Identification and quantitation of 7,12-dimethylbenz[a]anthracene-DNA adducts formed in mouse skin

Journal Article · · Chemical Research in Toxicology; (United States)

DOI:https://doi.org/10.1021/tx00033a018· OSTI ID:7026192

Devanesan, P D; RamaKrishna, N V.S.; Padmavathi, N S; Higginbotham, S; Rogan, E G; Cavalieri, E L; Marsch, G A ^[1]; Jankowiak, R; Small, G J ^[2]

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1. Univ. of Nebraska Medical Center, Omaha, NE (United States)
2. Iowa State Univ., Ames, IA (United States)

Identification and quantitation of the depurination and stable DNA adducts of 7,12-dimethylbenz[a]anthracene (DMBA) formed by cytochrome P450 in rat liver microsomes previously established one-electron oxidation as the predominant mechanism of activation of DMBA to bind to DNA. In this paper we report the identification and quantitation of the depurination and stable DMBA-DNA adducts formed in mouse skin. The depurination adducts, which constitute 99% of all the adducts detected, are DMBA bound at the 12-methyl group to the N-7 of adenine or guanine, namely, 7-methylbenz[a]anthracene (MBA)-12-CH[sub 2]-N7Ade and 7-MBA-12-CH[sub 2]-N7Gua. The depurination adducts were identified by HPLC and fluorescence line narrowing spectroscopy. The stable DNA adducts were analyzed by the [sup 32]P-postlabeling method. Almost 4 times as much of the depurination adduct 7-MBA-12-CH[sub 2]-N7Ade (79%) was formed compared to 7-MBA-12-CH[sub 2]-N7Gua (20%). The stable adducts accounted for only 1% of all the adducts detected and 80% of these were formed from DMBA diolepoxide. The binding of DMBA to DNA specifically at the 12-CH[sub 3] group is consistent with the results of carcinogenicity experiments in which this group plays a key role. When DMBA was bound to RNA or denatured DNA in reactions catalyzed by microsomes or by horseradish peroxidase (HRP), no depurination DNA adducts of DMBA were detected. The amount of stable DNA adducts observed with denatured DNA was 70% lower in the HRP system and 30% lower in the microsomal system compared to native DNA. In the microsomal system, just the two major adduct spots decreased, whereas the amounts of all of the adducts decreased with HRP. These results demonstrate that in mouse skin, DMBA-DNA adducts are predominantly formed via one-electron oxidation and that the adducts formed by the diolepoxide pathway are minor. 28 refs., 8 figs., 2 tabs.

• OSTI ID: 7026192
• Journal Information: Chemical Research in Toxicology; (United States), Journal Name: Chemical Research in Toxicology; (United States) Vol. 6:3; ISSN CRTOEC; ISSN 0893-228X
• Country of Publication: United States
• Language: English

Related Subjects

550200 -- Biochemistry
560300* -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ADDUCTS
ANIMALS
AROMATICS
BENZOPYRENE
BIOLOGICAL PATHWAYS
BIOSYNTHESIS
BODY
CELL CONSTITUENTS
CONDENSED AROMATICS
DNA ADDUCTS
EMISSION SPECTROSCOPY
FLUORESCENCE SPECTROSCOPY
HYDROCARBONS
MAMMALS
MICE
MICROSOMES
ORGANIC COMPOUNDS
ORGANS
RIBOSOMES
RODENTS
SKIN
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
SYNTHESIS
TOXICITY
VERTEBRATES