New mutations show how cancers grow

Scientists have discovered two new genetic mutations that occur together in 71% of malignant melanoma tumours, an aggressive and deadly cancer of the skin, a study published said.

The mutations, detected in a part of the cancer genome that controls genes but not in the genes themselves, could aid understanding and lead to treatment of one of the world's most lethal cancers or stop its progression.

It "represents an initial foray into the 'dark matter' of the cancer genome," said Dr Levi Garraway, of the Dana-Farber Cancer Institute and the Broad Institute of Harvard and Massachusetts Institute of Technology (MIT).

"In addition, this represents the discovery of two of the most prevalent melanoma gene mutations," he said of the findings, which were part of two studies published in the online edition of the US journal Science.

How the mutations were found

The researchers said the cancer-associated mutations were the first to be discovered in the vast regions of DNA in cancer cells that do not contain genetic instructions for making proteins - the mutations are located in non-protein-coding DNA that regulates the activity of genes.

The mutations were discovered when the scientists sifted through data from whole-genome sequencing of malignant melanoma tumours.

Unlike "whole-exome" searches that examine only the protein-coding DNA of a cell's genome, whole-genome searches scan all of the DNA, including the non-coding regions.

In analysing whole-genome data, the researchers found the two mutations in 17 of 19 (89%) of the tumours. They then examined a larger number of melanoma tumours and found the two mutations in 71% of them in total.

The researchers said the two mutations are present in cells found in liver and bladder cancers.

(Sapa, January 2013)

Read more:
The three types of skin cancer