Ovarian cancer is the most lethal type of gynecological cancer. Due to its high heterogeneity and complicated pathological mechanisms, the 5-year survival rate of patients with ovarian cancer is <40%. Tumor cytoreductive surgery and systemic chemotherapy of platinum combined with paclitaxel are currently considered the gold standard for the treatment of ovarian cancer, and chemotherapy resistance has become a key constraint in improving the cure rate of ovarian cancer. Therefore, it is important to identify novel treatment methods and strategies for ovarian cancer. Targeted drugs can not only be used in combination with chemotherapy, but also act as maintenance therapy to promote patient survival time. PARP inhibitor is a novel type of ovarian cancer treatment targeted drug, which can induce an anticancer effect by inhibiting DNA damage and repair of ovarian cancer cells. The present study investigated the different effects of olaparib, cisplatin and paclitaxel in several dosages by single use and combinations on the proliferation of different human ovarian cancer cell lines, in order to verify the synergistic effects of the combinations of the three anticancer agents in pairs. The proliferation inhibitory rate of the cell lines was determined using a Cell Counting Kit-8 assay, while the combination index (CI) value of the combination of three agents in pairs was analyzed using Compusyn software. The proliferation was observed using a crystal violet assay, and the apoptosis ratio was measured via flow cytometry. The results of the present study revealed that the combination of cisplatin with olaparib group had a higher inhibition effect than each single group and had a higher dose-reduction index of >1 than the other two combinations at all concentrations in A2780 and OVCAR-3 cell lines. The difference in proliferation inhibition and induced apoptosis rate of A2780 cell lines was significant in the combination of cisplatin with olaparib group and the control group (P<0.01) at 0.25x IC₅₀. For the OVCAR-3 cell line, the difference was also significant between two groups (P<0.05). The CI values in the A2780 cell line revealed significant differences between the low-dose group (0.0625x, 0.125x and 0.25x IC₅₀) and the high-dose group (0.5x, 1.0x and 2.0x IC₅₀) for the group that received the combination of cisplatin with olaparib (P<0.05). The present study highlighted that the group receiving a combination of cisplatin with olaparib exhibited the most significant synergistic effects among the three combinations, particularly at low doses.

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