New Imaging Technique Reveals Bacterial Biofilms in Colon Cancer Patients

Scientists have learned a bit more about cancer by examining biofilms. They've discovered that cancerous tumors in the ascending colon are characterized by biofilms, which are dense clumps of bacterial cells encased in a self-produced matrix.

In order to better examine tumors, the researchers employed a combinatorial imaging technique. Different colors of fluorescent probes "lit up" different species of bacteria in biofilms. This, in turn, revealed the 3D structure of the microbial community.

"This is the first time that biofilms have been shown to be associated with colon cancer, to our knowledge," said Jessica Mark Welch, one of the researchers, in a news release.

In healthy individuals, the colon is covered in a mucus layer, called the mucosa, that helps keep bacteria away from the colon's skin, called its epithelia. Yet colon cancer patients who have tumor-associated biofilms also have biofilms on tumor-free areas of the nearby mucosa.

"This suggests that either the tumor allows the biofilm to form, or the biofilm is helping to cause the tumor," said Mark Welch, one of the researchers. "The breaching of the mucus layer could allow bacteria to come into contact with the host epithelial cells, and that is one thing that could lead to cancer."

Interestingly, though, the researchers found that tumors in the descending colon do not have associated biofilms. Yet the biofilms associated with ascending colon tumors were composed of many species of bacteria that were diverse.

The findings could help researchers develop better treatments for colon cancer. This, in turn, may help patients in the future.

The findings are published in the journal Proceedings of the National Academy of Sciences.

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