UK News

UK scientists say they have found cancer driver in junk DNA

The study suggests that junk DNA is potentially destructive to cells
Scientists in the UK think they have understood the mechanism behind junk DNA, which is implicated in cancer. Junk DNA is a term used to describe the 97% of the genetic sequence in human cells found between the 3% coding for our 20,000 genes, once thought to be inert.
In the past, studies have focused on repetitive sequences of DNA that account for around half of our DNA – sometimes called the ‘repeatome’, and thought to originate from ancient viral infections – have suggested they could interfere with the replication and repair of the genome.
To study the process behind junk DNA, scientists reconstituted the entire process of DNA replication in a test tube, so that they could examine it in detail. They showed how repetitive patterns of DNA are copied during replication, and found evidence that they can stall the process entirely, increasing the risk of errors that can be an early driver of cancer, according to a paper published in Nature Communications.
The research team found that when the DNA replication machinery encountered repetitive DNA, it was able to unwind the DNA strands, but it sometimes failed to copy the opposite DNA strand. This error could cause replication to stall, resulting in collapse of the replication machinery in a manner similar to that induced by DNA damage, potentially allowing mutations to accumulate.
“We wanted to understand why it seems more difficult for cells to copy repetitive DNA sequences than other parts of the genome,” said study leader Dr Gideon Coster.
“Our study suggests that socalled 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.”