A quantitative comparison of dibenzo[a,l]pyrene-DNA adduct formation by recombinant human cytochrome P450 microsomes

King, Leon C.; Adams, Linda; Allison, J. C.; Kohan, Michael J.; Nelson, Garret B.; Desai, Dhimant; Amin, Shantu; Ross, Jeffrey A.

doi:10.1002/(sici)1098-2744(199910)26:2<74::aid-mc2>3.0.co;2-9

Cited by 15 publications

(2 citation statements)

References 33 publications

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“…On the other hand, mEH and CYP1B1 have been implicated in participating in the metabolic activation of DMBA 11, 21, 23. DB[ a,l ]P is metabolically converted to the ultimate form by CYP1A1, CYP1B1 and mEH 20, 24, 25. In the present study, in contrast to B[ a ]P and DMBA, DB[ a,l ]P induced a low level of CYP1A1 in the AhR−/− mouse skin.…”

Section: Discussionsupporting

confidence: 43%

Dibenzo[A,L]pyrene‐induced genotoxic and carcinogenic responses are dramatically suppressed in aryl hydrocarbon receptor‐deficient mice

Nakatsuru

Wakabayashi

Fujii‐Kuriyama

et al. 2004

Intl Journal of Cancer

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Dibenzo[a,l]pyrene (DB[a,l]P), a notorious air pollutant, is the most powerful carcinogenic polycyclic aromatic hydrocarbon (PAH) ever tested. Although the carcinogenicity of PAH may be primarily mediated by the aryl hydrocarbon receptor (AhR), the in vivo role of AhR in skin carcinogenesis remains to be defined. In this context, we investigated the genotoxic and carcinogenic responses of the AhR-deficient mouse skin to DB[a,l]P. A single painting resulted in a striking epidermal hyperplasia in AhR؉/؉ mice but not in AhR؊/؊ mice. Bromodeoxyuridine-labeling index and accumulation of p53 protein in epidermal cells of AhR؉/؉ mice were 8-and 33-fold higher than those of AhR؊/؊ mice, respectively. 4 The metabolic pathway of PAH has been extensively studied and well characterized. 5,6 Most PAH bind to the aryl hydrocarbon receptor (AhR) in the cytoplasm and the liganded AhR translocates to nuclei, where it forms a heterodimer with an AhR-nuclear translocator (Arnt). Subsequently, ligand-activated AhR-Arnt complex binds to the xenobiotic-responsive element in the upstream region of several genes encoding cytochrome P450 (CYP) superfamily such as CYP1A1, CYP1A2 and CYP1B1. 7,8 The inducible cytochrome P450 metabolizes PAH to generate ultimate forms that can covalently bind to DNA. These PAH-DNA adducts may induce mutation in the H-ras codon 61, one of the key event in tumor initiation in mouse skin. 9 Since AhR plays a role as a transcriptional regulator of CYP family, an AhR-deficient mouse is a faithful model for studying the biological responses to PAH in vivo. 10,11 We already reported that the skin carcinogenicity of B[a]P was completely lost in AhRϪ/Ϫ mice. 12 In B[a]P-treated AhRϪ/Ϫ mouse skin, the expression of CYP1A1, a typical AhR target gene, was not evident. These findings implicated the AhR-mediated induction of CYP1A1 as a critical step in mouse skin carcinogenesis by B[a]P. In this report, we extended our approach to the study of a potent human carcinogen DB[a,l]P and found that in contrast to B[a]P, AhRϪ/Ϫ mice are incompletely resistant to carcinogenic stress response. MATERIAL AND METHODS MiceAhR-deficient mice on a mixed 129/SV and C57BL/6J background were established as described previously. 13 In our study, the 1st generation of AhR ϩ/Ϫ mice were backcrossed repeatedly and maintained on the stable C57BL/6J genetic background. The genotype of each pup was determined by polymerase chain reaction (PCR) with tail tip DNA. 12,13 Genotype analyses were repeated at the end of the following experiments to confirm the results. Skin response to DB[a,l]P applicationAt 6 -8 weeks of age, the dorsal skins of AhRϪ/Ϫ and AhRϩ/ϩ mice were shaved 3 days before treatment. Each experiment panel consisted of 3 to 5 female mice. The solutions of DB[a,l]P (Sigma Chemical Co., St. Louis, MO) were prepared in acetone and epicutaneously applied to the shaved backs in a volume of 200 l. DB[a,l]P is highly toxic to the mouse skin (Fig. 1a,b); reluctantly, the following experiments were performed with a different treatment p...

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Section: Discussionsupporting

confidence: 43%

Dibenzo[A,L]pyrene‐induced genotoxic and carcinogenic responses are dramatically suppressed in aryl hydrocarbon receptor‐deficient mice

Nakatsuru

Wakabayashi

Fujii‐Kuriyama

et al. 2004

Intl Journal of Cancer

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“…In V79 Chinese hamster cells expressing either human P4501A1 or P4501B1, DB[a,l]P is oxidized to its fjord-region DEs (36). Studies with recombinant human P450 microsomes have further demonstrated that P450s 1A1 and 1B1 catalyze the activation of DB[a,l]P leading to formation of DNA adducts (37). Furthermore, a role for P4501B1 has also been supported by findings that Cyp1b1(-/-) mice have fewer tumors and a greater survival time as compared to WT mice treated intragastrically with DB[a,l]P (38).…”

Section: Discussionmentioning

confidence: 93%

Role of Cytochrome P4501 Family Members in the Metabolic Activation of Polycyclic Aromatic Hydrocarbons in Mouse Epidermis

Kleiner

Vulimiri

Hatten

et al. 2004

Chem. Res. Toxicol.

