Two species of bacteria appear to work together to help the formation of colon cancer in patients with a hereditary form of the disease, according to a pair of new studies published in Cell Host & Microbe and Science.
Cynthia Sears, MD, professor of medicine and researcher at the Johns Hopkins Kimmel Cancer Center’s Bloomberg-Kimmel Institute, and colleagues wrote that Bacteroides fragilis and Escherichia coli each create substances that promote cancer growth in patients with familial adenomatous polyposis (FAP), a hereditary syndrome that causes about 5% of colon cancers.
“It’s the combination of these effects, requiring the coexistence of these two bacteria, that creates the ‘perfect storm’ to drive colon cancer development,” Sears said in a press release.
The research was built on earlier investigations by Sears and colleagues that examined how certain strains of bacteria can invade colon mucus in about half of patients who develop colon cancers. The bacteria can get past the protective mucus layer and form a sticky biofilm next to the colon epithelial cells where colon cancers generally begin, according to the press release.
Sears and colleagues studied colon tissue removed from six patients with FAP, and found sections of biofilms along the colon’s length in approximately 70% of the patients.
In these samples, they found that the biofilms were mainly comprised of B. fragilis and E. coli bacteria.
The investigators wrote that the subtype of B. fragilis found in the biofilms creates a toxin that triggers cancer-promoting pathways in colon epithelial cells and causes inflammation. In addition, E. coli produces a substance that can cause DNA mutations in the cells.
According to the complementary study published in Cell Host & Microbe, these bacteria need to work together to promote cancer growth.
Using a model of colon cancer in mice, Sears and colleagues found that animals who were colonized with both species developed more tumors than those who had only one of the strains of bacteria.
The findings could lead to new screening techniques to help identify patients with FAP earlier and could be applied to other non-hereditary colon cancers, according to Sears.
“FAP is a devastating disease that ultimately results in the removal of the colon, and our findings could point us to new and less invasive ways to prevent colon cancer from developing,” Sears said in the press release. – by Alex Young
Disclosures: The authors report no relevant financial disclosures.