other slow progressing types of cancer.
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Affiliation(s)
- Ignacio A Rodriguez-Brenes
- Department of Mathematics, University of California, Irvine, CA 92651, USA; Department of Ecology and Evolution, University of California, Irvine, CA 92651, USA.
| | - Dominik Wodarz
- Department of Mathematics, University of California, Irvine, CA 92651, USA; Department of Ecology and Evolution, University of California, Irvine, CA 92651, USA
| | - Natalia L Komarova
- Department of Mathematics, University of California, Irvine, CA 92651, USA; Department of Ecology and Evolution, University of California, Irvine, CA 92651, USA
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31
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Abstract
In this overview of my research, I have aimed to give the background as to how I came to be involved in my various areas of interest, with an emphasis on the early phases of my career, which largely determined my future directions. I had the enormous good fortune to have worked under two of the most outstanding scientists of the twentieth century, R.A. Fisher and Joshua Lederberg. From mathematics and statistics, I went to population genetics and the early use of computers for modeling and simulation. Molecular biology took me into the laboratory and eventually to somatic cell genetics and human gene mapping. One chance encounter led me into the HLA field and another led me into research on cancer, especially colorectal cancer. On the way, I became a champion of the Human Genome Project and of the need for scientists to help promote the public understanding of science.
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Affiliation(s)
- Walter Bodmer
- Cancer and Immunogenetics Laboratory, Weatherall Institute of Molecular Medicine, Oxford OX3 9DS, United Kingdom
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The Interplay between Wnt Mediated Expansion and Negative Regulation of Growth Promotes Robust Intestinal Crypt Structure and Homeostasis. PLoS Comput Biol 2015; 11:e1004285. [PMID: 26288152 PMCID: PMC4543550 DOI: 10.1371/journal.pcbi.1004285] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 03/31/2015] [Indexed: 12/22/2022] Open
Abstract
The epithelium of the small intestinal crypt, which has a vital role in protecting the underlying tissue from the harsh intestinal environment, is completely renewed every 4–5 days by a small pool of stem cells at the base of each crypt. How is this renewal controlled and homeostasis maintained, particularly given the rapid nature of this process? Here, based on the recent observations from in vitro “mini gut” studies, we use a hybrid stochastic model of the crypt to investigate how exogenous niche signaling (from Wnt and BMP) combines with auto-regulation to promote homeostasis. This model builds on the sub-cellular element method to account for the three-dimensional structure of the crypt, external regulation by Wnt and BMP, internal regulation by Notch signaling, as well as regulation by internally generated diffusible signals. Results show that Paneth cell derived Wnt signals, which have been observed experimentally to sustain crypts in cultured organs, have a dramatically different influence on niche dynamics than does mesenchyme derived Wnt. While this signaling can indeed act as a redundant backup to the exogenous gradient, it introduces a positive feedback that destabilizes the niche and causes its uncontrolled expansion. We find that in this setting, BMP has a critical role in constraining this expansion, consistent with observations that its removal leads to crypt fission. Further results also point to a new hypothesis for the role of Ephrin mediated motility of Paneth cells, specifically that it is required to constrain niche expansion and maintain the crypt’s spatial structure. Combined, these provide an alternative view of crypt homeostasis where the niche is in a constant state of expansion and the spatial structure of the crypt arises as a balance between this expansion and the action of various sources of negative regulation that hold it in check. The small intestinal epithelium, like our skin, is constantly being renewed. In the intestine however, this epithelium is exposed to the harsh digestive environment, necessitating much more rapid renewal. Remarkably, the entire epithelium is renewed every 4–5 days. This raises the question, how can the size and structure of this tissue be maintained given this pace. Motivated by recent experimental observations, we construct a three-dimensional, hybrid stochastic model to investigate the mechanisms responsible for homeostasis of this tissue. We find that there are redundant signals created by both the epithelium itself and surrounding tissues that act in parallel to maintain epithelial structure. This redundancy comes at a price however: it introduces the possibility of explosive stem cell population growth. Additional results suggest that other signals along with choreographed motion of cells are responsible for repressing this expansion. Taken together, our results provide a novel hypothesis for how robust but fast renewal of the crypt is achieved: as a balance between expansion, which drives fast renewal and repression, which holds that expansion in check to maintain the crypt’s structure.
