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，是胃癌的主要原因，也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的高危人群，并制定新的干预战略。我们已经直接发现，胃上皮细胞对幽门螺杆菌的异常信号反应与表皮生长因子受体(PEGFR)的磷酸化和精胺氧化酶(SMO)的诱导有关。我们已发表的和初步的数据表明，SMO氧化多胺精胺会产生H2 02，这是感染的胃上皮细胞DNA损伤的原因，而pEGFR是SMO表达所必需的，并介导了具有SMO驱动的DNA损伤的细胞亚群的产生，这些细胞对凋亡具有抵抗力。这些事件发生在条件永生化的胃上皮细胞和胃癌变的活体模型中(INS-GAS小鼠和蒙古沙土鼠)，人类组织显示出SMO与DNA损伤的强烈相关性。抑制多胺合成或SMO可减少沙土鼠的胃异型增生和癌症。我们的磷蛋白质组学和人类组织微阵列研究表明，除了SMO信号外，EGFR和ErbB2信号还与胃癌的发生有关。此外，尽管pEGFR显著增加，在体外和体内耗尽多胺可以减少DNA氧化损伤和癌症。我们的假设是，多胺决定了EGFR磷酸化在幽门螺杆菌诱导的炎症、DNA损伤和胃癌发生中的作用。我们的具体目标是确定以下在幽门螺杆菌诱导的胃癌发生中的作用：1)EGFR反式激活和抗凋亡细胞的作用；2)pEGFR的有害作用是否需要多胺；以及3)EGFR信号的正负调控因子。这些研究将纳入独特的体外和体外模型，如胃器官，以及在整个PPG中采用的已证实的小鼠和沙土鼠胃不典型增生和癌症模型，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，包括交换来自我们不同动物系统的幽门螺杆菌突变菌株和输出菌株，共享与信号转导相关的样本和专业知识，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AIM 3的蛋白质组学核心8的卓越质量，并将受益于Vanderbilt在幽门螺杆菌和胃癌研究方面独特的强大环境。

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.