A study from Canada, using human samples and mice, has found that large portions of the human genome previously labelled as ‘junk DNA’ may protect against colon cancer. 

Inflammatory bowel disease (IBD), which includes conditions such as ulcerative colitis and Crohn’s disease, is characterised by chronic inflammation of the gut. Over time, repeated damage to the colon increases the risk of colorectal cancer. However, it has remained unclear why some patientsdevelop cancer while others do not.  

Previous studies have shown that chronic inflammation awakens pieces of DNA that are not used by the cell – ‘junk DNA’ – that, once activated, make cells behave as if they are under viral attack – a process called viral mimicry, – activating the immune system.  

Researchers at Western University, an EARA member, and London Health Sciences Centre Research Institute used colon biopsies from healthy individuals and patients with IBD and mice, to determine whether viral mimicry can suppress cancer development.  

They observed that this antiviral response was present only in patients with IBD who had not developed cancer. Mice genetically modified to have this antiviral response switched off no longerhad the immune response caused by ‘junk DNA’, thus cancer cells grew. 

“These findings are significant because they have implications for how cancer could be prevented in the future (…) It could also impact how we treat cancer in the future as we identify new ways to activate these viral responses,” said Samuel Asfaha, from London Health Sciences Centre Research Institute and lead author of the study published in Nature Communications.