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Shahriyari L, Komarova NL. The role of the bi-compartmental stem cell niche in delaying cancer. Phys Biol 2015; 12:055001. [PMID: 26228740 DOI: 10.1088/1478-3975/12/5/055001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In recent years, by using modern imaging techniques, scientists have found evidence of collaboration between different types of stem cells (SCs), and proposed a bi-compartmental organization of the SC niche. Here we create a class of stochastic models to simulate the dynamics of such a heterogeneous SC niche. We consider two SC groups: the border compartment, S1, is in direct contact with transit-amplifying (TA) cells, and the central compartment, S2, is hierarchically upstream from S1. The S1 SCs differentiate or divide asymmetrically when the tissue needs TA cells. Both groups proliferate when the tissue requires SCs (thus maintaining homeostasis). There is an influx of S2 cells into the border compartment, either by migration, or by proliferation. We examine this model in the context of double-hit mutant generation, which is a rate-limiting step in the development of many cancers. We discover that this type of a cooperative pattern in the stem niche with two compartments leads to a significantly smaller rate of double-hit mutant production compared with a homogeneous, one-compartmental SC niche. Furthermore, the minimum probability of double-hit mutant generation corresponds to purely symmetric division of SCs, consistent with the literature. Finally, the optimal architecture (which minimizes the rate of double-hit mutant production) requires a large proliferation rate of S1 cells along with a small, but non-zero, proliferation rate of S2 cells. This result is remarkably similar to the niche structure described recently by several authors, where one of the two SC compartments was found more actively engaged in tissue homeostasis and turnover, while the other was characterized by higher levels of quiescence (but contributed strongly to injury recovery). Both numerical and analytical results are presented.
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Affiliation(s)
- Leili Shahriyari
- Mathematical Biosciences Institute, Ohio State University, Columbus, OH, USA
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34
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Yang J, Sun Z, Komarova NL. Analysis of stochastic stem cell models with control. Math Biosci 2015; 266:93-107. [PMID: 26073965 DOI: 10.1016/j.mbs.2015.06.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 05/28/2015] [Accepted: 06/03/2015] [Indexed: 12/11/2022]
Abstract
Understanding the dynamics of stem cell lineages is of central importance both for healthy and cancerous tissues. We study stochastic population dynamics of stem cells and differentiated cells, where cell decisions, such as proliferation vs. differentiation decisions, or division and death decisions, are under regulation from surrounding cells. The goal is to understand how different types of control mechanisms affect the means and variances of cell numbers. We use the assumption of weak dependencies of the regulatory functions (the controls) on the cell populations near the equilibrium to formulate moment equations. We then study three different methods of closure, showing that they all lead to the same results for the highest order terms in the expressions for the moments. We derive simple explicit expressions for the means and the variances of stem cell and differentiated cell numbers. It turns out that the variance is expressed as an algebraic function of partial derivatives of the controls with respect to the population sizes at the equilibrium. We demonstrate that these findings are consistent with the results previously obtained in the context of particular systems, and also present two novel examples with negative and positive control of division and differentiation decisions. This methodology is formulated without any specific assumptions on the functional form of the controls, and thus can be used for any biological system.
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Affiliation(s)
- Jienian Yang
- Department of Mathematics, University of California Irvine, Irvine, CA 92617, United States
| | - Zheng Sun
- Department of Mathematics, University of California Irvine, Irvine, CA 92617, United States
| | - Natalia L Komarova
- Department of Mathematics, University of California Irvine, Irvine, CA 92617, United States.
