Don't Forget to Brush: Link Between Colon Cancer and Mouth Bacteria Uncovered

Researchers have uncovered a link between a common mouth bacterium and colorectal cancer, as well as how to prevent the microorganism, called Fusobacterium nucleatum (Fn), from attaching to colon cells and triggering the changes that can lead to cancer.

The study appears in the journal Cell Host & Microbe along with a second report from a separate team of researchers explaining how the bacteria can cause an increase in the speed at which cancerous cells accumulate.

Led by Yiping Han from Case Western Reserve University School of Dental Medicine, the study on Fn builds on a discovery Han and her colleagues made in 2011 when they identified an adhesive molecule on the microbe's surface, called FadA, capable of attaching to the cell receptor from the cadherin group on blood vessels known as VE-cadherin.

Han explains that, in a moment of sheer serendipity, just as she was finishing her work on FadA and VE-cadherin, researchers from Harvard University and the University of British Columbia announced a discovery of their own revealing Fn was higher in malignant tumors compared to the surrounding tissue.

Immediately, Han grew suspicious of Fn, hypothesizing that it interacted with cells in the colon the same as those in blood vessels.

Given their previous work, it didn't take Han and her team long to determine just how FadA attached to the E-cadherin receptors in the colon. As they observed, they discovered that FadA's attachment to E-cadherin set in motion a protein called ß-catenin, which produces an inflammatory response that alters the immune system in addition to spurring the growth of cancer cells.

Furthermore, they found that the FadA gene levels were 10 to 100 times higher than normal in precancerous and malignant colon polyps.

Based on these results, Han argues that "FadA can be used as a diagnostic marker for early detection of colon cancer" as well as determining "if treatment works effectively at reducing Fn load in the colon and the mouth."

Finally, the researchers report that they succeeded in developing a novel synthetic peptide to prevent FadA from attaching to E-cadherin and inciting actions that lead to cancer development, the patent for which they have already applied for.

Ultimately, however, Han points out that the study underscores a very basic fact, which is the benefit of dental hygiene. Fn, she explained, is a bacterium that increases dramatically in gum disease.