肠化生是胃癌最重要的癌前病变，胃转录因子SOX2的表达降低被认为是肠化生的关键因素, 但其机制尚不清楚。前期研究发现miR-145靶向负调控SOX2，其表达在肠化生组织中负相关；而miR-145上游存在多个NF-kB结合位点：提示miR-145/SOX2通路可能受NF-kB调控并对肠化生具有重要调控功能。本项目拟通过原位杂交、免疫组化等方法验证大规模样本肠化生组织miR-145同SOX2的相关关系；通过慢病毒载体、siRNA沉默等技术构建miR-145及SOX2的功能获得缺失模型；通过免疫印迹、PCR等技术检测肠化生相关分子表达研究miR-145的功能及SOX2对其功能的介导；最后采用染色质免疫共沉淀、DNA凝胶阻滞和报告基因等技术探索NF-kB激活miR-145的机制。本项目旨在阐释miR-145/SOX2通路在胃粘膜上皮肠化生中的调控作用及受调控机制，为胃癌癌前病变诊治提供新策略。

Gastric intestinal metaplasia (IM) is the most important precancerous lesion of gastric carcinoma.It is reported that loss of SOX2,which is specifically expressed in gastric epethelial cells, may be a key factor during the development of gastric intestinal metaplasia, but the mechanism remains to be fully elucidated. Our previous work confirmed that miR-145 inhibits SOX2 expression by directly binding to its 3'-UTR.We also found that expression of miR-145 and SOX2 in gastric IM are negtively correlated.Interestingly, our results showed that the upstream sequence of miR-145 promoter includes several potential binding sites of NF-kB, which was found to induce IM by directly activates CDX2, a intestinal specific transcription factor. These indicates that miR-145/SOX2 pathway may be regulated by NF-kB and plays vital roles in gastric IM. This project is going to explore the correlation of miR-145 and SOX2 expressions in clinical gastric IM tissues using in situ hybridization and immunohistochemisty;To investigate the functions of miR-145 and SOX2 in gastric IM in gain-of-function and loss-of-function model using lentiviral vector and siRNA;To explore the mechanism of NF-kB-induced miR-145 activation through Ch-IP,EMSA, and luciferase reporter gene assay. This project aims at elucidating the function and mechanism of miR-145/SOX2 pathway in gastric IM, further understanding intestinal metaplasia on microRNA and transcriptional factor level, and offering theoretical and experimental proof for the diagnosis and treatment of gastric precancerous lesion.