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35
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Abstract
This review discusses quantitative modeling studies of stem and non-stem cancer cell interactions and the fraction of cancer stem cells.
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Affiliation(s)
- Heiko Enderling
- Department of Integrated Mathematical Oncology
- H. Lee Moffitt Cancer Center & Research Institute
- Tampa
- USA
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36
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Stochastic control of proliferation and differentiation in stem cell dynamics. J Math Biol 2014; 71:883-901. [PMID: 25319118 DOI: 10.1007/s00285-014-0835-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 10/31/2012] [Indexed: 12/24/2022]
Abstract
In self-renewing tissues, cell lineages consisting of stem cell and classes of daughter cells are the basic units which are responsible for the correct functioning of the organ. Cell proliferation and differentiation in lineages is thought to be mediated by feedback signals. In the simplest case a lineage is comprised of stem cells and differentiated cells. We create a model where stem cell proliferation and differentiation are controlled by the size of cell populations by means of a negative feedback loop. This two-dimensional Markov process allows for an analytical solution for the mean numbers and variances of stem and daughter cells. The mean values and the amounts of variation in cell numbers can be tightly regulated by the parameters of the control loop.
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37
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A mathematical-biological joint effort to investigate the tumor-initiating ability of Cancer Stem Cells. PLoS One 2014; 9:e106193. [PMID: 25184361 PMCID: PMC4153566 DOI: 10.1371/journal.pone.0106193] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 07/29/2014] [Indexed: 01/06/2023] Open
Abstract
The involvement of Cancer Stem Cells (CSCs) in tumor progression and tumor recurrence is one of the most studied subjects in current cancer research. The CSC hypothesis states that cancer cell populations are characterized by a hierarchical structure that affects cancer progression. Due to the complex dynamics involving CSCs and the other cancer cell subpopulations, a robust theory explaining their action has not been established yet. Some indications can be obtained by combining mathematical modeling and experimental data to understand tumor dynamics and to generate new experimental hypotheses. Here, we present a model describing the initial phase of ErbB2+ mammary cancer progression, which arises from a joint effort combing mathematical modeling and cancer biology. The proposed model represents a new approach to investigate the CSC-driven tumorigenesis and to analyze the relations among crucial events involving cancer cell subpopulations. Using in vivo and in vitro data we tuned the model to reproduce the initial dynamics of cancer growth, and we used its solution to characterize observed cancer progression with respect to mutual CSC and progenitor cell variation. The model was also used to investigate which association occurs among cell phenotypes when specific cell markers are considered. Finally, we found various correlations among model parameters which cannot be directly inferred from the available biological data and these dependencies were used to characterize the dynamics of cancer subpopulations during the initial phase of ErbB2+ mammary cancer progression.
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38
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Carulli AJ, Samuelson LC, Schnell S. Unraveling intestinal stem cell behavior with models of crypt dynamics. Integr Biol (Camb) 2014; 6:243-57. [PMID: 24480852 PMCID: PMC4007491 DOI: 10.1039/c3ib40163d] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The definition, regulation and function of intestinal stem cells (ISCs) has been hotly debated. Recent discoveries have started to clarify the nature of ISCs, but many questions remain. This review discusses the current advances and controversies of ISC biology as well as theoretical compartmental models that have been coupled with in vivo experimentation to investigate the mechanisms of ISC dynamics during homeostasis, tumorigenesis, repair and development. We conclude our review by discussing the key lingering questions in the field and proposing how many of these questions can be addressed using both compartmental models and experimental techniques.
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Affiliation(s)
- Alexis J. Carulli
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
| | - Linda C. Samuelson
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
- Department of Internal Medicine, Division of Gastroenterology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
| | - Santiago Schnell
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
- Department for Computational Medicine & Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan, USA.
