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1
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Shao H, Zhu Q, Lu H, Chang A, Gao C, Zhou Q, Luo K. HEXIM1 controls P-TEFb processing and regulates drug sensitivity in triple-negative breast cancer. Mol Biol Cell 2020; 31:1867-1878. [PMID: 32520633 PMCID: PMC7525814 DOI: 10.1091/mbc.e19-12-0704] [Citation(s) in RCA: 7] [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: 12/20/2019] [Revised: 05/28/2020] [Accepted: 06/02/2020] [Indexed: 11/16/2022] Open
Abstract
The positive transcription elongation factor b (P-TEFb), composed of CDK9 and cyclin T, stimulates transcriptional elongation by RNA polymerase (Pol) II and regulates cell growth and differentiation. Recently, we demonstrated that P-TEFb also controls the expression of EMT regulators to promote breast cancer progression. In the nucleus, more than half of P-TEFb are sequestered in the inactive-state 7SK snRNP complex. Here, we show that the assembly of the 7SK snRNP is preceded by an intermediate complex between HEXIM1 and P-TEFb that allows transfer of the kinase active P-TEFb from Hsp90 to 7SK snRNP for its suppression. Down-regulation of HEXIM1 locks P-TEFb in the Hsp90 complex, keeping it in the active state to enhance breast cancer progression, but also rendering the cells highly sensitive to Hsp90 inhibition. Because HEXIM1 is often down-regulated in human triple-negative breast cancer (TNBC), these cells are particularly sensitive to Hsp90 inhibition. Our study provides a mechanistic explanation for the increased sensitivity of TNBC to Hsp90 inhibition.
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Affiliation(s)
- Hengyi Shao
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Qingwei Zhu
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Huasong Lu
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Amanda Chang
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Carol Gao
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Qiang Zhou
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Kunxin Luo
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
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2
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Pulikkan JA, Hegde M, Ahmad HM, Belaghzal H, Illendula A, Yu J, O'Hagan K, Ou J, Muller-Tidow C, Wolfe SA, Zhu LJ, Dekker J, Bushweller JH, Castilla LH. CBFβ-SMMHC Inhibition Triggers Apoptosis by Disrupting MYC Chromatin Dynamics in Acute Myeloid Leukemia. Cell 2018; 174:172-186.e21. [PMID: 29958106 PMCID: PMC6211564 DOI: 10.1016/j.cell.2018.05.048] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 02/12/2018] [Accepted: 05/23/2018] [Indexed: 12/25/2022]
Abstract
The fusion oncoprotein CBFβ-SMMHC, expressed in leukemia cases with chromosome 16 inversion, drives leukemia development and maintenance by altering the activity of the transcription factor RUNX1. Here, we demonstrate that CBFβ-SMMHC maintains cell viability by neutralizing RUNX1-mediated repression of MYC expression. Upon pharmacologic inhibition of the CBFβ-SMMHC/RUNX1 interaction, RUNX1 shows increased binding at three MYC distal enhancers, where it represses MYC expression by mediating the replacement of the SWI/SNF complex component BRG1 with the polycomb-repressive complex component RING1B, leading to apoptosis. Combining the CBFβ-SMMHC inhibitor with the BET inhibitor JQ1 eliminates inv(16) leukemia in human cells and a mouse model. Enhancer-interaction analysis indicated that the three enhancers are physically connected with the MYC promoter, and genome-editing analysis demonstrated that they are functionally implicated in deregulation of MYC expression. This study reveals a mechanism whereby CBFβ-SMMHC drives leukemia maintenance and suggests that inhibitors targeting chromatin activity may prove effective in inv(16) leukemia therapy.
