SCIENTISTS AT NUI Galway (NUIG) have discovered a new “micro” gene involved in breast cancer which could improve diagnostic screening procedures.
The genetic control system involving the novel gene has been identified by Prof Charles Spillane’s Genetics and Biotechnology Laboratory in collaboration with Prof Michael J Kerin of the National Breast Cancer Research Institute, both based at NUIG.
The majority of genes are encoded in DNA that produce long RNA molecules, Prof Spillane explained. These are “translated” into protein molecules necessary for proper functioning of our cells.
However, a new class of small genes called microRNAs have been identified over the past decade which produce only small RNA molecules.
Such microRNAs regulate hundreds of other genes and can determine whether a cell stays normal or becomes cancerous.
Working closely with Prof Spillane and Prof Kerin, NUIG molecular biologist Dr Sadan Duygu Selcuklu discovered that one particular microRNA gene – identified as miR-9 – normally acts to suppress the growth of breast cells.
While miR-9 normally regulates the levels of hundreds of other genes, tests showed that when miR-9 levels dropped in a cancer cell, the levels of a breast-cancer promoting gene called MTHFD2 levels went on to increase – triggering breast cancer cell development.
“There are over 1,500 different types of these small microRNA genes identified so far in human cells and it is a major scientific challenge for us to understand which ones can make the difference between a normal and a cancer cell,” according to Prof Spillane.
Dr Duygu Selcuklu said the findings were important as they showed that high levels of miR-9 in cancer cells slowed down tumour cell growth by “down-regulating” cancer-promoting genes (known as oncogenes) such as MTHFD2.
“Measuring the levels of miR-9 and MTHFD2 in patient samples holds promise for use in the clinic as a novel biomarker in breast cancer diagnostics,” she said.
Prof Spillane added that these small RNAs provided “new leads” for development of improved low-cost and non-invasive diagnostic testing.
A major challenge here was the “lack of stable long-term public-sector funding mechanisms to support such fundamental biosciences research”, he added.
About 2,700 new cases of breast cancer are diagnosed in Ireland each year, according to Prof Kerin.
The research on microRNAs was funded by the Irish Cancer Society, the Health Research Board and the National Breast Cancer Research Institute in Galway. The findings have been published in the latest issue of the Journal of Biological Chemistry.
