‘Junk’ genes could be causing cell mutations that lead to cancer, study claims

Large sections of our DNA that were previously thought to be harmless and inert, could in fact be interrupting DNA replication and causing cell mutations that lead to cancer, a new study by the Institute of Cancer Research (ICR) has claimed.

At least half of the genetic code that makes up a strand of our DNA is thought to be “junk” genetic material that does not hold useful information. This useless DNA was shown to get in the way and disrupt the genetic copying that occurs when our cells multiply, potentially causing mutations and eventually cancer.

Though issues with replicating DNA have previously been put forward as the cause of mutation, how this happens was previously unknown. Professor Kristian Helin, Chief Executive of the ICR, said understanding this mechanism opens the door to a new range of cancer treatments.

She said: “Understanding the mechanisms underlying genetic mutation and instability is critical if we are to find innovative new ways to treat cancer that exploit fundamental weaknesses in cancer cells.”

In their study, scientists at the ICR in London reconstructed the DNA copying process within a test tube to examine the replication mechanism in greater detail.

They found that the repetitive patterns of useless DNA increased the risk of replicating genetic errors and stalling the process entirely, which would be an early driver of cancerous growth. The scientists hope that this insight will help develop better drugs and treatments for many cancers.

The ICR team believe their work could specifically help to improve the identification and treatment of notoriously stealthy cancers like bowel cancer, where errors in the copying of this junk genetic data could indicate whether a cancer is starting to progress.

Study lead, Dr Gideon Coster, Team Leader in Genome Replication at The Institute of Cancer Research, London, said: “We wanted to understand why it seems more difficult for cells to copy repetitive DNA sequences than other parts of the genome.

“Our study suggests that so-called junk DNA is actually playing an important and potentially damaging role in cells, by blocking DNA replication and potentially opening the door to cancerous mutations.

“We now believe that repetitive DNA sequences trigger a response that is very similar to the one induced by DNA damage, which we know can lead to cancer. Our study therefore fundamentally advances our understanding of cancer, and I’m hopeful it will help us come up with new treatments in the future.”