Overexpression of miR-221 inhibits proliferation and promotes apoptosis of human astrocytoma cells.

microRNAs (miRNAs) play tumor-promoting roles in a variety of tumors. This study investigated the expression of miRNA-211 (miR-221) in human astrocytoma, and its effect on proliferation and apoptosis of human astrocytoma cells in vitro. miR-221 expression was detected in 10 astrocytoma tissues and 4 adjacent tissues by real-time quantitative PCR (qRT-PCR). miR-221 expression in situ was significantly higher in astrocytoma tissues than in adjacent tissues (P<0.05). To determine whether the upregulation of miR-221 could be associated with tumor development or progression, a synthetic miR-221 mimic was transiently transfected into U251 astrocytoma cells in vitro. qRT-PCR confirmed that the mimic significantly increased the expression of miR-221 in these cells. An MTT colorimetric assay indicated that proliferation was significantly higher in U251 cells transfected with miR-221 mimic than in scramble-transfected control cells (P<0.05). Further analysis of miR-221 transfected cells by flow cytometry revealed an altered cell cycle progression, with more cells in S and G1 phase, as well as an inhibition of apoptosis (P<0.05). These findings indicate that the upregulation of miR-221 in astrocytoma tissues may be associated with development or progression of these tumors. Thus, miR-221 should be explored as a potential molecular marker for the diagnosis and treatment of astrocytoma.