UK and Canadian scientists have identified a new gene involved in breast and ovarian cancer, which they say provides a link between the inherited and non-inherited (sporadic) forms of the diseases. The gene, dubbed EMSY, appears to trigger sporadic breast cancer by shutting down the BRCA2 gene, which is one of the genes involved in inherited breast and ovarian cancer. 'Discovering such an important new gene is very exciting and gives us the piece of the jigsaw we've been looking for' said team leader Tony Kouzarides, of the Wellcome Trust/Cancer Research UK Institute at the University of Cambridge.
Most cases of breast cancer are not inherited, but in around five per cent of patients, the disease is associated with mutations in one of two genes: BRCA1 and BRCA2. Women who inherit a BRCA1 or BRCA2 mutated gene have a higher risk of developing breast and ovarian cancer. In the case of BRCA2, the estimated lifetime risk is 40-60 per cent of developing breast cancer, and a 10-20 per cent risk of ovarian cancer.
Scientists think that BRCA2 makes a protein that repairs DNA damage, so women with a faulty BRCA2 gene are more at risk of accumulating genetic errors in their cells, damage that can eventually trigger cancer. Now, researchers at the University of Cambridge and the British Colombia Cancer Agency in Canada have identified a new gene, EMSY, that makes a protein that can stick to and 'switch off' the BRCA2 gene. Like inheriting a faulty version of BRCA2, switching off BRCA2 would also leave a cell vulnerable to the effects of DNA damage.
Because of the link with BRCA2, a known breast cancer gene, the scientists decided to see if the EMSY gene is involved in sporadic cases of breast and ovarian cancer. They found that extra copies of the gene were present in 13 per cent of the 551 breast tumours they studied, and 17 per cent of the 360 ovarian tumours. Team member Carlos Caldas said: 'We've always known that factors that are important in inherited breast cancers should also be playing a role in other kinds', adding that 'it's heartening to know we haven't been barking up the wrong tree'.
EMSY, which the researchers named after Emma Hughes-Davies, a cancer nurse and sister of Luke Hughes-Davies, who discovered the gene, seems to be particularly important in the aggressive forms of breast cancer. Women whose tumours had extra copies of the EMSY gene survived for an average of 6.4 years, compared to 14 years for those with normal amounts of EMSY. The researchers hope that their findings, published in the journal Cell, will lead to new tests that predict how aggressive a tumour is likely to become, and also to new, targeted drug treatments against breast and ovarian cancer.
Sources and References
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Genetic, non-inherited cancer linked
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New breast cancer gene discovered
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New breast cancer gene is 'missing link' in medical mystery
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Study links genetic, non-inherited breast cancer
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