EGFR Activation and Polyamines in H.Pylori-Induced Gastric Cancer

幽门螺杆菌感染了世界上一半的人口，是导致胃癌的主要原因，而胃癌是全球癌症死亡的第二大原因。然而，普遍根除是不可行的，迫切需要确定癌症发展高风险人群并制定新的干预战略。我们已经在胃上皮细胞对幽门螺杆菌的异常信号反应中直接涉及了表皮生长因子受体（pEGFR）的磷酸化和精胺氧化酶（SMO）的诱导。我们发表的和初步的数据表明，SMO氧化多胺精胺导致H2 02的产生，这是受感染的胃上皮细胞DNA损伤的原因，并且pEGFR是SMO表达所必需的，并介导具有SMO驱动的DNA损伤的细胞亚群的产生，这些细胞亚群对细胞凋亡具有抗性。这些事件发生在条件永生化的胃上皮细胞和体内胃癌模型（INS-GAS小鼠和蒙古沙鼠）中，人类组织显示出SMO和DNA损伤的强相关性。抑制多胺合成或SMO可减少沙鼠胃发育不良和胃癌。我们的磷酸蛋白组学和人体组织微阵列研究表明，除了SMO外，EGFR和ErbB2信号也参与胃癌的发生。此外，体外和体内多胺的消耗减少了氧化DNA损伤和癌症，尽管pEGFR显著增加。我们的假设是，多胺决定了EGFR磷酸化对幽门螺杆菌诱导的炎症、DNA损伤和胃癌发生的影响。我们的具体目的是确定以下因素在幽门螺杆菌诱导的胃癌发生中：1)EGFR反活化和凋亡抵抗细胞的作用；2)如果pEGFR的有害作用需要多胺；3) EGFR信号的正向和负向调节因子。这些研究将结合独特的体外和离体模型，如胃类器官，以及经过验证的小鼠和沙鼠胃发育不良和癌模型，这些模型将在PPG中使用，以实现这些目标。我们将受益于与项目1和项目3的持续密切合作，包括交换来自不同动物系统的幽门螺杆菌突变菌株和输出菌株，分享与信号相关的样品和专业知识，以及我们对smo诱导的氧化应激和DNA损伤的分析。该项目将利用Aims 1-3的组织病理学核心A和Aims 3的蛋白质组学核心8的卓越质量，并将受益于范德比尔特大学幽门螺杆菌和胃癌研究的独特强大环境。

Helicobacter pylori infects half the world and is the principal cause of gastric cancer, the second leading cause of cancer death worldwide. However, universal eradication is not feasible and there is a strong need to identify persons at high risk for cancer development and develop new strategies for intervention. We have directly implicated phosphorylation of the epidermal growth factor receptor (pEGFR) and induction of spermine oxidase (SMO) in the aberrant signaling response to H. pylori in gastric epithelial cells. Our published and preliminary data show that oxidation of the polyamine spermine by SMO results in generation of H2 02 that is the cause of DNA damage in infected gastric epithelial cells, and that pEGFR is required for SMO expression and mediates the generation of a subpopulation of cells with SMO-driven DNA damage that are resistant to apoptosis. These events occur in conditionally immortalized gastric epithelial cells and in in vivo models of gastric carcinogenesis (INS-GAS mice and Mongolian gerbils), and human tissues exhibit a strong correlation of SMO and DNA damage. Inhibition of polyamine synthesis or SMO reduces gastric dysplasia and carcinoma in gerbils. Our phosphoproteomics and human tissue microarray studies have implicated EGFR and ErbB2 signaling in addition to SMO in the initiation of gastric carcinogenesis. Additionally, depletion of polyamines in vitro and in vivo reduces oxidative DNA damage and carcinoma despite substantially increasing pEGFR. Our hypothesis is that polyamines determine the effects of EGFR phosphorylation on H. pylori-induced inflammation, DNA damage, and gastric carcinogenesis. Our Specific Aims are to determine the following in H. pylori-induced gastric carcinogenesis: 1) the role of EGFR transactivation and apoptosis-resistant cells; 2) if polyamines are required for the deleterious effects of pEGFR; and 3) the positive and negative regulators of EGFR signaling that are involved. These studies will incorporate unique in vitro and ex vivo models such as gastric organoids, and proven models of gastric dysplasia and carcinoma in mice and gerbils that are employed across this PPG to pursue these aims. We will benefit from continued close collaborations with Projects 1 and 3 that will include exchange of H. pylori mutant strains and output strains from our different animals systems, sharing of samples and expertise related to signaling, and our analysis of SMO-induced oxidative stress and DNA damage. This project will leverage the exceptional quality of Histopathology Core A for Aims 1-3 and Proteomics Core 8 for Aim 3, and will benefit from the uniquely strong environment at Vanderbilt for studies of H. pylori and gastric cancer.