miR-449b-5p inhibits ovarian cancer cell growth and cell cycle progression by targeting Cyclin E2 / 中国肿瘤生物治疗杂志

ABSTRACT

@#[Abstract] Objective: To investigate the effect and mechanism of miR-449b-5p on the proliferation of ovarian cancer cells. Methods: Cancer tissue and corresponding para-cancerous tissue specimens from 20 patients who underwent surgery in the Department of Obstetrics and Gynecology of Sichuan Provincial People's Hospital from June 2018 to June 2020 were collected for this study; in addition, normal ovarian epithelial cell line (HOSEpiC) and six human cervical cancer cell lines (SKOV3, ES-2, OVCAR-3, HO8910, CaOV-3 and A2780) were also selected. mRNA expressions of miR-449b-5p and CCNE2 in ovarian cancer tissues and cells were detected by qPCR. The plasmids miR-NC, miR-499b-5p mimic, miR-499b-5p inhibitor and pc-CCNE2 were transfected into SKOV3 cells separately or in combination. Cell growth and cell cycle were measured by the CCK-8 method and Flow cytometry, the expression of CCNE2 protein was detected by WB assay, respectively. The targeting relationship between miR-449b-5p and CCNE2 was verified by Dual luciferase reporter assay. miR-499b-5p transfected SKOV3 cells were injected subcutaneously in nude mice to construct xenograft model, and the tumor volume was measured weekly. Nude mice were sacrificed at day 42. The weight of the subcutaneous tumors was weighed by an electronic balance, and the expressions of CCNE2 and Ki67 were detected by immunohistochemistry. Results: Compared with normal ovarian tissues and epithelial cell line HOSEpiC, miR-499b expression was significantly downregulated in human cervical cancer tissues and cell lines SKOV3, ES-2, OVCAR-3, HO8910, CaOV-3 and A2780 (P<0.01). Compared with the Control group, the proliferation of SKOV3 cells in the miR-499b mimic group was significantly reduced (P<0.01) and the cell proportion in G0/G1 phase was significantly increased ( P<0.01); while the proliferation of SKOV3 cells in the miR-499b inhibitor group was significantly increased (P<0.01) and the cell proportion in G0/G1 phase was significantly reduced (P<0.01). Over-expression of miR-499b-5p significantly inhibited the luciferase activity of wild type CCNE2 plasmid (P<0.01) but had no effect on the luciferase activity of the mutant CCNE2 plasmid. Compared with the miR-499b mimic group, the growth of SKOV3 cells in the miR-499b mimic+pc-CCNE2 group was significantly increased (P<0.01) and the cell proportion in G0/G1 phase was significantly reduced (P<0.01). Compared with the miR-NC group, the tumor volume and weight of nude mice in the miR-499b mimic group were significantly reduced (all P<0.01), and the proportion of CCNE2 and Ki67 positive cells was significantly decreased (P<0.01). Conclusion: miR-449b-5p inhibits the growth and cell cycle progression of ovarian cancer cells by targeting Cyclin E2.