New 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