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MESH Headings
- Animals
- Apoptosis/drug effects
- Azepines/pharmacology
- Azepines/therapeutic use
- Benzimidazoles/pharmacology
- Benzimidazoles/therapeutic use
- Cell Line, Tumor
- Chromatin/metabolism
- Chromosomal Proteins, Non-Histone/chemistry
- Chromosomal Proteins, Non-Histone/metabolism
- Chromosome Inversion/drug effects
- Core Binding Factor Alpha 2 Subunit/chemistry
- Core Binding Factor Alpha 2 Subunit/metabolism
- DNA/chemistry
- DNA/metabolism
- DNA Helicases/metabolism
- Disease Models, Animal
- Humans
- Kaplan-Meier Estimate
- Leukemia, Myeloid, Acute/drug therapy
- Leukemia, Myeloid, Acute/mortality
- Leukemia, Myeloid, Acute/pathology
- Mice
- Mice, Inbred C57BL
- Nuclear Proteins/metabolism
- Oncogene Proteins, Fusion/antagonists & inhibitors
- Oncogene Proteins, Fusion/metabolism
- Polycomb Repressive Complex 1/metabolism
- Promoter Regions, Genetic
- Protein Binding
- Proto-Oncogene Proteins c-myc/genetics
- Proto-Oncogene Proteins c-myc/metabolism
- Transcription Factors/chemistry
- Transcription Factors/metabolism
- Triazoles/pharmacology
- Triazoles/therapeutic use
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Affiliation(s)
- John Anto Pulikkan
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Mahesh Hegde
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Hafiz Mohd Ahmad
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Houda Belaghzal
- Howard Hughes Medical Institute, Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Anuradha Illendula
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Jun Yu
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Kelsey O'Hagan
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Jianhong Ou
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Carsten Muller-Tidow
- Department of Medicine, Hematology, Oncology, and Rheumatology, University Hospital Heidelberg, Heidelberg, Germany
| | - Scot A Wolfe
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Lihua Julie Zhu
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Job Dekker
- Howard Hughes Medical Institute, Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
| | - John Hackett Bushweller
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Lucio Hernán Castilla
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, USA.
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3
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miR-3140 suppresses tumor cell growth by targeting BRD4 via its coding sequence and downregulates the BRD4-NUT fusion oncoprotein. Sci Rep 2018. [PMID: 29540837 PMCID: PMC5852021 DOI: 10.1038/s41598-018-22767-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Bromodomain Containing 4 (BRD4) mediates transcriptional elongation of the oncogene MYC by binding to acetylated histones. BRD4 has been shown to play a critical role in tumorigenesis in several cancers, and the BRD4-NUT fusion gene is a driver of NUT midline carcinoma (NMC), a rare but highly lethal cancer. microRNAs (miRNAs) are endogenous small non-coding RNAs that suppress target gene expression by binding to complementary mRNA sequences. Here, we show that miR-3140, which was identified as a novel tumor suppressive miRNA by function-based screening of a library containing 1090 miRNA mimics, directly suppressed BRD4 by binding to its coding sequence (CDS). miR-3140 concurrently downregulated BRD3 by bind to its CDS as well as CDK2 and EGFR by binding to their 3' untranslated regions. miR-3140 inhibited tumor cell growth in vitro in various cancer cell lines, including EGFR tyrosine kinase inhibitor-resistant cells. Interestingly, we found that miR-3140 downregulated the BRD4-NUT fusion protein and suppressed in vitro tumor cell growth in a NMC cell line, Ty-82 cells. Furthermore, administration of miR-3140 suppressed in vivo tumor growth in a xenograft mouse model. Our results suggest that miR-3140 is a candidate for the development of miRNA-based cancer therapeutics.
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4
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Yan G, Hou M, Luo J, Pu C, Hou X, Lan S, Li R. Pharmacophore-based virtual screening, molecular docking, molecular dynamics simulation, and biological evaluation for the discovery of novel BRD4 inhibitors. Chem Biol Drug Des 2017; 91:478-490. [PMID: 28901664 DOI: 10.1111/cbdd.13109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 08/21/2017] [Accepted: 08/22/2017] [Indexed: 02/05/2023]
Abstract
Bromodomain is a recognition module in the signal transduction of acetylated histone. BRD4, one of the bromodomain members, is emerging as an attractive therapeutic target for several types of cancer. Therefore, in this study, an attempt has been made to screen compounds from an integrated database containing 5.5 million compounds for BRD4 inhibitors using pharmacophore-based virtual screening, molecular docking, and molecular dynamics simulations. As a result, two molecules of twelve hits were found to be active in bioactivity tests. Among the molecules, compound 5 exhibited potent anticancer activity, and the IC50 values against human cancer cell lines MV4-11, A375, and HeLa were 4.2, 7.1, and 11.6 μm, respectively. After that, colony formation assay, cell cycle, apoptosis analysis, wound-healing migration assay, and Western blotting were carried out to learn the bioactivity of compound 5.
