幽门螺杆菌CagA蛋白调控α-烯醇酶表达及在胃癌变进程中的意义

Helicobacter pylori cagA gene is closely associated with development and progression of gastric cancer, but the involved mechanism still remains undefined. This research group previously observed that the cagA gene was related to the overexpression of α-enolase (ENO1) by using a co-culture model of H. pylori and gastric carcinoma cells, and made the first report in 2014 on identification of a cellular signal pathway for the CagA regulation of ENO1 expression. Nevertheless, it has not been evidenced that CagA regulates the expression of ENO1 in human and animals. Thus, we propose the hypothesis that in vivo CagA might promote gastric carcinogenesis by regulating ENO1 expression. This project is formulated to establish gerbil models of H. pylori infection using cagA positive and knockout strains, respectively, measure mRNA expression levels of ENO1 in the gastric epithelial cells, perform pathologic grading of gastric lesions at regular intervals during the process from gastric infection to cancer, and carry out logistic regression analysis of the data, with the aim to ascertain the associations of the ENO1 expression with CagA as well as the progress of gastric canceration. The conclusion of the animal experiments will be confirmed with the data from examination of clinical gastric specimens, and basing on the findings of this study together with the present data, the hypothesis will be demonstrated. This study is hopeful to impact significantly the researches on H. pylori-involved carcinogenic mechanisms, and provide the crucial theory basis for early diagnosis and prevention of stomach cancer.

幽门螺杆菌(Hp)cagA基因与胃癌发生发展密切相关，但其机制不明。本课题组应用Hp与胃癌细胞共培养模型，发现Hp cagA基因阳性与肿瘤相关蛋白α-烯醇酶(ENO1)高表达有关，并于2014年首次报道CagA蛋白调控ENO1表达的信号通路。但CagA对ENO1表达的调控作用尚未在人或动物体内证实。因此，提出假说：CagA蛋白在体内通过调控ENO1表达促进胃癌发生。项目同时采用Hp cagA阳性菌株和基因敲除菌株构建Hp感染沙鼠动物模型，在从Hp感染至胃癌发生期间，定期检测胃上皮细胞ENO1 mRNA表达水平，并对胃部病变进行病理学分级量化，经logistic回归分析，探讨ENO1表达与CagA及胃部癌变进程的关系；并用临床标本的检测结果印证动物实验结论；结合本研究发现与现有证据，证实假说。项目有望对Hp感染致癌机制研究产生重大影响，并为胃癌的早期诊断和预防提供关键性理论依据。

幽门螺杆菌(Hp)cagA基因与胃癌发生发展密切相关，但其机制不明。α-烯醇酶ENO1 是糖酵解的关键酶，具有催化磷酸甘油向磷酸烯醇式丙酮酸转化的功能，对肿瘤细胞适应低氧微环境、增殖、浸润及转移至关重要。课题组基于文献和前期研究提出假说：在Hp宿主体内，CagA蛋白可能通过调控胃黏膜上皮细胞ENO1的表达促进胃癌变进程。为验证假说，该研究利用人群胃组织标本、动物模型及细胞转染技术，探讨了Hp CagA蛋白对胃黏膜组织ENO1表达及病变发展的作用。研究收集了临床浅表性胃炎、萎缩性胃炎、胃溃疡、肠上皮化生、异型增生、胃癌标本共计264例。qPCR检测结果显示，Hp阳性病例胃组织ENO1 mRNA表达水平高于Hp阴性病例；Hp阳性病例中，cagA+病例组ENO1表达水平高于cagA-病例组；胃癌组织ENO1表达水平高于癌旁组织和浅表性胃炎组织。动物实验显示，Hp感染8周后，沙鼠胃黏膜ENO1表达水平随感染时间延长呈升高趋势；cagA+组ENO1表达水平高于cagA-组；cagA+组病变程度较cagA-组高。免疫组化检测显示，在胃癌组织中，ENO1主要表达于胞质，在癌旁组织和良性病变组织中，ENO1表达于胞质和胞核。Hp与细胞共培养实验证明：Hp感染可调节胃黏膜上皮细胞ENO1的表达，其表达水平与Hp感染量及感染持续时间有关。cagA基因转染细胞实验表明：胃黏膜上皮细胞中ENO1表达水平与CagA蛋白在细胞内的表达水平有关。研究结果为证明CagA通过调控 ENO1 表达促进胃部癌变进程的假设提供了重要实验证据，为揭示Hp感染相关胃癌发生发展机制提供了新的关键基础。胃癌是人类常见恶性肿瘤，发病机制不明制约防控发展。本研究有望对Hp感染相关胃癌发病机制和早期防治研究产生积极影响。