A bane of many visitors to developing countries could help scientists in their fight against cancer. According to a report published online this week by the Proceedings of the National Academy of Sciences, the bacterium responsible for so-called traveler's diarrhea can halt the growth of cultured colorectal cancer cells.

Colorectal cancer is the fourth most common type of the disease worldwide, but its distribution is not uniform. Instead, it strikes predominantly in industrialized nations. Developing nations, in contrast, have lower colorectal cancer rates and higher incidences of intestinal E. coli infections. Noting this inverse relationship, Giovanni M. Pitari of Thomas Jefferson University and his colleagues tested a toxin produced by E. coli on human colon cancer cells. They found that cell growth slowed shortly after exposure to the toxin. Specifically, the researchers determined that the toxin suppressed a previously unrecognized signaling pathway within the cells. They suggest that this pathway could provide a novel target for preventative and therapeutic treatment of colorectal cancer.