Objective To investigate the effects of microRNA(miRNA)-375 on gastric cancer cell function and the possible mechanism.Methods miRNA-375 eukaryotic expression vector was stably transfected into human gastric cancer cell line HGC-27.A miRNA-375 highly expressed gastric cancer cell line PC3,1-375 was screened and established.Blank plasmid transfection group (PC3.1 group) and blank control group were also established.The cell proliferation ability and apoptosis rate in three groups were detected by cell counting kit-8 (CCK-8) method and flow cytometry.The protein expression of astrocyte elevated gene 1 (AEG-1) in three groups was determined by Western blotting.The nude mouse subcutaneous xenografts model was also established.After 30 days,the nude mice were executed and the xenografts were dissociated and measured.The expression ofAEG-1 in the tumors at protein level was tested by immunohistochemistry method.The statistical inference includes t-test and analysis of variance.Results After stable transfection and cell screening,compared with that of blank control group,the expression of miRNA-375 in PC3.1-375 group significantly increased (t=2.82,2.01,bothP＜0.05).The cell proliferation of PC3.1-375 group was significantly lower than that of PC3.1 group and blank control group and the difference reached a maximum in day 3 (t3d=3.56,2.79,both P＜0.05).But with the apoptosis rate of PC3.1-375 group,the opposite was true (t=2.05,2.96,both P＜0.05).The results of Western blot shows that the expression of AEG-1 at protein level of PC3.1-375 group decreased compared with that of blank control group and PC3.1 group.The xenografts growth rate,average weight and tumor volume of PC3.1-375 group were significantly lower than those of blank control group and PC3.1 group (t=3.78,2.26,both P＜0.05).By the end of experiment,the volume of nude mouse subcutaneous xenografts in blank control group ((3.12 ± 0.77) cm3) and PC3.1 group ((3.76 ± 0.65) cm3) was significant bigger than that inPC3.1-375 group (0.72±0.21) cm3,t=5.67,6.92,both P＜0.05).The average weight of xenografts in PC3.1-375 group ((0.85 ± 0.15)g) was obviously lower than that in PC3.1 group ((4.01±0.52) g) and blank control group ((3.86±0.56) g,t=4.56,5.01,both P＜0.05).The results of immunohistochemistry indicated that the expression of AEG-1 protein in xenografts in PC3.1-375 group was remarkably decreased compared with that in blank control group and PC3.1 group (F=35.000,P＜0.05).Conclusions miRNA-375 can effectively inhibit the cell proliferation of gastric cancer,promote cells apoptosis and it's a tumor suppression factor in gastric cancer.AEG-1 may be a target gene of miRNA-375.