We hypothesized that combining progesterone with PARP inhibitors could enhance antitumor effects by modulating TRC-protective pathways.<h4>Methods</h4> The BRCA1/2 wild-type ovarian cancer cell line SHIN-3 (PR-negative and mPR-positive), which is considered resistant to PARP inhibitors, was treated with progesterone (100-400 μM) and three PARP inhibitors (niraparib, olaparib, and AZD2461). Here, BRCA1 is linked to ovarian cancer.