幽门螺杆菌（H.pylori）是胃癌I类致癌因子，但H.pylori感染的胃癌患者有更长的生存期，其机制尚不清楚。我们在前期工作中利用芯片技术发现H.pylori阳性和阴性的胃癌组织有43条miRNAs呈差异表达，经qRT-PCR验证，miR-100-5p、miR-143-3p和miR-145-5p在H.pylori阳性胃癌组织显著上调。由此推测，H.pylori感染的胃癌患者生存期的延长与以上差异表达的miRNAs有关。本项目在此基础上，将miRNA mimics/inhibitors转染不同细胞，观察细胞增殖、凋亡、侵袭迁移的变化，分析其调控的下游靶基因和上游调控机制，阐明相关信号通路，并通过荷瘤小鼠动物模型和临床标本研究差异miRNAs对胃癌侵袭转移的影响及对靶基因的调控。本研究不仅有助于阐明H.pylori感染胃癌患者生存期延长的机制，也将为寻找胃癌治疗的新靶点提供实验依据。

Helicobacter pylori (H.pylori) was classified as a definite group 1 carcinogen of gastric cancer. However, patients positive for H.pylori showed improved overall survival and relapse-free survival. To date, the molecular mechanism remains unclear. In our preliminary experiment, we analyzed and identified the differentially expressed miRNA profiles in gastric cancer tissues with and without H.pylori infection by using μParaflo microfluidic microarrays. A total of 43 miRNAs were significantly differentially expressed. Then, verification of differentially expressed miRNA was performed using qRT-PCR method. As a result, miR-100-5p, miR-143-3p and miR-145-5p were significantly upregulated in H.pylori-positive gastric cancer tissues. Based on our promising preliminary experiment results, a hypothesis has been put forward that the improved overall survival for H.pylori-positive gastric cancer patients is associated with these differentially expressed miRNAs. In our project, miRNA mimics or inhibitors will be transfected into different gastric cancer cells at first. In addition, the functional effects of miRNAs on gastric cancer cells will be validated by cell proliferation assay, apoptosis assay and cell invasion and migration assays. Secondly, their target genes and related signal pathways will be predicted and confirmed. Thirdly, preclinical studies including in vitro cell culture system and in vivo tumor-bearing mouse models will be performed to test the effects of these obtained miRNAs on gastric cancer invasion and migration. Thus, this study will not only provide evidence for exploring the novel mechanism of improved survival for H.pylori-positive gastric cancer patients, but also provide solid experimental evidence for searching new target of gasric cancer therapy in the future.