Intestinal bacterium linked to cancer
24th September 2008
Enterococcus faecalis, a type of bacterium that lives in our intestines, has been linked with the development of colon cancer. Whilst harmless in the vast majority of people, US scientists have found that the bacterium can produce harmful chemicals. The Journal of Medical Microbiology found that in certain individuals these chemicals can damage DNA, and prompt gene activity that is linked to cancer.
E.faecalis, sometimes also known as Group D Streptococcus, was found in research by the Department of Veterans Affairs Medical Center in Oklahoma City, to produce superoxide whilst in a fermentation state. Superoxide, a type of oxygen molecule, can cause damage to DNA in surrounding cells. Professor Mark Huycke, who led the research: "We found that superoxide led to strong signalling in immune cells called macrophages - it also altered the way some cells in the gut grew and divided and even increased the productivity of genes which are associated with cancer." In total, the expression of 42 genes linked to vital processes in human cells was altered by the presence of E. faecalis in this state. "This research puts into perspective the complexity of the effects normal gut bacteria can have on the health of the individual."
Dr Barry Campbell, a gut microbiology researcher from the University of Liverpool, agreed this was plausible, however stressed that E. Faecalis is unlikely to be the only bacterium that could have this effect. He said: "There is not going to be only one culprit. Our own team is interested in a particular type of E.coli with this in mind.There are also many other factors which are involved, such as genetics and environment."
Professor Ian Rowland, a specialist in gut bacteria from Reading University, said: "This shows how it could happen, although whether this actually does happen in a human is another matter. "There is a lot of circumstantial evidence that gut bacteria are important in colorectal cancer, although we don't fully understand why. In the case of Enterococcus faecalis, we know that most people have this in their gut, but most people don't get colon cancer, so there must be other factors involved."