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39
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Pei QM, Zhan X, Yang LJ, Bao C, Cao W, Li AB, Rozi A, Jia Y. Fluctuations of cell population in a colonic crypt. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 89:032715. [PMID: 24730882 DOI: 10.1103/physreve.89.032715] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Indexed: 06/03/2023]
Abstract
The number of stem cells in a colonic crypt is often very small, which leads to large intrinsic fluctuations in the cell population. Based on the model of cell population dynamics with linear feedback in a colonic crypt, we present a stochastic dynamics of the cell population [including stem cells (SCs), transit amplifying cells (TACs), and fully differentiated cells (FDCs)]. The Fano factor, covariance, and susceptibility formulas of the cell population around the steady state are derived by using the Langevin theory. In the range of physiologically reasonable parameter values, it is found that the stationary populations of TACs and FDCs exhibit an approximately threshold behavior as a function of the net growth rate of TACs, and the reproductions of TACs and FDCs can be classified into three regimens: controlled, crossover, and uncontrolled. With the increasing of the net growth rate of TACs, there is a maximum of the relative intrinsic fluctuations (i.e., the Fano factors) of TACs and FDCs in the crossover region. For a fixed differentiation rate and the net growth rate of SCs, the covariance of fluctuations between SCs and TACs has a maximum in the crossover region. However, the susceptibilities of both TACs and FDCs to the net growth rate of TACs have a minimum in the crossover region.
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Affiliation(s)
- Qi-ming Pei
- Department of Physics and Institute of Biophysics, Central China Normal University, Wuhan 430079, China and School of Physical Science and Technology, Yangtze University, Jingzhou 434023, China
| | - Xuan Zhan
- Department of Physics and Institute of Biophysics, Central China Normal University, Wuhan 430079, China
| | - Li-jian Yang
- Department of Physics and Institute of Biophysics, Central China Normal University, Wuhan 430079, China
| | - Chun Bao
- Department of Physics and Institute of Biophysics, Central China Normal University, Wuhan 430079, China
| | - Wei Cao
- Department of Physics and Institute of Biophysics, Central China Normal University, Wuhan 430079, China and College of Science, Huazhong Agricultural University, Wuhan 430070, China
| | - An-bang Li
- Department of Physics and Institute of Biophysics, Central China Normal University, Wuhan 430079, China
| | - Anvar Rozi
- Department of Physics and Institute of Biophysics, Central China Normal University, Wuhan 430079, China and Department of Physics, Kashgar Teachers College, Kashgar 844007, China
| | - Ya Jia
- Department of Physics and Institute of Biophysics, Central China Normal University, Wuhan 430079, China
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40
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Smallbone K, M Corfe B. A mathematical model of the colon crypt capturing compositional dynamic interactions between cell types. Int J Exp Pathol 2014; 95:1-7. [PMID: 24354351 PMCID: PMC3919643 DOI: 10.1111/iep.12062] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 09/24/2013] [Indexed: 12/27/2022] Open
Abstract
Models of the development and early progression of colorectal cancer are based upon understanding the cycle of stem cell turnover, proliferation, differentiation and death. Existing crypt compartmental models feature a linear pathway of cell types, with little regulatory mechanism. Previous work has shown that there are perturbations in the enteroendocrine cell population of macroscopically normal crypts, a compartment not included in existing models. We show that existing models do not adequately recapitulate the dynamics of cell fate pathways in the crypt. We report the progressive development, iterative testing and fitting of a developed compartmental model with additional cell types, and which includes feedback mechanisms and cross-regulatory mechanisms between cell types. The fitting of the model to existing data sets suggests a need to invoke cross-talk between cell types as a feature of colon crypt cycle models.
