miR-92a在胃粘膜肠上皮化生中调控CDX2的作用机制研究

Gastric intestinal metaplasia(IM) is the most common precancerous lesion of gastric cancer. Caudal-related homeobox 2(CDX2) has been considered playing a pivotal role in the induction of IM. However, the mechanism of CDX2 activation remains unclear. In our previous study, we confirmed that miR-92a, a member of miR-17-92 cluster, was most up-regulated in the gastric IM model compared with normal gastric epithelial cells; we further found that CDX2 expression in gastric epithelial cells was increased after being transfected with miR-92a mimics. Thus we hypothesized that miR-92a may promote CDX2 expression through regulation of targets, leading gastric epithelial cells to transdifferentiate from gastric phenotype to intestinal phenotype. This project is going to validate the function of miR-92a through detecting IM marker; to combine dual luciferase reporter and western-blot to verify miR-92a targets;to exprlore the targets-CDX2 regulating mechanism by protein-protein interaction experiments; to verify the relationship of miR-92a, its targes and CDX2 expression in clinical IM and normal samples. This project aims at exploring the key pathways of miR-92a in gastric IM invoving CDX2 regualtion, deep deepening the relization of gastric IM on microRNA level, and providing the theories and experimental proofs to block gastric precancerous lesions.

胃粘膜肠上皮化生是胃癌最常见的癌前病变，转录因子CDX2被认为是促进肠化生的关键调控分子,但其被激活机制尚不清楚。申请者前期通过建立胃粘膜肠上皮化生细胞模型并与正常的胃上皮细胞进行对比，microRNA芯片筛选发现miR-17-92簇成员miR-92a的上调最为明显；随后在胃细胞过表达miR-92a后，CDX2的表达也明显升高。因此miR-92a可能通过调控靶分子影响CDX2的表达，进而促进肠化生。本项目拟通过检测肠化生标志物研究miR-92a调控肠化生的功能；双荧光素酶报告基因实验以及免疫蛋白印迹方法验证miR-92a靶分子；通过蛋白相互作用实验研究靶分子调控CDX2机制；最终在临床标本中验证表达相关关系。本研究旨在探索miR-92a通过CDX2调控胃细胞肠化生的信号通路，在microRNA水平深度阐释胃细胞肠化生分子调控网络，以期为理解肠化生的发生机制，遏制胃癌癌前病变进展提供理论依据

胃粘膜肠上皮化生是胃癌最常见的癌前病变，项目组通过深入探索miR-92a调控靶分子及下游基因的机制、靶分子同CDX2的表达和活性的内在联系，从microRNA水平阐述胃粘膜上皮肠化生的调控机制。项目组通过病例对照研究发现我国西北地区胃粘膜肠上皮化生的危险因素为年龄>60岁、幽门螺杆菌感染、吸烟、胃癌家族史、高盐饮食、辛辣饮食和胆汁反流。进一步通过体外实验证实胆汁酸能够诱导miR-92a在胃上皮细胞中的表达； miR-92a能够通过调控NF-kB的表达和活性而调控CDX2的表达；继而确定了miR-92a/FOXD1/NF-kB/CDX2通路在肠化生尤其是胆汁酸诱导肠化生的过程中的重要作用。项目组还发现miR-92a不仅在胃粘膜肠化生中起作用, miR-92a及miR-17-92簇的多个成员可作为胃癌早期诊断标志物；miR-520d-5p/CypB/STAT3通路在幽门螺杆菌感染参与胃癌发生的过程中发挥了重要的作用。