Friday, August 17, 2012
A new UNC-led study published online this week by the journal Science finds that an ordinarily harmless strain of Escherichia coli (E. coli), a common gut bacterium, can cause cancer when the gut is inflamed.
The study was led by Christian Jobin, PhD, associate professor in the Division of Gastroenterology and Hepatology in the University of North Carolina School of Medicine.
The publication of its results was reported as news by Nature, the influential weekly journal of science.
Here's how Nature explained Jobin's study:
Jobin and his team reared mice with a mutation that makes them susceptible to inflammatory bowel disease in germ-free cages. They then moved these mice to cages where mice teeming with bacteria had previously lived. After five months, all of the mutant mice had developed bowel disease, and 60–80% of them had colon cancer.
The mutant mice also developed a different gut microbiome than normal mice, with a much higher proportion of E. coli. One strain, called E. coli NC101, stood out. It has been linked to aggressive forms of bowel disease in mice and makes colibactin, a protein that damages DNA.
E. coli strains that did not make colibactin also flourished in the guts of the mutant mice, causing bowel disease but not colorectal tumours, the researchers report. ... He hypothesizes that gut inflammation causes colibactin-producing strains to bloom while simultaneously weakening epithelial cells that line the gut, making them more susceptible to DNA damage. If this happens for long enough, a cell will turn cancerous, Jobin suggests.
Working out these steps in the human gut could help to prevent cancer, he adds.