Gut microbes may play a role in colorectal cancer

Date: Mar-04-2014New research from the US suggests an individual's particular mix of gut microbes may

help the development of colorectal cancer tumors by interacting with genes and inflammatory

responses.

Colorectal cancer happens because healthy cells in the gut start to behave oddly

following changes or mutations in their genes. These changes cause the cells to become

progressively cancerous, forming polyps that can eventually become malignant tumors.

But although genetic mutations can happen anywhere in the gut, certain types of colorectal

cancer develop in certain locations along the intestine, suggesting non-genetic factors also

play a role.

Now, researchers from the Icahn School of Medicine at Mount Sinai, New York, NY, report they

have succeeded in preventing the development of polyps in mice by changing the mix of microbes

in the animals' guts.

The team, led by Sergio Lira, professor of Medicine and Clinical Immunology, reports its

findings in the Journal of Experimental Medicine.

In previous work, the researchers discovered that when mice had gene mutations known to cause

polyps, they only developed polyps in certain areas, even though there were mutations in cells

all along the gut.

In this new study, they again took mice with gene mutations known to cause polyps and

disrupted the microbe populations in their guts by giving them antibiotics.

The result was the mice did not develop polyps, indicating that gut microbes are somehow

involved in spurring early tumor formation in such animals.

Killing off certain gut bacteria may reduce risk of colorectal cancer

Although they did not test this, the researchers believe the antibiotics may have killed off

bacteria that would otherwise have penetrated the intestinal wall, causing inflammation that in

turn triggered tumor formation.

They suggest further studies should now try to identify the exact types of bacteria that

might be involved in triggering early tumor growth. Removing such bacteria from the gut may be a

possible way to reduce risk of colorectal cancer in genetically susceptible people.

Dr. Lira says their findings may also explain why non-genetic factors like obesity and diet

affect risk of colorectal cancer. "Some of these lifestyle factors appear to affect the types of

bacteria present in the gut," he says, adding:

"Ultimately, understanding the interplay between genetic mutations, gut microbes, and

inflammation may lead to novel diagnostics and therapies for intestinal cancer."

Meanwhile, Medical News Today recently learned of a study that found gut bacteria can boost the effect of

chemotherapy. French researchers found that the ability of the chemotherapy drug cyclophosphamide

to stimulate an anti-tumor response in the immune system may get a helping hand from gut

microbes.

Written by Catharine Paddock PhD




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