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Affiliation(s)
- Guoyi Yan
- Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, Sichuan, China
| | - Manzhou Hou
- Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, Sichuan, China
| | - Jiang Luo
- Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, Sichuan, China
| | - Chunlan Pu
- Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, Sichuan, China
| | - Xueyan Hou
- Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, Sichuan, China
| | - Suke Lan
- Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, Sichuan, China
| | - Rui Li
- Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, Sichuan, China
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5
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Raj U, Kumar H, Varadwaj PK. Molecular docking and dynamics simulation study of flavonoids as BET bromodomain inhibitors. J Biomol Struct Dyn 2016; 35:2351-2362. [PMID: 27494802 DOI: 10.1080/07391102.2016.1217276] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Bromodomains (BRDs) are the epigenetic proteins responsible for transcriptional regulation through its interaction with methylated or acetylated histone residues. The lysine residues of Bromodomain-1 (BD1) of Brd4 undergo ε-N-Acetylation posttranslational modifications to control transcription of genes. Due to its role in diverse cellular functions, Brd4 of bromodomain family, was considered as a prominent target for many diseases such as cancer, obesity, kidney disease, lung fibrosis, inflammatory diseases, etc. In this study, an attempt has been made to screen compounds from flavonoids and extended flavonoids libraries targeting acetylated lysine (KAc) binding site of BD1 of Brd4 using docking and molecular dynamics simulations. Two different docking programs AutoDock and Glide were used to compare their suitability for the receptor. Interestingly, in both the docking programs, the screened flavonoids have occupied the same binding pocket confirming the selection of active site. Further the MMGBSA binding free energy calculations and ADME analysis were carried out on screened compounds to establish their anti-cancerous properties. We have identified a flavonoid which shows docking and Glide e-model score comparatively much higher than those of already reported known inhibitors against Brd4. The protein-ligand complex with top-ranked flavonoid was used for dynamics simulation study for 50 ns in order to validate its stability inside the active site of Brd4 receptor. The results provide valuable information for structure-based drug design of Brd4 inhibitors.
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Affiliation(s)
- Utkarsh Raj
- a Department of Bioinformatics , Indian Institute of Information Technology-Allahabad , CC2-4203, Jhalwa Campus, Deoghat, Allahabad - 211012 , Uttar Pradesh , India
| | - Himansu Kumar
- a Department of Bioinformatics , Indian Institute of Information Technology-Allahabad , CC2-4203, Jhalwa Campus, Deoghat, Allahabad - 211012 , Uttar Pradesh , India
| | - Pritish Kumar Varadwaj
- a Department of Bioinformatics , Indian Institute of Information Technology-Allahabad , CC2-4203, Jhalwa Campus, Deoghat, Allahabad - 211012 , Uttar Pradesh , India
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6
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Abstract
Multiple new drugs are being developed to treat acute myeloid leukemia (AML), including novel formulations of traditional chemotherapy-antibody drug conjugates and agents that target specific mutant enzymes. Next-generation sequencing has allowed us to discover the genetic mutations that lead to the development and clinical progression of AML. Studies of clonal hierarchy suggest which mutations occur early and dominate. This has led to targeted therapy against mutant driver proteins as well as the development of drugs such as CPX-351 and SGN-CD33A whose mechanisms of action and efficacy may not be dependent on mutational complexity. In this brief review, we discuss drugs that may emerge as important for the treatment of AML in the next 10 years.
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7
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Coudé MM, Braun T, Berrou J, Dupont M, Bertrand S, Masse A, Raffoux E, Itzykson R, Delord M, Riveiro ME, Herait P, Baruchel A, Dombret H, Gardin C. BET inhibitor OTX015 targets BRD2 and BRD4 and decreases c-MYC in acute leukemia cells. Oncotarget 2015; 6:17698-712. [PMID: 25989842 PMCID: PMC4627339 DOI: 10.18632/oncotarget.4131] [Citation(s) in RCA: 207] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 04/08/2015] [Indexed: 11/25/2022] Open
Abstract
The bromodomain (BRD) and extraterminal (BET) proteins including BRD2, BRD3 and BRD4 have been identified as key targets for leukemia maintenance. A novel oral inhibitor of BRD2/3/4, the thienotriazolodiazepine compound OTX015, suitable for human use, is available. Here we report its biological effects in AML and ALL cell lines and leukemic samples. Exposure to OTX015 lead to cell growth inhibition, cell cycle arrest and apoptosis at submicromolar concentrations in acute leukemia cell lines and patient-derived leukemic cells, as described with the canonical JQ1 BET inhibitor. Treatment with JQ1 and OTX15 induces similar gene expression profiles in sensitive cell lines, including a c-MYC decrease and an HEXIM1 increase. OTX015 exposure also induced a strong decrease of BRD2, BRD4 and c-MYC and increase of HEXIM1 proteins, while BRD3 expression was unchanged. c-MYC, BRD2, BRD3, BRD4 and HEXIM1 mRNA levels did not correlate however with viability following exposure to OTX015. Sequential combinations of OTX015 with other epigenetic modifying drugs, panobinostat and azacitidine have a synergic effect on growth of the KASUMI cell line. Our results indicate that OTX015 and JQ1 have similar biological effects in leukemic cells, supporting OTX015 evaluation in a Phase Ib trial in relapsed/refractory leukemia patients.
