DNA damage ultimately causes 80-90% of human cancer. The purine and pyrimidine bases in DNA are critical cellular targets for damage by radiation and various oxidizing and alkylating agents. Chemical carcinogens or their active metabolites can react with DNA to form covalently bound products, known as DNA adducts. Adduct formation at particular sites in DNA is known to lead to the activation of oncogenes, and may also lead to suppression of tumor-suppressor genes. The critical role of DNA damage makes it essential to develop sensitive and reliable assays for DNA damage. Such assays should further understanding of the biological consequences of DNA modification and enzymatic repair of DNA damage.
Currently available techniques for measuring DNA damage can suffer from several drawbacks: (i) poor sensitivity (e.g. immunoassays), (ii) poor specificity (e.g. assays based on induction of DNA strand-breaks), and (iii) use of large quantities of radioactivity (e.g. 32P-postlabeling assay. The sensitivity of these assays is often insufficient for direct sample analysis. Thus many DNA damage and repair studies have been carried out with unrealistically high levels of the DNA damaging agents compared with the environmentally and clinically relevant doses. We are interested in developing ultrasensitive bio-analytical techniques for detecting DNA damage. We are using state-of-the-art capillary electrophoresis separation, laser induced fluorescence detection, and affinity chromatography to achieve high sensitivity and selectivity. We will use the new technology to assay DNA photo-induced damage and DNA adducts of chemical carcinogens.