The function of super-enhancers (SEs) in pulmonary hypertension (PH), especially in the proliferation of pulmonary artery smooth muscle cells (PASMCs), is currently unknown. We identified SEs-targeted genes in PASMCs with chromatin immunoprecipitation (ChIP)-sequence by H3K27ac antibody and proved that CBP/p300-interacting transactivator with Glu/Asp-rich C-terminal domain, 2 (CITED2) is an SEs-targeted gene through bioinformatics prediction, ChIP-PCR, dual-luciferase reporter gene assays and other experimental methods. We also found that the expression of CITED2 and the transcription factor Forkhead Box J3 (FOXJ3) was reduced in hypoxic mouse PASMCs. In addition, the expression of CITED2 and FOXJ3 also decreased in both the patients with idiopathic pulmonary arterial hypertension (iPAH) and the human PASMCs exposed to hypoxia. The decreased expression of CITED2 was reversed by co-transfection of FOXJ3 and SEs plasmids. Overexpressing of CITED2 attenuated the PASMCs proliferation induced by hypoxia. Lentiviral overexpression of CITED2 also reversed hypoxia-induced pulmonary hypertension mice model. Mechanically, the expression of CITED2 by affecting by FOXJ3, which binding with three SEs located in the about 2000 bp of TSS. In conclusion, we first identified that CITED2 is a kind of SEs-targeted gene, modulated by FOXJ3. The FOXJ3/SEs/CITED2 axis may become a new therapeutic target of PH.

Cyclin-dependent kinase 7 (CDK7) regulates cell cycle and transcription, which are central for cancer progression. CDK7 inhibitors exhibit substantial anticancer activities in preclinical studies and are currently being evaluated in clinical trials. CDK7 is widely expressed in the body. However, the impact of CDK7 inhibition on normal tissues has received little attention. Here, we review the biological functions of CDK7, followed by its emerging roles in development, homeostasis and diseases. We discuss the regulatory mechanisms of CDK7 kinase activation and provide an overview of CDK7 substrates identified to date. Moreover, we highlight unanswered questions and propose key areas for future investigation. An advanced understanding of CDK7 will facilitate the pharmaceutical development of CDK7 inhibitors and help minimize undesirable adverse effects.

Transcription, a crucial step in the regulation of gene expression, is tightly controlled and involves several essential processes, such as chromatin organization, recognition of the specific genomic sequences, DNA binding, and ultimately recruiting the transcriptional machinery to facilitate transcript synthesis. At the center of this regulation are transcription factors (TFs), which comprise at least one DNA-binding domain (DBD) and an effector domain (ED). Although the structure and function of DBDs have been well studied, our knowledge of the structure and function of effector domains is limited. EDs are of particular importance in generating distinct transcriptional responses between protein members of the same TF family that have similar DBDs and specificities. The study of transcriptional activity conferred by effector domains has traditionally been conducted through examining protein-protein interactions. However, recent research has uncovered alternative mechanisms by which EDs regulate gene expression, such as the formation of condensates that increase the local concentration of transcription factors, cofactors, and coregulated genes, as well as DNA binding. Here, we provide a comprehensive overview of the known roles of transcription factor EDs, with a specific focus on disordered regions. Additionally, we emphasize the significance of intrinsically disordered regions (IDRs) during transcriptional regulation. We examine the mechanisms underlying the establishment and maintenance of transcriptional specificity through the structural properties of predominantly disordered EDs. We then provide a comprehensive overview of the current understanding of these domains, including their physical and chemical characteristics, as well as their functional roles.

Defects in the tumor suppressor protein p53 are found in the majority of cancers. The p53 protein (393 amino acids long) contains the folded DNA-binding domain (DBD) and tetramerization domain (TET), with the remainder of the sequence being intrinsically disordered. Since cancer-causing mutations occur primarily in the DBD, this has been the focus of most of the research on p53. However, recent reports show that the disordered N-terminal activation domain (NTAD) and C-terminal regulatory domain (CTD) function synergistically with the DBD to regulate p53 activity. We propose a mechanistic model in which intermolecular and intramolecular interactions of the disordered regions, modulated by post-translational modifications, perform a central role in the regulation and activation of p53 in response to cellular stress.

Acetylation is critically required for p53 activation, though it remains poorly understood how p53 acetylation is regulated in glioblastoma (GBM). This study reveals that p53 acetylation is a favorable prognostic marker for GBM, regardless of p53 status, and that Smad1, a key negative regulator of p53 acetylation, is involved in this process. Smad1 forms a complex with p53 and p300, inhibiting p300's interaction with p53 and leading to reduced p53 acetylation and increased Smad1 acetylation in GBM. This results in enhanced tumor growth and resistance to chemotherapy, particularly in tumors with missense mutant p53. Acetylation of K373 is found to be essential for Smad1's oncogenic function but does not confer chemoresistance in the absence of p53. Through molecular docking, it is discovered that Smad1 and p53 both interact with the acetyltransferase domain of p300, but at different amino acid sites. Disturbing the interface of Smad1 through amino acid mutations abolishes the Smad1-p300 complex and promotes p53 acetylation. Therefore, a small molecule is identified through virtual screening that specifically disrupts the Smad1-p300 interaction, offering a promising strategy for inhibiting GBM and increasing chemosensitivity by inhibiting Smad1 acetylation and restoring p53 acetylation.