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Affiliation(s)
- Marie-Magdelaine Coudé
- Laboratoire de Transfert des Leucémies, Institut Universitaire d'Hématologie, University Paris VII, Paris, France
- Laboratory of Hematology, Hôpital Saint-Louis (Assistance Publique - Hôpitaux de Paris and University Paris VII), Paris, France
| | - Thorsten Braun
- Laboratoire de Transfert des Leucémies, Institut Universitaire d'Hématologie, University Paris VII, Paris, France
- Hematology Department, Hôpital Avicenne (Assistance Publique - Hôpitaux de Paris and University Paris XIII), Bobigny, France
| | - Jeannig Berrou
- Laboratoire de Transfert des Leucémies, Institut Universitaire d'Hématologie, University Paris VII, Paris, France
| | - Mélanie Dupont
- Laboratoire de Transfert des Leucémies, Institut Universitaire d'Hématologie, University Paris VII, Paris, France
| | - Sibyl Bertrand
- Laboratoire de Transfert des Leucémies, Institut Universitaire d'Hématologie, University Paris VII, Paris, France
| | - Aline Masse
- Laboratoire de Transfert des Leucémies, Institut Universitaire d'Hématologie, University Paris VII, Paris, France
| | - Emmanuel Raffoux
- Laboratoire de Transfert des Leucémies, Institut Universitaire d'Hématologie, University Paris VII, Paris, France
- Leukemia Unit, Hematology Department, Hôpital Saint-Louis (Assistance Publique - Hôpitaux de Paris and University Paris VII), Paris, France
| | - Raphaël Itzykson
- Laboratoire de Transfert des Leucémies, Institut Universitaire d'Hématologie, University Paris VII, Paris, France
- Leukemia Unit, Hematology Department, Hôpital Saint-Louis (Assistance Publique - Hôpitaux de Paris and University Paris VII), Paris, France
| | - Marc Delord
- Bioinformatics, Institut Universitaire d'Hématologie, University Paris VII, Paris, France
| | | | | | - André Baruchel
- Laboratoire de Transfert des Leucémies, Institut Universitaire d'Hématologie, University Paris VII, Paris, France
- Department of Pediatric Hemato-Immunology, Hôpital Robert Debré (Assistance Publique - Hôpitaux de Paris and University Paris VII), Paris, France
| | - Hervé Dombret
- Laboratoire de Transfert des Leucémies, Institut Universitaire d'Hématologie, University Paris VII, Paris, France
- Leukemia Unit, Hematology Department, Hôpital Saint-Louis (Assistance Publique - Hôpitaux de Paris and University Paris VII), Paris, France
| | - Claude Gardin
- Laboratoire de Transfert des Leucémies, Institut Universitaire d'Hématologie, University Paris VII, Paris, France
- Hematology Department, Hôpital Avicenne (Assistance Publique - Hôpitaux de Paris and University Paris XIII), Bobigny, France
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8
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Abstract
There is a scarcity of novel treatments to address many unmet medical needs. Industry and academia are finally coming to terms with the fact that the prevalent models and incentives for innovation in early stage drug discovery are failing to promote progress quickly enough. Here we will examine how an open model of precompetitive public-private research partnership is enabling efficient derisking and acceleration in the early stages of drug discovery, whilst also widening the range of communities participating in the process, such as patient and disease foundations.
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Affiliation(s)
- Wen Hwa Lee
- Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
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9
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Stein EM. Molecularly targeted therapies for acute myeloid leukemia. HEMATOLOGY. AMERICAN SOCIETY OF HEMATOLOGY. EDUCATION PROGRAM 2015; 2015:579-583. [PMID: 26637775 DOI: 10.1182/asheducation-2015.1.579] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The past 15 years have seen major leaps in our understanding of the molecular genetic mutations that act as drivers of acute myeloid leukemia (AML). Clinical trials of agents against specific mutant proteins, such as FLT3-internal tandem duplications (ITDs) and isocitrate dehydrogenase mutations (IDHs) are ongoing. This review discusses agents in clinical trials that target specific gene mutations and/or epigenetic targets.
