Biology subjects

Erkek Ozhan, S.

Publications and source records attributed to Erkek Ozhan, S..

3 recordsLinked to original sources

bioRxiv2023

Retinoids and EZH2 inhibitors cooperate to orchestrate cytotoxic effects on bladder cancer cells

Emerging evidence has highlighted the importance of targeting EZH2 in bladder cancer owing to the highly mutated nature of bladder cancers harboring mutations in chromatin regulatory genes opposing Polycomb-mediated repression. Besides, enhanced expression of EZH2 contributes to pathogenesis. Furthermore, the critical role of the retinoic acid signaling pathway in the development and homeostasis of the urothelium is well established. Here we report that coordinated targeting of EZH2 and the retinoic acid signaling pathway caused cytotoxic effects on bladder cancer cells by inducing a synergistic reduction in proliferative potential that was associated with increased apoptosis and cell cycle arrest in a cooperative and orchestrated manner. Moreover, combined treatment caused the modulation of the expression of genes associated with an anti-oncogenic profile, as reflected by the stimulation of marker genes associated with apoptosis and differentiation. We further portrayed a molecular mechanism whereby EZH2 maintains H3K27me3-mediated repression of certain genes associated with unfolded protein response and some metabolic processes. This work also characterized an apoptotic program centered on the master transcriptional regulators C/EBP{beta} and CHOP. These findings highlight the importance of co-targeting the EZH2/retinoic acid pathway in bladder cancers and encourage the design of novel treatments employing retinoids coupled with EZH2 inhibitors in bladder carcinoma.

cancer biology↗

bioRxiv2022

Truncated KDM6A exhibits differential chromatin occupancy and regulatory interactions

Epigenetic deregulation is a critical theme which needs further investigation for bladder cancer research. One of the highly mutated genes in bladder cancer is KDM6A, functioning as a H3K27 demethylase and is part of the MLL3/4 complexes. To decipher the role of KDM6A in normal versus tumor setting, we identified the genomic landscape of KDM6A in normal, immortalized and cancer bladder cells. Our results showed differential KDM6A occupancy at the genes involved in cell differentiation, chromatin organization and Notch signaling depending on the cell type and the mutation status of KDM6A. Transcription factor motif analysis revealed HES1 to be enriched at KDM6A peaks identified for T24 bladder cancer cell line, which has a truncating mutation in KDM6A, lacking demethylase domain. Our co-immunoprecipitation experiments reveal TLE co-repressors and HES1 as potential truncated and wild type KDM6A interactors. With the aid of structural modeling, we explored how the truncated KDM6A could interact with TLE, HES1, as well RUNX, HHEX transcription factors. These structures provide a solid mean to study the functions of KDM6A independent of its demethylase activity. Collectively, our work provides important contributions to the understanding of KDM6A malfunction in bladder cancer.

cancer biology↗

bioRxiv2021

FLI1 and FRA1 transcription factors drive the transcriptional regulatory networks characterizing muscle invasive bladder cancer

Bladder cancer is mostly present in the form of urothelium carcinoma, causing over 150,000 deaths each year. Its histopathological classification as muscle invasive (MIBC) and non-muscle invasive (NMIBC) is the most prominent aspect, affecting the prognosis and progression of this disease. In this study, we defined the active regulatory landscape of MIBC and NMIBC cell lines using H3K27ac ChIP-seq and used an integrative approach to combine our findings with existing data. Our analysis revealed FRA1 and FLI1 as two critical transcription factors differentially regulating MIBC regulatory landscape. We show that FRA1 and FLI1 regulate the genes involved in epithelial cell migration and cell junction organization. Knock-down of FRA1 and FLI1 in MIBC revealed the downregulation of several EMT-related genes such as MAP4K4 and FLOT1. Further, ChIP-SICAP performed for FRA1 and FLI1 enabled us to infer chromatin binding partners of these transcription factors and link this information with their target genes. Finally, for the first time we show that knock-down of FRA1 and FLI1 result in significant reduction of invasion capacity of MIBC cells towards muscle microenvironment using IC-CHIP assays. Our results collectively highlight the role of these transcription factors in selection and design of targeted options for treatment of MIBC.

cancer biology↗