Certain stress of the intestinal flora provokes cancerous tumors

Stress in the intestinal microbiota promotes tumor growth

Cell stress in combination with changes in the intestinal flora drives tumor growth in the colon. To this unexpected result, a German research team comes in the study of intestinal bacteria. This realization is completely new. So far, scientists have assumed that intestinal bacteria in combination with cell stress are involved only in the development of inflammatory bowel disease.

The microbiota in the gut (intestinal flora) is involved in tumor growth in the colon. The team led by Professor Dirk Haller at the Technische Universität München (TUM) in a study on intestinal bacteria comes to this astounding insight. The results were recently published in the journal "Gastroenterology".

Surprising study results: In combination with cell stress, bacteria from the intestinal flora are involved in the development of cancerous tumors in the colon. The originally suspected as a cause of chronic inflammation, however, have no influence on a tumor development. (Image: Alex / fotolia.com)

New triggering factors identified by colon cancer

Actually, the team wanted to learn more about the development of intestinal inflammation. "With our study, we originally wanted to clarify what contribution bacteria in the intestine have to the development of intestinal inflammation," says Professor Haller from the Department of Nutrition and Immunology at the Weihenstephan Science Center of the TUM. Then the researchers came up with an unexpected result.

Cell stress and altered intestinal flora drive tumor growth

"Cell stress in combination with an altered microbiota in the large intestine drives tumor growth," the TUM experts explain in a press release about the study results. These are hitherto unknown factors in the development of colon cancer.

Tumor growth without inflammatory reactions

"However, the surprising result for us was that changes in the microbial ecosystem together with stress in the intestinal cells lead to the development of tumors," says Professor Haller. The researchers were able to observe this phenomenon exclusively in the colon - without any inflammatory reactions.

How does cell stress develop in the intestine??

As the TUM experts report, a specific protein (transcription factor ATF6) regulates and activates stress in the cells. Diseases increase both the duration and the intensity of this stress activation. "It is not the cellular stress alone that leads to tumor growth, but the cooperation of stress and microbiota, which favors cancer growth," emphasizes Haller.

Course of the study

The researchers gained their insights on the mouse model. Mice that live in sterile, ie germ-free, conditions, have no intestinal flora. In the first step, the researchers activated the transcription factor ATF6, which provided stress activation in the intestinal mucosa (intestinal epithelium). The team was unable to detect any faulty changes. Only when they returned their intestinal flora to the animals did the rodent develop cancer in the large intestine.

The cooking postulates provided the proof

Using the Henle Koch postulates, the researchers were able to prove that microorganisms in the gut are involved in the development of colon cancer. The postulates are a recognized method of verifying that certain microorganisms can be properly described as pathogens.

Checking on humans

In collaboration with the Klinikum rechts der Isar, the team reviewed the results based on data from 541 colorectal cancer patients. The scientists found that patients with a significantly higher proportion of the protein transcription factor ATF6 also had a significantly higher relapse rate.

A new marker for colon cancer?

"In certain patients, the protein ATF6 could serve as a diagnostic marker for an increased risk of colon cancer," sums up Professor Haller. This could be started early with a therapy. Even a microbial therapy is conceivable. However, one must first learn more about the composition of the bacteria. However, one thing was made clear by the study: "Chronic inflammations have no influence on the development of cancer in the colon," say the TUM experts.

So important is a healthy intestinal flora

The study underlines the importance of a healthy intestinal flora for our health. It is a good protection against diseases and health complaints. Should the delicate balance be disturbed for example by drugs such as antibiotics, a colon cleansing can help to build up the intestinal flora. (Vb)