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Affiliation(s)
- Eytan M Stein
- Leukemia Service, Memorial Sloan Kettering Cancer Center, New York, NY
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10
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Wyce A, Degenhardt Y, Bai Y, Le B, Korenchuk S, Crouthame MC, McHugh CF, Vessella R, Creasy CL, Tummino PJ, Barbash O. Inhibition of BET bromodomain proteins as a therapeutic approach in prostate cancer. Oncotarget 2014; 4:2419-29. [PMID: 24293458 PMCID: PMC3926837 DOI: 10.18632/oncotarget.1572] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
BET (bromodomain and extra-terminal) proteins regulate gene expression through their ability to bind to acetylated chromatin and subsequently activate RNA PolII-driven transcriptional elongation. Small molecule BET inhibitors prevent binding of BET proteins to acetylated histones and inhibit transcriptional activation of BET target genes. BET inhibitors attenuate cell growth and survival in several hematologic cancer models, partially through the down-regulation of the critical oncogene, MYC. We hypothesized that BET inhibitors will regulate MYC expression in solid tumors that frequently over-express MYC. Here we describe the effects of the highly specific BET inhibitor, I-BET762, on MYC expression in prostate cancer models. I-BET762 potently reduced MYC expression in prostate cancer cell lines and a patient-derived tumor model with subsequent inhibition of cell growth and reduction of tumor burden in vivo. Our data suggests that I-BET762 effects are partially driven by MYC down-regulation and underlines the critical importance of additional mechanisms of I-BET762 induced phenotypes.
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Affiliation(s)
- Anastasia Wyce
- Cancer Epigenetics DPU, Oncology R and D GlaxoSmithKline, Collegeville, PA, USA
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11
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Zhou J, Chng WJ. Identification and targeting leukemia stem cells: The path to the cure for acute myeloid leukemia. World J Stem Cells 2014; 6:473-484. [PMID: 25258669 PMCID: PMC4172676 DOI: 10.4252/wjsc.v6.i4.473] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 08/22/2014] [Accepted: 08/30/2014] [Indexed: 02/06/2023] Open
Abstract
Accumulating evidence support the notion that acute myeloid leukemia (AML) is organized in a hierarchical system, originating from a special proportion of leukemia stem cells (LSC). Similar to their normal counterpart, hematopoietic stem cells (HSC), LSC possess self-renewal capacity and are responsible for the continued growth and proliferation of the bulk of leukemia cells in the blood and bone marrow. It is believed that LSC are also the root cause for the treatment failure and relapse of AML because LSC are often resistant to chemotherapy. In the past decade, we have made significant advancement in identification and understanding the molecular biology of LSC, but it remains a daunting task to specifically targeting LSC, while sparing normal HSC. In this review, we will first provide a historical overview of the discovery of LSC, followed by a summary of identification and separation of LSC by either cell surface markers or functional assays. Next, the review will focus on the current, various strategies for eradicating LSC. Finally, we will highlight future directions and challenges ahead of our ultimate goal for the cure of AML by targeting LSC.
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Affiliation(s)
- Jianbiao Zhou
- Jianbiao Zhou, Wee-Joo Chng, Cancer Science Institute of Singapore, National University of Singapore, Centre for Translational Medicine, Singapore 117599, Singapore
| | - Wee-Joo Chng
- Jianbiao Zhou, Wee-Joo Chng, Cancer Science Institute of Singapore, National University of Singapore, Centre for Translational Medicine, Singapore 117599, Singapore
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12
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Hu X, Lu X, Liu R, Ai N, Cao Z, Li Y, Liu J, Yu B, Liu K, Wang H, Zhou C, Wang Y, Han A, Ding F, Chen R. Histone cross-talk connects protein phosphatase 1α (PP1α) and histone deacetylase (HDAC) pathways to regulate the functional transition of bromodomain-containing 4 (BRD4) for inducible gene expression. J Biol Chem 2014; 289:23154-23167. [PMID: 24939842 PMCID: PMC4132813 DOI: 10.1074/jbc.m114.570812] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Transcription elongation has been recognized as a rate-limiting step for the expression of signal-inducible genes. Through recruitment of positive transcription elongation factor P-TEFb, the bromodomain-containing protein BRD4 plays critical roles in regulating the transcription elongation of a vast array of inducible genes that are important for multiple cellular processes. The diverse biological roles of BRD4 have been proposed to rely on its functional transition between chromatin targeting and transcription regulation. The signaling pathways and the molecular mechanism for regulating this transition process, however, are largely unknown. Here, we report a novel role of phosphorylated Ser(10) of histone H3 (H3S10ph) in governing the functional transition of BRD4. We identified that the acetylated lysines 5 and 8 of nucleosomal histone H4 (H4K5ac/K8ac) is the BRD4 binding site, and the protein phosphatase PP1α and class I histone deacetylase (HDAC1/2/3) signaling pathways are essential for the stress-induced BRD4 release from chromatin. In the unstressed state, phosphorylated H3S10 prevents the deacetylation of nucleosomal H4K5ac/K8ac by HDAC1/2/3, thereby locking up the majority of BRD4 onto chromatin. Upon stress, PP1α-mediated dephosphorylation of H3S10ph allows the deacetylation of nucleosomal H4K5ac/K8ac by HDAC1/2/3, thereby leading to the release of chromatin-bound BRD4 for subsequent recruitment of P-TEFb to enhance the expression of inducible genes. Therefore, our study revealed a novel mechanism that the histone cross-talk between H3S10ph and H4K5ac/K8ac connects PP1α and HDACs to govern the functional transition of BRD4. Combined with previous studies on the regulation of P-TEFb activation, the intricate signaling network for the tight control of transcription elongation is established.