O-GlcNAcylation, a modification of nucleocytoplasmic proteins in mammals, plays a critical role in various cellular processes. However, the interplay and their underlying mechanisms in chemotherapy-induced tumor regression between O-GlcNAcylation and pyroptosis, a form of programmed cell death associated with innate immunity, remains unclear. Here, we observed that during the etoposide-induced pyroptosis of SH-SY5Y and A549 cells, overall O-GlcNAcylation levels are substantially reduced. Pharmacological inhibition or genetic manipulation of O-GlcNAcylation, such as OGT inhibition or OGA overexpression, sensitized these cells to etoposide-induced pyroptosis both in vitro and in vivo. Mechanistically, mutations at S96 and S149 residues attenuated p53 O-GlcNAcylation, weakening its interaction with MDM2, reducing p53 ubiquitination, and increasing protein stability. These results suggest that S96 may be a putative O-GlcNAcylation site. Therefore, p53 target genes-Fas, DR-5, Puma, and PIDD-were transcriptionally upregulated, leading to activation of the caspase-3-GSDME axis and promoting etoposide-induced pyroptosis in various tumor cells. This study demonstrates a previously uncharacterized association between O-GlcNAcylation and chemotherapy-induced pyroptosis, offering potential therapeutic interventions for pyroptosis-related diseases.

Acetyltransferases are enzymes that catalyze the transfer of an acetyl group to a substrate, a modification referred to as acetylation. Loss-of-function variants in genes encoding acetyltransferases can lead to congenital disorders, often characterized by intellectual disability and heart and muscle defects. Their activity is influenced by dietary nutrients that alter acetyl coenzyme A levels, a key cofactor. Cardiovascular diseases, including ischemic, hypertensive, and diabetic heart diseases - leading causes of mortality in the elderly - are largely attributed to prolonged lifespan and the growing prevalence of metabolic syndrome. Acetyltransferases thus serve as a crucial link between lifestyle modifications, cardiometabolic disease, and aging through both epigenomic and non-epigenomic mechanisms. In this review, we discuss the roles and relevance of acetyltransferases. While the sirtuin family of deacetylases has been extensively studied in longevity, particularly through fasting-mediated NAD+ metabolism, recent research has brought attention to the essential roles of acetyltransferases in health and aging-related pathways, including cell proliferation, DNA damage response, mitochondrial function, inflammation, and senescence. We begin with an overview of acetyltransferases, classifying them by domain structure, including canonical and non-canonical lysine acetyltransferases, N-terminal acetyltransferases, and sialic acid O-acetyltransferases. We then discuss recent advances in understanding acetyltransferase-related pathologies, particularly focusing on cardiovascular disease and aging, and explore their potential therapeutic applications for promoting health in older individuals.

DNA damage can lead to mutations that can alter the function of oncogenes or tumor suppressor genes, thus promoting the development of cancer. p53 plays a multifaceted and complex role in the DNA damage response and cancer progression and is known as the 'guardian of the gene'. When DNA damage occurs, p53 is activated through a series of post-translational modifications, which stabilize the protein and enhance its function as a transcription factor. It regulates processes including cell cycle checkpoints, DNA repair and apoptosis, thereby preventing the spread of damaged DNA and maintaining genome integrity. On the one hand, p53 can initiate cell cycle arrest and induce cells to enter the G1/S and G2/M checkpoints, preventing cells with damaged DNA from continuing to proliferate and gaining time for DNA repair. At the same time, p53 can promote the activation of DNA repair pathways, including base excision repair, nucleotide excision repair and other repair pathways, to ensure the integrity of genetic material. If the damage is too severe to repair, p53 will trigger the apoptosis process to eliminate potential cancer risks in time. p53 also plays a pivotal role in cancer progression. Mutations in the p53 gene are frequently found in many cancers, and the mutated p53 not only loses its normal tumor suppressor function but may even acquire pro-cancer activity. Therefore, we also discuss therapeutic strategies targeting the p53 pathway, such as the use of small-molecule drugs to restore the function of wild-type p53, the inhibition of negative regulatory factors and synthetic lethality approaches for p53-deficient tumors. This review therefore highlights the important role of p53 in maintaining genomic stability and its potential in therapeutic strategies for cancer.

Post-translational modifications (PTMs) dynamically regulate the critical stress response and tumor suppressive functions of p53. Among these, acetylation events mediated by multiple acetyltransferases lead to differential target gene activation and subsequent cell fate. However, our understanding of these events is incomplete due to, in part, the inability to selectively and dynamically control p53 acetylation. We recently developed a heterobifunctional small molecule system, AceTAG, to direct the acetyltransferase p300/CBP for targeted protein acetylation in cells. Here, we expand AceTAG to leverage the acetyltransferase PCAF/GCN5 and apply these tools to investigate the functional consequences of targeted p53 acetylation in human cancer cells. We demonstrate that the recruitment of p300/CBP or PCAF/GCN5 to p53 results in distinct acetylation events and differentiated transcriptional activities. Further, we show that chemically induced acetylation of multiple hotspot p53 mutants results in increased stabilization and enhancement of transcriptional activity. Collectively, these studies demonstrate the utility of AceTAG for functional investigations of protein acetylation.

Acute myeloid leukemia (AML), an aggressive malignancy of hematopoietic stem cells, is characterized by the blockade of cell differentiation, uncontrolled proliferation, and cell expansion that impairs healthy hematopoiesis and results in pancytopenia and susceptibility to infections. Several genetic and chromosomal aberrations play a role in AML and influence patient outcomes. TP53 is a key tumor suppressor gene involved in a variety of cell features, such as cell-cycle regulation, genome stability, proliferation, differentiation, stem-cell homeostasis, apoptosis, metabolism, senescence, and the repair of DNA damage in response to cellular stress. In AML, TP53 alterations occur in 5%-12% of de novo AML cases. These mutations form an important molecular subgroup, and patients with these mutations have the worst prognosis and shortest overall survival among patients with AML, even when treated with aggressive chemotherapy and allogeneic stem cell transplant. The frequency of TP53-mutations increases in relapsed and recurrent AML and is associated with chemoresistance. Progress in AML genetics and biology has brought the novel therapies, however, the clinical benefit of these agents for patients whose disease is driven by TP53 mutations remains largely unexplored. This review focuses on the molecular characteristics of TP53-mutated disease; the impact of TP53 on selected hallmarks of leukemia, particularly metabolic rewiring and immune evasion, the clinical importance of TP53 mutations; and the current progress in the development of preclinical and clinical therapeutic strategies to treat TP53-mutated disease.

