Scientists close in on breast cancer breakthrough
Scientists are hot on the trail of a new genetic link to breast cancer that could be the key to many inherited cases.
They are targeting a gene called Rap80, a vital component of the DNA repair mechanism that normally keeps breast cancer at bay.
Two breast cancer causing “oncogenes”, BRCA 1 and BRCA 2, are already known.
If a woman has a faulty version of one of these DNA-repair genes, she has an up to 80% chance of developing breast cancer.
However, defects in BRCA 1 and BRCA 2 are responsible for just 2% to 5% of inherited breast cancers, as well as a small proportion of ovarian cancers.
Now scientists are closing in on a missing part of the puzzle. They have discovered that Rap80 is required for BRCA 1 to function normally. Without it, the BRCA 1 repair protein cannot be marshalled to sites of DNA damage.
In the 1990s, researchers discovered that BRCA 1 helped to maintain the normal number and structure of chromosomes, the bundled packages of DNA in cell nuclei.
DNA breaks that go unrepaired can lead to cancer.
Dr Roger Greenberg, from the University of Pennsylvania in Philadelphia, US, a member of the investigating team that reported its results today in the journal Science, said: “With this current discovery, we have made significant new insights into the molecular mechanism by which BRCA 1 recognises sites of DNA damage that breast-cancer-causing mutated forms of BRCA 1 cannot recognise.
“Rap80, by interacting with a BRCA 1 region that is essential for BRCA tumour suppression, now becomes a candidate to investigate as another breast cancer disease gene in families that do not have BRCA 1 and BRCA 2 mutations, but have a history of breast and/or ovarian cancer.”
Of the 44,000 new cases of breast cancer diagnosed each year in the UK, around 5% to 10% are inherited.