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Affiliation(s)
- Xiangming Hu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361101, China
| | - Xiaodong Lu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361101, China
| | - Runzhong Liu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361101, China
| | - Nanping Ai
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361101, China
| | - Zhenhua Cao
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361101, China
| | - Yannan Li
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361101, China
| | - Jiangfang Liu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361101, China
| | - Bin Yu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361101, China
| | - Kai Liu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361101, China
| | - Huiping Wang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361101, China
| | - Chao Zhou
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361101, China
| | - Yu Wang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361101, China
| | - Aidong Han
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361101, China
| | - Feng Ding
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361101, China.
| | - Ruichuan Chen
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361101, China.
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13
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Ji X, Lu H, Zhou Q, Luo K. LARP7 suppresses P-TEFb activity to inhibit breast cancer progression and metastasis. eLife 2014; 3:e02907. [PMID: 25053741 PMCID: PMC4126343 DOI: 10.7554/elife.02907] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Transcriptional elongation by RNA polymerase (Pol) II is essential for gene expression during cell growth and differentiation. The positive transcription elongation factor b (P-TEFb) stimulates transcriptional elongation by phosphorylating Pol II and antagonizing negative elongation factors. A reservoir of P-TEFb is sequestered in the inactive 7SK snRNP where 7SK snRNA and the La-related protein LARP7 are required for the integrity of this complex. Here, we show that P-TEFb activity is important for the epithelial–mesenchymal transition (EMT) and breast cancer progression. Decreased levels of LARP7 and 7SK snRNA redistribute P-TEFb to the transcriptionally active super elongation complex, resulting in P-TEFb activation and increased transcription of EMT transcription factors, including Slug, FOXC2, ZEB2, and Twist1, to promote breast cancer EMT, invasion, and metastasis. Our data provide the first demonstration that the transcription elongation machinery plays a key role in promoting breast cancer progression by directly controlling the expression of upstream EMT regulators. DOI:http://dx.doi.org/10.7554/eLife.02907.001 To express a gene to make a protein, the gene's DNA must first be transcribed to produce molecules of messenger RNA. The start of the transcription process features two milestones. First, an enzyme called RNA Polymerase II starts the process. Shortly afterwards, however, the process pauses and only starts again when other proteins are recruited. This second step, called transcriptional elongation, is essential for gene expression in cells that are growing and specializing into specific cell types. However, it is unclear how important this second step is for the progression of human cancers, such as breast cancer. In humans, two proteins join together to form a complex called ‘positive transcription elongation factor b’ (or P-TEFb for short). This elongation factor encourages the transcriptional elongation step by adding phosphate groups onto RNA Polymerase II and by outcompeting other proteins that act to stop the process. However, some of the P-TEFb proteins in the cell's nucleus are unable to do this because they are held within a complex, which also contains an RNA molecule and some other proteins including one called LARP7. This protein–RNA complex is thought to help to prevent a number of cancers, for example breast cancer or stomach cancer; however the effect of P-TEFb proteins on cancers in humans is not known. Less LARP7 protein is made in breast cancer cells compared to healthy cells. And when Ji et al. reduced the levels of the LARP7 protein (or the RNA molecule involved in the complex), the P-TEFb proteins were released from the complex and were free to encourage transcriptional elongation. This led to the increased expression of other proteins that switch other genes on or off, including genes that allow breast cancer cells to spread around the body. On the other hand, Ji et al. revealed that freeing the P-TEFb proteins from the complex in the nucleus did not appear to cause new tumors to develop or existing tumors to grow. Ji et al. suggest that the LARP7 protein normally helps to prevent the spread of breast cancers by keeping the P-TEFb proteins inactive as a part of the protein–RNA complex. One of the next challenges will be to see if drugs that can inhibit the P-TEFb proteins might be useful as new treatments for late stage breast cancer. DOI:http://dx.doi.org/10.7554/eLife.02907.002
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Affiliation(s)
- Xiaodan Ji
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Huasong Lu
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Qiang Zhou
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Kunxin Luo
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, United States
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14
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Knoechel B, Roderick JE, Williamson KE, Zhu J, Lohr JG, Cotton MJ, Gillespie SM, Fernandez D, Ku M, Wang H, Piccioni F, Silver SJ, Jain M, Pearson D, Kluk MJ, Ott CJ, Shultz LD, Brehm MA, Greiner DL, Gutierrez A, Stegmaier K, Kung AL, Root DE, Bradner JE, Aster JC, Kelliher MA, Bernstein BE. An epigenetic mechanism of resistance to targeted therapy in T cell acute lymphoblastic leukemia. Nat Genet 2014; 46:364-70. [PMID: 24584072 PMCID: PMC4086945 DOI: 10.1038/ng.2913] [Citation(s) in RCA: 290] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 02/06/2014] [Indexed: 12/13/2022]
Abstract
