Abstract: OBJECTIVE To investigate the correlation between the overexpression of Helicobacter pylori related miRNA-148b in gastric cancer and the H.pylori infections and observe the molecular mechanisms in proliferation and invasion of gastric cancer cells.METHODS A stable H.pylori infected human gastric epithelial cell model was firstly established in the study, the change of expression spectrum of miRNAs in gastric epithelial cells was detected before and after the H.pylori infection, and the study objects that showed remarkable up-regulated expression of miRNA-148b after the infection were screened out.Gastric cancer cell line AGS, HGC-27, SGC-7901 and human normal gastric epithelial cell line GES-1 were selected as the research subjects.The over expression plasmids of miRNA-148b specific siRNA and miRNA-148b were designed and synthesized to inhibit or overexpress the level of expression of miRNA-148b.The role of miRNA-148b in the proliferation and invasion of the gastric cancer cells was studied by means of apoptosis through experiment and Transwell cell invasion experiment.The molecular mechanisms of miRNA-148b in the proliferation and invasion of the gastric cancer cells were explored.RESULTS The results of real-time PCR detection showed that the level of expression of miR-148b was elevated after the gastric epithelial cells GES-1 and gastric cancer cell lines AGS, HGC-27, and SGC-7901 were infected with H.pylori, the level of expression of miR-148b was lower in the gastric cancer cell lines than in the normal gastric mucosa, it was found that the miR-148b in vitro could promote the proliferation of gastric cancer cell lines AGS, HGC-27, and SGC-7901 cell and inhibit the apoptosis of SGC-7901 cells of gastric cancer cell strain.It was concluded that the tumor suppressor gene TP53 INP1 and oncogene PAI-1 were the target genes of miR-148b, and the expression levels of miR-148b and PAI-1 in gastric cancer cell lines and gastric cancer tissues were significantly negatively correlated.CONCLUSIONThe detection of expression of miR-148b in gastric epithelial cells before and after the infection with H.pylori has verified the result of the previous miRNAs chip test, the overexpression of miR-148b in vitro can promote the proliferation of the gastric cancer cell strains and inhibit the apoptosis, indicating that the body may slow down the process of excessive apoptosis of gastric epithelial cells induced by the early H.pylori infection, thus, it plays the corresponding protective role. Compared with the normal gastric mucosa tissues, the down-regulated expression of miR-148b in gastric cancer cell strains implies that the miR-148b may be inhibited as a tumor suppressor gene during the development of gastric cancer.It is confirmed that the tumor suppressor gene TP53 INP1 and oncogene PAI-1 are the target genets of miR-148b, indicating that the function of miR-148b varies in different stages of H.pylori infections and gastric cancer; the specific mechanisms need to be further studied.