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27 result(s) for "Chakrabarty, Sanjiban"
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A comprehensive review on the carcinogenic potential of bisphenol A: clues and evidence
Bisphenol A [BPA; (CH 3 ) 2 C(C 6 H 4 OH) 2 ] is a synthetic chemical used as a precursor material for the manufacturing of plastics and resins. It gained attention due to its high chances of human exposure and predisposing individuals at extremely low doses to diseases, including cancer. It enters the human body via oral, inhaled, and dermal routes as leach-out products. BPA may be anticipated as a probable human carcinogen. Studies using in vitro cell lines, rodent models, and epidemiological analysis have convincingly shown the increasing susceptibility to cancer at doses below the oral reference dose set by the Environmental Protection Agency for BPA. Furthermore, BPA exerts its toxicological effects at the genetic and epigenetic levels, influencing various cell signaling pathways. The present review summarizes the available data on BPA and its potential impact on cancer and its clinical outcome.
Dynamic de novo heterochromatin assembly and disassembly at replication forks ensures fork stability
Chromatin is dynamically reorganized when DNA replication forks are challenged. However, the process of epigenetic reorganization and its implication for fork stability is poorly understood. Here we discover a checkpoint-regulated cascade of chromatin signalling that activates the histone methyltransferase EHMT2/G9a to catalyse heterochromatin assembly at stressed replication forks. Using biochemical and single molecule chromatin fibre approaches, we show that G9a together with SUV39h1 induces chromatin compaction by accumulating the repressive modifications, H3K9me1/me2/me3, in the vicinity of stressed replication forks. This closed conformation is also favoured by the G9a-dependent exclusion of the H3K9-demethylase JMJD1A/KDM3A, which facilitates heterochromatin disassembly upon fork restart. Untimely heterochromatin disassembly from stressed forks by KDM3A enables PRIMPOL access, triggering single-stranded DNA gap formation and sensitizing cells towards chemotherapeutic drugs. These findings may help in explaining chemotherapy resistance and poor prognosis observed in patients with cancer displaying elevated levels of G9a/H3K9me3. Gaggioli, Lo et al. show that the histone methyltransferase EHMT2/G9a catalyses heterochromatin assembly at stressed replication forks. Untimely heterochromatin disassembly by demethylase KDM3A exposes forks to PRIMPOL-mediated genome instability.
Antiapoptotic PON2 expression and its clinical implications in locally advanced oral squamous cell carcinoma
Locally advanced oral squamous cell carcinoma poses a significant challenge in oncology due to its rising incidence and mortality rates. Despite therapeutic progress, understanding molecular intricacies is essential. This study explored the role of PON2, a multifunctional enzyme implicated in antiapoptotic mechanisms. Aberrant PON2 expression in oral cancers raises questions regarding its involvement in evading programmed cell death and treatment resistance. Patients with locally advanced disease were enrolled, and molecular analyses were undertaken on the collected tumor and normal tissues. Utilizing computational datasets, this study used in silico gene expression analysis, differential gene expression analysis in our patient cohort, survival analysis, and gene set enrichment analysis to unravel role of PON2 in disease prognosis. The results showed elevated PON2 levels in advanced tumor stages, correlating with factors such as tobacco exposure, higher tumor grade, and nodal metastasis. Survival analysis revealed prognostic relevance of PON2, with lower expression linked to extended survival rates. Gene set enrichment analysis identified pathways aiding in cancer metastasis influenced by PON2. This study underscores the significance of PON2 expression as a prognostic marker for oral malignancies, with increased expression associated with advanced disease stages. Understanding the molecular profile of the PON2 gene suggests its potential as a valuable biomarker for the management of cancer. Role of PON2 in regulating diverse molecular pathways influenced by PON2 during cancer progression and metastasis.
