BC Cancer Agency and Dana-Farber Cancer Institute research teams independently identify first infectious agent associated with colon cancer
October 18, 2011 – For the first time, a specific microorganism has been found to be associated with human colorectal cancer. Colon cancer ranks as the second leading cause of cancer deaths, and while the underlying cause remains unclear, inflammation is known to be a risk factor. Gastric cancers have been previously linked to inflammation mediated by the microorganism H. pylori, so it is possible that some of the many species of microbes found in the gut could be associated with colorectal cancers.
Two independent research teams have now identified a potential link between a microorganism and colon cancer, making the unexpected observation that a single genus of bacteria, Fusobacterium, is found more often in colon cancer tissues than normal tissue. Their research is published in Genome Research (www.genome.org).
Castellarin M, Warren RL, Freeman D, Dreolini L, Krzywinski M, Strauss J, Barnes R, Watson P, Allen-Vercoe E, Moore RA, Holt RA. Fusobacterium nucleatum infection is prevalent in human colorectal carcinoma. Genome Res doi: 10.1101/gr.126516.111.
Kostic AD, Gevers D, Pedamallu CS, Michaud M, Duke F, Earl AM, Ojesina AI, Jung J, Bass AJ, Tabernero J, Baselga J, Liu C, Shivdasani RA, Ogino S, Birren BW, Huttenhower C, Garrett WS, Meyerson M. Genomic analysis identifies association of Fusobacterium with colorectal carcinoma. Genome Res doi: 10.1101/gr.126573.111.
“This was especially surprising because although Fusobacterium, the bacterium we found in colon tumors, is a known pathogen,” said Dr. Robert Holt of the BC Cancer Agency and Simon Fraser University, and senior author of one of the reports, “it is a very rare constituent of the normal gut microbiome and has not been associated previously with cancer.”
“It was also surprising that … Fusobacterium has also previously been reported to be associated to be with ulcerative colitis, which is itself a risk factor for colon cancer,” noted Dr. Matthew Meyerson of the Dana-Farber Cancer Institute and senior author of the other study.
Holt’s group identified Fusobacterium by sequencing the RNA present in colon cancer tissue and compared this to RNA from normal colon tissue, looking for sequences that originate from microorganisms, while Meyerson’s team sequenced the DNA present in the cancer tissues and normal tissues to find microbial sequences.
Holt and Meyerson both noted that although it is unclear at this time whether Fusobacterium infection is a cause or consequence of colorectal tumors, the microbe could prove to be very useful in the clinic as a marker for cancer. If Fusobacterium is found to be causative for disease, clinical trials could evaluate the effectiveness of antiobiotics or vaccines to treat or prevent cancer.
Research carried out by Rob Holt's research group on this project has been funded by Genome BC, the Canadian Institutes of Health Research (CIHR), Crohn’s & Colitis Foundation of Canada, and the BC Clinical Genomics Network (BCCGN).