Each type of damaging agent has its own unique effect on DNA, says Dr. Doetsch. Chemical carcinogens enter the cell's nucleus, bond with a component of DNA, and cause bulky formations that hang from the DNA strand. Nonionizing radiation, such as ultraviolet light, damages DNA through a photochemical process. Dr. Paul Doetsch specializes in DNA repair enzymes, which work to reverse many different types of genetic damage to the cell. But it is actually the lack of these enzymes, or a defect in their function, that can lead to cancer.
Unrepaired damage can either block cell replication or cause a mutation.
In a recent issue of the journal Nature , Dr. Doetsch reported on an enzyme he and his research team found in yeast that repairs ultraviolet-induced genetic damage. Dr. Doetsch believes the study of the YPDE enzyme and its relationship to human enzymes may eventually lead to genetic testing for sunlight sensitivity and ways of beefing up the DNA repair process. Two biotechnology firms, along with scientists at the University of Vermont, Dana Farber Cancer Institute, and Johns Hopkins School of Medicine, recently announced the discovery of another DNA repair enzyme in humans which is the equivalent of an enzyme originally found in yeast and bacteria. These researchers found that a particular DNA repair gene with a defective version of this enzyme is linked to hereditary nonpolyposis colon cancer and perhaps other types of colon cancer as well. We could also develop new therapies by exploiting enzyme defects in cancer cells to kill them.