Preventive medicine is the rational response to the rising medical costs. This response includes a renewed emphasis on antioxidant foods and supplements to lower risk from cancer, which is now the number one fatal disease. Current theories of cancer highlight hypoxia in microenvironments where oxidative stress damages DNA and promotes mutagenesis. Our major aim is to evaluate suppression of mutagenesis by sulfhydryl antioxidant N-acetylcysteine (NAC), and alpha-lipoic acid, both of which potentiate glutathione activity, the gold standard of antioxidants. Vitamin C will be used as a standard. Surprisingly, few antioxidant studies have addressed directly the suppression of mutagenesis. Most rely on end points of survival times, anticarcinogenic activity, or chromosomal damage. We hypothesize that the sulfhydryl antioxidants will prevent mutations induced by gamma radiation, which mimics endogenous mutagenesis by OH radicals. Mutation frequencies (mf) will be quantitated by measuring mutations in a LacI repressor gene, contained in the chromosome of live transgenic Big Blue mice. Mutations will be detected because the inoperant LacI will not be able to repress the expression of the reporter gene (b- galactosidase) in a bacterial system, rendering the resulting plaque blue. DNA damage, a precursor to mutagenesis, will be assessed by quantification of apurinic/apirimidinic (AP) sites in the DNA. The degree of chemoprotection against mutations afforded by antioxidants in live Big Blue mice subjected to gamma radiation will be evaluated by two methods: LacI gene mutations and AP site production. Mutations will be isolated and sequenced to detect any patterns and to catalog them. This work will test the notion that antioxidants can effectively block mutations caused by oxidative damage. In addition, our results will provide a basis for a rational policy on the use of antioxidant supplements in humans, either as an anticancer strategy or for counteracting age-related diseases. PUBLIC HEALTH RELEVANCE: This project will test the idea that certain antioxidants in food and supplements can reduce mutations in the DNA of a live animal. Mutations are thought to cause cancer and other age related diseases. We will test the protection against mutations and DNA damage, which is a precursor to mutations. If antioxidants work, they may be used to reduce risk of cancer and other diseases typical of old age.

SC3GM088087

2009-08-01

2014-06-30