Silencing thyroid hormone receptor interactor 13/kinetochore-associated 1 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 inhibitors, such as Olaparib, particularly in patients with breast cancer gene-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, coimmunoprecipitation, immunofluorescence, comet assays, and an OVCAR3 xenograft model. Bioinformatic analyses indicated that thyroid hormone receptor interactor 13 (TRIP13) and kinetochore-associated 1 (KNTC1) were highly expressed in Olaparib-resistant cells and were associated with poor prognosis. Their elevated expression was further confirmed by real-time quantitative polymerase chain reaction, 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, coimmunoprecipitation and immunofluorescence analyses confirmed a cytoplasmic interaction between TRIP13 and KNTC1. TRIP13 knockdown impaired nonhomologous 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, whereas 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 breast cancer gene-proficient OC. Targeting the TRIP13/KNTC1 axis may therefore enhance the therapeutic efficacy of Olaparib and provide a promising strategy for overcoming poly (ADP-ribose) polymerase inhibitor resistance. SIGNIFICANCE STATEMENT: Olaparib resistance remains a major obstacle to effective ovarian cancer treatment. This study demonstrates that the thyroid hormone receptor interactor 13/kinetochore-associated 1 axis promotes Olaparib resistance in ovarian cancer by enhancing nonhomologous end joining-mediated DNA damage repair. Targeting this axis restored Olaparib sensitivity in resistant cells, thereby highlighting thyroid hormone receptor interactor 13/kinetochore-associated 1 as a potential therapeutic target for improving the response to poly (ADP-ribose) polymerase inhibitors.