Helicobacter pylori Blood Biomarker for Gastric Cancer Risk in East Asia

The current R01 has sought to examine serum antibody titers against 15 H. pylori blood biomarkers in a cohort of over 3,000 gastric cancer patients from East Asia to assess the utility of these H. pylori antigens in predicting cancer risk. We have found that two previously uncharacterized H. pylori proteins, an outer membrane protein, Omp (HP1564) and the hypothetical protein HP0305 are significantly associated with cancer risk. Our studies have shown that antibody response levels to these proteins are superior at predicting cancer risk compared to detecting H. pylori alone or its secreted oncoprotein, CagA. Thus, characterization of the HP1564 and HP0305 proteins may help to elucidate their role in carcinogenesis and highlight important H. pylori proteins that may be targetable for therapeutic interventions. Studies examining the role of HP0305 or HP1564 in H. pylori virulence and its association with carcinogenesis on the molecular level have not yet been conducted. By examining the molecular mechanism by which these proteins promote oncogenesis, combined with our population-based studies, our results will inform the public health as to how to selectively target the highest gastriccancer risk patients with interventional therapies while protecting those at low-risk, but remain infected with H. pylori, from increased harm due to adverse outcomes resulting from eradication therapy. The work to be conducted in the Shaffer lab will investigate the role of these H. pylori proteins in promoting pro-inflammatory responses in gastric epithelial cells. Specifically, the following experiments will be performed at the University of Kentucky: Generation and characterization of HP0305 and HP1564 isogenic mutants and corresponding genetically complemented and epitope-tagged strains; Analysis of HP0305 and HP1564 mutants in various in vitro cell culture systems to evaluate the ability of H. pylori to translocate CagA, induce cytokine secretion, and stimulate TLR9 activation; Analysis of HP0305 and HP1564 protein localization in the bacterial cell using various microscopy and biochemical methodologies; Determine whether HP0305 and HP1564 interact with additional virulence determinants via immunopurification and mass spectrometry analysis; Quantify HP0305 and HP1564 gene expression in response to environmental stimuli using qPCR analysis and semi-quantitative protein assays. Work resulting from this sub-award will be incorporated into manuscripts submitted to peerreviewed publications. Resulting data may also be included in future extramural funding applications (e.g., NIH R01 and R21 funding mechanisms and private foundation RFAs).