RESUMO
@# Objective: To investigate the effect of down-regulation of miR-221 on cell proliferation and apoptosis of chronic myeloid leukemia (CML) K562 cells and its related regulatory mechanism. Methods: K562 cells were divided into control group, miRNAnegative control (miR-NC) group, miR-221 inhibitor group, miR-221 inhibitor+ negative control siRNA(NC siRNA) group and miR-221 inhibitor+SOCS3 siRNA group. The cells in the control group received no additional treatment. Cells in miR-NC group and miR-221 inhibitor group were transfected with miR-NC and miR-221 inhibitor, respectively. Cells in miR-221 inhibitor+NC siRNA group and miR-221 inhibitor+SOCS3 siRNA group were transfected with NC siRNA and SOCS3 siRNA, respectively, on the basis of successful transfection with miR-221 inhibitor. The transfection efficiency of miR-221 inhibitor was identified by qPCR. Cell viability in each group was measured by CCK-8 assay. Apoptosis in each group was detected by Annexin V-FITC/PI staining using a flow cytometry. The protein expressions of SOCS3, p-JAK1, p-JAK2, p-STAT3 and survivin in each group were detected by WB. Results: Compared with the control group, miR-221 expression was significantly down-regulated in miR-221 inhibitor group (P<0.01), cell viability was significantly reduced at 48 and 72 h after transfection (P<0.05 or P<0.01), the number of apoptotic cells was significantly increased (P< 0.01), the expression of SOCS3 was significantly increased (P<0.01) and the expression levels of p-JAK1, p-JAK2, p-STAT3 and survivin were significantly reduced (all P<0.01). Compared with miR-221 inhibitor group, cell viability was significantly increased at 24, 48 and 72 h after transfection (P<0.05 or P<0.01), the number of apoptotic cells was significantly decreased (P<0.01) and the expression levels of p-JAK1, p-JAK2, p-STAT3 and survivin were significantly increased in miR-221 inhibitor+SOCS3 siRNA group (all P< 0.01). Conclusion: Down-regulation of miR-221 inhibits proliferation and promotes apoptosis of K562 cells, the mechanism of which may be related with up-regulating SOCS3 expression to suppress JAK-STAT3 signaling pathway.