中文摘要：

目的探讨miR-181a对胃癌细胞增殖、周期及凋亡的影响及其作用机制。方法荧光实时定量PCR检测5种胃癌细胞及人胃黏膜细胞系GES-1中miR-181a的表达情况,以及胃癌细胞AGS瞬时转染miR-181amimic后miR-181a的表达情况;MTT法和流式细胞仪检测上调miR-181a表达对胃癌细胞AGS增殖、周期和凋亡等生物学行为的影响;Western blot检测上调miR-181a后细胞周期调控蛋白（CDC25A、cyclinA2、cyclinD1、p21）和凋亡相关蛋白（Bcl-2和Bax）的表达变化。结果与人胃黏膜细胞系GES-1比较,miR-181a在人胃癌细胞株SGC-7901和MKN28表达升高（P均〈0.01）,在MGC-803、BGC-823、AGS表达差异无统计学意义（P均〉0.05）;瞬时转染miR-181amimic后,胃癌细胞AGS中miR-181a的表达明显上调（P〈0.05）;转染miR-181amimics后AGS细胞增殖明显,G0/G1期细胞减少,S期细胞明显增多,细胞凋亡明显减弱（P均〈0.05）。Western blot结果显示,上调miR-181a后胃癌细胞AGS中CDC25A、cyclinA2和Bcl-2表达升高（P均〈0.05）,cyclinD1和p21表达差异没有统计学意义（P〉0.05）,Bax表达降低（P〈0.05）。结论上调miR-181a可以促进胃癌细胞AGS增殖,其作用机制可能与CDC25A、CyclinA2表达升高有关;上调miR-181a可抑制胃癌细胞凋亡,其作用机制可能与Bcl-2表达升高及Bax表达降低有关。

英文摘要：

Objective To investigate the effect of miR-181 a on the proliferation and apoptosis of gastric cancer cells and its possible mechanism.Methods miR-181 a expression in 5 types of gastric cancer cells and normal gastric mucosal cell line GES-1 was detected by Real-time PCR.miR-181 a mimics was transfected transiently into gastric cancer cell line AGS to up-regulate the expression of miR-181 a.The influences of up-regulation of miR-181 a on cell growth,cell cycle and apoptosis were evaluated by MTT and flow cytometry.Protein levels of CDC25 A,cyclinA2,cyclinD1,p21,Bcl-2 and Bax were detected by Western blot.Result Compared with GES-1,the expression levels of miR-181 a in gastric cancer cell lines SGC-7901 and MKN28 were significantly higher（both P〈0.01）,while miR-181 a had no significant differences in MGC-803,BGC-823 and AGS（all P〈0.05）.The transfection of miR-181 a mimics up-regulated miR-181 a expression in AGS（P〈0.05）.In AGS cell after transfection with miR-181 a 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-181 a up-regulated AGS cell,the protein expressions of CDC25 A,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）.ConclusionOverexpression of miR-181 apromotes cell growth and cell cycle in AGS;up-regulation of CDC25 A and CyclinA2 may be one of the mechanisms.Overexpression of miR-181 a inhibits cell apoptosis in AGS,and up-regulation of Bcl-2and down-regulation of Bax may be involved in the process.