US researchers identify another possible 'breast cancer gene'

In collaboration with the Press Association

Scientists have discovered that a previously known gene might be involved in breast cancer risk when damaged.

Researchers at the University of Pennsylvania's Abramson Family Cancer Research Institute and the Dana-Farber Cancer Institute report that the Rap80 gene is required for the well-known breast cancer gene BRCA1 to carry out its normal DNA-repair function.

As a result, damage to Rap80 could also lead to a cell becoming cancerous.

BRCA1 is known to repair DNA by maintaining the normal number and structure of chromosomes.

When mutations occur in the BRCA1 protein, it can no longer identify damaged DNA and repair it, allowing cancer-causing mutations to accumulate. This can lead to breast and ovarian cancer.

This latest study found that Rap80 helps BRCA1 recognise sites of DNA damage. So, in theory, damage to Rap80 could also lead to damage accumulating.

Co-senior author Dr Roger Greenberg, assistant professor of cancer biology at Penn, said: "With this current discovery, we have made significant new insights into the molecular mechanism by which BRCA1 recognises sites of DNA damage that breast cancer-causing mutated forms of BRCA1 cannot recognise.

"Now we have gained a partial understanding of the molecular basis between cancer-causing BRCA1 failures to fix DNA damage versus normal BRCA1's ability to fix DNA damage."

Dr Greenberg said that the finding could have implications for families with a history of breast cancer, as less than 50 per cent of inherited cases can be accounted for by BRCA1 and BRCA2 mutations.

The result comes at the same time as Cancer Research UK scientists announced that they had identified five new regions of DNA that, when damaged, increase the chances of breast cancer developing.

The team is now collaborating with other researchers to discover whether families with a history of breast cancer who do not carry BRCA mutations have any mutations in the Rap80 gene.