Regulation and tumor‐suppressive function of the miR‐379/miR‐656 (C14MC) cluster in cervical cancer
Cervical cancer (CC) is a key contributor to cancer‐related mortality in several countries. The identification of molecular markers and the underlying mechanism may help improve CC management. We studied the regulation and biological function of the chromosome 14 microRNA cluster (C14MC; miR‐379/miR‐656) in CC. Most C14MC members exhibited considerably lower expression in CC tissues and cell lines in The Cancer Genome Atlas (TCGA) cervical squamous cell carcinoma and endocervical adenocarcinoma patient cohorts. Bisulfite Sanger sequencing revealed hypermethylation of the C14MC promoter in CC tissues and cell lines. 5‐aza‐2 deoxy cytidine treatment reactivated expression of the C14MC members. We demonstrated that C14MC is a methylation‐regulated miRNA cluster via artificial methylation and luciferase reporter assays. C14MC downregulation correlated with poor overall survival and may promote metastasis. C14MC activation via the lentiviral‐based CRISPRa approach inhibited growth, proliferation, migration, and invasion; enhanced G2/M arrest; and induced senescence. Post‐transcriptional regulatory network analysis of C14MC transcriptomic data revealed enrichment of key cancer‐related pathways, such as metabolism, the cell cycle, and phosphatidylinositol 3‐kinase (PI3K)–AKT signaling. Reduced cell proliferation, growth, migration, invasion, and senescence correlated with the downregulation of active AKT, MYC, and cyclin E1 (CCNE1) and the overexpression of p16, p21, and p27. We showed that C14MC miRNA activation increases reactive oxygen species (ROS) levels, intracellular Ca2+ levels, and lipid peroxidation rates, and inhibits epithelial–mesenchymal transition (EMT). C14MC targets pyruvate dehydrogenase kinase‐3 (PDK3) according to the luciferase reporter assay. PDK3 is overexpressed in CC and is inversely correlated with C14MC. Both miR‐494‐mimic transfection and C14MC activation inhibited PDK3 expression. Reduced glucose uptake and lactate production, and upregulation of PDK3 upon C14MC activation suggest the potential role of these proteins in metabolic reprogramming. Finally, we showed that C14MC activation may inhibit EMT signaling. Thus, C14MC is a tumor‐suppressive and methylation‐regulated miRNA cluster in CC. Reactivation of C14MC can be useful in the management of CC. miR‐379/miR‐656 (C14MC) is the second largest microRNA cluster in the human genome. C14MC is a methylation‐driven tumor‐suppressive miRNA cluster in cervical cancer. C14MC activation inhibited cell growth, proliferation, migration, invasion, G2/M arrest, and senescence induction. C14MC activation increased ROS, intracellular Ca2+ and lipid peroxidation, and inhibited epithelial–mesenchymal transition. C14MC activation targets pyruvate dehydrogenase kinase 3.
Contribution of nuclear and mitochondrial gene mutations in mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome
BackgroundMitochondrial disorders are clinically complex and have highly variable phenotypes among all inherited disorders. Mutations in mitochon drial DNA (mtDNA) and nuclear genome or both have been reported in mitochondrial diseases suggesting common pathophysiological pathways. Considering the clinical heterogeneity of mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) phenotype including focal neurological deficits, it is important to look beyond mitochondrial gene mutation.MethodsThe clinical, histopathological, biochemical analysis for OXPHOS enzyme activity, and electron microscopic, and neuroimaging analysis was performed to diagnose 11 patients with MELAS syndrome with a multisystem presentation. In addition, whole exome sequencing (WES) and whole mitochondrial genome sequencing were performed to identify nuclear and mitochondrial mutations.ResultsAnalysis of whole mtDNA sequence identified classical pathogenic mutation m.3243A > G in seven out of 11 patients. Exome sequencing identified pathogenic mutation in several nuclear genes associated with mitochondrial encephalopathy, sensorineural hearing loss, diabetes, epilepsy, seizure and cardiomyopathy (POLG, DGUOK, SUCLG2, TRNT1, LOXHD1, KCNQ1, KCNQ2, NEUROD1, MYH7) that may contribute to classical mitochondrial disease phenotype alone or in combination with m.3243A > G mutation.ConclusionIndividuals with MELAS exhibit clinical phenotypes with varying degree of severity affecting multiple systems including auditory, visual, cardiovascular, endocrine, and nervous system. This is the first report to show that nuclear genetic factors influence the clinical outcomes/manifestations of MELAS subjects alone or in combination with m.3243A > G mutation.
