Bacteroides fragilis as a potential cause of cancer

Infections and inflammation are increasingly recognised as potentially carcinogenic.Enterotoxigenic Bacteroides fragilis (ETBF) is carried asymptomatically in the gut of up to 20% of the population. ETBF is also associated with diarrhoea and inflammatory bowel disease (IBD). The latter can predispose to colon cancer, which remains the third most prevalent cancer in Western Society. ETBF is likely to be a contributory factor in carcinogenesis, and a small study supports this view. ETBF colonisation of the APC min mouse, a model for intestinal carcinogenesis, induces colonic tumours. The ETBF toxin (BFT) activates β-catenin, which is closely linked to colon carcinogenesis the APC gene.

This project will assess the role of ETBF in colorectal neoplasms. We have a unique collection of gut tissue at Guy’s and St Thomas’ Hospital (normal and IBD) and have a well established set-up for recruitment of suitable patients for such studies. Target groups will be those undergoing surveillance for colorectal polyps and long standing IBD. Samples (stool and gut mucosa) would be probed for the presence of B. fragilis, the different BFT subtypes and the adjacent genes that are known to regulate expression. qPCR will be used to determine colonisation levels. Tissues would also be stained for β-catenin distribution and for cytokine profiles.

Duration of project: 3 years