Biofilms and specific bacteria in colorectal cancer development, with Prof. Cynthia L. Sears, MD
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This episode features Prof. Cynthia L. Sears, MD from the Johns Hopkins University School of Medicine and the Bloomberg School of Public Health (USA), speaking about both biofilms and specific gut microorganisms that may contribute to colorectal cancer development. Initially, Prof. Sears became interested in enterotoxigenic Bacteroides fragilis in connection with colon cancer. Further investigation found complex biofilms with multiple bacteria fixed to the surface of the tumor. The biofilms were shown to be oncogenic, and they reassembled very quickly after antibiotic treatment. Interestingly, the biofilms were found to have C. difficile. A subset of the biofilms have a dominant amount of Fusobacterium, and the latest work shows that these bacteria are associated with advancing cancer, stage 2 or beyond. These bacteria and/or biofilms don’t necessarily trigger the onset of mutations that lead to colon cancer, but they accelerate tumor growth. Over time, the gut microbiota may be perturbed in various ways (including by antibiotics), allowing the organisms to create a niche for themselves that ultimately harms the colonic epithelial cells. Prof. Sears is optimistic about prevention strategies for colorectal cancer, such as a tool that helps predict risk in younger populations. Targeted prebiotics, too, show promise for encouraging the growth of beneficial bacteria that prevent the oncogenic species from finding a niche.
Episode abbreviations and links:
- 2014 review by Sears and Garrett on the role of microbes in colon cancer: Microbes, Microbiota, and Colon Cancer
- One of the landmark 2012 papers linking Fusobacterium nucleatum to colorectal cancer: Fusobacterium nucleatum infection is prevalent in human colorectal carcinoma
- Examination of biofilms on colon cancer polyps: Epidemiology of bacterial biofilms on polyps and normal tissues in a screening colonoscopy cohort
- Association of Fusobacterium with advancing (stage 2) colorectal cancer: Tumor-Associated Fusobacterium nucleatum and Aggressive Architectural Features in Stage II Colorectal Cancer
- Paper showing genotoxic microbes increasing colon tumor burden: Combining genotoxic gut bacterial strains increases tumor burden and accelerates onset in a germ-free mouse model of colon carcinogenesis
About Prof. Cynthia L. Sears, MD:
Cynthia L. Sears, M.D. is Professor of Medicine, Oncology and Molecular Microbiology and Immunology at the Johns Hopkins University School of Medicine and the Bloomberg School of Public Health. Through her work as an infectious diseases specialist, she studies how bacteria and the microbiome impact gut diseases, particularly human colon cancer. She has long been an active member of the Infectious Diseases Society of America (IDSA), serving as President of IDSA in 2019, is an AAAS Fellow and is currently Editor-in-Chief of The Journal of Infectious Diseases, the flagship journal of the IDSA.
