Genes carried by E.coli bacteria linked to colon cancer

Scientists at the University of Liverpool have identified a type of E.coli bacteria that may encourage the development of colon cancer.

The Liverpool team had previously shown that people with colon cancer and with the inflammatory bowel diseases, Crohn's disease and ulcerative colitis, have high numbers of a sticky type of E.coli in their colons.

Approximately two thirds of patients with colon cancer carry these E. coli compared with one in five with a healthy colon

The team have now found that E.coli bacteria, which carry pks genes that encode a toxin that damages DNA in the cells of the gut lining, are more commonly found in the colons of patients that have inflammatory bowel disease and colon cancer than those that do not have these conditions.  Approximately two thirds of patients with colon cancer carry these E. coli compared with one in five with a healthy colon.

Research, in collaboration with the University of North Carolina, showed that mice with colitis are more likely to carry these E. coli and they often develop colon cancer when carrying E. coli containing pks genes.  They did not, however, develop cancer with identical E. coli that did not contain pks.  They also found that the presence of E. coli carrying the pks genes did not appear to increase inflammation of the gut.

Professor Jonathan Rhodes, from the University's Institute of Translational Medicine, said: ''The fact that the pks-positive E. coli seemed to promote colon cancer in mice without causing increased inflammation led us to investigate its possible role in human colon cancer.