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  • CONTAMINANT 3-NITROBENZANTHRONE  (9)
Keywords
  • 1
    Keywords: BLOOD ; Germany ; LUNG ; DNA adducts ; EXPOSURE ; liver ; TISSUE ; HEART ; DNA ; kidney ; 3-nitrobenzanthrone ; DIESEL EXHAUST ; DNA ADDUCT FORMATION ; POSTLABELING ANALYSIS ; RAT ; BIOMARKERS ; CONTAMINANT 3-NITROBENZANTHRONE ; ENRICHMENT ; HPLC ; RATS ; METABOLITES ; HUMANS ; URINARY-BLADDER ; HUMAN ACETYLTRANSFERASES ; METABOLIC-ACTIVATION ; NUCLEOTIDES ; POLLUTANT 3-NITROBENZANTHRONE ; ADDUCTS ; PERFORMANCE LIQUID-CHROMATOGRAPHY ; DNA-ADDUCTS ; SURFACE SOIL ; V79 CELLS ; SINGLE ; RE ; EMISSIONS ; CARCINOGEN ; ADDUCT ; biomarker ; MUTAGEN 3-NITROBENZANTHRONE ; DNA ADDUCT ; intratracheal instillation ; P-32-postlabeling
    Abstract: 3-Nitrobenzanthrone (3-NBA) is an environmental pollutant and suspected human carcinogen found in emissions from diesel and gasoline engines and on the surface of ambient air particulate matter; human exposure to 3-NBA is likely to occur primarily via the respiratory tract. In our study female Sprague Dawley rats were treated by intratracheal instillation with a single dose of 0.2 or 2 mg/kg body weight of 3-NBA. Using the butanol enrichment version of the P-32-postlabeling method, DNA adduct formation by 3-NBA 48 hr after intratracheal administration in different organs (lung, pancreas, kidney, urinary bladder, heart, small intestine and liver) and in blood was investigated. The same adduct pattern consisting of up to 5 DNA adduct spots was detected by thin layer chromatography in all tissues and blood and at both doses. Highest total adduct levels were found in lung and pancreas (350 +/- 139 and 620 +/- 370 adducts per 10(8) nucleotides for the high dose and 39 +/- 18 and 55 +/- 34 adducts per 10(8) nucleotides for the low dose, respectively) followed by kidney, urinary bladder, heart, small intestine and liver. Adduct levels were dose-dependent in all organs (approximately 10-fold difference between doses). It was demonstrated by high performance liquid chromatography (HPLC) that all 5 3-NBA-derived DNA adducts formed in rats after intratracheal instillation are identical to those formed by other routes of application and are, as previously shown, formed from reductive metabolites bound to purine bases. Although total adduct levels in the blood were much lower (41 +/- 27 and 9.5 +/- 1.9 adducts per 10(8) nucleotides for the high and low dose, respectively) than those found in the lung, they were related to dose and to the levels found in lung. These results show that uptake of 3-NBA by the lung induces high levels of specific DNA adducts in several organs of the rat and an identical adduct pattern in DNA from blood. Therefore, 3-NBA-DNA adducts present in the blood are useful biomarkers for exposure to 3-NBA and may help to assess the effective biological dose in humans exposed to it. (C) 2005 Wiley-Liss, Inc
    Type of Publication: Journal article published
    PubMed ID: 15856450
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  • 2
    Keywords: EXPRESSION ; human ; liver ; ENZYMES ; PROTEIN ; TIME ; ACTIVATION ; DNA ; 3-aminobenzanthrone ; 3-nitrobenzanthrone ; DIESEL EXHAUST ; DNA ADDUCT FORMATION ; AIR-POLLUTION ; INDUCTION ; LIVER-MICROSOMES ; RAT ; SUDAN-I ; CONTAMINANT 3-NITROBENZANTHRONE ; RATS ; RAT-LIVER ; HUMAN ACETYLTRANSFERASES ; BODY ; air pollution ; INCREASE ; WEIGHT ; LEVEL ; ENZYME ; P-32-postlabeling ; reductive activation ; P-32-POSTLABELING ANALYSIS ; BIOTRANSFORMATION ENZYMES ; NAD(P)H-QUINONE OXIDOREDUCTASE ; NITROPOLYCYCLIC AROMATIC-HYDROCARBONS
