TY - JOUR
T1 - 5-methylchrysene metabolism in mouse epidermis in vivo, diol epoxide-DNA adduct persistence, and diol epoxide reactivity with DNA as potential factors influencing the predominance of 5-methylchrysene-1,2-diol-3,4-epoxide-DNA adducts in mouse epidermis
AU - Melikian, Assieh A.
AU - Voie, Edmond J.la
AU - Hecht, Stephen S.
AU - Hoffmann, Dietrich
N1 - Funding Information:
This study was supported by Grant CA32242 from the National Cancer Institute.
PY - 1983
Y1 - 1983
N2 - 5-Methylcbrysene (5-MeC) can form two bay region dihydrodiol epoxides: 1,2-dihydroxy-3-4-epoxy-1,2,3,4-tetrahydro-5-methylchrysene (DE-I) which has the methyl group and the epoxide ring in the same bay region, and 7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydro-5-methylchrysene (DE-II). In a previous study, we observed that the ratio of DE-I:DNA adduds to DE-II:DNA adducts in mouse epidermis, 24 h after application of [3H]5-MeC metabolites was 2.7 to 1. To investigate the basis for this observation we have now studied: (i) the formation of [3H]5-MeC in mouse epidermis in vivo at various time intervals from 0.33 to 24 h; (II) the persistence of DE-I:DNA adducts and DE-II:DNA adducts in mouse epidermis at 4-48 h after application of [3H]5-MeC and (iii) the reactions of DE-I and DE-II with calf thymus DNA in vitro. In contrast to results obtained with mouse liver 9000 g supernatant, the dihydrodiol precursors of DE-I and DE-II were present in equivalent quantities in mouse epidermis in vivo at every time point studied. The ratio of DE-I:DNA adducts to DE-II:DNA adducts in mouse epidermis was constant throughout the time period studied. However, the extent of formation of DE-I:DNA adducts was greater than that of DE-II:DNA adducts upon reaction of DE-I or DE-II with calf thymus DNA in vitro. These results suggest that differences in reactivity with DNA of DE-I and DE-II may be responsible for the higher levels in mouse epidermis of DE-I:DNA adducts compared with DE-II:DNA adducts and provide a possible basis for the observed enhancing effect of a bay region methyl group on the carcinogenicity of polynuclear aromatic hydrocarbons.
AB - 5-Methylcbrysene (5-MeC) can form two bay region dihydrodiol epoxides: 1,2-dihydroxy-3-4-epoxy-1,2,3,4-tetrahydro-5-methylchrysene (DE-I) which has the methyl group and the epoxide ring in the same bay region, and 7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydro-5-methylchrysene (DE-II). In a previous study, we observed that the ratio of DE-I:DNA adduds to DE-II:DNA adducts in mouse epidermis, 24 h after application of [3H]5-MeC metabolites was 2.7 to 1. To investigate the basis for this observation we have now studied: (i) the formation of [3H]5-MeC in mouse epidermis in vivo at various time intervals from 0.33 to 24 h; (II) the persistence of DE-I:DNA adducts and DE-II:DNA adducts in mouse epidermis at 4-48 h after application of [3H]5-MeC and (iii) the reactions of DE-I and DE-II with calf thymus DNA in vitro. In contrast to results obtained with mouse liver 9000 g supernatant, the dihydrodiol precursors of DE-I and DE-II were present in equivalent quantities in mouse epidermis in vivo at every time point studied. The ratio of DE-I:DNA adducts to DE-II:DNA adducts in mouse epidermis was constant throughout the time period studied. However, the extent of formation of DE-I:DNA adducts was greater than that of DE-II:DNA adducts upon reaction of DE-I or DE-II with calf thymus DNA in vitro. These results suggest that differences in reactivity with DNA of DE-I and DE-II may be responsible for the higher levels in mouse epidermis of DE-I:DNA adducts compared with DE-II:DNA adducts and provide a possible basis for the observed enhancing effect of a bay region methyl group on the carcinogenicity of polynuclear aromatic hydrocarbons.
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U2 - 10.1093/carcin/4.7.843
DO - 10.1093/carcin/4.7.843
M3 - Article
C2 - 6872139
AN - SCOPUS:0020955158
SN - 0143-3334
VL - 4
SP - 843
EP - 849
JO - Carcinogenesis
JF - Carcinogenesis
IS - 7
ER -