In many parts of the world, including Southeast Asia and sub-Saharan Africa, exposure to a fungal product called aflatoxin is believed to cause up to 80 percent of liver cancer cases. This fungus is often found in corn, peanuts, and other crops that are dietary staples in those regions. MIT researchers have now developed a way to determine, by sequencing DNA of liver cells, whether those cells have been exposed to aflatoxin. This profile of mutations could be used to predict whether someone has a high risk of developing liver cancer, potentially many years before tumors actually appear. “What we’re doing is creating a fingerprint,” says John Essigmann, Ph.D., the William R. and Betsy P. Leitch Professor of Biological Engineering and Chemistry at MIT. “It’s really a measure of prior exposure to something that causes cancer.” This approach could also be used to generate profiles for other common carcinogens, says Dr. Essigmann, who is the senior author of a paper describing the findings in the Proceedings of the National Academy of Sciences the week of March 27, 2017. The paper’s lead author is MIT postdoc Supawadee Chawanthayatham. Other MIT authors are technical assistant Charles Valentine, research scientists Bogdan Fedeles and Robert Croy, BioMicro Center Director Stuart Levine, postdoc Stephen Slocum, and Professor of Biological Engineering Emeritus Gerald Wogan. University of Washington researchers Edward Fox and Lawrence Loeb are also authors of the study. As Dr. Essigmann’s lab has previously reported, exposure to aflatoxin usually results in a genetic mutation that converts the DNA base guanine to thymine.
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