Silencing TRIP13/KNTC1 inhibits DNA damage repair and enhances Olaparib sensitivity in ovarian cancer

Ovarian cancer (OC) is associated with high mortality and frequent resistance to poly (ADP-ribose) polymerase (PARP) inhibitors, such as Olaparib, particularly in patients with breast cancer gene (BRCA)-proficient tumors. To explore the potential mechanisms underlying Olaparib resistance, Olaparib-resistant OC cell lines were established through stepwise drug induction. Candidate resistance-related genes were screened using bioinformatic analyses and subsequently validated in clinical specimens. Their biological functions and underlying mechanisms were further investigated through gene silencing, co-immunoprecipitation, immunofluorescence, comet assays, and an OVCAR3 xenograft model. Bioinformatic analyses indicated that TRIP13 and KNTC1 were highly expressed in Olaparib-resistant cells and were associated with poor prognosis. Their elevated expression was further confirmed by RT-qPCR, western blotting, and immunohistochemistry. Functional studies showed that silencing either TRIP13 or KNTC1 inhibited cell proliferation and induced apoptosis in Olaparib-resistant OC cells. Mechanistically, co-immunoprecipitation and immunofluorescence analyses confirmed a cytoplasmic interaction between TRIP13 and KNTC1. TRIP13 knockdown impaired non-homologous end joining (NHEJ)-mediated DNA repair, as evidenced by decreased expression of NHEJ-related proteins, increased γH2AX accumulation, and enhanced comet tail formation. Conversely, TRIP13 overexpression promoted NHEJ repair and reduced Olaparib-induced DNA damage, whereas these effects were partially reversed by the NHEJ inhibitor SCR130. In vivo , TRIP13 overexpression promoted tumor growth and reduced sensitivity to Olaparib, while KNTC1 knockdown reversed these effects. Collectively, these findings suggest that TRIP13 and KNTC1 cooperatively promote NHEJ-mediated DNA repair, thereby contributing to Olaparib resistance in BRCA-proficient OC. Targeting the TRIP13/KNTC1 axis may therefore enhance the therapeutic efficacy of Olaparib and provide a promising strategy for overcoming PARP inhibitor resistance.