Wild-type (wt) p53 and mutant forms (mutp53) play a key but opposite role in carcinogenesis. wtP53 acts as an oncosuppressor, preventing oncogenic transformation, while mutp53, which loses this property, may instead favor this process. This suggests that a better understanding of the mechanisms activating wtp53 while inhibiting mutp53 may help to design more effective anti-cancer treatments. In this review, we examine possible PTMs with which both wt- and mutp53 can be decorated and discuss how their manipulation could represent a possible strategy to control the stability and function of these proteins, focusing in particular on mutp53. The impact of ubiquitination, phosphorylation, acetylation, and methylation of p53, in the context of several solid and hematologic cancers, will be discussed. Finally, we will describe some of the recent studies reporting that wt- and mutp53 may influence the expression and activity of enzymes responsible for epigenetic changes such as acetylation, methylation, and microRNA regulation and the possible consequences of such changes.

Epigenetic changes are common in cancer and include aberrant DNA methylation and histone modifications, including both acetylation or methylation. DNA methylation in the promoter regions and histone deacetylation are usually accompanied by gene silencing, and may lead to the suppression of tumor suppressors in cancer cells. An interaction between epigenetic pathways has been reported that could be exploited to more efficiently target aggressive cancer cells, particularly those against which current treatments usually fail, such as pancreatic cancer. In this study, we explored the possibility to combine the DNA demethylating agent 5-AZA with HDAC inhibitor SAHA to treat pancreatic cancer cell lines, focusing on the acetylation of mutp53 and the consequences on its stability, as well as on the interaction of this protein with c-myc and BRCA-1, key molecules in cancer survival. The results obtained suggest that SAHA/5-AZA combination was more effective than single treatments to promote the degradation of mutp53, to upregulate p21 and downregulate c-Myc and BRCA-1, thus increasing DNA damage and cytotoxicity in pancreatic cancer cells.

Daunorubicin, also known as daunomycin, is a DNA‑targeting anticancer drug that is used as chemotherapy, mainly for patients with leukemia. It has also been shown to have anticancer effects in monotherapy or combination therapy in solid tumors, but at present it has not been adequately studied in colorectal cancer (CRC). In the present study, from a screening using an FDA‑approved drug library, it was found that daunorubicin suppresses GLI‑dependent luciferase reporter activity. Daunorubicin also increased p53 levels, which contributed to both GLI1 suppression and apoptosis. The current detailed investigation showed that daunorubicin promoted the β‑TrCP‑mediated ubiquitination and proteasomal degradation of GLI1. Moreover, a competition experiment using BODIPY‑cyclopamine, a well‑known Smo inhibitor, suggested that daunorubicin does not bind to Smo in HCT116 cells. Administration of daunorubicin (2 mg/kg, ip, qod, 15 days) into HCT116 xenograft mice profoundly suppressed tumor progress and the GLI1 level in tumor tissues. Taken together, the present results revealed that daunorubicin suppresses canonical Hedgehog pathways in CRC. Ultimately, the present study discloses a new mechanism of daunorubicin's anticancer effect and might provide a rationale for expanding the clinical application of daunorubicin.

Lung adenocarcinoma (LUAD) accounts for a high proportion of tumor deaths globally, while methyltransferase-related lncRNAs in LUAD were poorly studied.

In our study, we focused on two distinct cohorts, TCGA-LUAD and GSE3021, to establish a signature of methyltransferase-related long non-coding RNAs (MeRlncRNAs) in LUAD. We employed univariate Cox and LASSO regression analyses as our main analytical tools. The GSE30219 cohort served as the validation cohort for our findings. Furthermore, to explore the differential pathway enrichments between groups stratified by risk, we utilized Gene Set Enrichment Analysis (GSEA). Additionally, single-sample GSEA (ssGSEA) was conducted to assess the immune infiltration landscape within each sample. Reverse transcription quantitative PCR (RT-qPCR) was also performed to verify the expression of prognostic lncRNAs in both clinically normal and LUAD samples.

In LUAD, we identified a set of 32 MeRlncRNAs. We further narrowed our focus to six prognostic lncRNAs to develop gene signatures. The TCGA-LUAD cohort and GSE30219 were utilized to validate the risk score model derived from these signatures. Our analysis showed that the risk score served as an independent prognostic factor, linked to immune-related pathways. Additionally, the analysis of immune infiltration revealed that the immune landscape in high-risk groups was suppressed, which could contribute to poorer prognoses. We also constructed a regulatory network comprising 6 prognostic lncRNAs, 19 miRNAs, and 21 mRNAs. Confirmatory RT-qPCR results aligned with public database findings, verifying the expression of these prognostic lncRNAs in the samples.

The prognostic gene signature of LUAD associated with MeRlncRNAs that we provided, may offer us a comprehensive picture of the prognosis prediction for LUAD patients.

Cellular membranes serve as an epicentre combining extracellular and cytosolic components with membranous effectors, which together support numerous fundamental cellular signalling pathways that mediate biological responses. To execute their functions, membrane proteins, lipids and carbohydrates arrange, in a highly coordinated manner, into well-defined assemblies displaying diverse biological and biophysical characteristics that modulate several signalling events. The loss of membrane homeostasis can trigger oncogenic signalling. More recently, it has been documented that select membrane active dietaries (MADs) can reshape biological membranes and subsequently decrease cancer risk. In this review, we emphasize the significance of membrane domain structure, organization and their signalling functionalities as well as how loss of membrane homeostasis can steer aberrant signalling. Moreover, we describe in detail the complexities associated with the examination of these membrane domains and their association with cancer. Finally, we summarize the current literature on MADs and their effects on cellular membranes, including various mechanisms of dietary chemoprevention/interception and the functional links between nutritional bioactives, membrane homeostasis and cancer biology.