Analysis of miR-497/195 cluster identifies new therapeutic targets in cervical cancer
Objective miR-497/195, located at 17p13.1, is a highly conserved miRNA cluster whose abnormal expression is a key regulator of carcinogenesis. We performed a comprehensive analysis of the miR-497/195 cluster to determine its prognostic utility and role in cervical cancer (CC) using publicly available datasets. Results In silico analysis and validation revealed that this cluster is downregulated in CC. A total of 60 target genes of miR-497/195 cluster were identified as differentially expressed between normal and CC samples. ShinyGO, STRING, CytoHubba, Timer 2.0, HPA, and HCMBD were used for functional enrichment, PPIN network construction, hub gene identification, immune infiltration correlation, histopathological expression, and determination of the metastatic potential of miR-497/195 cluster and their target genes. PPIN analysis identified CCNE1, CCNE2, ANLN, RACGAP1, KIF23, CHEK1, CDC25A, E2F7, CDK1, and CEP55 as the top 10 hub genes (HGs). Furthermore, the upregulation of RECK, ATD5, and BCL2, downregulation of OSBPL3, RCAN3, and HIST1H3H effected overall survival of CC patients. We identified 6 targets (TFAP2A, CLSPN, RASEF, HIST1H3H, AKT3, and ITPR1) of miR-497/195 cluster to influence metastasis. In addition, 8 druggable genes and 38 potential drugs were also identified. Our study identified miR-497/195 cluster target genes and pathways that could be used for prognostic and therapeutic applications in CC.
Identification of HOX signatures contributing to oral cancer phenotype
The role of evolutionarily conserved homeobox-containing HOX genes as transcriptional regulators in the developmental specification of organisms is well known. The contribution of HOX genes involvement in oral cancer phenotype has yet to be fully ascertained. TCGA-HNSC HTSeq-counts and clinical data were retrieved from the GDC portal for oral cavity neoplasms. GEO datasets (GSE72627, GSE30784, GSE37991) were accessed and analyzed using GEO2R. Differential HOX gene expression was profiled using the DESeq2 R package with a log2 fold change cut-off (− 1 and + 1) and Benjamini–Hochberg p -adjusted value at ≤ 0.01. Gene set over-representation analysis and semantic analysis associated with the disease ontology was performed using the ClusterProfiler R package, and pathway over-representation analysis was performed using IMPaLa. HOX protein interaction network was constructed using the Pathfind R package. HOX phenotype associations were performed using Mammalian Phenotype Ontology, Human Phenotype Ontology, PhenGenI associations, Jensen tissues, and OMIM entries. Drug connectivity mapping was carried out with Dr. Insight R package. HOXA2 was upregulated in oral dysplasia but silenced during tumor progression. Loss of HOXB2 expression was consistent in the potentially malignant oral lesions as well as in the primary tumor. HOXA7, HOXA10, HOXB7, HOXC6, HOXC10, HOXD10, and HOXD11 were consistently upregulated from premalignancy to malignancy and were notably associated with risk factors. Overrepresentation analysis suggested HOXA10 was involved in the transcriptional misregulation contributing to the oral cancer phenotype. HOX genes subnetwork analysis showed crucial interactions with cell cycle regulators, growth responsive elements, and proto-oncogenes. Phenotype associations specific to the oral region involving HOX genes provide intrinsic cues to tumor development. The 5′ HOX genes were aberrantly upregulated during oral carcinogenesis reflecting their posterior prevalence.
