MicroRNA320e augments the synthetic lethality of olaparib by regulating homologous recombination repair via PI3K-AKT-mTOR pathway

Abstract

Abstract Background: With the increase of drug resistance in ovarian cancer(OC), poly ADP-ribose polymerase inhibitors (PARPi) for the treatment of homologous recombination repair defects (HRD) have faced new challenges. MicroRNA320e (miR-320e) plays a negative regulatory role in the progression of many cancers. Therefore, we overexpressed miR-320e in both A2780 cells with HRD and SKOV3 cells without HRD. Methods: 20 patients with high-grade serous ovarian cancer (HGSOC)and 20 patients with benign conditions were included in the experiment, and the expression of miR-320e and FN1 were measured through fluorescence in situ hybridization (FISH) and immunohistochemistry experiments. CCK8, clone formation experiment, EdU assay and Transwell experiment were used to determine the proliferation, invasion, and migration ability of OC cells. The determination of the degree of cell apoptosis were achieved through flow cytometry and immunofluorescence experiments. The effects of miR-320e on the PI3K-AKT-mTOR signaling pathway and autophagy and cell apoptosis were validated through Western Blot experiments. In addition, the xenograft tumor growth study in nude mice investigated how miR-320e affects ovarian cancer progression in vivo. In addition, this study also investigated whether miR-320e affects the sensitivity of OC cells to Olaparib treatment in vitro and in vivo. Results: The expression level of miR-320e is low, while the expression level of FN1 is actually high in the HGSOC patients. The results showed that after transfection with miR-320e, the proliferation, invasion, and migration abilities of both cells were significantly reduced, while the degree of autophagy and apoptosis increased(all p<0.05). The PI3K-AKT-mTOR signaling pathway was also significantly inhibited in the two-cell treatment groups (all p<0.05). Meanwhile, overexpression of miR-320e significantly inhibited tumor growth in nude mice(P<0.05). At the same time, the experimental results showed that overexpression of miR-320e could enhance the sensitivity of OC cells to olaparib therapy (all p<0.05). Conclusions: Our study showed that miR-320e, as a key signaling molecule upstream affecting the malignant progression of ovarian cancer, inhibits the activation of PI3K-AKT-mTOR signaling pathway by negatively regulating the expression of downstream FN1 gene, thereby inhibiting the malignant development of ovarian cancer and promoting the sensitivity of cancer cells to olaparib therapy in vivo and in vitro.