    Abstract: 3-Nitrobenzanthrone (3-NBA), a suspected human carcinogen occurring in diesel exhaust and air pollution, and its human metabolite 3-aminobenzanthrone (3-ABA) were investigated for their ability to induce biotransformation enzymes in rat liver and the influence of such induction on DNA adduct formation by the compounds. Rats were treated (i.p.) with 0.4, 4, or 40 mg/kg body weight 3-NBA or 3-ABA. When hepatic cytosolic fractions from rats treated with 40 mg/kg body weight 3-NBA or 3-ABA were incubated with 3-NBA, DNA adduct formation, measured by P-32-postlabeling analysis, was 10-fold higher in incubations with cytosols from pretreated rats than with controls. The increase in 3-NBAderived DNA adduct formation corresponded to a dose-dependent increase in protein levels and enzymatic activity of NAD(P) H: quinone oxidoreductase (NQO1). NQO1 is the major enzyme reducing 3-NBA in human and rat livers. Incubations of 3-ABA with hepatic microsomes of rats treated with 3-NBA or 3-ABA (40 mg/ kg body weight) led to as much as a 12-fold increase in 3-ABA-derived DNA adduct formation compared with controls. The observed stimulation of DNA adduct formation by both compounds was attributed to their potential to induce protein expression and enzymatic activity of cytochromes P450 1A1 and/ or -1A2 (CYP1A1/2), the major enzymes responsible for 3-ABA activation in human and rat livers. Collectively, these results demonstrate for the first time, to our knowledge, that by inducing hepatic NQO1 and CYP1A1/2, both 3-NBA and 3-ABA increase the enzymatic activation of these two compounds to reactive DNA adduct-forming species, thereby enhancing their own genotoxic potential
    Type of Publication: Journal article published
    PubMed ID: 16714372
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  • 3
    Keywords: INHIBITOR ; IN-VIVO ; INHIBITION ; LUNG ; LUNG-CANCER ; DNA adducts ; liver ; ENZYMES ; TISSUE ; MICE ; ACTIVATION ; DNA ; kidney ; 3-nitrobenzanthrone ; CARCINOGENESIS ; DIESEL EXHAUST ; AIR-POLLUTION ; CONTAMINANT 3-NITROBENZANTHRONE ; BINDING ; DNA-BINDING ; METABOLIC-ACTIVATION ; ADDUCTS ; rodent ; DT-DIAPHORASE ; RAT-LIVER CYTOSOL ; XANTHINE-OXIDASE ; DNA-ADDUCTS ; V79 CELLS ; ACETYLTRANSFERASE ; ADDUCT ; COFACTOR ; CARCINOGENIC ARISTOLOCHIC ACIDS ; CYTOCHROME-P450 1A1 ; MUTAGEN 3-NITROBENZANTHRONE ; SULFOTRANSFERASES ; DNA ADDUCT ; sulfotransferase
    Abstract: 3-Nitrobenzanthrone (3-nitro-7H-benz[de]anthracen-7-one, 3-NBA) is a potent mutagen and suspected human carcinogen identified in diesel exhaust and air pollution. We compared the ability of human hepatic cytosolic samples to catalyze DNA adduct formation by 3-NBA. Using the (32)p-postlabeling method, we found that 12/12 hepatic cytosols activated 3-NBA to form multiple DNA adducts similar to those formed in vivo in rodents. By comparing 3-NBA-DNA adduct formation in the presence of cofactors of NAD(P)H:quinone oxidoreductase (NQO1) and xanthine oxidase, most of the reductive activation of 3-NBA in human hepatic cytosols was attributed to NQO1. Inhibition of adduct formation by dicoumarol, an NQO1 inhibitor, supported this finding and was confirmed with human recombinant NQO1. When cofactors of N,O-acetyltransferases (NAT) and sulfotransferases (SUIT) were added to cytosolic samples, 3-NBA-DNA adduct formation increased 10- to 35-fold. Using human recombinant NQO1 and NATs or SULTs, we found that mainly NAT2, followed by SULT1A2, NAT1, and, to a lesser extent, SULT1A1 activate 3-NBA. We also evaluated the role of hepatic NADPH:cytochrome P450 oxidoreductase (POR) in the activation of 3-NBA in vivo by treating hepatic POR-null mice and wild-type littermates i.p. with 0.2 or 2 mg/kg body weight of 3-NBA. No difference in DNA binding was found in any tissue examined (liver, lung, kidney, bladder, and colon) between null and wild-type mice, indicating that 3-NBA is predominantly activated by cytosolic nitroreductases rather than microsomal POR. Collectively, these results show the role of human hepatic NQO1 to reduce 3-NBA to species being further activated by NATs and SULTs
