A trio of scientists was awarded the Nobel Prize in chemistry for describing how cells repair damaged DNA, breakthroughs that are helping to guide the development of new cancer drugs. The prize was shared by Tomas Lindahl of Sweden, Paul Modrich of the U.S., and Aziz Sancar, a dual American and Turkish citizen. Their research—done independently of one another—provid ed crucial insights into how a living cell functions, about the molecular causes of several hereditary diseases, and about mechanisms behind both cancer development and aging, the Royal Swedish Academy of Sciences said. Scientists used to believe that DNA, the molecule of life, was stable. But in the 1970s, Dr. Lindahl realized that DNA undergoes decay because it is subject to thousands of potentially devastating injuries every day, whether from ultraviolet radiation, free radicals, or carcinogenic substances such as cigarette smoke. Dr. Lindahl figured that the cell must have molecular systems for repairing the various DNA defects. He then identified a bacterial enzyme that is part of the cell’s toolbox for DNA repair and published the finding in 1974.
In particular, Dr. Lindahl discovered a molecular machinery called “base excision repair,” which constantly fends off the collapse of DNA. Separately, Dr. Sancar mapped a process known as “nucleotide excision repair,” which enables cells to repair UV damage to DNA. People who inherit defects in this repair mechanism can develop skin cancer when exposed to sunlight. Dr. Modrich was recognized for demonstrating how cells use a mechanism, called “mismatch repair,” to fix errors that occur when DNA is replicated during cell division. Dr. Lindahl is emeritus director of Cancer Research U.K. at Clare Hall Laboratory. Dr. Modrich is a professor of biochemistry at Duke University School of Medicine in Durham, N.C. Dr. Sancar is a professor of biochemistry and biophysics at the University of North Carolina School of Medicine in Chapel Hill, N.C.