BITS Faculty Publications
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Item A switch from histone methyltransferase-EZH2 to demethylase KDM6A activity marks reinitiation of proliferation in cisplatin treated colorectal cancer cells(Elsevier, 2026-01) Chowdhury, Shibasish; Mukherjee, Sudeshna; Chowdhury, RajdeepColorectal cancer (CRC) is one of the deadliest cancers, ranking third in cancer incidence worldwide. These tumor cells often adopt unique strategies under chemotherapeutic stress to attain a reversible drug-tolerant state and evade cell death. However, the molecular adaptations associated with this transitory emergence of the drug-tolerant state remain elusive. Herein, epigenetic alterations often dictate such reversible dynamic changes, and this study aims to characterize the role of specific epigenetic modifiers governing CRC cell survival under cisplatin exposure and their subsequent relapse. We observed that under cisplatin-stress there is a drastic increase in the histone-repressive mark-H3K27me3, linked to an enhanced expression of EZH2, driving transcriptional inhibition of cell proliferation-associated genes and a proliferative arrest. Interestingly, cisplatin-induced oxidative stress increased the expression of P65 protein, which was found to interact with and regulate EZH2 expression. Quenching of ROS, cisplatin-rescue, or P65 inactivation compromised EZH2 activity, concurrent with a re-initiation of cell proliferation. Interestingly, this reversal to proliferative state was associated with an elevated activity of the histone lysine demethylase-KDM6A. The promoter elements of the proliferative genes were now occupied by KDM6A instead of EZH2. Accordingly, a genetic knockdown or pharmacological inhibition of KDM6A in vitro not only resulted in increased cell death but also prevented emergence of the re-proliferative CRC cells. Furthermore, KDM6A inhibition in combination with cisplatin, resulted in an increased tumor regression in vivo. Our study thus highlights the importance of KDM6A as a therapeutic target in preventing CRC growth and relapse which can have future therapeutic implications.Item Emerging in diabetic cardiomyopathy: molecular pathways and targets for therapeutic intervention(Wiley, 2025) Jadhav, Hemant R.Amongst various complications presented by diabetes, diabetic cardiomyopathy (DCM) is one of the most prominent and vexing complications. Due to the absence of consensus on prevention and treatment strategies, along with limitations in current therapies, a fresh perspective is essential and a requirement of the time. The succeeding review explores research that provides insights into novel molecular targets that could possibly evolve as breakthroughs in restraining the pathological hallmarks of DCM, such as inhibition of cardiomyocyte fibrosis or modulation of various inflammatory pathways, apoptotic pathways such as PANoptosis, cuproptosis, and ferroptosis, and mitochondrial dysfunction. This review shall also explore various RNA-targeting therapeutic areas that can combat the consecution of DCM. Therapeutic intervention targeting Phosphodiesterase 4D (PDE4D), LGR6 (G-protein-coupled receptor containing leucine-rich repeats 6), Interferon gamma inducible protein 16 (IFI16), Growth differentiation factor 11(GDF11), Transcription factor EB(TFEB), Secreted frizzled-related protein 1 (SFRP1), Fibroblast growth factor -21 (FGF21), Takeda G protein-coupled receptor-5 (TGR5), Nuclear receptor of the subfamily 4 (NR4A3), Enhancer of zeste homolog 2 (EZH2), and RNA-based therapeutics such as piR112710 and TUG1 are reviewed. Moreover, how these molecular targets intersect with DCM pathology, and how they can be further explored in a drug discovery paradigm for DCM management, is discussed.Item S-nitrosylation of EZH2 at C329 and C700 interplay with PRC2 complex assembly, methyltransferase activity, and EZH2 stability to regulate endothelial functions(2024) Sundriyal, Sandeep; Chowdhury, Shibasish; Majumder, SyamantakNitric oxide (NO), a versatile bio-active molecule modulates cellular function through diverse mechanisms including S-nitrosylation of proteins. However, the role of this post-translational modification in regulating epigenetic pathways was very limitedly explored. Herein, we report that NO causes S-nitrosylation of selected cysteine residues of EZH2 in endothelial cells (EC) resulting in SUZ12 dissociation from EZH2 bound PRC2 complex, reduced methyltransferase activity, and diminished nuclear localization eventually hampering its stability. We detected a significant reduction in H3K27me3 upon exposure to NO as contributed by the early dissociation of SUZ12 from the PRC2 complex. Longer exposure to NO donors caused EZH2 cytosolic translocation, its ubiquitination, and further degradation primarily through the autophagosome-lysosome pathway. Through in silico S-nitrosylation prediction analysis and site-directed mutagenesis assay, we identified three cysteine residues namely at locations 260, 329, and 700 in EZH2 and further determined that S-nitrosylation of cysteine 329 induced EZH2 instability while S-nitrosylation of cysteine 700 abrogated EZH2’s catalytic activity. A double mutant of EZH2 containing mutations at Cysteine 329 and 700 remained undeterred to NO exposure. Furthermore, reinforcing H3K27me3 in NO exposed EC through the use of an inhibitor of H3K27me3 demethylase, we confirmed a significant contribution of the EZH2-H3K27me3 axis in defining NO-mediated regulation of endothelial gene expression and migration. Molecular dynamics simulation study revealed SUZ12’s inability in efficiently binding to the SAL domain of EZH2 upon S-nitrosylation of C329 and C700. Taken together, our study for the first-time reports that S-nitrosylation dependent regulation of EZH2 and its associated PRC2 complex influences endothelial homeostasis.Item Transforming growth factor- β mediated regulation of epigenome is required for epithelial to mesenchymal transition associated features in liver cancer cells(Elsevier, 2023-04) Chowdhury, Shibasish; Chowdhury, Rajdeep; Mukherjee, SudeshnaHepatocellular carcinoma (HCC) frequently unfolds under an inflammatory condition, which is a hub for a plethora of cytokines. A better understanding of the cytokine functions and their contributions to disease development is key to design of future therapeutic strategies and reduction of global HCC burden. In this context, one of the major cytokines present in the HCC tumour milieu is the transforming growth factor-β (TGF-β). One of its classical functions involve facilitation of epithelial to mesenchymal transition (EMT), in tumour cells, promoting an invasive phenotype. In spite of its clinical relevance, the cellular events associated with TGF-β-induced EMT and its molecular regulation is poorly elucidated. Therefore, as part of this study, we treated HCC cells with TGF-β and characterized the cellular processes associated with EMT. Interestingly, EMT triggered by TGF-β was found to be associated with cytostasis and altered cellular metabolism. TGF-β resulted in down-regulation of cell cycle-associated transcripts, like Cyclin A2 (CCNA2), and metabolic genes, like Glutamic-oxaloacetic transaminase 1 (GOT1) through epigenetic silencing. An overall increase in total histone repressive mark (H3K27me3) associated with a specific enrichment of H3K27me3 at the upstream promoter region of CCNA2 and GOT1 was observed after TGF-β exposure, leading to their down-regulation. Importantly, TGF-β-downstream signalling mediator- SMAD and chromatin repressive complex member-enhancer of zeste homolog 2 (EZH2) were found to co-immunoprecipitate and were required for the above effects. Overall, our findings reflect that HCC cells undergoing EMT, attain cytostasis and modulate metabolic demands to efficiently facilitate the EMT differentiation switch, and these events are regulated at the epigenomic level through TGF-β-mediated signalling. Our results provide better understanding of cellular invasive features which can lead to development of novel therapeutic strategies.