Cancer is a leading cause of death worldwide. Targeted therapies aimed at key oncogenic driver mutations in combination with chemotherapy and radiotherapy as well as immunotherapy have benefited cancer patients considerably. Tumor protein p53 (TP53), a crucial tumor suppressor gene encoding p53, regulates numerous downstream genes and cellular phenotypes in response to various stressors. The affected genes are involved in diverse processes, including cell cycle arrest, DNA repair, cellular senescence, metabolic homeostasis, apoptosis, and autophagy. However, accumulating recent studies have continued to reveal novel and unexpected functions of p53 in governing the fate of tumors, for example, functions in ferroptosis, immunity, the tumor microenvironment and microbiome metabolism. Among the possibilities, the evolutionary plasticity of p53 is the most controversial, partially due to the dizzying array of biological functions that have been attributed to different regulatory mechanisms of p53 signaling. Nearly 40 years after its discovery, this key tumor suppressor remains somewhat enigmatic. The intricate and diverse functions of p53 in regulating cell fate during cancer treatment are only the tip of the iceberg with respect to its equally complicated structural biology, which has been painstakingly revealed. Additionally, TP53 mutation is one of the most significant genetic alterations in cancer, contributing to rapid cancer cell growth and tumor progression. Here, we summarized recent advances that implicate altered p53 in modulating the response to various cancer therapies, including chemotherapy, radiotherapy, and immunotherapy. Furthermore, we also discussed potential strategies for targeting p53 as a therapeutic option for cancer.

Hepatocellular carcinoma (HCC) is among the main causes of death by cancer worldwide, representing about 80-90% of all liver cancers. Treatments available for advanced HCC include atezolizumab, bevacizumab, sorafenib, among others. Atezolizumab and bevacizumab are immunological options recently incorporated into first-line treatments, along with sorafenib, for which great treatment achievements have been reached. However, sorafenib resistance is developed in most patients, and therapeutical combinations targeting cancer hallmark mechanisms and intracellular signaling have been proposed. In this review, we compiled evidence of the mechanisms of cell death caused by sorafenib administered alone or in combination with valproic acid and metformin and discussed them from a molecular perspective.

REV7 is an abundant, multifunctional protein that is a known factor in cell cycle regulation and in several key DNA repair pathways including Trans-Lesion Synthesis (TLS), the Fanconi Anemia (FA) pathway, and DNA Double-Strand Break (DSB) repair pathway choice. Thus far, no direct role has been studied for REV7 in the DNA damage response (DDR) signaling pathway. Here we describe a novel function for REV7 in DSB-induced p53 signaling. We show that REV7 binds directly to p53 to block ATM-dependent p53 Ser15 phosphorylation. We also report that REV7 is involved in the destabilization of p53. These findings affirm REV7's participation in fundamental cell cycle and DNA repair pathways. Furthermore, they highlight REV7 as a critical factor for the integration of multiple processes that determine viability and genome stability.

Maintaining a tumour cell's resistance to apoptosis (organized cell death) is essential for cancer to metastasize. Signal molecules play a critical function in the tightly regulated apoptotic process. Apoptosis may be triggered by a wide variety of cellular stresses, including DNA damage, but its ultimate goal is always the same: the removal of damaged cells that might otherwise develop into tumours. Many chemotherapy drugs rely on cancer cells being able to undergo apoptosis as a means of killing them. The mechanisms by which DNA-damaging agents trigger apoptosis, the interplay between pro- and apoptosis-inducing signals, and the potential for alteration of these pathways in cancer are the primary topics of this review.

Non-homologous end joining, an important DNA-double-stranded break repair pathway, plays a prominent role in conferring resistance to radiotherapeutic agents, resulting in cancer progression and relapse.

The molecular players involved in the radio-sensitizing effects of piperine and many other phytocompounds remain evasive to a great extent. The study is designed to assess if piperine, a plant alkaloid can alter the radioresistance by modulating the expression of non-homologous end-joining machinery.

Estrogen receptor-positive/negative, breast cancer cells were cultured to understand the synergetic effects of piperine with radiotherapy. Cisplatin and Bazedoxifene were used as positive controls. Cells were exposed to γ- radiation using Low Dose gamma Irradiator-2000. The piperine effect on Estrogen receptor modulation, DNA-Damage, DNA-Damage-Response, and apoptosis was done by western blotting, immunofluorescence, yeast-based-estrogen-receptor-LacZ-reporter assay, and nuclear translocation analysis. Micronuclei assay was done for DNA damage and genotoxicity, and DSBs were quantified by γH2AX-foci-staining using confocal microscopy. Flow cytometry analysis was done to determine the cell cycle, mitochondrial membrane depolarization, and Reactive oxygen species generation. Pharmacophore analysis and protein-ligand interaction studies were done using Schrodinger software. Synergy was computed by compusyn-statistical analysis. Standard errors/deviation/significance were computed with GraphPad prism.

Using piperine, we propose a new strategy for overcoming acquired radioresistance through estrogen receptor-mediated modulation of the NHEJ pathway. This is the first comprehensive study elucidating the mechanism of radio sensitizing potential of piperine. Piperine enhanced the radiation-induced cell death and enhanced the expression and activation of Estrogen receptor β, while Estrogen receptor α expression and activation were reduced. In addition, piperine shares common pharmacophore features with most of the known estrogen agonists and antagonists. It altered the estrogen receptor α/β ratio and the expression of estrogen-responsive proteins of DDR and NHEJ pathway. Enhanced expression of DDR proteins, ATM, p53, and P-p53 with low DNA-PK repair complex (comprising of DNA-PKcs/Ku70/Ku80), resulted in the accumulation of radiation-induced DNA double-stranded breaks (as evidenced by MNi and γH2AX-foci) culminating in cell cycle arrest and mitochondrial-pathway of apoptosis.

