LAUSR

MicroRNAs (miRNAs, miR) are of critical importance in growth and metastasis of cancer cells; however, the underlying functions of miRNAs in osteosarcoma (OS) remain largely unknown. This study was aimed to elucidate the role of miR‐221 in regulating the biological behavior of OS cells. The proliferation ability was examined by cell counting kit‐8 (CCK‐8) and cell cycle assay. The abilities of cell migration, invasion, and apoptosis were monitored by transwell assay and flow cytometry, respectively. The effect of miR‐221 on cyclin‐dependent kinase inhibitor 1B (CDKN1B) expression was evaluated by luciferase assays, real‐time polymerase chain reaction, and Western blot analysis. We found that miR‐221 was elevated in OS cell lines compared with the normal osteoblastic cell line. Transfection of the miR‐221 inhibitor into MG63 and U‐2OS cell lines obviously suppressed cell proliferation, migration, and invasion, which is accompanied with cell cycle arrest in G0/G1 phase. Furthermore, luciferase reporter assays indicated that CDKN1B is directly targeted by miR‐221 in OS cells. Knockdown of CDKN1B inhibited the effects of miR‐221 inhibitor, along with decreased Bax and caspase‐3 and increased cyclin E, cyclin D1, Bcl‐2, Snail, and Twist1 expression. The results suggested that miR‐221 might act as a potentially useful target for treatment of OS.