Expression Of MiRNA-34a In Human Gastric Cancer And Its Effects On The Proliferation And Apoptosis Of Gastric Cancer Cells

ObjectiveTo investigate the expression level of miR-34a in human gastric cancer tissues and some human gastric cancer cell lines. To explore the role of miR-34a in the proliferation, cell cycle and apoptosis of human gastric cancer cell line SGC-7901 by constructing and infecting the lentiviral system expressing miR-34a, meanwhile predict possible tumor related targets of miR-34a. To study the role of miR-34a in the occurrence and development of gastric cancer and its possible mechanisms.Methods1.The expression levels of miR-34a in 34 human gastric cancer tissues and pericarcinomatous normal tissues as well as in human gastric mucosal epithelial cells GES and human gastric cancer cell lines AGS, SGC-7901, MKN-45, BGC-823 were detected by Real-time PCR.2.Gastric cancer SGC-7901 cells were infected with the lentiviral system expressing miR-34a or negative control in vitro. The infected cells status was evaluated by fluorescence microscope. The proliferation, cell cycle and apoptosis were measured by MTT and flow cytometry.3.Through online prediction software miRanda, TargetScan and PICTAR to predict and select possible tumor related targets of miR-34a.4.All the data for the statistical analysis by SPSS 19.0 software.Results1.The relative expression of miR-34a in gastric cancer tissues was 0.65+0.69, which was significantly lower than that of normal tissues 1.02±0.04(t=3.085, P<0.01). But there was no significant correlation between the relative expression of miR-34a and differentiated degree, depth of invasion, lymphatic metastasis in gastric cancer.(P>0.05)2.The relative expression of miR-34a in ACS, SGC-7901, MKN-45, BGC-823 were 0.24±0.01,0.03±0.00,0.31±0.04 andO.25±0.05, which was significantly decreased compared with the relative expression of miR-34a in GES 0.98±0.07(t=17.522,22.879, 13.836,14.393, P<0.05), and the most obvious difference was in SGC-7901 (P<0.01).3.The relative proliferation ratios of miR-34a lentiviral infected group in the detection of 3 to 5 days compared with negative control group were (1.39±0.19,1.82±0.16, 2.37±0.04) vs (1.84±0.10,2.46±0.11,3.14±0.38), and the former is obviously lower than the latter(t=4.567,7.265,4.500, P<0.01).4.The ratio of cells arrested at G1/GO phsae in miR-34a lentiviral infected group was 58.72%,which was higher than negative control group 56.36%, the difference was statistically significant/=-4.804, P<0.05).5.The ratio of apoptosis was significantly increased in miR-34a lentiviral infected group compared with negative control group(6.44±0.41 vs 3.06±0.16,/=-13.226, P<0.01).6. The selected possible tumor related targets of miR-34a were E2F3, MET, NOTCH1, SIRT1, Bcl-2, YY1 and CCNE2, which were predicted by miRanda, TargetScan and PICTAR.Conclusion1.MiR-34a has lower expression level in gastric cancer tissues and some gastric cancer cell lines, which indicate that miR-34a may closely associate with the occurrence and development of gastric cancer.2.MiR-34a can inhibit the proliferation, induce cell cycle arrest and cell apoptosis of gastric cancer cell line SGC7901, thus playing the role of tumor suppressor genes.The anti-tumor effects of miR-34a by promoting proliferation inhibition, cell cycle arrest and apoptosis of gastric cancer may relate to its inhibiting E2F3, MET, NOTCH 1, SIRT1, Bcl-2, YY1 and CCNE2.