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Affiliation(s)
- Kieran Smallbone
- Manchester Centre for Integrative Systems Biology, University of Manchester, Manchester, UK
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41
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Hannezo E, Prost J, Joanny JF. Growth, homeostatic regulation and stem cell dynamics in tissues. J R Soc Interface 2014; 11:20130895. [PMID: 24478279 DOI: 10.1098/rsif.2013.0895] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The regulation of cell growth in animal tissues is a question of critical importance: most tissues contain different types of cells in interconversion and the fraction of each type has to be controlled in a precise way, by mechanisms that remain unclear. Here, we provide a theoretical framework for the homeostasis of stem-cell-containing epithelial tissues using mechanical equations, which describe the size of the tissue and kinetic equations, which describe the interconversions of the cell populations. We show that several features, such as the evolution of stem cell fractions during intestinal development, the shape of a developing intestinal wall, as well as the increase in the proliferative compartment in cancer initiation, can be studied and understood from generic modelling which does not rely on a particular regulatory mechanism. Finally, inspired by recent experiments, we propose a model where cell division rates are regulated by the mechanical stresses in the epithelial sheet. We show that pressure-controlled growth can, in addition to the previous features, also explain with few parameters the formation of stem cell compartments as well as the morphologies observed when a colonic crypt becomes cancerous. We also discuss optimal strategies of wound healing, in connection with experiments on the cornea.
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Affiliation(s)
- E Hannezo
- Physicochimie Curie (Institut Curie/CNRS-UMR168/UPMC), Institut Curie, Centre de Recherche, , 26 rue d'Ulm, 75248 Paris Cedex 05, France
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42
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Shahriyari L, Komarova NL. Symmetric vs. asymmetric stem cell divisions: an adaptation against cancer? PLoS One 2013; 8:e76195. [PMID: 24204602 PMCID: PMC3812169 DOI: 10.1371/journal.pone.0076195] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 08/21/2013] [Indexed: 01/17/2023] Open
Abstract
Traditionally, it has been held that a central characteristic of stem cells is their ability to divide asymmetrically. Recent advances in inducible genetic labeling provided ample evidence that symmetric stem cell divisions play an important role in adult mammalian homeostasis. It is well understood that the two types of cell divisions differ in terms of the stem cells' flexibility to expand when needed. On the contrary, the implications of symmetric and asymmetric divisions for mutation accumulation are still poorly understood. In this paper we study a stochastic model of a renewing tissue, and address the optimization problem of tissue architecture in the context of mutant production. Specifically, we study the process of tumor suppressor gene inactivation which usually takes place as a consequence of two “hits”, and which is one of the most common patterns in carcinogenesis. We compare and contrast symmetric and asymmetric (and mixed) stem cell divisions, and focus on the rate at which double-hit mutants are generated. It turns out that symmetrically-dividing cells generate such mutants at a rate which is significantly lower than that of asymmetrically-dividing cells. This result holds whether single-hit (intermediate) mutants are disadvantageous, neutral, or advantageous. It is also independent on whether the carcinogenic double-hit mutants are produced only among the stem cells or also among more specialized cells. We argue that symmetric stem cell divisions in mammals could be an adaptation which helps delay the onset of cancers. We further investigate the question of the optimal fraction of stem cells in the tissue, and quantify the contribution of non-stem cells in mutant production. Our work provides a hypothesis to explain the observation that in mammalian cells, symmetric patterns of stem cell division seem to be very common.
