Previous studies in our laboratory have shown that carcinogen-DNA adduct levels were associated with inheritable susceptibilities, which were modified by the amount of cigarette smoke exposure. This study of 90 autopsy donors is now being expanded to study the determinants of carcinogen-DNA adduct formation that are affected by these genes, or induce them. Gene-gene and gene-environment interactions are being studied. This year, we have developed methods to determine the level of metabolizing enzymes in human lung tissues of the same autopsy donors. Methods have been developed to determine the levels of CYP1A1, CYP2D6, CYP2E1, epoxide hydrolase and glutathione-S-transferase (M1). All except CYP2D6 have been found in the lung tissues. These methods will allow us to seek correlations with carcinogen-DNA adduct formation, protein level and protein activity so that they may be related to inherited susceptibilities. We also have developed methods to determine congener-specific levels of polychlorinated hydrocarbons in human lung tissues. Nineteen persons have been analyzed to date. Although the numbers of study subjects is small, we have identified correlations for specific congeners with age, pesticide levels and serum cotinine. One of the most important findings to date is that the most commonly detected congeners are similar to those found in the lung for laboratory monkey models. One of our collaborators, Dr. Gerald Wogan, has recently developed a procedure for the detection of carcinogen-DNA adducts in human tissues (ADAM). In collaboration with Dr. Wogan, we have detected polycyclic aromatic hydrocarbons in all five human lung tissue samples, indicating that this procedure is more sensitive than existing assays in our laboratory. Two of the samples were from infants. This procedure, following and additional validation step, will be used to analyze our existing study sets as described above. In conjunction with collaborators Dr. Kari Hemminki and Chris Wild, we have begun an interlaboratory comparison study of methods for determining 7-alkyl-DNA adducts in human lung tissues. Dr. Hemminki uses a method similar to ours and Dr. Wild uses an electrochemical detection method. Thirty samples were analyzed. Levels of adducts were within the same order of magnitude for the two 32P-postlabeling methods. There was a greater than tenfold difference when compared to the electrochemical method. Additional studies are being conducted to better validate the methods.
