Addictions are so strong that some people think they can’t live without them. For cancer cells, that’s actually the case. Cancer cells’ DNA methylation addiction actually keeps them alive, according to a group of California researchers.
Altered DNA methylation is just one of many changes that go down when a cell becomes cancerous. The researchers wondered whether this mod was a consequence of other changes or if it was really required for cancer cells to survive in their new transformed state.
They found that colon cancer cells preferentially keep DNA methylation at certain regions (566 CpG sites) when knocking out or severely knocking down DNA methyltransferase expression, suggesting that DNA methylation is required for their survival.
Looking at data from The Cancer Genome Atlas, they saw that 92 CpGs that were unmethylated in normal cells became methylated in colon cancer cells—in what might be a cancer-specific profile. The group got similar results with lung cancer cells, too. Somatic tissue-specific and cell culture-specific profiles also emerged. In fact, the researchers caution that the cell culture-specific profile shows the importance of being very careful when interpreting cell culture data in epigenetics experiments.
Cancer cells with a severely impaired (truncated) DNA methyltransferase had a very high incidence of cell death, so maintaining DNA methylation was extremely important to these cells. And re-expression of genes that were methylated in these cancer cells decreased their viability.
It all points to the fact that cancer cells just can’t quit DNA methylation.
Don’t quit now—read all the details at Cancer Cell, May 2012.