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Polycyclic aromatic hydrocarbons (PAHs) are known to be activated by the cytochrome P450 (P450) 1 family. However, the precise role of individual P4501 family members in PAH bioactivation remains to be fully elucidated. We therefore investigated the formation of PAH-DNA adducts in the epidermis of Cyp1a2(-/-), Cyp1b1(-/-), and Ahr(-/-) knockout mice. A panel of different PAHs was used, ranging in carcinogenic potency. Mice were treated topically on the dorsal skin with the following tritium-labeled PAHs: dibenzo[a,l]pyre-ne (DB[a,l]P), 7,12-dimethylbenz[a]anthracene (DMBA), benzo[a]pyrene (B[a]P), dibenzo[a,h]anthracene (DB[a,h]A), benzo[g]chrysene (B[g]C), and benzo[c]phenanthrene (B[c]P). At 24 h after treatment, mice (two male and two female mice per group) were sacrificed, and epidermal DNA was isolated and hydrolyzed with DNase I; subsequently, DNA adducts were quantitated by liquid scintillation counting. In the DB[a,l]P-treated mice, levels of DNA adducts were significantly lower in Cyp1a2(-/-) and Cyp1b1(-/-) mice by 57 and 46%, respectively, as compared to wild-type (WT) mice (C57BL/6 background). The levels of DB[a,l]P DNA adducts formed in Ahr(-/-) mice were 26% lower, but this was not statistically significant. The levels of DMBA-DNA adducts in Cyp1a2(-/-) mice were not different than the WT mice but were significantly lower in Cyp1b1(-/-) and Ahr(-/-) mice by 64 and 52%, respectively. DMBA-DNA adduct samples were further analyzed by HPLC following further digestion to deoxyribonucleosides. HPLC analysis of individual DMBA-DNA adducts revealed differences in the ratio of syn-DMBA-diol epoxide- to anti-DMBA-diol epoxide-derived adducts in the Ahr(-/-) and Cyp1b1(-/-) mice. The ratio of syn-/anti-derived adducts in WT mice was 0.49. This ratio was 0.23 in the Cyp1b1(-/-) mice and 0.87 in the Ahr(-/-) mice. In contrast to the results with DB[a,l]P and DMBA, the levels of B[a]P-, DB[a,h]A-, B[g]C-, and B[c]P-DNA adducts were significantly lower in Ahr(-/-) mice by 73, 75, 50, and 81%, respectively, as compared to WT mice but were not significantly lower in the Cyp1a2(-/-) or Cyp1b1(-/-) mice. Collectively, these and other results support a role for both P4501A1 and P4501B1 in the bioactivation of DMBA; P4501A2, P4501B1, and possibly P4501A1 in the bioactivation of DB[a,l]P; and P4501A1 in the bioactivation of B[a]P, DB[a,h]A, B[g]C, and B[c]P in mouse epidermis. Furthermore, in the metabolic activation of DMBA in mouse epidermis, P4501B1 shows a preference for the formation of syn-DMBA-diol epoxide adducts, whereas P4501A1 shows a preference for the formation of anti-DMBA-diol epoxide adducts.

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Assessment of multiple types of DNA damage in human placentas from smoking and nonsmoking women in the Czech Republic

Pratt

King

Adams

et al. 2011

Environ and Mol Mutagen

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Three classes of DNA damage were assessed in human placentas collected (in 2000-4) from 51 women living in the Teplice region of the Czech Republic, a mining area considered to have some of the worst environmental pollution in Europe in the 1980s. Polycyclic aromatic hydrocarbon (PAH)-DNA adducts were localized and semiquantified using immunohistochemistry (IHC) and the Automated Cellular Imaging System (ACIS). More generalized DNA damage was measured both by 32 P-postlabeling and by abasic (AB) site analysis. Placenta stained with antiserum elicited against DNA modified with r7, t8-dihydroxy-t-9, 10-oxy-7,8,9,10-tetrahydro-benzo[a]pyrene (BPDE) revealed PAH-DNA adduct localization in nuclei of the cytotrophoblast (CT) cells and syncytiotrophoblast (ST) knots lining the chorionic villi. The highest levels of DNA damage, 49-312 PAH-DNA adducts/10 8 nucleotides, were found by IHC/ACIS in 14 immediately-fixed placenta samples. An additional 37 placenta samples were stored frozen before fixation and embedding, and because PAH-DNA adducts were largely undetectable in these samples, freezing was implicated in the loss of IHC signal. The same placentas (n = 37) contained 1.7 -8.6 stable/ bulky DNA adducts/10 8 nucleotides and 0.6 -47.2 AB sites/10 5 nucleotides. For all methods there was no correlation among types of DNA damage and no difference in extent of DNA damage between smokers and non-smokers. Therefore, the data show that DNA from placentas obtained in Teplice contained multiple types of DNA damage, which likely arose from various environmental exposures. In addition, PAH-DNA adducts were present at high concentrations in the CT cells and ST knots of the chorionic villi.

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A quantitative comparison of dibenzo[a,l]pyrene-DNA adduct formation by recombinant human cytochrome P450 microsomes

Cited by 15 publications

References 33 publications

Dibenzo[A,L]pyrene‐induced genotoxic and carcinogenic responses are dramatically suppressed in aryl hydrocarbon receptor‐deficient mice

Dibenzo[A,L]pyrene‐induced genotoxic and carcinogenic responses are dramatically suppressed in aryl hydrocarbon receptor‐deficient mice

Role of Cytochrome P4501 Family Members in the Metabolic Activation of Polycyclic Aromatic Hydrocarbons in Mouse Epidermis

Assessment of multiple types of DNA damage in human placentas from smoking and nonsmoking women in the Czech Republic

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