Influence of up-regulation of miR-181a expression on proliferation and apoptosis of gastric cancer cell AGS

Objective: To investigate the effect of miR-181a on the proliferation and apoptosis of gastric cancer cells and its possible mechanism. Methods: miR-181a expression in 5 types of gastric cancer cells and normal gastric mucosal cell line GES-1 was detected by Real-time PCR. miR-181a mimics was transfected transiently into gastric cancer cell line AGS to up-regulate the expression of miR-181a. The influences of up-regulation of miR-181a on cell growth, cell cycle and apoptosis were evaluated by MTT and flow cytometry. Protein levels of CDC25A, cyclinA2, cyclinD1, p21, Bcl-2 and Bax were detected by Western blot. Result: Compared with GES-1, the expression levels of miR-181a in gastric cancer cell lines SGC-7901 and MKN28 were significantly higher (both P<0.01), while miR-181a had no significant differences in MGC-803, BGC-823 and AGS (all P>0.05). The transfection of miR-181a mimics up-regulated miR-181a expression in AGS (P<0.05). In AGS cell after transfection with miR-181a minics, the proliferative ability was increased, G0/G1 phase cell ratio was decreased, S phase cell ratio was increased, and apoptosis rate was reduced (all P<0.05). In miR-181a up-regulated AGS cell, the protein expressions of CDC25A, cyclinA2 and Bcl-2 was increased, and the expression of Bax was decreased (all P<0.05). But the expressions of cyclinD1 and p21 had no statistical differences(both P>0.05). Conclusion: Overexpression of miR-181a promotes cell growth and cell cycle in AGS; up-regulation of CDC25A and CyclinA2 may be one of the mechanisms. Overexpression of miR-181a inhibits cell apoptosis in AGS, and up-regulation of Bcl-2 and down-regulation of Bax may be involved in the process.