MicroRNA320e Augments the Synthetic Lethality of Olaparib by Regulating the PI3K-AKT-mTOR Pathway

Abstract

Objectives: Given the increasing drug resistance in ovarian cancer (OC), the use of poly ADP-ribose polymerase inhibitors (PARPi) for treating homologous recombination repair defects (HRD) has encountered new challenges. MicroRNA320e (miR-320e) exerts a negative regulatory role in the progression of multiple cancers. This study aimed to investigate the association between miR-320e and drug resistance in ovarian cancer. Methods: The Cell Counting Kit-8 (CCK-8) assay, migration and invasion assays, and colony formation assay were employed to evaluate the proliferation, migration, and invasion abilities of cells. Western blot (WB) analysis was used to verify the expression levels of proteins related to the relevant signaling pathways in cells. The xenograft subcutaneous tumor model was established to investigate the effect of miR-320e on in vivo tumor growth. Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) assays were performed to detect the expression levels of related proteins and miR-320e in tumor tissues from patients and animals, respectively. Results: miR-320e was overexpressed in both A2780 and SKOV3 cells. The results showed that transfection with miR-320e significantly reduced cell proliferation, invasion, and migration, while enhancing autophagy and apoptosis. Additionally, the PI3K-AKT-mTOR signaling pathway was significantly inhibited in the treatment groups. In nude mouse models, overexpression of miR-320e also significantly suppressed tumor growth. These findings indicate that overexpression of miR-320e enhances the sensitivity of OC cells to olaparib therapy. Conclusion: In conclusion, miR-320e overexpression significantly inhibits the malignancy of ovarian cancer and increases the sensitivity of ovarian cancer cells to olaparib.