Sharmila A Bapat

Functional balance between Tcf21–Slug defines cellular plasticity and migratory modalities in high grade serous ovarian cancer cell lines

Abstract Cellular plasticity and transitional phenotypes add to complexities of cancer metastasis that can be initiated by single cell epithelial to mesenchymal transition (EMT) or cooperative cell migration (CCM). Our study identifies novel regulatory cross-talks between Tcf21 and Slug in mediating phenotypic and migration plasticity in high-grade serous ovarian adenocarcinoma (HGSC). Differential expression and subcellular localization associate Tcf21, Slug with epithelial, mesenchymal phenotypes, respectively; however, gene manipulation approaches identify their association with additional intermediate phenotypic states, implying the existence of a multistep epithelial-mesenchymal transition program. Live imaging further associated distinct migratory modalities with the Tcf21/Slug status of cell systems and discerned proliferative/passive CCM, active CCM and EMT modes of migration. Tcf21–Slug balance identified across a phenotypic spectrum in HGSC cell lines, associated with microenvironment-induced transitions and the emergence of an epithelial phenotype following drug exposure. Phenotypic transitions and associated functionalities following drug exposure were affirmed to ensue from occupancy of Slug promoter E-box sequences by Tcf21. Our study effectively provides a framework for understanding the relevance of ovarian cancer plasticity as a function of two transcription factors.

Harnessing m6A-regulated cholesterol biosynthesis helps impede tumor burden and stemness in high-garde serous ovarian carcinoma mesenchymal phenotype

Post-transcriptional RNA modifications have emerged as critical regulators of stemness, cellular plasticity, adaptation to stress and transformation. Amongst these the N6-methyladenosine (m

Targeting mitochondrial translation and OXPHOS in high-grade serous ovarian carcinoma eliminates stem-like cells

Abstract Ex vivo stem cell self-renewal and maintenance is supported by absence of serum-derived mitogens. In the present study, we sought to elucidate the proteomes of stem-like cells grown in serum-free media across a panel of high-grade serous ovarian cancer cell lines, which encompass a gradient from epithelial, intermediate and mesenchymal cell phenotypes to recapitulate the heterogeneity of the disease. MaxQuant-based label-free quantification of proteins identified that despite their different cellular and molecular architectures, all phenotypes exhibited mitochondria- and stemness-related pathways under conditions of serum starvation, although the specific proteins involved were discrete to each phenotype. This suggests that common cellular programs in a disease can be mediated through variable biological networks that generates molecular heterogeneity. We further explored if these pathways are inter-related, co-regulated or just incidentally associated in response to an environment depleted of growth factors and mitogens. Irrespective of their phenotype, cell lines on serum-starvation displayed an increased amount of mitochondrial DNA, mitochondrial biogenesis and mitochondrial activity with a switch from glycolysis to oxidative phosphorylation fuelled by the fatty acid oxidation. Ultra-structural studies implicated this metabolic fluctuation was regulated by dynamic mitochondrial remodelling. This also led us to explore a possible therapeutic strategy of targeting mitochondrial function to restrict tumor regenerative potential and disease recurrence. Conclusively, these new avenues contribute to a more comprehensive understanding of ovarian cancer.