PPG PROJECT 2 SUMMARY H. pylori is the strongest risk factor for gastric cancer, the fourth leading cause of cancer deaths, and >50% of humans harbor this infection. With the other PPG Projects and Cores, new insights into gastric carcinogenesis from Project 2 during the current award period included a deeper understanding of the role of polyamines in epithelial dysfunction and immunoregulation, altered immune cell remodeling/metabolism, and implication of electrophiles in gastric cancer. By elucidating mechanisms of carcinogenesis, we will now address our goal of new interventions for cancer prevention and treatment. We have demonstrated the essential role of spermine oxidase (SMOX) in H. pylori-induced carcinogenesis. We have new evidence that this occurs independently of the conversion of spermine to spermidine, and is likely due to acrolein and H2O2, also products of SMOX activity. Acrolein is a highly reactive aldehyde and electrophile, which exhibits a half-life far longer than transient reactive oxygen species. Acrolein and H2O2 support lipid peroxidation, enhancing generation of other potent dicarbonyl hese strong oxidants form irreversible adducts with proteins and DNA, leading to changes in cell signaling, somatic genomic abnormalities, and epigenetic changes, but their role We recently reported that dicarbonyl electrophile adducts are increased in H. pylori-infected gastric tissues and . electrophiles. T in carcinogenesis is unproven. Linking SMOX-derived electrophiles to gastric cancer is a new concept. patient-derived gastric organoids 2- hydroxybenzylamine (2-HOBA) is a scavenger of reactive electrophiles that prevents adduct formation with macromolecules. We reported that an analog of 2-HOBA reduced somatic genomic abnormalities and prevented cancer development in rodents infected with H. pylori. We will now focus on 2-HOBA itself, because: 1) it is a natural product that is not toxic or mutagenic; 2) Phase 1 clinical trials at VUMC have demonstrated its safety; 3) we have shown that 2-HOBA prevents H. pylori gastritis and carcinogenesis in INS-GAS mice, and restricts growth of tumor xenografts; and 4) we have a partnership with MTI Biotech for use of 2-HOBA. Our hypothesis is that reactive aldehydes derived from SMOX activity are major contributors to gastric carcinogenesis and tumor growth and are a therapeutic target for both cancer prevention and treatment. Through the strong integration in this PPG we will address our Aims, which are to determine: 1) if effects of SMOX in gastric carcinogenesis are mediated by electrophiles in vivo; we will use cancer prone INS-GAS mice +/- Smox deletion and +/- 2-HOBA treatment, and study cancer development and its mechanisms; 2) effects of SMOX-derived reactive aldehydes in human gastric organoids, assessing carcinogenic signaling and effects on the transcriptome/proteome and on H. pylori; 3) if electrophiles are a therapeutic target for gastric cancer development, by investigating human tis...