World’s largest DNA study of melanoma

Scientists at the Queensland Institute of Medical Research, in conjunction with Yale University in the US, have identified a new gene mutation in almost 10% of melanoma cases.

Professor Nick Hayward, from QIMR’s Oncogenomics Laboratory, said the finding published in Nature Genetics provided fresh leads for treatments.

“This is an activating mutation, which drives cancer development,” Professor Hayward said.

“This makes it a good drug target, and could lead to new therapies for the nine per cent of people with this type of melanoma.”

Scientists at Yale University School of Medicine analysed every gene in 147 melanomas to discover the abnormality in the RAC1 gene. QIMR scientists validated the discovery, in the largest DNA sequencing study of melanoma ever undertaken.

It’s the third most frequent gene mutation, after BRAF and NRAS, and provides a clear path for developing new therapies.

The mutation was almost exclusively found in melanomas from sun-exposed body sites and has the telltale hallmarks of being caused by exposure to ultraviolet radiation.

“We now have our most comprehensive picture yet of the molecular landscape of melanoma,” Professor Hayward said.

“This opens the door to further targeted therapies tailored to the individual patient, which should improve overall survival rates.”

The Yale team, led by Ruth Halaban and Michael Krauthammer, devised a mathematical model to sift the relevant DNA alterations from more than 25,000 mutations.

The study found that the mutant protein accelerated changes to normal pigment cells, which are the cells from which melanoma originates.

“It most likely occurs at an early stage of tumour development and promotes malignant cell growth, spreading to distant sites in the body,” Professor Halaban said.

The study appears in the July 29 online publication of Nature Genetics.