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Affiliation(s)
- Leili Shahriyari
- Department of Mathematics, University of California Irvine, Irvine, California, United States of America
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Abstract
Identifying the exact regulatory circuits that can stably maintain tissue homeostasis is critical for our basic understanding of multicellular organisms, and equally critical for identifying how tumors circumvent this regulation, thus providing targets for treatment. Despite great strides in the understanding of the molecular components of stem-cell regulation, the overall mechanisms orchestrating tissue homeostasis are still far from being understood. Typically, tissue contains the stem cells, transit amplifying cells, and terminally differentiated cells. Each of these cell types can potentially secrete regulatory factors and/or respond to factors secreted by other types. The feedback can be positive or negative in nature. This gives rise to a bewildering array of possible mechanisms that drive tissue regulation. In this paper, we propose a novel method of studying stem cell lineage regulation, and identify possible numbers, types, and directions of control loops that are compatible with stability, keep the variance low, and possess a certain degree of robustness. For example, there are exactly two minimal (two-loop) control networks that can regulate two-compartment (stem and differentiated cell) tissues, and 20 such networks in three-compartment tissues. If division and differentiation decisions are coupled, then there must be a negative control loop regulating divisions of stem cells (e.g. by means of contact inhibition). While this mechanism is associated with the highest robustness, there could be systems that maintain stability by means of positive divisions control, coupled with specific types of differentiation control. Some of the control mechanisms that we find have been proposed before, but most of them are new, and we describe evidence for their existence in data that have been previously published. By specifying the types of feedback interactions that can maintain homeostasis, our mathematical analysis can be used as a guide to experimentally zero in on the exact molecular mechanisms in specific tissues.
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Affiliation(s)
- Natalia L. Komarova
- Department of Mathematics, University of California Irvine, Irvine, California, United States of America
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Gentry SN, Jackson TL. A mathematical model of cancer stem cell driven tumor initiation: implications of niche size and loss of homeostatic regulatory mechanisms. PLoS One 2013; 8:e71128. [PMID: 23990931 PMCID: PMC3747196 DOI: 10.1371/journal.pone.0071128] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 06/28/2013] [Indexed: 12/23/2022] Open
Abstract
Hierarchical organized tissue structures, with stem cell driven cell differentiation, are critical to the homeostatic maintenance of most tissues, and this underlying cellular architecture is potentially a critical player in the development of a many cancers. Here, we develop a mathematical model of mutation acquisition to investigate how deregulation of the mechanisms preserving stem cell homeostasis contributes to tumor initiation. A novel feature of the model is the inclusion of both extrinsic and intrinsic chemical signaling and interaction with the niche to control stem cell self-renewal. We use the model to simulate the effects of a variety of types and sequences of mutations and then compare and contrast all mutation pathways in order to determine which ones generate cancer cells fastest. The model predicts that the sequence in which mutations occur significantly affects the pace of tumorigenesis. In addition, tumor composition varies for different mutation pathways, so that some sequences generate tumors that are dominated by cancerous cells with all possible mutations, while others are primarily comprised of cells that more closely resemble normal cells with only one or two mutations. We are also able to show that, under certain circumstances, healthy stem cells diminish due to the displacement by mutated cells that have a competitive advantage in the niche. Finally, in the event that all homeostatic regulation is lost, exponential growth of the cancer population occurs in addition to the depletion of normal cells. This model helps to advance our understanding of how mutation acquisition affects mechanisms that influence cell-fate decisions and leads to the initiation of cancers.
