Bacteria-mediated metabolic rewiring of stem cells for CRC

Perturbance of a healthy gut microbiota is a common consequence to lifestyle, medication and disease, with certain microbial compositions but also specific strains and their metabolites associated and in part causally linked to sporadic colorectal cancer (CRC). Even though host metabolic reprogramming is recognized as an early and key step in CRC (cancer hallmark), studies investigating the potential of cancer-associated bacteria to control host metabolism are sparse. We aim to fill this gap by metabolically linking CRC-associated bacteria to cancer initiation with the potential to be therapeutically targeted. Work done in the last decades has described many oncogenic pathways regulating metabolic reprogramming, however, little is known about the non-genetic events contributing to cancer metabolism. A potential driver of metabolic reprogramming are certain members of the trillions of microbes co-existing with human cells, or colonizing pathogens. Some CRC- associated bacteria were reported to reprogram metabolism of cancer cells and differentiated colonocytes. Yet, it remains unknown whether cancer-associated bacteria can metabolically control intestinal stem cell (ISC) activity and tumorigenesis, which is highly relevant given the wide acceptance of ISCs as cancer origins. We will utilize mouse models of CRC and intestinal organoids (a 3D culture system) for infection with CRC-associated bacteria, and unique genetically encoded metabolic reporters in both systems to mark, ablate and trace intestinal (stem) cells of interest and in response to infection. Metabolic reprogramming on the single cell level and during tumorigenesis will be followed by imaging and chemical analyses of intestinal cells and tumors. To provide context to human CRC and reduce mouse bias, we will also perform experiments on human organoids from CRC patients (patient-derived organoids/PDOs) and will orthotopically transplant (reporter)-PDOs into mice as a model system. The relation between bacteria and host will be further assessed by bacterial fitness and host cellular activity studies in the context of metabolic reprogramming. Understanding bacteria- induced tumorigenesis as an environmental trigger for sporadic CRC is indispensable for early diagnosis, disease prevention and therapy. With this study we aim to provide a link between bacteria and intestinal cell metabolism in the context of CRC, in order to open strategies for targeting such cellular metabolic switches, the responsible bacteria or their metabolites.