High-grade serous ovarian carcinomas (HGSOCs) with BRCA1/2 mutations exhibit improved outcome and sensitivity to double-strand DNA break (DSB)-inducing agents [i.e. platinum and Poly(ADP-ribose) polymerase inhibitors (PARPis)] due to an underlying defect in homologous recombination (HR). However, resistance to platinum and PARPis represents a significant barrier to the long-term survival of these patients. Although, BRCA1/2-reversion mutations are a clinically validated resistance mechanism, they account for less than half of platinum resistant BRCA1/2-mutated HGSOCs. We uncover a resistance mechanism by which a microRNA, miR-622 induces resistance to PARPis and platinum in BRCA1-mutant HGSOCs by targeting the Ku complex and restoring HR-mediated DSB repair., Physiologically, miR-622 inversely correlates with Ku expression during the cell cycle, suppressing non-homologous end joining and facilitating HR-mediated DSB repair in S-phase. Importantly, high expression of miR-622 in BRCA1-deficient HGSOCs is associated with worse outcome after platinum chemotherapy, indicating microRNA-mediated resistance through HR rescue.

No abstract

No abstract