Prognostic role of 14q32.31 miRNA cluster in various carcinomas: a systematic review and meta-analysis
Deregulated miR-379/miR-656 cluster expression is considered as important for carcinogenesis and can be used as a potential prognostic marker. Hence, the meta-analysis was conducted to test the utility of miR-379/miR-656 cluster as a prognostic marker in various cancers. A literature search was performed using Web of Science, PubMed and Cochrane Library to obtain relevant studies and were subjected to various subgroup and bioinformatics analyses. Selected twenty-three studies contained 13 cancer types comprising of 3294 patients from 7 nations. Univariate and multivariate data showed an association of high expression of miRNAs with the poor prognosis of cancer patients (p < 0.001). The subgroup analysis showed that lung cancer, breast cancer and papillary renal cell carcinoma (p < 0.001) have a negative association with the survival of patients. Our study is the first meta-analysis showing the association of miR-379/miR-656 cluster expression and overall survival, suggesting its potential as a prognostic indicator in multiple cancers.
Investigation of the Molecular Mechanisms of Paraoxonase‐2 Mediated Radiotherapy and Chemotherapy Resistance in Oral Squamous Cell Carcinoma
Oral squamous cell carcinoma (OSCC) is a common form of cancer, with 390,000 new cases estimated for 2022. OSCC has a poor prognosis, largely due to a high recurrence rate and resistance to therapy. Cancer cells develop resistance to standard therapy owing to various factors, such as genetic predispositions, alterations in the apoptotic pathway coupled with DNA repair pathways, drug efflux, and drug detoxification. This review is aimed at exploring the crucial role of paraoxonase 2 (PON2) in conferring resistance to chemotherapy and radiotherapy in OSCC cells. PON2, an antioxidant enzyme, protects cancer cells from the oxidative stress caused by these treatments. By influencing apoptotic pathways and DNA repair mechanisms, PON2 can reduce the effectiveness of therapy. This review is an attempt to explore the complex molecular mechanisms modulated by PON2, such as the mitigation of oxidative stress, enhancement of DNA repair, apoptosis regulation, drug efflux modulation, and drug detoxification, which decrease treatment efficacy.
Inflammatory milieu and role of epigenetic modifications in high-grade serous ovarian cancer
High-grade serous ovarian cancer (HGSOC) is often diagnosed at advanced stages (III/IV), with approximately 80% of patients experiencing relapse due to therapeutic resistance. The disease progression is largely influenced by a dynamic tumor microenvironment (TME), which is marked by sustained inflammation, immune evasion, and epigenetic reprogramming. This review investigates the dual role of inflammatory pathways and epigenetic alterations in driving HGSOC progression and chemo-resistance. A comprehensive literature search of articles from 2000 to 2025 was conducted across PubMed, Google Scholar, and Research Rabbit using search terms including “HGSOC,” “epigenetics,” “inflammation,” and “chemoresistance.” Of 1,166 identified publications, 593 peer-reviewed studies comprising original research, clinical trials, meta-analyses, and reviews were critically analyzed. Findings reveal that chronic inflammation in the TME enhances tumor proliferation, immune suppression, epithelial-mesenchymal transition, and metastasis through cytokines, interferons, and chemokines. Epigenetic mechanisms such as DNA methylation, histone modifications, miRNA and lncRNA contribute to tumor plasticity and treatment failure. Emerging therapies, including histone deacetylase inhibitors, DNA methyltransferase inhibitors, and immune checkpoint inhibitors, anti-inflammatory drugs demonstrate potential in overcoming resistance when used in combination. Integrative treatment strategies that target both inflammatory signaling and epigenetic dysregulation offer a promising avenue for improving patient outcomes. Further clinical exploration of such combination therapies is warranted to address the urgent need for effective interventions in HGSOC.