‘Junk DNA’ could help diagnose breast and bowel cancer
14 January 2010
Scientists at The University of Nottingham have found that a
group of genetic rogue elements, produced by DNA sequences commonly
known as ‘junk DNA’, could help diagnose breast and bowel cancer.
Their research, funded by Cancer Research UK, is published in this
month’s Genomics journal.
The researchers, led by Dr Cristina Tufarelli, in the School of
Graduate Entry Medicine and Health Sciences, discovered that seven of
these faulty genetic elements — known as chimeric transcripts — are more
common in breast cancer cells. Five were only present in breast cancer
cells while two were found in both normal and breast cancer cells.
These rogue elements are produced by DNA sequences called LINE-1
(L1). Despite being labelled as ‘junk DNA’ it is 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 the
genetic rogue elements that can sabotage the normal functioning of
cells. To prevent the potentially damaging effects of these rogue
elements, normal cells silence L1s with a chemical ‘off switch’. In
cancerous cells this ‘off switch’ is often missing, leading to the
production of these genetic rogue elements.
Dr Tufarelli, a lecturer at the University who has also received
funding from a Royal Society Dorothy Hodgkin Research Fellowship, said:
“This study 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 extended their studies to look at two bowel cancer
cell lines. Two of the genetic rogue elements 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.
Dr Tufarelli said: “If this ‘junk DNA’ does turn out to play a role
in cancer then we could be at the tip of the iceberg in understanding a
completely new mechanism behind the disease. If we do find out that they
are playing a role then they could be useful targets for new
Dr Lesley Walker, Cancer Research UK’s director of cancer
information, said: “These really interesting findings are the most
comprehensive study of these transcripts that have ever been carried
out. We are learning more about the genes involved in cancer but these
so-called ‘junk’ regions receive relatively little attention. We are
beginning to see that they could play a really important role.”