In conclusion, our study for the first time reported that piperine sensitizes breast cancer cells to radiation by accumulating DNA breaks, through altering the expression of DNA-PK Complex, and DDR proteins, via selective estrogen receptor modulation, offering a novel strategy for combating radioresistance.

Adenosine triphosphate (ATP) induced cell death (AICD) is a critical cellular process that has garnered substantial scientific interest for its profound relevance to cancer biology and to therapeutic interventions. This comprehensive review unveils the intricate web of AICD mechanisms and their intricate connections with cancer biology. This review offers a comprehensive framework for comprehending the multifaceted role of AICD in the context of cancer. This is achieved by elucidating the dynamic interplay between systemic and cellular ATP homeostasis, deciphering the intricate mechanisms governing AICD, elucidating its intricate involvement in cancer signaling pathways, and scrutinizing validated key genes. Moreover, the exploration of AICD as a potential avenue for cancer treatment underscores its essential role in shaping the future landscape of cancer therapeutics.

TP53 plays a critical role as a tumor suppressor by controlling cell cycle progression, DNA repair, and apoptosis. Post-translational modifications such as acetylation of specific lysine residues in the DNA binding and carboxy-terminus regulatory domains modulate its tumor suppressor activities. In this study, we addressed the functional consequences of the germline TP53 p.K164E (NM_000546.5: c.490A>G) variant identified in a patient with early-onset breast cancer and a significant family history of cancer. K164 is a conserved residue located in the L2 loop of the p53 DNA binding domain that is post-translationally modified by acetylation. In silico, in vitro, and in vivo analyses demonstrated that the glutamate substitution at K164 marginally destabilizes the p53 protein structure but significantly impairs sequence-specific DNA binding, transactivation, and tumor cell growth inhibition. Although p.K164E is currently considered a variant of unknown significance by different clinical genetic testing laboratories, the clinical and laboratory-based findings presented here provide strong evidence to reclassify TP53 p.K164E as a likely pathogenic variant.

α-Catenin plays a critical role in tissue integrity, repair, and embryonic development. However, the post-translational modifications of α-catenin and the correlative roles in regulating cancer progression remain unclear. Here, we report that α-catenin is acetylated by p300, and identify three acetylation sites, K45, K866, and K881. Conversely, α-catenin acetylation can be reversed by deacetylase HDAC6. Mechanistically, α-catenin acetylation releases the transcriptional coactivator Yes-associated protein 1 (Yap1) by blocking the interaction between α-catenin and Yap1, and promotes the accumulation of Yap1 in the nucleus. Through this mechanism, acetylation weakens the capacity of α-catenin to inhibit breast cancer cell proliferation and tumor growth in mice. Meanwhile, we show that CDDP induces acetylation of α-catenin, and acetylated α-catenin resists the apoptosis under CDDP conditions. Additionally, acetylation inhibits the proteasome-dependent degradation of α-catenin, thus enhancing the stability of α-catenin for storage. Taken together, our results demonstrate that α-catenin can be acetylated, an event that is key for the subcellular distribution of Yap1 and subsequent facilitation of breast tumorigenesis.

Radiation-induced lung injury (RILI) is a common side effect in thoracic tumor patients undergoing radiotherapy. At present, there is no ideal radio-protective agent which is widely used in RILI treatment. Astilbin (AST), a bioactive flavonoid, exhibits various biological effects, including anti-inflammatory, antioxidant, and anti-fibrotic activities, which partly result from reducing oxidative stress and inflammation in various pathogenic conditions. However, the protective efficacy of AST to ameliorate RILI has not been reported. In this study, we employed network pharmacology, RNA sequencing, and experimental evaluation to reveal the effects and pharmacological mechanism of AST to treat RILI in vivo and in vitro. We observed that AST reduced radiation-induced apoptosis, DNA damage, inflammatory reactions, and the reactive oxygen species (ROS) level in human normal lung epithelial cells BEAS-2B. Further study showed that AST treatment significantly ameliorated RILI by reducing the radiation-induced pathology changes and inflammatory reaction of lung tissue in C57BL/6J mice. Mechanistically, the expression of epithelial-mesenchymal transition (EMT) markers and radiation-triggered acetylation of the p53 protein were alleviated by AST treatment. Furthermore, AST alleviated the acetylation of p53 after intervention of Trichostatin A (TSA). Our data indicate that AST can alleviate RILI by inhibiting inflammatory reactions and the EMT process through decreasing the expression of p53 acetylation. In conclusion, our study suggests that AST has great potential to be a new protective and therapeutic compound for RILI.

The C-terminal of tumor suppressor protein p53 is intrinsically disordered while unbound. This particular segment often shows structural plasticity when bound to other binding partners. The disordered component undergoes a disordered to ordered transition upon recognition. Post-translational modifications (PTMs), namely phosphorylation and acetylation, significantly alter the structural motifs of the segment. Among the various types of PTMs, phosphorylation, and acetylation of p53 at both N- and C- terminals lead to stabilization and activation. It has been noted experimentally that phosphorylation often regulates (enhances or reduces) the acetylation at specific sites. The phosphorylation of Thr377 and Ser378 reduces the acetylation of Lys373 and Lys382. Mutations of Thr377 and Ser378 to neutral Ala enhance and phospho mimic Asp reduce the acetylation of Lys373 and Lys382. Simulations of several single-point and pair-wise mutated systems have been generated to compare how the presence or absence of phosphorylation favors or disfavors the acetylation by thermodynamic and conformational analysis. We are using implicit solvent replica exchange molecular dynamics simulations to get 200 ns well-converged conformational ensembles of each system. Different sets of systems having both single and double PTMs are simulated. The results admit the appreciable change in the secondary structural level upon specific PTM. Also, the residual structure of the unbound p53 with single-point PTM varies significantly with pair-wise modifications. These observations further shed light on the relationship between the interdependencies of the specific PTM sites and the secondary structural levels.Communicated by Ramaswamy H. Sarma.

