Trabectedin Induces Synthetic Lethality via the p53-Dependent Apoptotic Pathway in Ovarian Cancer Cells Without BRCA Mutations When Used in Combination with Niraparib

This study investigated whether combining niraparib and trabectedin in BRCA-proficient epithelial ovarian cancer induces deficiencies in ssDNA break repair and dsDNA homologous recombination, leading to synthetic lethality. A2780 and SKOV3 ovarian cancer cell lines were treated with niraparib and trabectedin. Cell viability was assessed using CCK-8 assays, while RT-qPCR and Western blot analyzed the expression of DNA repair and apoptosis-related genes. Apoptosis was evaluated via Annexin V/PI assays. The combination therapy exhibited a synergistic effect on A2780 cells but not on SKOV3 cells. Treatment reduced BRCA1, BRCA2, RAD51, PARP1, and PARP2 expression, indicating impaired DNA repair. γ-H2AX levels increased, suggesting DNA damage. The therapy also upregulated p53, PUMA, NOXA, BAX, BAK, and p21, promoting p53-mediated apoptosis and cell cycle arrest. Apoptosis induction was confirmed via Annexin V/PI assays. Silencing p53 with siRNA abolished all synergistic effects in A2780 cells. Niraparib and trabectedin combination therapy impairs DNA repair in BRCA-proficient ovarian cancer, leading to synthetic lethality through p53-dependent apoptosis.