Shaping of the Microenvironment in Colonic Pre-Cancer by Epithelia and Microbiota

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The Vanderbilt TBEL Center assembles a multi-disciplinary team of field-specific experts to collaboratively investigate the basic and translational pathways of colonic pre-cancer progression. Our foundational work on two subtypes of colonic pre-cancers, adenomas (ADs) and sessile serrated lesions (SSLs), depicts the early origins of tumorigenesis that are shaped by modulation of the immune microenvironment via neoplastic cells and the microbiota. We have shown that SSLs originate from gastric metaplasia arising from the mucosal surface in a cytotoxic immune microenvironment, whereas ADs arise from stem cell-derived WNT activation at the crypt base. In this center, we will extend our investigation of specific biological mechanisms towards the developmental trajectories of these pre-malignant lesions into progression or indolence. Basic Project 1 investigates the contribution of neutrophil-AD crosstalk, largely via dipeptidase 1 (DPEP1) both at the cell surface and released in small extracellular vesicles, in the course of AD progression. Translational Project 2 investigates, in human prospective studies, the association of pks+ Escherichia coli that induces genotoxic stress with pre-cancer progression, as well as colon epithelial cell and mucosa mechanisms that may contribute to a polyp-promoting microenvironment. Basic Project 3 investigates acquisition of stemness in modulating antigen presentation to cytotoxic T cells in the context of co-evolution between neoplastic cells and the immune system. Joint analysis of common colorectal pre-cancer tissues will facilitate an ongoing process of iteration and integration across all projects. Our TBEL Center offers a complementary blend, from reductionist and systems biology approaches, to investigate critical factors involved in the progression of pre-cancerous tumors of the colon to CRC. The work will utilize cutting-edge technologies on human tissues, including single-cell and spatial transcriptomics, small extracellular vesicle profiling, multiplex imaging, longitudinal data analysis, and next-generation computational algorithms. In addition, substantial human polyp resources previously established by the Vanderbilt GI Specialized Programs of Research Excellence and the NCI Moonshot Human Tumor Atlas Network will be leveraged by the same team of investigators in the TBEL Center. In addition, an innovative co-culture system will be employed by each project, where polarizing pre-cancer organoids can be co-cultured with key microenvironment elements exposed to neoplastic cells from the luminal or basal side. This work will inform the modeling of tumor development trajectories and identify mechanisms of progression that will enable improvements in risk stratification, precision prevention, and interception for individuals with colorectal pre- cancers.