Changes caused by smoking block tumour-fighting genes

• 13:10 12 October 2010 by Nic Fleming
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The first direct evidence has been found linking smoking to epigenetic changes in genes that help fight cancer. Reversing these changes may one day provide a new route to treating cancer.

Women with cervical cancer are known to have higher levels of epigenetic modifications – methyl groups attached to particular sites on their DNA – affecting a gene called p16, which is known to be involved in suppressing tumours.

To find out more, Yuk Ting Ma at the University of Birmingham, UK, re-analysed samples from a series of cervical smear tests taken over four years from 1075 women. Ma found evidence of p16 methylation in the cervical cells of 37 per cent of smokers compared to 9.3 per cent of non-smokers. Women who started smoking during the study were 3.7 times more likely to acquirep16 methylation than non-smokers.

In two-thirds of the 19 smokers with p16 methylation who gave up smoking during the trial, the methylation disappeared. This suggests not only that smoking caused the changes, but also that it might be possible to reverse them before they lead to cancer.

The results were presented on Saturday at the European Society for Medical Oncology meeting in Milan, Italy.