STUDY ON ROLE AND MECHANISM OF LET-7I IN THE BIOLOGICAL BEHAVIOR OF THE OVARIAN CANCER CELLS

Yiming Tang¹, Jianhua Li², huiJun Xu³

¹Institute of Integrative Medicine, Qingdao University Medical College, Qingdao Shandong 266021, P.R. China - ²Orthopedics department, The 88th Hospital of PLA, Taian Shandong271000, P.R. China - ³Gynecology department, Qingdao Haici Hospital, Qingdao, Shandong 266033, P.R. China

 Objective: To explore the effects of cell biological behavior on the overexpression of let-7i in ovarian cancer cells and to predict and verify the target gene of let-7i. The key genes in ovarian cancer are identified by data mining methods to study the role of let-7i and its molecular mechanisms in the development of ovarian cancer.

Method: Ovarian cancer SKOV3, human immortalized ovarian epithelial cells IOSE and ovarian cancer resistant cell line SKOV3/DDP cells were cultured. A2780/DDP cells were induced by increasing concentrations and doses. The expression of let-7i in the above cells was detected by real-time fluorescent quantitative PCR. EdU and CCK-8 experiments were used to detect the effects of let-7i on A2780 cell proliferation and SKOV3 in ovarian cancer. The Transwell assay was used to study its effect on the migration and invasion of A2780 cells and ovarian cancer SKOV3. The MTT assay was used to study the effect of let-7i on cisplatin sensitivity in ovarian cancer-resistant SKOV3/DDP and A2780/DDP cells.

Result: The expression of let-7i in SKOV3 cells, A2780 cells and IOSE cells under real-time fluorescent quantitative PCR was compared. The results showed that the expression of let-7i was significantly down-regulated in SKOV3 cells and A2780 cells (P<0.01). In the drug-resistant cells, the results were consistent with the above, and the expression was significantly down-regulated (P < 0.01). After transfection of let-7i mimics, the expression level of let-7i increased significantly (P<0.01). After overexpression of let-7i, the results of MTT and CCK-8 assay showed that the proliferation of A2780 cells and SKOV3 cells decreased (P<0.05). Transwell results showed that the migration ability of SKOV3 cells and A2780 cells was decreased (P<0.05). In addition, the invasive ability of SKOV3 cells decreased (P<0.05).

Conclusion: In ovarian cancer cells, let-7i expression is down-regulated. Overexpression of let-7i can inhibit the growth, mi- gration and invasion of A2780 cells and ovarian cancer SKOV3 cells and can reverse the drug resistance of cisplatin-resistant cells SKOV3/DDP and A2780/DDP.