Researchers have found a set of gene mutations that seem to play a part in some cases of skin cancer. Cancer geneticist Michael Berger of the Broad Institute of Harvard and MIT in Cambridge, Massachusetts, and his colleagues sequenced the genomes of 25 melanoma tumours that had been donated by patients and compared them to the patients' normal cells. They found that one gene, PREX2, was mutated in 11 of the 25 tumour samples, and that genetic rearrangements occurred near this gene in nine patients. PREX2 produces a protein that curtails the action of another protein called PTEN, which is involved in preventing cancer development.
Berger and his colleagues also found potentially damaging PREX2 mutations in 14% of 107 tumours that were not part of the initial study. And when they transplanted human skin cells containing PREX2 mutations into mice that had been engineered to develop skin cancer, four of the six different PREX2 mutations accelerated development of the tumours in mice. This led the researchers to suggest that PREX2 might have a similar role in human skin cancers. Their work is published in Nature today1. The team also confirmed some findings from earlier studies2, including the effect that sun exposure can have on the mutation rate of tumour DNA. Tumours from areas of the body that are not frequently exposed to sunlight had around 3 to 14 mutations every million base pairs, whereas one patient who was known to have had high levels of sun exposure had 111 mutations every million base pairs.