Cisplatin is the effective chemotherapeutic drug in colon cancer treatment, but its therapeutic efficacy is limited by intrinsic or acquired drug resistance and detrimental side effects. Therefore, improving the effect of cisplatin chemotherapy remains a great challenge. The previous study identified that USP39 was relevant to cisplatin resistance of lung cancer. However, the function and mechanisms of USP39 regulating the chemosensitivity of cisplatin in colorectal cancer remain unclear. In this study, we reveal that USP39 is associated with colon cancer cells sensitivity to cisplatin. Depletion of USP39 enhances the cisplatin-induced apoptosis in HCT116 cells. Conversely, overexpression of USP39 attenuates apoptosis in RKO cells. Furthermore, we demonstrate that USP39 depletion promotes apoptosis induced by cisplatin, which is related with the induction of oxidative stress and DNA damage response. Further studies show that USP39 regulates cisplatin-induced apoptosis dependent on p53. The underlying mechanism is demonstrated by knocking down USP39, that results in p53 upregulation, associated with its prolonged half-life. Collectively, our findings reveal that USP39 might be a negative factor of the p53 mediated cisplatin sensitivity of colon cancer, and suggest USP39 as a potential molecular target for cisplatin chemotherapy of colon cancer.

Double strand break (DSB) repair is critical to maintaining the integrity of the genome. DSB repair deficiency underlies multiple pathologies, including cancer, chromosome instability syndromes, and, potentially, neurodevelopmental defects. DSB repair is mainly handled by two pathways: highly accurate homologous recombination (HR), which requires a sister chromatid for template-based repair, limited to S/G2 phases of the cell cycle, and canonical non-homologous end joining (c-NHEJ), available throughout the cell cycle in which minimum homology is sufficient for highly efficient yet error-prone repair. Some circumstances, such as cancer, require alternative highly mutagenic DSB repair pathways like microhomology-mediated end-joining (MMEJ) and single-strand annealing (SSA), which are triggered to attend to DNA damage. These non-canonical repair alternatives are emerging as prominent drivers of resistance in drug-based tumor therapies. Multiple DSB repair options require tight inter-pathway regulation to prevent unscheduled activities. In addition to this complexity, epigenetic modifications of the histones surrounding the DSB region are emerging as critical regulators of the DSB repair pathway choice. Modeling approaches to understanding DSBs repair pathway choice are advantageous to perform simulations and generate predictions on previously uncharacterized aspects of DSBs response. In this work, we present a Boolean network model of the DSB repair pathway choice that incorporates the knowledge, into a dynamic system, of the inter-pathways regulation involved in DSB repair, i.e., HR, c-NHEJ, SSA, and MMEJ. Our model recapitulates the well-characterized HR activity observed in wild-type cells in response to DSBs. It also recovers clinically relevant behaviors of BRCA1/FANCS mutants, and their corresponding drug resistance mechanisms ascribed to DNA repair gain-of-function pathogenic variants. Since epigenetic modifiers are dynamic and possible druggable targets, we incorporated them into our model to better characterize their involvement in DSB repair. Our model predicted that loss of the TIP60 complex and its corresponding histone acetylation activity leads to activation of SSA in response to DSBs. Our experimental validation showed that TIP60 effectively prevents activation of RAD52, a key SSA executor, and confirms the suitable use of Boolean network modeling for understanding DNA DSB repair.

A series of novel thiosemicarbazone derivatives containing 5-methoxy isatin were designed and synthesized with modification on N(4) position. Derivatives considering structure-activity relationship have been designed and synthesized by condensing thiosemicarbazide with 5-methoxy isatin. The synthesized compounds were characterized by elemental analysis, FT-IR spectroscopy, UV-visible spectroscopy, NMR (1H, 13C) spectroscopy, mass spectrometry, and a single-crystal study. Biological evaluation of the synthesized compounds revealed that MeOIstPyrd is the most promising compound against skin cancer cell line, A431, with an IC50 value of 0.9 μM. In addition, MeOIstPyrd also exhibited low toxicity against the normal human fibroblast and the human embryonic kidney 293 cell line, HLF-1, and HEK293, respectively. Furthermore, the mechanistic study revealed that MeOIstPyrd efficiently inhibited cell proliferation, migration, and spheroid formation by activating the mitochondrial intrinsic apoptotic pathway. MeOIstPyrd also induces DNA damage and activates p53 irrespective of the p53 status. It increases the half-life of p53 and stabilizes p53 by phosphorylating it at ser15. Moreover, MeOIstPyrd was found to bind to MDM2 in the p53 sub-pocket and, therefore, block p53-MDM2 interaction. Our result exhibited potential anticancer activity of MeOIstPyrd in the A431 cell line and its ability in restoring mutant p53, which is an interesting and promising strategy for cancer therapeutics.