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Affiliation(s)
- Sara N. Gentry
- Department of Mathematics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Trachette L. Jackson
- Department of Mathematics, University of Michigan, Ann Arbor, Michigan, United States of America
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Kershaw SK, Byrne HM, Gavaghan DJ, Osborne JM. Colorectal cancer through simulation and experiment. IET Syst Biol 2013; 7:57-73. [DOI: 10.1049/iet-syb.2012.0019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Affiliation(s)
- Sophie K. Kershaw
- Department of Computer ScienceComputational Biology GroupWolfson Building, Parks RoadOxfordOX1 3QDUK
| | - Helen M. Byrne
- Department of Computer ScienceComputational Biology GroupWolfson Building, Parks RoadOxfordOX1 3QDUK
- OCCAM, Mathematical Institute24-29 St. Giles’OxfordOX1 3LBUK
| | - David J. Gavaghan
- Department of Computer ScienceComputational Biology GroupWolfson Building, Parks RoadOxfordOX1 3QDUK
- Department of BiochemistryOxford Centre for Integrative Systems BiologySouth Parks RoadOxfordOX1 3QUUK
| | - James M. Osborne
- Department of Computer ScienceComputational Biology GroupWolfson Building, Parks RoadOxfordOX1 3QDUK
- Department of BiochemistryOxford Centre for Integrative Systems BiologySouth Parks RoadOxfordOX1 3QUUK
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Wu Y, Garmire LX, Fan R. Inter-cellular signaling network reveals a mechanistic transition in tumor microenvironment. Integr Biol (Camb) 2013; 4:1478-86. [PMID: 23080410 DOI: 10.1039/c2ib20044a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We conducted inter-cellular cytokine correlation and network analysis based upon a stochastic population dynamics model that comprises five cell types and fifteen signaling molecules inter-connected through a large number of cell-cell communication pathways. We observed that the signaling molecules are tightly correlated even at very early stages (e.g. the first month) of human glioma, but such correlation rapidly diminishes when tumor grows to a size that can be clinically detected. Further analysis suggests that paracrine is shown to be the dominant force during tumor initiation and priming, while autocrine supersedes it and supports a robust tumor expansion. In correspondence, the cytokine correlation network evolves through an increasing to decreasing complexity. This study indicates a possible mechanistic transition from the microenvironment-controlled, paracrine-based regulatory mechanism to self-sustained rapid progression to fetal malignancy. It also reveals key nodes that are responsible for such transition and can be potentially harnessed for the design of new anti-cancer therapies.
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Affiliation(s)
- Yu Wu
- Department of Biomedical Engineering, Yale University, New Haven, CT 06511, USA
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Rodriguez-Brenes IA, Wodarz D, Komarova NL. Stem cell control, oscillations, and tissue regeneration in spatial and non-spatial models. Front Oncol 2013; 3:82. [PMID: 23596567 PMCID: PMC3625858 DOI: 10.3389/fonc.2013.00082] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 03/29/2013] [Indexed: 12/17/2022] Open
Abstract
Normal human tissue is organized into cell lineages, in which the highly differentiated mature cells that perform tissue functions are the end product of an orderly tissue-specific sequence of divisions that start with stem cells or progenitor cells. Tissue homeostasis and effective regeneration after injuries requires tight regulation of these cell lineages and feedback loops play a fundamental role in this regard. In particular, signals secreted from differentiated cells that inhibit stem cell division and stem cell self-renewal are important in establishing control. In this article we study in detail the cell dynamics that arise from this control mechanism. These dynamics are fundamental to our understanding of cancer, given that tumor initiation requires an escape from tissue regulation. Knowledge on the processes of cellular control can provide insights into the pathways that lead to deregulation and consequently cancer development.
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Sun Z, Komarova NL. Stochastic modeling of stem-cell dynamics with control. Math Biosci 2012; 240:231-40. [PMID: 22960597 PMCID: PMC3921979 DOI: 10.1016/j.mbs.2012.08.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 08/14/2012] [Accepted: 08/20/2012] [Indexed: 12/12/2022]
Abstract
Tissue development and homeostasis are thought to be regulated endogenously by control loops that ensure that the numbers of stem cells and daughter cells are maintained at desired levels, and that the cell dynamics are robust to perturbations. In this paper we consider several classes of stochastic models that describe stem/daughter cell dynamics in a population of constant size, which are generalizations of the Moran process that include negative control loops that affect differentiation probabilities for stem cells. We present analytical solutions for the steady-state expectations and variances of the numbers of stem and daughter cells; these results remain valid for non-constant cell populations. We show that in the absence of differentiation/proliferation control, the number of stem cells is subject to extinction or overflow. In the presence of linear control, a steady state may be maintained but no tunable parameters are available to control the mean and the spread of the cell population sizes. Two types of nonlinear control considered here incorporate tunable parameters that allow specification of the expected number of stem cells and also provide control over the size of the standard deviation. We show that under a hyperbolic control law, there is a trade-off between minimizing standard deviations and maintaining the system robustness against external perturbations. For the Hill-type control, the standard deviation is inversely proportional to the Hill coefficient of the control loop. Biologically this means that ultrasensitive response that is observed in a number of regulatory loops may have evolved in order to reduce fluctuations while maintaining the desired population levels.
