DETECTION OF 1,N-2-PROPANODEOXYGUANOSINE ADDUCTS AS POTENTIAL ENDOGENOUS DNA LESIONS IN RODENT AND HUMAN TISSUES

Our previous study (R. G. Nath and F-L. Chung; Proc. Natl. Acad. Sci. USA, 91: 7491-7495, 1994), using a P-32 postlabeling method combined w ith high-performance liquid chromatography specifically developed for exocyclic adducts, has shown that acrolein- and crotonaldehyde-derived 1,N-2-propanodeoxyguanosine adducts (AdG and CdG, respectively) are p resent in the liver DNA from humans and rodents without carcinogen tre atment. Those findings raised important questions regarding their role as potential endogenous DNA lesions in carcinogenesis, In this study, using a similar assay, we examined a variety of tissues from untreate d rats and mice (lung, kidney, brain, breast, prostate, colon, skin, a nd leukocytes) and detected AdG and CdG in the DNA of these tissues, M ore significantly, we also obtained evidence for the presence of these adducts in the DNA of human leukocytes and mammary glands, The identi ties of these adducts were verified by comigration of 3',5'-bisphospha tes of the P-32-labeled adduct from DNA with the synthetic standards i n a reversed-phase high-performance liquid chromatography, Additional proof of identities was provided by enzymatic conversion of AdG and Cd G 3',5'-bisphosphates to the corresponding 5'-monophosphates, followed by comigration with their synthetic standards, The estimated ranges o f total AdG and CdG modifications in DNA of various tissues were from 0.10 to 1.60 mu mol/mol guanine for rodents and 0.01 to 0.78 mu mol/mo l guanine for humans, based on the recoveries of external standards, T his study demonstrated the ubiquity of these adducts in various tissue s, suggesting their potential role as endogeneous DNA lesions in roden ts and humans.