Pulmonary epithelial cells act as the first line of defense against various air pollutant particles. Previous studies have reported that particulate matter 2.5 (PM2.5) could trigger pulmonary inflammation and fibrosis by inducing pulmonary epithelial senescence and ferroptosis. Sirtuin 3 (SIRT3) is one of critical the mitochondrial NAD+-dependent deacetylases, exerting antioxidant and anti-aging effects in multiple diseases. The present study aimed to explore the role of SIRT3 in PM2.5-induced lung injury as well as possible mechanisms. The role of SIRT3 in PM2.5-induced lung injury was investigated by SIRT3 genetic depletion, adenovirus-mediated overexpression in type II alveolar epithelial (AT2) cells, and pharmacological activation by melatonin. The protein level and activity of SIRT3 in lung tissues and AT2 cells were significantly downregulated after PM2.5 stimulation. SIRT3 deficiency in AT2 cells aggravated inflammatory response and collagen deposition in PM2.5-treated lung tissues. RNA-sequence and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the differentially expressed genes (DEGs) between SIRT3 flox and SIRT3 CKO mice were mainly enriched in ferroptosis and cellular longevity. Western blot further showed that SIRT3 deficiency in AT2 cells significantly upregulated the proteins associated with ferroptosis and cell senescence in PM2.5-treated lung tissues. In vitro experiments also showed that SIRT3 overexpression could decrease the levels of ferroptosis and cell senescence in PM2.5-treated AT2 cells. In addition, we found that PM2.5 could increase the acetylation of P53 via triggering DNA damage in AT2 cells. And SIRT3 could deacetylate P53 at lysines 320 (K320), thus reducing its transcriptional activity. PM2.5 decreased the protein level of SIRT3 by inducing proteasome pathway through downregulating USP3. Finally, we found that SIRT3 agonist, melatonin treatment could alleviate PM2.5-induced senescence and ferroptosis in mice. In conclusion, targeting USP3-SIRT3-P53 axis may be a novel therapeutic strategy against PM2.5-induced pulmonary inflammation and fibrosis by decreasing pulmonary epithelial senescence and ferroptosis.

Breast cancer pathogenesis, treatment, and patient outcomes are shaped by tumor-intrinsic genomic alterations that divide breast tumors into molecular subtypes. These molecular subtypes often dictate viable therapeutic interventions and, ultimately, patient outcomes. However, heterogeneity in therapeutic response may be a result of underlying epigenetic features that may further stratify breast cancer patient outcomes. In this review, we examine non-genetic mechanisms that drive functional changes to chromatin in breast cancer to contribute to cell and tumor fitness and highlight how epigenetic activity may inform the therapeutic response. We conclude by providing perspectives on the future of therapeutic targeting of epigenetic enzymes, an approach that holds untapped potential to improve breast cancer patient outcomes.

Chromatin structure plays a fundamental role in regulating gene expression, with histone modifiers shaping the structure of chromatin by adding or removing chemical changes to histone proteins. The p53 transcription factor controls gene expression, binds target genes, and regulates their activity. While p53 has been extensively studied in cancer research, specifically in relation to fundamental cellular processes, including gene transcription, apoptosis, and cell cycle progression, its association with histone modifiers has received limited attention. This review explores the interplay between histone modifiers and p53 in regulating gene expression. We discuss how histone modifications can influence how p53 binds to target genes and how this interplay can be disrupted in cancer cells. This review provides insights into the complex mechanisms underlying gene regulation and their implications for potential cancer therapy.

Histone deacetylase 8 (HDAC8) aberrantly deacetylates histone and non-histone proteins. These include structural maintenance of chromosome 3 (SMC3) cohesin protein, retinoic acid induced 1 (RAI1), p53, etc and thus, regulating diverse processes such as leukemic stem cell (LSC) transformation and maintenance. HDAC8, one of the crucial HDACs, affects the gene silencing process in solid and hematological cancer progressions especially on acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). A specific HDAC8 inhibitor PCI-34051 showed promising results against both T-cell lymphoma and AML. Here, we summarize the role of HDAC8 in hematological malignancies, especially in AML and ALL. This article also introduces the structure/function of HDAC8 and a special attention has been paid to address the HDAC8 enzyme selectivity issue in hematological cancer especially against AML and ALL.

VprBP (also known as DCAF1) is a recently identified kinase that is overexpressed in cancer cells and serves as a major determinant for epigenetic gene silencing and tumorigenesis. The role of VprBP in driving target gene inactivation has been largely attributed to its ability to mediate histone H2A phosphorylation. However, whether VprBP also phosphorylates non-histone proteins and whether these phosphorylation events drive oncogenic signaling pathways have not been explored. Here we report that serine 367 phosphorylation (S367p) of p53 by VprBP is a key player in attenuating p53 transcriptional and growth suppressive activities. VprBP catalyzes p53S367p through a direct interaction with the C-terminal domain of p53. Mechanistically, VprBP-mediated S367p inhibits p53 function in the wake of promoting p53 proteasomal degradation, because blocking p53S367p increases p53 protein levels, thereby enhancing p53 transactivation. Furthermore, abrogation of VprBP-p53 interaction by p53 acetylation is critical for preventing p53S367p and potentiating p53 function in response to DNA damage. Together, our findings establish VprBP-mediated S367p as a negative regulator of p53 function and identify a previously uncharacterized mechanism by which S367p modulates p53 stability.

Though many folded proteins assume one stable structure that performs one function, a small-but-increasing number remodel their secondary and tertiary structures and change their functions in response to cellular stimuli. These fold-switching proteins regulate biological processes and are associated with autoimmune dysfunction, severe acute respiratory syndrome coronavirus-2 infection, and more. Despite their biological importance, it is difficult to computationally predict fold switching. With the aim of advancing computational prediction and experimental characterization of fold switchers, this review discusses several features that distinguish fold-switching proteins from their single-fold and intrinsically disordered counterparts. First, the isolated structures of fold switchers are less stable and more heterogeneous than single folders but more stable and less heterogeneous than intrinsically disordered proteins (IDPs). Second, the sequences of single fold, fold switching, and intrinsically disordered proteins can evolve at distinct rates. Third, proteins from these three classes are best predicted using different computational techniques. Finally, late-breaking results suggest that single folders, fold switchers, and IDPs have distinct patterns of residue-residue coevolution. The review closes by discussing high-throughput and medium-throughput experimental approaches that might be used to identify new fold-switching proteins.

