慢性胃炎恶性转化的基因调控网络及其关键节点的研究

The incurable chronic gastritis is one of the major initiators inducing gastric cancer. Hence, revealing mechanisms of chronic gastritis-inducing gastric cancer provides the experimental basis of identification and application of key factors in clinical control and intervention. The goal of this project is to disclose the molecular mechanisms of gastric cancer develop from chronic gastritis. We will get the clinical samples (normal gastric mucosea, intestinal metaplasia, dysplasia, and gastric cancer) animal models (induced by H.felis) and cell model specimens (retro-differentiate and trans-differentiate) and get high purity cells from these samples by laser capture microdissection. The datasets of DNA mutation, DNA methylation, mRNA and miRNA expression profiles will be developed by DNA sequencing and RNA sequencing. Identify the the methylation of regulator and transcription factors, driver variation and its signal transduction pathways which associated with chronic gastritis transformed into gastric cancer by integrating data analysis and building gene regulatory network. The validation experiments will be performed by perturbation the network in animal models and cell models. The significance will be verified by clinical samples..This project will contribute to the comprehensive understanding in mechanisms of the transformation from chronic gastritis to gastric cancer, and will provide new strategies and therapeutic targets for gastric cancer prevention and treatment.

非可治愈性慢性炎症是导致胃癌发生的重要因素之一。因此，了解慢性炎症致癌的机制，从中筛选调控关键基因是临床控制或者干预炎症致癌的实验基础。本项目从临床标本、动物模型和细胞模型三个层面出发，获得慢性胃炎恶性转化各个阶段样本，以激光显微切割获得高纯度细胞样品，以深度测序获得DNA变异、DNA甲基化、mRNA和miRNA表达谱数据，通过数据整构建动态复合基因调控网络，从而识别参与炎癌转化相关的甲基化调控子、转录因子、原因性变异及其信号转导通路等，以前期研究结果为先验知识对网络进行验证，并以这些关键因子对网络进行干预，观察网络的转归，同时以这些关键因子对细胞模型进行干预，观察细胞表型转变；然后，再以临床标本进行检验其临床病理学意义，以期揭示胃炎致胃癌发生发展的分子机制，为胃癌的防治提供新策略和新靶标。

MUC6在胃癌发生的过程中表达逐渐丢失，297例胃癌组织中MUC6阳性率只有23.91%，应用CRISPR/Cas9技术成功敲除C57BL/6J小鼠中的Muc6基因，可以导致小鼠胃黏膜经过炎症、增生、肠上皮化生、异型增生的顺序发展成为肿瘤。在30、40、50、60周的小鼠肿瘤发生率分别为16.67%，50.00%，, 66.67% ，和100% 。RNA-Seq结果表明，在5周的小鼠中Muc6缺失即可诱导炎症趋化因子显著升高，进而诱导炎症因子分泌，在40周的Muc6-/-小鼠中，有丝分裂、翻译、细胞周期和染色体解聚等生物过程是主要的分子事件。.通过临床样本研究发现，IM细胞的基因突变数目远高于正常胃腺体细胞，和胃炎细胞；大多数患者的IM细胞的基因突变较低，少数患者基因突变非常高，预示着这些细胞选择恶性突变的速度和概率都要高；大多数患者基因组上的突变是由于长期的慢性炎症产生。.我们基于39个胃上皮正常及异常分化相关的调控因子构建了胃上皮分化障碍内源性分子调控网络，揭示了正常及胃癌的稳态特征。发现REG4高表达型CDX2阳性胃癌预后明显更差且对5-FU存在原发性耐药。CDX2选择性招募CBP或EZH2至REG4启动子及增强子进而实现对REG4的差异转录表达调控是两种分子亚型形成的重要机制，也是REG4高表达亚型对EZH2及CBP抑制剂均较为敏感的机制，针对REG4高表达型CDX2阳性胃癌的靶向治疗及联合治疗策略，具有重要转化价值。