Scientists at Nottingham University have uncovered new biomarkers for breast and bowel cancer that are produced by so-called junk DNA.
The researchers, led by Cristina Tufarelli, in the School of Graduate Entry Medicine and Health Sciences, discovered seven chimeric transcripts that are more common in breast cancer cells. Five of the transcripts were only present in breast cancer cells while two were found in both normal and breast cancer cells.
These chimeric transcripts are rogue elements produced by DNA sequences called LINE-1 (L1). Despite being labelled as junk DNA it is now clear that some of these sequences have important roles in the genome, such as influencing when genes are switched on.
L1s carry a switch that is able to randomly turn on nearby genes. When genes are inappropriately switched on in this way they make chimeric transcripts, which can sabotage the normal functioning of cells. To prevent this, normal cells silence the effects of L1s. In cancerous cells this off switch is often missing, leading to the production of chimeric transcripts.
Tufarelli said the research has generated new research tools to investigate the role of ‘junk DNA’ in cancer development. “The next step is to find out if the switching on of these genes is driving cancer or if they are a result of the cancer. Even if they are innocent bystanders of cancer they could be useful biomarkers helping us to diagnose or monitor the disease.”
The researchers have extended their studies to look at two bowel cancer cell lines. Two chimeric transcripts were found in invasive bowel cancer cell lines, but not in the pre-invasive cells, suggesting that these sequences could play a role in cancer progression.