Schizophrenia (SZ) is a serious mental disorder that is typically treated with antipsychotic medication. Treatment-resistant schizophrenia (TRS) is the condition where symptoms remain after pharmacological intervention, resulting in long-lasting functional and social impairments. As the identification and treatment of a TRS patient requires previous failed treatments, early mechanisms of detection are needed in order to quicken the access to effective therapy, as well as improve treatment adherence. In this study, we aim to find a microRNA (miRNA) signature for TRS, as well as to shed some light on the molecular pathways potentially involved in this severe condition. To do this, we compared the blood miRNAs of schizophrenia patients that respond to medication and TRS patients, thus obtaining a 16-miRNA TRS profile. Then, we assessed the ability of this signature to separate responders and TRS patients using hierarchical clustering, observing that most of them are grouped correctly (~70% accuracy). We also conducted a network, pathway analysis, and bibliography search to spot molecular pathways potentially altered in TRS. We found that the response to stress seems to be a key factor in TRS and that proteins p53, SIRT1, MDM2, and TRIM28 could be the potential mediators of such responses. Finally, we suggest a molecular pathway potentially regulated by the miRNAs of the TRS profile.

Intrinsically disordered proteins are frequent targets for functional regulation through post-translational modification due to their high accessibility to modifying enzymes and the strong influence of changes in primary structure on their chemical properties. While lysine Nε-acetylation was first observed as a common modification of histone tails, proteomic data suggest that lysine acetylation is ubiquitous among both nuclear and cytosolic proteins. However, compared with our biophysical understanding of the other common post-translational modifications, mechanistic studies to document how lysine Nε-acetyl marks are placed, utilized to transduce signals, and eliminated when signals need to be turned off, have not kept pace with proteomic discoveries. Herein we report a nuclear magnetic resonance method to monitor Nε-lysine acetylation through enzymatic installation of a13C-acetyl probe on a protein substrate, followed by detection through 13C direct-detect spectroscopy. We demonstrate the ease and utility of this method using histone H3 tail acetylation as a model. The clearest advantage to this method is that it requires no exogenous tags that would otherwise add steric bulk, change the chemical properties of the modified lysine, or generally interfere with downstream biochemical processes. The non-perturbing nature of this tagging method is beneficial for application in any system where changes to local structure and chemical properties beyond those imparted by lysine modification are unacceptable, including intrinsically disordered proteins, bromodomain containing protein complexes, and lysine deacetylase enzyme assays.

Photodynamic therapy (PDT) is a promising non-invasive treatment modality for cancer and can be potentiated by combination with chemotherapy. Here, we combined PDT of novel porphyrin-based photosensitizers with low dose doxorubicin (Dox) to get maximum outcome. Dox potentiated and showed synergism with PDT under in vitro conditions on CT26.WT cells. The current colon cancer treatment strategies assure partial or even complete tumour regression but loco-regional relapse or distant metastasis is the major cause of death despite combination therapy. The spared cells after the treatment contribute to relapse and it is important to study their behaviour in host environment. Hence, we developed relapse models for PDT, Dox and combination treatments by transplanting respectively treated equal number of live cells to mice (n = 5) for tumour formation. Most of the treated cells lost tumour forming ability, but some treatment resistant cells developed tumours in few mice. These tumours served as relapse models and Western blot analysis of tumour samples provided clinically relevant information to delineate resistance strategies of individual as well as combination therapies at molecular level. Our results showed that low dose Dox helped in increasing the tumour inhibiting effect of PDT in combination therapy, but still there are indeed possibilities of relapse at later stages due to chemoresistance and immune suppression that may occur post-treatment. We observed that the combination therapy may also lead to the development of multidrug resistant (MDR) phenotype during relapse. Thus, this study provided clinically relevant information to further strengthen and improve PDT-drug combination therapy in order to avoid relapse and to treat cancer more effectively.

The C-terminal region of the tumor suppressor protein p53 contains three domains, nuclear localization signal (NLS), tetramerization domain (TET), and C-terminal regulatory domain (CTD), which are essential for p53 function. Characterization of the structure and interactions of these domains within full-length p53 has been limited by the overall size and flexibility of the p53 tetramer. Using trans-intein splicing, we have generated full-length p53 constructs in which the C-terminal region is isotopically labeled with 15N for NMR analysis, allowing us to obtain atomic-level information on the C-terminal domains in the context of the full-length protein. Resonances of NLS and CTD residues have narrow linewidths, showing that these regions are largely solvent-exposed and dynamically disordered, whereas resonances from the folded TET are broadened beyond detection. Two regions of the CTD, spanning residues 369-374 and 381-388 and with high lysine content, make dynamic and sequence-independent interactions with DNA in regions that flank the p53 recognition element. The population of DNA-bound states increases as the length of the flanking regions is extended up to approximately 20 base pairs on either side of the recognition element. Acetylation of K372, K373, and K382, using a construct of the transcriptional coactivator CBP containing the TAZ2 and acetyltransferase domains, inhibits interaction of the CTD with DNA. This work provides high-resolution insights into the behavior of the intrinsically disordered C-terminal regions of p53 within the full-length tetramer and the molecular basis by which the CTD mediates DNA binding and specificity.

The TP53 tumor suppressor gene is known as the guardian of the genome, playing a pivotal role in controlling genome integrity, and its functions are lost in more than 50% of human tumors due to somatic mutations. This percentage rises to 90% if mutations and alterations in the genes that code for regulators of p53 stability and activity are taken into account. Renal cell carcinoma (RCC) is a clear example of cancer that despite having a wild-type p53 shows poor prognosis because of the high rate of resistance to radiotherapy or chemotherapy, which leads to recurrence, metastasis and death. Remarkably, the fact that p53 is poorly mutated does not mean that it is functionally active, and increasing experimental evidences have demonstrated this. Therefore, RCC represents an extraordinary example of the importance of p53 pathway alterations in therapy resistance. The search for novel molecular biomarkers involved in the pathways that regulate altered p53 in RCC is mandatory for improving early diagnosis, evaluating the prognosis and developing novel potential therapeutic targets for better RCC treatment.