Project Summary Pancreatic adenocarcinoma is a devastating disease with a five-year survival of only 10%. The rise of immunotherapy has led to breakthrough treatments in many cancers, like melanoma, drastically improving survival outcomes. However, unlike malignant melanoma, we have seen minimal changes in survival for pancreatic cancer because we still do not completely understand the regulators of immunity in this disease. Bacterial dysbiosis is emerging as an accomplice to carcinogenesis and is associated with pancreatic cancer progression and poorer survival. We found that gut bacteria can directly access the pancreas, and pancreatic tumors harbor a unique microbiome. The tumor-associated microbiome regulates pancreatic cancer progression by skewing tumor-infiltrating immune cells towards an immunosuppressive phenotype. However, the exact mechanisms via which bacteria regulate immune cell function is still unknown. Inflammatory signaling in cancer cells and stromal cells in the tumor microenvironment has been shown to greatly regulate the immune cell infiltrate in pancreatic cancer. Our preliminary data suggests that pathogenic bacteria can directly interact with pancreatic epithelial cells inducing proliferation and an inflammatory response. Furthermore, we found that the presence of bacteria in tumors skews fibroblast differentiation towards an inflammatory, tumor-promoting phenotype. In this proposal, we seek to determine how tumor-associated bacteria modulate the epithelial and stromal compartments in the pancreatic tumor microenvironment thereby aiding their ability to promote pancreatic cancer progression. The overall goal of this application is to support my continued training and development to become an independent investigator in microbiology and pancreas cancer biology. The career development plan is based on formal didactic coursework, experiential learning, and mentored basic science training. I have received generous support and protected time from my department and will work closely with my mentor Dr. Marina Pasca di Magliano, PhD a respected and experienced pancreatic cancer biologist. I have also constructed an advisory committee, with expertise in microbiology and bacteria-host interaction to further my microbiology training while completing this project. The major themes of my research interests are reflected in the Specific Aims of this proposal: (1) to determine the influence of tumor-associated bacteria on pancreatic cancer cells (2) to determine their ability to activate and differentiate pancreatic stromal cells and (3) to further characterize the mechanisms of pathogenicity unique to pancreatic cancer-associated bacteria. Successful completion of these proposed experiments will delineate the mechanisms via which microbes interface with non-immune cells in the tumor microenvironment, and provide insight into therapeutic strategies for gut microbial modulation in treating pancreatic cancer.