    Type of Publication: Journal article published
    PubMed ID: 15805261
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  • 4
    Keywords: IN-VIVO ; LUNG-CANCER ; SYSTEM ; TISSUE ; DNA ; CARCINOGENESIS ; DIESEL EXHAUST ; AIR-POLLUTION ; RAT ; CONTAMINANT 3-NITROBENZANTHRONE ; RATS ; LINKAGE ; IDENTIFICATION ; genotoxicity ; HUMAN ACETYLTRANSFERASES ; METABOLIC-ACTIVATION ; POLLUTANT 3-NITROBENZANTHRONE ; Jun ; ADDUCTS ; rodent ; STANDARD ; V79 CELLS ; RE ; ADDUCT ; MUTAGEN 3-NITROBENZANTHRONE ; SULFOTRANSFERASES ; DNA ADDUCT
    Abstract: 3-Nitrobenzanthrone (3-NBA) is a potent mutagen and potential human carcinogen identified in diesel exhaust and ambient air particulate matter. 3-NBA forms DNA adducts in rodent tissues that arise principally through reduction to N-hydroxy-3-aminobenzanthrone (N-OHABA), esterification to its acetate or sulfate ester, and reaction of this activated ester with DNA. We detected 3-NBA-derived DNA adducts in rodent tissues by P-32-postlabeling and generated them chemically by acid-catalyzed reaction of N-OH-ABA with DNA, but their structural identification has not yet been reported. We have now prepared 3-NBA-derived adducts by reaction of a possible reactive metabolite, N-acetoxy-N-acetyl-3-aminobenzanthrone (N-Aco-N-Ac-ABA), with purine nucleosides and nucleotides, characterized them, and have shown that they are present in DNA treated with this 3-NBA derivative. Three of these adducts have been characterized as the C-C adduct N-acetyl-3-amino-2-(2'-deoxyguanosin-8-yl)benzanthrone, the C-N adduct N-acetyl-N-(2'-deoxyguanosin-8-yl)-3-aminobenzanthrone, and an unusual 3-acetylaminobenzanthrone adduct of deoxyadenosine, which involves a double linkage between adenine and benzanthrone (N1 to C1, N6 to C11b), creating a five-membered imidazo type ring system. According to IUPAC fused ring conventions, we propose the following systematic name for this adduct: (9'-(2"-deoxyribofuranosyl))purino[6',1':2,3]imidazo[5,4-p]-(1,11b-dihyd ro-(N-acetyl-3-amino))benzanthrone. The X-phosphates of these novel adducts could be 5'-postlabeled using [gamma-P-32]ATP, although the efficiency of labeling was found to be low (less than 20%). However, none of these adducts could be detected in DNA from 3-NBA-treated rats by P-32-postlabeling. Two of these synthetic adducts were treated with alkali to generate nonacetylated adducts, and these were also shown by HPLC to differ from those adducts found in rat DNA. Therefore, a different approach to the synthesis of authentic standards is needed for the structural characterization of 3-NBA-derived DNA adducts formed in vivo
    Type of Publication: Journal article published
    PubMed ID: 15962941
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  • 5
    Keywords: CELLS ; IN-VITRO ; CELL ; human ; IN-VIVO ; LUNG ; MODEL ; PATHWAY ; PATHWAYS ; VITRO ; VIVO ; SYSTEM ; liver ; MICE ; TIME ; ACTIVATION ; DNA ; 3-aminobenzanthrone ; 3-nitrobenzanthrone ; AIR ; CARCINOGENESIS ; DIESEL EXHAUST ; DNA ADDUCT FORMATION ; CONTAMINANT 3-NITROBENZANTHRONE ; BINDING ; bone marrow ; BONE-MARROW ; MOUSE ; MUTANT ; TRANSGENIC MICE ; ASSAY ; genetics ; genotoxicity ; DNA-BINDING ; METABOLIC-ACTIVATION ; NUCLEOTIDES ; POLYCYCLIC AROMATIC-HYDROCARBONS ; EPITHELIAL-CELLS ; ADDUCTS ; heredity ; BODIES ; RE ; air pollution ; INCREASE ; ADDUCT FORMATION ; LEVEL ; BONE ; ENGLAND ; PREDICT ; INCREASES ; ENVIRONMENTAL-POLLUTANT 3-NITROBENZANTHRONE ; NOV ; outcome ; MARROW ; NUCLEOTIDE ; CARCINOGEN 3-NITROBENZANTHRONE ; HUMAN METABOLITE ; URBAN AIR-POLLUTION
