miR-221 promotes proliferation of lung cancer A549 cells by down-regulating PTEN

AIM: To explore the effect of microRNA-221 (miR-221) on the proliferation of lung cancer A549 cells, and to investigate its mechanism. METHODS: The A549 cells were transfected with miR-221 mimics by Lipofectamine 2000. The expression of miR-221 was detected by RT-qPCR. The expression of PTEN at mRNA and protein le-vels was detected by RT-qPCR and Western blot, respectively. The cell proliferation was examined by CCK-8 assay and colony formation assay. The 3'-UTR of PTEN was cloned into luciferase reporter vector and its enzymatic activity was detected to verify whether miR-221 targeted to PTEN. RESULTS: The expression level of miR-221 in the A549 cells was significantly increased after transfection with miR-221 mimics as compared with negative control group and blank group (P<0.01). The mRNA and protein levels of PTEN were significantly down-regulated compared with control group and blank group (P<0.05). In addition, miR-221 over-expression significantly promoted the proliferation of A549 cells (P<0.05). Moreover, miR-221 inhibited the enzymatic activity of luciferase reporter vector of PTEN. CONCLUSION: Over-expression of miR-221 significantly promotes the proliferation ability of human lung cancer A549 cells by down-regulation of PTEN.