Written By: Debjani Arora | Published : September 19, 2018 1:15 PM IST
Scientists discover new colon cancer triggers. © Shutterstock
There are various risk factors that can make one prone to colon cancer like family history, age, faulty diet habits (lack of fibre), dependency on junk, etc. Colorectal cancer (also known as colon cancer or bowel cancer) is the 6th common cause of cancer deaths in India. It develops due to overgrowth of cells lining the colon and the rectum. The colon is a 5 feet long twisted tube that helps in the absorption of water and various nutrients from the food you eat, whereas the end portion (about 6 inches) of the digestive tract that serves as a passage for excretion of stool is called the rectum. Colorectal cancer develops when cancerous tumours originate from the linings of the colon and rectum. Previously it was thought that inflammation in the colon could be a reason for developing cancer in the area. But scientists have recently found out that cell stress along with an altered microbiota in the colon drives tumour growth.
This comes as a surprise to the researchers as till date it was thought that cell stress and bacterial flora was only responsible for inflammatory intestinal diseases. A research led by Professor Dirk Haller from the Department of Nutrition and Immunology at the Weihenstephan Science Centre of the TUM showed that it is not cell stress alone that leads to tumour growth, but the cooperation of stress and microbiota that could lead to colon cancer. The researchers originally wanted to study the role of bacteria in the intestines in the development of intestinal inflammation. But they stumbled on a new finding. "However, the surprising result for us was the discovery that bacteria together with stress in cells caused tumours (exclusively in the colon) and without the involvement of inflammation," said Prof. Haller.
The investigations were initially carried out using the mouse model. In germ-free (i.e. sterile) animals, in which the activated transcription factor ATF6 regulated stress in the intestinal mucosa (intestinal epithelium), no change could be observed. But as soon as the microbiota, i.e. all the microorganisms in the intestine, were transplanted back into germ-free animals, tumours developed in the colon of the mice. Using Koch's postulates, Haller and his team were able to show that microorganisms are involved in the development of cancer in the colon. The transcription factor ATF6 regulates stress in cells, which was found to be increased in colon cancer patients.
Talking about the new finding Prof. Haller said that in certain patients, the protein ATF6 could serve as a diagnostic marker for an increased risk of colon cancer and could indicate the start of therapy at an early stage.