    Abstract: FE1 lung epithelial cells derived from Muta (TM) Mouse are a new model system to provide in vitro mutagenicity data with the potential to predict the outcome of an in vivo Muta (TM) Mouse test. 3-Nitrobenzanthrone (3-NBA) is a potent mutagen and suspected human carcinogen identified in diesel exhaust and urban air pollution. We investigated the mutagenicity and DNA binding of 3-NBA and its main metabolite 3-aminobenzanthrone (3-ABA) in vitro and in vivo in the Muta (TM) Mouse assay. Mice were treated with 3-NBA or 3-ABA (0, 2 or 5 mg/kg body weight/day) by gavage for 28 days and 28 days later lacZ mutant frequency (MF) was determined in liver, lung and bone marrow. For both compounds, dose-related increases in MF were seen in liver and bone marrow, but not in lung; mutagenic activity was similar to 2-fold lower for 3-ABA than for 3-NBA. With 3-NBA, highest DNA adduct levels (measured by P-32-post-labelling) were found in liver (similar to 230 adducts per 10(8) nucleotides) with levels 20- to 40-fold lower in bone marrow and lung. With 3-ABA, DNA adduct levels were again highest in the liver, but similar to 4-fold lower than for 3-NBA. FE1 cells were exposed to up to 10 mu g/ml 3-NBA or 3-ABA for 6 h with or without exogenous activation (S9) and harvested after 3 days. For 3-NBA, there was a dose-related increase in MF both with and without S9 mix, which was 〉 10 times higher than observed in vivo. At the highest concentration of 3-ABA (10 mu g/ml), we found only around a 2-fold increase in MF relative to controls. DNA adduct formation in FE1 cells was dose-dependent for both compounds, but 10- to 20-fold higher for 3-NBA compared to 3-ABA. Collectively, our data indicate that Muta (TM) Mouse FE1 cells are well suited for cost-effective testing of suspected mutagens with different metabolic activation pathways as a guide for subsequent in vivo Muta (TM) Mouse testing
    Type of Publication: Journal article published
    PubMed ID: 18635558
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  • 6
    Keywords: CELLS ; IN-VITRO ; human ; IN-VIVO ; LUNG ; PATHWAYS ; VIVO ; DNA adducts ; EXPOSURE ; liver ; ENZYMES ; TISSUE ; HEART ; ACTIVATION ; DNA ; kidney ; 3-aminobenzanthrone ; 3-nitrobenzanthrone ; CARCINOGENESIS ; DIESEL EXHAUST ; DNA ADDUCT FORMATION ; metabolic activation ; nitro-PAH ; RAT ; animals ; AROMATIC-AMINES ; BASE ; BIOMARKERS ; BODY-WEIGHT ; colon ; CONTAMINANT 3-NITROBENZANTHRONE ; ENRICHMENT ; HPLC ; P-32-postlabelling ; RATS ; TISSUES ; tumour
    Abstract: Diesel exhaust is known to induce tumours in animals and is suspected of being carcinogenic in humans. Of the compounds found in diesel exhaust, 3-nitrobenzanthrone (3-NBA) is an extremely potent mutagen and suspected human carcinogen forming multiple DNA adducts in vitro. 3-Aminobenzanthrone (3-ABA). 3- acetylaminobenzanthrone (3-Ac-ABA), and N-acetyl-N-hydroxy-3- aminobenzanthrone (N-Ac-N-OH-ABA) were identified as 3-NBA metabolites. In order to gain insight into the pathways of metabolic activation leading to 3-NBA-derived DNA adducts we treated Wistar rats intraperitoneally with 2 mg/kg body weight of 3-NBA, 3-ABA. 3-Ac-ABA, or N-Ac-N-OH-ABA and compared DNA adducts present in different organs, With each compound either four or five DNA adduct spots were detected by TLC in all tissues examined (lung, liver. kidney, heart, pancreas, and colon) using the nuclease P1 or butanol enrichment version of the P-32-postlabelling method, respectively. Using HPLC co- chromatographic analysis we showed that all major 3-NBA-DNA adducts produced in vivo in rats are derived from reductive metabolites bound to purine bases and lack an N-acetyl group. Our results indicate that 3-NBA metabolites (3-ABA, 3-Ac-ABA and AT-Ac-N-OH-ABA) undergo several biotransformations and that N-hydroxy-3-aminobenzanthrone (N-OH-ABA) appears to be the common intermediate in 3-NBA-derived DNA adduct formation. Therefore, 3-NBA-DNA adducts are useful biomarkers for exposure to 3-NBA and its metabolites and may help to identify enzymes involved in their metabolic activation. (C) 2002 Elsevier Science (USA). All rights reserved
