Identifying changes in cell cycle regulatory proteins during clobetasol-induced quiescence in UMSCV-4 vulvar cancer cells

Quiescence is a reversible state in which cells temporarily exit the cell cycle in response to stress, with the capacity to re-enter the cycle once the given stress is relieved. Growing evidence suggests that quiescent cancer cells may underlie long-term tumor dormancy and late relapse. We found that a subpopulation of the vulvar squamous cell carcinoma line UMSCV-4 enters quiescence following exposure to the corticosteroid clobetasol (clob). Upon removal of clob, these cells re-enter the cell cycle. To characterize this process, we quantified changes in proliferation using BrdU incorporation and assessed the timing of cell cycle re-entry after clob withdrawal. We hypothesized that clob treatment would downregulate key cell-cycle-promoting proteins while upregulating cell-cycle inhibitors, and that these changes would reverse within three days of clob removal, coinciding with increased DNA synthesis and the reappearance of mitotic figures. Using Western blot analysis, we examined the expression of cell-cycle promoters (cyclin D1, cyclin D3, CDK2, CDK4, CDK6) and inhibitors (p21Waf1/Cip1 and p18INK4C). RNA seq analysis is being used to evaluate corresponding changes in mRNA abundance and to identify additional regulators associated with clob-induced arrest. Together, these studies aim to define the molecular mechanisms by which clobetasol promotes quiescence in vulvar cancer cells.