The identification of activating NOTCH1 mutations in T cell acute lymphoblastic leukemia (T-ALL) led to clinical testing of γ-secretase inhibitors (GSIs) that prevent NOTCH1 activation. However, responses to these inhibitors have been transient, suggesting that resistance limits their clinical efficacy. Here we modeled T-ALL resistance, identifying GSI-tolerant 'persister' cells that expand in the absence of NOTCH1 signaling. Rare persisters are already present in naive T-ALL populations, and the reversibility of their phenotype suggests an epigenetic mechanism. Relative to GSI-sensitive cells, persister cells activate distinct signaling and transcriptional programs and exhibit chromatin compaction. A knockdown screen identified chromatin regulators essential for persister viability, including BRD4. BRD4 binds enhancers near critical T-ALL genes, including MYC and BCL2. The BRD4 inhibitor JQ1 downregulates expression of these targets and induces growth arrest and apoptosis in persister cells, at doses well tolerated by GSI-sensitive cells. Consistently, the GSI-JQ1 combination was found to be effective against primary human leukemias in vivo. Our findings establish a role for epigenetic heterogeneity in leukemia resistance that may be addressed by incorporating epigenetic modulators in combination therapy.
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Affiliation(s)
- Birgit Knoechel
- 1] Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA. [2] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA. [3] Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA. [4] Division of Hematology/Oncology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, USA. [5]
| | - Justine E Roderick
- 1] Department of Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA. [2]
| | - Kaylyn E Williamson
- 1] Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA. [2] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA. [3] Center for Cancer Research, Massachusetts General Hospital, Boston, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
| | - Jiang Zhu
- 1] Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA. [2] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA. [3] Center for Cancer Research, Massachusetts General Hospital, Boston, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
| | - Jens G Lohr
- 1] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA. [2] Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Matthew J Cotton
- 1] Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA. [2] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA. [3] Center for Cancer Research, Massachusetts General Hospital, Boston, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
| | - Shawn M Gillespie
- 1] Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA. [2] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA. [3] Center for Cancer Research, Massachusetts General Hospital, Boston, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
| | - Daniel Fernandez
- 1] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA. [2] Biostatistics Graduate Program, Harvard University, Cambridge, Massachusetts, USA
| | - Manching Ku
- 1] Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA. [2] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA. [3] Center for Cancer Research, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Hongfang Wang
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | | | - Serena J Silver
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Mohit Jain
- 1] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA. [2] Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, USA. [3] Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Daniel Pearson
- 1] Division of Hematology/Oncology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, USA. [2] Biological and Biomedical Sciences Graduate Program, Harvard Medical School, Boston, Massachusetts, USA
| | - Michael J Kluk
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Christopher J Ott
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | | | - Michael A Brehm
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Dale L Greiner
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Alejandro Gutierrez
- 1] Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA. [2] Division of Hematology/Oncology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Kimberly Stegmaier
- 1] Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA. [2] Division of Hematology/Oncology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Andrew L Kung
- 1] Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA. [2] Division of Hematology/Oncology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - David E Root
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - James E Bradner
- 1] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA. [2] Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Jon C Aster
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Michelle A Kelliher
- Department of Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Bradley E Bernstein
- 1] Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA. [2] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA. [3] Center for Cancer Research, Massachusetts General Hospital, Boston, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
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15
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Brd4 and HEXIM1: multiple roles in P-TEFb regulation and cancer. BIOMED RESEARCH INTERNATIONAL 2014; 2014:232870. [PMID: 24592384 PMCID: PMC3925632 DOI: 10.1155/2014/232870] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 12/19/2013] [Indexed: 12/31/2022]
Abstract
Bromodomain-containing protein 4 (Brd4) and hexamethylene bisacetamide (HMBA) inducible protein 1 (HEXIM1) are two opposing regulators of the positive transcription elongation factor b (P-TEFb), which is the master modulator of RNA polymerase II during transcriptional elongation. While Brd4 recruits P-TEFb to promoter-proximal chromatins to activate transcription, HEXIM1 sequesters P-TEFb into an inactive complex containing the 7SK small nuclear RNA. Besides regulating P-TEFb's transcriptional activity, recent evidence demonstrates that both Brd4 and HEXIM1 also play novel roles in cell cycle progression and tumorigenesis. Here we will discuss the current knowledge on Brd4 and HEXIM1 and their implication as novel therapeutic options against cancer.
