Is there a universal cancer fingerprint? Researchers at the National Institutes of Health believe they may have found a potential common biomarker for 5 different tumor types. The clue is a “methylation signature”—evidence of a chemical modification of DNA. Methylation controls the expression of genes, and higher amounts of DNA methylation reduce a gene’s activity, like a dimmer switch on a light fixture.
In an earlier study using DNA taken from solid tumors, the researchers found a methylation signature in 15 tumor types in 13 different organs around the gene called ZNF154. In the new study, the researchers uncovered methylation in colon, lung, breast, stomach, and endometrial cancers. All the tumor types and subtypes consistently produced the same methylation mark around ZNF154.
Researchers developed a computer program that looked at methylation marks in the DNA of people with and without cancer and were able to predict a threshold for detecting tumor DNA. Because tumors often shed DNA into the bloodstream, the researchers were able to calculate the proportions of circulating tumor DNA. The researchers hope their results lead to a blood test that can diagnose cancers at early stages.
Currently, blood tests are specific to a known tumor type. Clinicians must first find the tumor and then sequence a sample from it before they can track the tumor-specific mutations in the blood. By contrast, a method derived from the methylation signatures would mean no prior knowledge of the cancer was required. The tests would be less intrusive than that of other screening methods and could be used to follow high-risk patients or monitor the activity of a tumor during treatment.
Source:
National Institutes of Health. NIH researchers identify striking genomic signature shared by five types of cancer [news release]. National Institutes of Health Website. http://www.nih.gov/news-events/news-releases/nih-researchers-identify-striking-genomic-signature-shared-five-types-cancer. Published February 5, 2016. Accessed February 29, 2016.