RESUMO
Objective: To investigate the effects of microRNA let-7a on the biological behaviors of Ewing's sarcoma cell lines A673 and SK-ES-1, and to explore the possible mechanisms. Methods: Has-miR-let-7a mimic was transfected into A673 and SK-ES-1 cells. Three groups were designed in this study, including let-7a (transfected with has-miR-let-7a mimic), control (transfected with has-miR-let-7a mimic-control) and the untreated (transfected with liposomes) groups. The expression levels of let-7a in A673 and SK-ES-1 cells after transfection with has-miR-let-7a mimic were examined by real-time fluorescence quantitative-PCR. The proliferation, migration and invasion abilities were detected by cell counting kit (CCK-8) and Transwell chamber assay, respectively. The cell cycle distribution and the apoptotic rates of A673 and SK-ES-1 cells were measured by flow cytometry. The expression levels of cyclin-dependent kinase 6 (CDK6), Rb and p-Rb proteins in A673 and SK-ES-1 cells were detected by Western blotting. Results: As compared with the control group and the untreated group, the expression levels of let-7a in A673 and SK-ES-1 cells after transfection with has-miR-let-7a mimic were up-regulated (P < 0.01), and the abilities of proliferation, migration and invasion were inhibited (all P < 0.01). The cell cycle was arrested at G0/G1-phase (P < 0.01) and the early apoptosis was increased (P < 0.01). The expression levels of CDK6 and p-Rb were down-regulated (P < 0.01), but the expression level of Rb had no change. Conclusion: Let-7a may inhibit the proliferation, migration and invasion abilities of Ewing's sarcoma A673 and SK-ES-1 cells and promote the apoptosis. This effect may be partially related to let-7a targeting the inhibition of CDK6 expression. Copyright © 2013 by TUMOR.