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16
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Abstract
Since its discovery as an oncogene carried by the avian acute leukemia virus MC29 in myelocytomatosis (Roussel et al. 1979) and its cloning (Vennstrom et al. 1982), c-MYC (MYC), as well as its paralogs MYCN and MYCL1, has been shown to play essential roles in cycling progenitor cells born from proliferating zones during embryonic development, and in all proliferating cells after birth. MYC deletion induces cell-cycle exit or cell death, depending on the cell type and milieu, whereas MYC and MYCN amplification or overexpression promotes cell proliferation and occurs in many cancers. Here, we review the relationship of MYC family proteins to the four molecularly distinct medulloblastoma subgroups, discuss the possible roles MYC plays in each of these subgroups and in the developing cells of the posterior fossa, and speculate on possible therapeutic strategies targeting MYC.
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Affiliation(s)
- Martine F Roussel
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
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Vidler LR, Filippakopoulos P, Fedorov O, Picaud S, Martin S, Tomsett M, Woodward H, Brown N, Knapp S, Hoelder S. Discovery of novel small-molecule inhibitors of BRD4 using structure-based virtual screening. J Med Chem 2013; 56:8073-88. [PMID: 24090311 PMCID: PMC3807807 DOI: 10.1021/jm4011302] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
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Bromodomains
(BRDs) are epigenetic readers that recognize acetylated-lysine
(KAc) on proteins and are implicated in a number of diseases. We describe
a virtual screening approach to identify BRD inhibitors. Key elements
of this approach are the extensive design and use of substructure
queries to compile a set of commercially available compounds featuring
novel putative KAc mimetics and docking this set for final compound
selection. We describe the validation of this approach by applying
it to the first BRD of BRD4. The selection and testing of 143 compounds
lead to the discovery of six novel hits, including four unprecedented
KAc mimetics. We solved the crystal structure of four hits, determined
their binding mode, and improved their potency through synthesis and
the purchase of derivatives. This work provides a validated virtual
screening approach that is applicable to other BRDs and describes
novel KAc mimetics that can be further explored to design more potent
inhibitors.
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Affiliation(s)
- Lewis R Vidler
- Division of Cancer Therapeutics, Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research , 15 Cotswold Road, Sutton, Surrey SM2 5NG, United Kingdom
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18
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Abstract
The bromodomain is a highly conserved motif of 110 amino acids that is bundled into four anti-parallel α-helices and found in proteins that interact with chromatin, such as transcription factors, histone acetylases and nucleosome remodelling complexes. Bromodomain proteins are chromatin 'readers'; they recruit chromatin-regulating enzymes, including 'writers' and 'erasers' of histone modification, to target promoters and to regulate gene expression. Conventional wisdom held that complexes involved in chromatin dynamics are not 'druggable' targets. However, small molecules that inhibit bromodomain and extraterminal (BET) proteins have been described. We examine these developments and discuss the implications for small molecule epigenetic targeting of chromatin networks in cancer.
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Affiliation(s)
- Anna C Belkina
- Cancer Research Center, Nutrition Obesity Research Center, Departments of Medicine and Pharmacology, Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118, USA
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Abstract
In recent years, numerous new targets have been identified and new experimental therapeutics have been developed. Importantly, existing non-cancer drugs found novel use in cancer therapy. And even more importantly, new original therapeutic strategies to increase potency, selectivity and decrease detrimental side effects have been evaluated. Here we review some recent advances in targeting cancer.
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Affiliation(s)
- Zoya N Demidenko
- Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
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20
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Senger C, Grüning BA, Erxleben A, Döring K, Patel H, Flemming S, Merfort I, Günther S. Mining and evaluation of molecular relationships in literature. Bioinformatics 2012; 28:709-14. [DOI: 10.1093/bioinformatics/bts026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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