THE HUMAN genetic blueprint is slowly evolving in an attempt to beat cancer. A Dublin-based researcher has found clear evidence that genes are gradually changing in the ongoing battle against the disease.
Human evolution has not ended, but continues as part of an ongoing process, according to Dr Mary O’Connell of Dublin City University. “It isn’t just something from the ancient past – it is occurring in humans today,” she said.
Dr O’Connell is a lecturer and Science Foundation Ireland principal investigator in DCU’s school of biotechnology. She also holds the chair of bioinformatics, a subject that uses powerful computers to study and compare genetic material or DNA.
She used the supercomputers available at the Irish Centre for High End Computing to analyse DNA from modern day humans and mammals, but also used the genetic material to track back 100 million years of genetic history.
She adopted an evolutionary approach to cancer, given that it is seen in all life forms, from insects to fish to humans. “Cancer is a very ancient disease. If you think about it as an ancient disease, then we must have evolved systems to keep cancer in check.”
One of these is our DNA repair system. Cancer arises when there is damage to DNA, as can occur, for example, when too much ultraviolet light strikes our skin. Mostly, the repair systems fix the damage but cancer can ensue if they don’t.
Dr O’Connell looked at one pathway of this system: BRCA-1. If this system fails, it increases a woman’s risk of breast cancer.
Dr O’Connell used a computer with the power of 600 desktops that ran for “weeks and weeks” to provide information about the BRCA-1 pathway, comparing across mammals, but also casting back 100 million years to much older DNA changes.
Successful evolution meant something had changed in a gene to enhance its ability to survive, something called "positive selection", Dr O'Connell said. "These are changes that make genes work better. These are the kinds of selection that we see in the DNA repair pathway." Details of her work were published this week in the Journal of Molecular Evolution.
Dr O’Connell found that of the 15 genes in the BRCA-1 pathway, 11 showed signs of positive selection changes to enhance survival.
