Purification and recovery of bulky hydrophobic DNA adducts

Monitoring of DNA Adducts in Humans and 32P-Postlabelling Methods. A Review

DNA adduct formation in humans is a promising biomarker for elucidating the molecular epidemiology of cancer. For detection of DNA adducts, the most widely used methods include mass spectroscopy, fluorescence spectroscopy, immunoassays and 32P-postlabelling. Among them, the 32P-postlabelling method appears to meet best the criteria of sensitivity and amount of DNA needed, and, therefore, is one of the most appropriate methods for biomonitoring of human DNA adducts. Most classes of carcinogens have been subjected to 32P-postlabelling analysis, ranging from bulky and/or aromatic compounds to small and/or aliphatic compounds; it has also been used, with modifications, to detect apurinic sites in DNA, oxidative damage to DNA, UV-induced photodimers and, to a lesser extent, DNA damage caused by cytotoxic drugs. It has been used in human biomonitoring studies to detect DNA damage from occupational exposure to carcinogens, and also from environmental (i.e. non-occupational) exposures. It has also led to the discovery of the presence of numerous modifications in DNA arising from endogenous processes. The principle of the method is the enzymatic digestion of DNA to nucleotides, 5'-labelling of these nucleotides with an isotopically labelled phosphate group, and the resolution, detection and quantitation of the labelled products. Since the development of the original procedure in the early 1980s, many methods have been developed to increase the sensitivity by enrichment of modified nucleotides prior to labelling. The review presents the individual 32P-postlabelling techniques (standard procedure, enrichment methods) and a critical evaluation of these assays, besides reviewing the applications of the method to different DNA modifications, and its utilization in human biomonitoring studies. A review with 179 references.

Applications of capillary electrophoresis with laser-induced fluorescence for analysis of dGMP-BPDE adduct

DNA adducts are thought to be crucial to the initiation of mutational and carcinogenic processes. Polycyclic aromatic hydrocarbons (PAHs) have been identified as one major source of carcinogenic risk since they can bind to DNA thus forming an adduct. Quantification of this adduct is important because it may correlate to the risk for cancer development. In this study, the adduct formed between 2'-deoxyguanosine 5'-monophosphate and benzo[ a]pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE) was analyzed by capillary electrophoresis. Both capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MECC) modes with laser-induced fluorescence detection were used for the separation and analysis of DNA adducts. The exploration of capillary electrophoresis in several modes provided different separation mechanisms in which the stereochemical forms of the adduct could be separated. The best result obtained was using a coated fused-silica capillary in Tris-TAPS buffer, which provided high sensitivity with a detection limit of 2.5x10(-9) mol L(-1). MECC separation of the BPDE adduct, although less sensitive, provided an efficient enantioselective separation option.