"Extra Baggage" on DNA Seems to be Permanent
We all carry extra baggage that we don't want. It turns out that DNA is no different; it accumulates some barnacles, too – tiny changes that don't look like much, but which make a gene unable to function properly. Scientists used to think that these methylation changes were "plastic" – that they weren't necessarily permanent. But a recent study by William Nelson, M.D., Ph.D., the Marion I. Knott Director of the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, and Vasan Yegnasubramanian, M.D., Ph.D., is changing that viewpoint.
DNA accumulates some barnacles
To test whether these epigenetic defects in cancer cells go away as the disease progresses, Nelson and Yegnasubramanian invented a new platform for genome analysis that can simultaneously assess DNA methylation defects and the alterations in next-generation cells in different samples of metastatic cells from men who had died of prostate cancer. "Our logic was that if DNA methylation changes were stable, then similar, if not identical, alterations should be present in each metastatic deposit recovered from any man who had died of prostate cancer." This proved to be the case, leading Nelson and Yegnasubramanian to conclude that DNA methylation changes are equivalent to mutations, and "thus could formally be considered drivers of cancer."