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Affiliation(s)
- Zheng Sun
- Department of Mathematics, University of California Irvine, Irvine, CA 92617
| | - Natalia L. Komarova
- Department of Mathematics, University of California Irvine, Irvine, CA 92617
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Zhang L, Lander AD, Nie Q. A reaction-diffusion mechanism influences cell lineage progression as a basis for formation, regeneration, and stability of intestinal crypts. BMC SYSTEMS BIOLOGY 2012; 6:93. [PMID: 22849824 PMCID: PMC3434027 DOI: 10.1186/1752-0509-6-93] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 07/04/2012] [Indexed: 11/29/2022]
Abstract
Background Colon crypts, a single sheet of epithelia cells, consist of a periodic pattern of stem cells, transit-amplifying cells, and terminally differentiated cells that constantly renew and turnover. Experimental evidence suggests that Wnt signaling promotes and regulates stem cell division, differentiation, and possible cell migrations while intestinal BMP signaling inhibits stem cell self-renewal and repression in crypt formation. As more molecular details on Wnt and BMP in crypts are being discovered, little is still known about how complex interactions among Wnt, BMP, and different types of cells, and surrounding environments may lead to de novo formation of multiple crypts or how such interactions affect regeneration and stability of crypts. Results We present a mathematical model that contains Wnt and BMP, a cell lineage, and their feedback regulations to study formation, regeneration, and stability of multiple crypts. The computational explorations and linear stability analysis of the model suggest a reaction–diffusion mechanism, which exhibits a short-range activation of Wnt plus a long-range inhibition with modulation of BMP signals in a growing tissue of cell lineage, can account for spontaneous formation of multiple crypts with the spatial and temporal pattern observed in experiments. Through this mechanism, the model can recapitulate some distinctive and important experimental findings such as crypt regeneration and crypt multiplication. BMP is important in maintaining stability of crypts and loss of BMP usually leads to crypt multiplication with a fingering pattern. Conclusions The study provides a mechanism for de novo formation of multiple intestinal crypts and demonstrates a synergetic role of Wnt and BMP in regeneration and stability of intestinal crypts. The proposed model presents a robust framework for studying spatial and temporal dynamics of cell lineages in growing tissues driven by multiple signaling molecules.
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Affiliation(s)
- Lei Zhang
- Department of Mathematics, University of California, Irvine, CA 92697, USA
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Howk CL, Levine HA, Smiley MW, Mallapragada SK, Nilsen-Hamilton M, Oh J, Sakaguchi DS. A mathematical model for selective differentiation of neural progenitor cells on micropatterned polymer substrates. Math Biosci 2012; 238:65-79. [PMID: 22569338 DOI: 10.1016/j.mbs.2012.04.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 02/20/2012] [Accepted: 04/02/2012] [Indexed: 01/25/2023]
Abstract
The biological hypothesis that the astrocyte-secreted cytokine, interleukin-6 (IL6), stimulates differentiation of adult rat hippocampal progenitor cells (AHPCs) is considered from a mathematical perspective. The proposed mathematical model includes two different mechanisms for stimulation and is based on mass-action kinetics. Both biological mechanisms involve sequential binding, with one pathway solely utilizing surface receptors while the other pathway also involves soluble receptors. Choosing biologically-reasonable values for parameters, simulations of the mathematical model show good agreement with experimental results. A global sensitivity analysis is also conducted to determine both the most influential and non-influential parameters on cellular differentiation, providing additional insights into the biological mechanisms.
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Affiliation(s)
- Cory L Howk
- Department of Mathematics, Iowa State University, Ames, IA 50011, USA.
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