Helicobacter pylori cag Pathogenicity Island and Gastric Carcinogenesis

革兰氏阴性细菌幽门螺杆菌在人胃中的持续定植是 与胃腺癌发生风险增加相关。H.幽门螺杆菌分离株， 不同的人类表现出相当程度的遗传多样性。一个染色体区域， 在一些H. pylori菌株，而不是其他菌株的cag致病岛（派），一个40 kb的区域，预计 编码27种不同的蛋白质H.携带cag致病岛的pylori菌株与 胃癌发病率明显高于缺乏cag致病岛的菌株。 cag派编码一种效应蛋白CagA，其通过IV型胶原转运到上皮细胞中。 分泌过程。 这项工作的长期目标是确定H。pylori cag PAI阳性菌株 诱发胃癌。我们实验室最近的研究揭示了盐在调节 CagA的表达及调节H.幽门螺杆菌引起异常的上皮细胞反应。这些 研究结果，结合大量的文献表明饮食中的盐在胃癌中的作用，使我们 提出研究盐调节CagA表达的机制的实验， 研究盐对H. py/ori体外诱导的细胞信号转导，并研究盐对H. py/on诱导的体内疾病进展。 目的1分析盐对CagA表达的调控机制。我们 将使用多种实验方法，包括将基因突变引入H。幽门，分离 的DNA-蛋白质复合物，和这种复合物的质谱分析。目标2将调查 胃上皮细胞对H.表达突变形式的幽门螺杆菌菌株 CagA。选择用于分析的表型将包括CagA易位到宿主细胞中，诱导IL-8 分泌、β-连环蛋白激活和EGFR反式激活（与Peek和Polk博士合作， 和细胞凋亡，因为这些表型中的每一种都与胃溃疡的发病机制有关。 癌目的3将这些体外结果推广到H. py/或/-诱导的癌症， Peek博士开发的实验动物，包括INS-GAS小鼠和蒙古沙鼠。 这些研究应该导致我们对分子机制的理解取得重要进展， 其中H。幽门螺杆菌调节胃上皮细胞的信号传导并刺激胃上皮细胞的发育。 癌最终，这些研究将导致恶性肿瘤预防和治疗的进展 在慢性炎症的情况下发展。

Persistent colonization of the human stomach with the Gram-negative bacterium Helicobacter pylori is associated with an increased risk for the development of gastric adenocarcinoma. H. pylori isolates from different humans exhibit a considerable level of genetic diversity. One chromosomal region that is present in some H. pylori strains but not others is the cag pathogenicity island (PAI), a 40 kb region that is predicted to encode 27 different proteins. H. pylori strains harboring the cag pathogenicity island are associated with a significantly higher rate of gastric cancer incidence than are strains that lack the cag pathogenicity island. The cag PAI encodes an effector protein, CagA, that is translocated into epithelial cells via a type IV secretion process. The long-term goal of this work is to define mechanisms through which H. pylori cag PAI-positive strains induce gastric cancer. Recent studies in our laboratory have revealed an important role of salt in regulating CagA expression and in modulating the ability of H. pylori to cause aberrant epithelial cell responses. These findings, in conjunction with extensive literature indicating a role of dietary salt in gastric cancer, have led us to propose experiments that investigate the mechanism by which salt modulates CagA expression, investigate effects of salt on H. py/ori-induced cell signaling in vitro, and investigate effects of salt on H. py/on-induced disease progression in vivo. Aim 1 proposes to analyze the regulatory mechanisms through which salt regulates expression of CagA. We will use multiple experimental approaches, including introduction of genetic mutations into H. pylori, isolation of DNA-protein complexes, and mass spectrometry analysis of such complexes. Aim 2 will investigate alterations in gastric epithelial cells that occur in response to H. pylori strains that express mutant forms of CagA. Phenotypes selected for analysis will include translocation of CagA into host cells, induction of IL-8 secretion, (3-catenin activation and EGFR transactivation (in collaboration with Drs. Peek and Polk, respectively), and apoptosis, since each of these phenotypes is relevant to the pathogenesis of gastric cancer. Aim 3 will extend these in vitro results into rodent models of H. py/or/-induced cancer that have been developed by Dr. Peek, including INS-GAS mice and Mongolian gerbils. These studies should lead to important advances in our understanding of the molecular mechanisms by which H. pylori modulates signaling in gastric epithelial cells and stimulates the development of gastric cancer. Ultimately, these studies should lead to advances in the prevention and therapy of malignancies that develop in the setting of chronic inflammation.