Gastric adenocarcinoma is the second leading cause of cancer-related death in the world. H. pylori is the strongest known risk factor for this malignancy, yet only a fraction of infected persons ever develop cancer. One H. pylori determinant that augments cancer risk is the cag pathogenicity island, and several cag genes encode components of a type IV bacterial secretion system which functions to export proteins (e.g., CagA) nto host epithelial cells. A host effector that may influence carcinogenesis is li-catenin, a downstream component of the Wnt pathway. When Wnt signaling is inactive, (l-catenin is constitutively phosphorylated and degraded;binding of Wnt to its receptor inhibits G-catenin phosphorylation, leading to its nuclear accumulation and the transcriptional activation of genes that influence carcinogenesis. Nuclear accumulation of fi-catenin is increased in gastric adenoma and dysplasia specimens, histologic stages that precede gastric adenocarcinoma. Our preliminary studies now demonstrate that a rodent-adapted H. pylori ?ag+ strain (7.13) rapidly induces gastric cancer in hypergastrinemic (INS-GAS) mice by 24 weeks and in Vlongolian gerbils by 4 weeks and that strain 7.13 induces nuclear translocation of G-catenin and activates a B-catenin-responsive reporter in vitro, indicating that li-catenin is functionally responsive to this prototype strain. IS-catenin activation by H. pylori is dependent upon translocation of CagA into epithelial cells, and nuclear accumulation of U-catenin is increased in gastric epithelium harvested from cag+-infected persons, compared to subjects carrying cag strains or uninfected persons. Our hypothesis is that H. pylori cag* strains selectively activate host signaling pathways, such as those mediated by R-catenin, thereby regulating cellular responses that contribute to the augmentation in carcinogenic risk associated with these strains. Thus, our specific aims are: 1. To define the effects of H. pylori constituents on activation of S-catenin in vitro and in vivo. 2. To determine the eukaryotic signaling pathways that regulate H. py/or/-induced fi-catenin activation. 3. To define differences in epithelial molecular responses to carcinogenic H. pylori versus mutant strains using a transgenic murine model of gastric cancer.
These studies will define bacterial and host factors that influence gastric cancer. Such findings may help to identify H. pylori infected persons at high risk for gastric cancer, who thereby warrant therapy.
|Sierra, Johanna C; Asim, Mohammad; Verriere, Thomas G et al. (2017) Epidermal growth factor receptor inhibition downregulates Helicobacter pylori-induced epithelial inflammatory responses, DNA damage and gastric carcinogenesis. Gut :|
|Hardbower, Dana M; Asim, Mohammad; Luis, Paula B et al. (2017) Ornithine decarboxylase regulates M1 macrophage activation and mucosal inflammation via histone modifications. Proc Natl Acad Sci U S A 114:E751-E760|
|Gobert, Alain P; Wilson, Keith T (2017) Effect of CO2 on Peroxynitrite-Mediated Bacteria Killing: Response to Tsikas et al. Trends Microbiol 25:602-603|
|Kyburz, A; Urban, S; Altobelli, A et al. (2017) Helicobacter pylori and its secreted immunomodulator VacA protect against anaphylaxis in experimental models of food allergy. Clin Exp Allergy 47:1331-1341|
|Varga, Matthew Gordon; Peek, Richard M (2017) DNA Transfer and Toll-like Receptor Modulation by Helicobacter pylori. Curr Top Microbiol Immunol 400:169-193|
|Feichtinger, René G; Neureiter, Daniel; Skaria, Tom et al. (2017) Oxidative Phosphorylation System in Gastric Carcinomas and Gastritis. Oxid Med Cell Longev 2017:1320241|
|Loh, John T; Beckett, Amber C; Scholz, Matthew B et al. (2017) High salt conditions alter transcription of Helicobacter pylori genes encoding outer membrane proteins. Infect Immun :|
|Kim, Aeryun; Servetas, Stephanie L; Kang, Jieun et al. (2017) Correction: Helicobacter pylori bab Paralog Distribution and Association with cagA, vacA, and homA/B Genotypes in American and South Korean Clinical Isolates. PLoS One 12:e0176468|
|Xiong, Menghua; Bao, Yan; Xu, Xin et al. (2017) Selective killing of Helicobacter pylori with pH-responsive helix-coil conformation transitionable antimicrobial polypeptides. Proc Natl Acad Sci U S A 114:12675-12680|
|Zhu, Shoumin; Soutto, Mohammed; Chen, Zheng et al. (2017) Helicobacter pylori-induced cell death is counteracted by NF-?B-mediated transcription of DARPP-32. Gut 66:761-762|
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