New mutations driving deadly skin cancers discovered

Cancer

Scientists have discovered two new mutations that collectively occur in 71 per cent of malignant melanoma tumours, the most deadly type of skin cancer.

Researchers from Dana-Farber Cancer Institute and the Broad Institute in US said the highly "recurrent" mutations - occurring in the tumours of many people - may be the most common mutations in melanoma cells found to date.

"This new finding represents an initial foray into the 'dark matter' of the cancer genome," said Levi Garraway, senior author of the study published in Science Express.

"In addition, this represents the discovery of two of the most prevalent melanoma gene mutations," Garraway said.

Researchers said these cancer-associated mutations are 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. This non-coding DNA, much of which was previously dismissed as "junk", accounts for 99 per cent of a cell's genome.

A large number of oncogenic mutations in cancer have been identified in the past several decades, but all have been found within the actual genetic blueprints for proteins. The newly discovered mutations affect a promoter region - a stretch of DNA code that regulates the expression of a gene adjacent to the TERT gene. TERT contains the recipe for making telomerase reverse transcriptase, an enzyme that can make cells virtually

immortal, and is often found overexpressed in cancer cells.

A promoter region of DNA controls the rate of a gene's

transcription - the copying of its DNA recipe into a message used by the cell to manufacture a protein.

"We think these mutations in the promoter region are potentially one way the TERT gene can be activated," Franklin Huang, co-first author of the report along with Eran Hodis said in a statement.

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