DNA methylation shown to promote development of co...(determine the impact of inducing methyla...)

Surprisingly and importantly, methylation appears to target specific regions of the DNA and the genes within them rather than being distributed randomly. "We found that key tumor-suppressor genes in certain DNA regions were silenced months before tumors appear," says Linhart. This specific targeting extends to organs as well: A given gene that is methylated in the colon, for example, does not become methylated in the spleen. The specificity of the process could prove a major advantage for diagnostic and therapeutic approaches based on DNA methylation.

"The enzymes that silence tumor-suppressing genes would be terrific targets for treatment," says senior author Rudolf Jaenisch. "If we can inactivate them and rescue the cancer-prevention functions of these genes, there would be predictably no side effects. And if we can examine circulating blood for signs of early methylation, we might be able to prevent tumors from developing."

Although this study focused on mice, Jaenisch notes that current clinical trials using a drug to inhibit methylation in people with leukemia appear to delay the disease."

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