Involvement of multiple cellular pathways in regulating resistance to tamoxifen in BIK-suppressed MCF-7 cells
Resistance to platinum-based therapies arises by multiple mechanisms, including by alterations to cell-cycle kinases that mediate G(2)-M phase arrest. In this study, we conducted parallel high-throughput screens for microRNAs (miRNA) that could restore sensitivity to cisplatin-resistant cells, and we screened for kinases targeted by miRNAs that mediated cisplatin resistance. Overexpression of the cell-cycle kinases WEE1 and CHK1 occurred commonly in cisplatin-resistant cells. miRNAs in the miR-15/16/195/424/497 family were found to sensitize cisplatin-resistant cells to apoptosis by targeting WEE1 and CHK1. Loss-of-function and gain-of-function studies showed that miR-15 family members controlled the expression of WEE1 and CHK1. Supporting these results, we found that in the presence of cisplatin altering expression of miR-16 or related genes altered cell cycle distribution. Our findings reveal critical regulation of miRNAs and their cell-cycle-associated kinase targets in mediating resistance to cisplatin.