Targeting CDK12 rescues C/EBPβ-mediated platinum and PARP inhibitor resistance in ovarian cancer.

Despite multimodality treatment efforts, resistance to platinum and PARP inhibitors represents a primary impediment to improve prognosis of ovarian cancer. Here, we found that ovarian cancer tissues had higher C/EBPβ expression compared with normal tissues and high C/EBPβ expression predicted unfavorable survival outcomes. Elevated C/EBPβ expression enhanced cisplatin resistance and olaparib resistance. C/EBPβ could affect DDR signals of ovarian cancer. CDK12, serving as a C/EBPβ-regulated DDR-related gene, was directly targeted by and bound with C/EBPβ. C/EBPβ could promote CDK12 expression and confer drug tolerance via CDK12. Manipulation of CDK12 could reverse the effects of C/EBPβ. Using CDK12 inhibitor THZ531 could rescue C/EBPβ-mediated cisplatin resistance and olaparib resistance. Our findings indicated that C/EBPβ is a potent DDR regulator of ovarian cancer, which directly targets CDK12 and upregulates its expression. High C/EBPβ expression mediates platinum resistance and PARP inhibitor resistance via CDK12. Targeting C/EBPβ via CDK12 inhibition could rescue drug responsiveness of ovarian cancer, thereby counteracting platinum and PARP inhibitor resistance. C/EBPβ could thus be exploited as a candidate prognostic biomarker in ovarian cancer.