Certain bacteria living in the mouth and gut can invade intestinal cells and trigger changes that lead to colorectal cancer.

A team led by Wendy Garrett at the Harvard School of Public Health in Boston, Massachusetts, found that the bacterium Fusobacterium nucleatum induced colonic tumours in genetically susceptible mice.

Separately, Yiping Han at Case Western Reserve University in Cleveland, Ohio, and her colleagues showed that FadA, an adhesion molecule produced by F. nucleatum, interacts with a counterpart on mammalian cells and triggers proliferation of colorectal-cancer cells. Colon tissue from patients with tumours had 100 times more copies of the gene encoding FadA than did tissue from healthy individuals.

Cell Host Microbe 14, 195–206; 207–215 (2013)