    Type of Publication: Journal article published
    PubMed ID: 12480528
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  • 7
    Keywords: EXPRESSION ; human ; LUNG ; DNA adducts ; PROTEIN ; ACTIVATION ; DNA ; kidney ; 3-aminobenzanthrone ; 3-nitrobenzanthrone ; AIR ; DIESEL EXHAUST ; DNA ADDUCT FORMATION ; GENETIC POLYMORPHISMS ; PHENOL SULFOTRANSFERASES ; INDUCTION ; RAT ; animals ; CONTAMINANT 3-NITROBENZANTHRONE ; P-32-postlabelling ; RATS ; STIMULATION ; TARGET ; HUMAN ACETYLTRANSFERASES ; METABOLIC-ACTIVATION ; ADDUCTS ; protein expression ; cytochrome P450 ; DNA-ADDUCTS ; air pollution ; INCREASE ; LEVEL ; pharmacology ; cyclooxygenase ; PROSTAGLANDIN-H SYNTHASE ; animal ; enzymatic ; QUINONE OXIDOREDUCTASE ; ANTIOXIDANT-RESPONSE-ELEMENT ; NAD(P)H : quinone oxidoreductase ; cytochrome p450 1A1
    Abstract: 3-Nitrobenzanthrone (3-NBA) is a carcinogen occurring in diesel exhaust and air pollution. Using the P-32-postlabelling method, we found that 3-NBA and its human metabolite, 3-aminobenzanthrone (3-ABA), are activated to species forming DNA adducts by cytosols and/or microsomes isolated from rat lung, the target organ for 3-NBA carcinogenicity, and kidney. Each compound generated identical five DNA adducts. We have demonstrated the importance of pulmonary and renal NAD(P)H:quinone oxidoreductase (NQO1) to reduce 3-NBA to species that are further activated by N,O-acetyltransferases and sulfotransferases. Cytochrome P450 (CYP) 1A1 is the essential enzyme for oxidative activation of 3-ABA in microsomes of both organs, while cyclooxygenase plays a minor role. 3-NBA was also investigated for its ability to induce NQO1 and CYP1A1 in lungs and kidneys, and for the influence of such induction on DNA adduct formation by 3-NBA and 3-ABA. When cytosols from rats treated i.p. with 40 mg/kg bw of 3-NBA were incubated with 3-NBA, DNA adduct formation was up to 2.1-fold higher than in incubations with cytosols from control animals. This increase corresponded to an increase in protein level and enzymatic activity of NQO1. Incubations of 3-ABA with microsomes of 3-NBA-treated rats led to up to a fivefold increase in DNA adduct formation relative to controls. The stimulation of DNA adduct formation correlated with the potential of 3-NBA to induce protein expression and activity of CYP1A1. These results demonstrate that 3-NBA is capable to induce NQO1 and CYP1A1 in lungs and kidney of rats thereby enhancing its own genotoxic and carcinogenic potential. (C) 2008 Elsevier Ireland Ltd. All rights reserved
    Type of Publication: Journal article published
    PubMed ID: 18329153
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  • 8
    Keywords: IN-VITRO ; human ; IN-VIVO ; LUNG ; VITRO ; VIVO ; DNA adducts ; liver ; NEW-YORK ; GENE ; TISSUE ; MICE ; ACTIVATION ; DNA ; kidney ; 3-nitrobenzanthrone ; DIESEL EXHAUST ; HETEROCYCLIC AMINES ; INDUCTION ; RAT ; BODY-WEIGHT ; CONTAMINANT 3-NITROBENZANTHRONE ; RATS ; TISSUES ; BINDING ; SEQUENCE ; treatment ; FREQUENCY ; METABOLITES ; MOUSE ; MUTANT ; TRANSGENIC MICE ; PATTERNS ; ASSAY ; MUTATION ; BLADDER ; DNA-BINDING ; NUCLEOTIDES ; POLLUTANT 3-NITROBENZANTHRONE ; MUTATIONS ; ADDUCTS ; TESTIS ; PERFORMANCE LIQUID-CHROMATOGRAPHY ; 3-nitrobenzanthrone,Muta Mouse,mutation spectra,cll,DNA adducts,P-32-post-labeling,diesel exhaust,ai ; CII GENE ; DEOXYADENOSINE ; DNA-ADDUCTS ; LAMBDA/LACZ TRANSGENIC MICE ; micronuclei ; POTENT ; SURFACE SOIL ; V79 CELLS
    Abstract: 3-nitrobenzanthrone (3-NBA) is an extremely potent mutagen in the Salmonella reversion assay and a suspected human carcinogen identified in diesel exhaust and in ambient airborne particulate matter. To evaluate the in vivo mutagenicity of 3-NBA, we analyzed the mutant frequency (MF) in the cll gene of various organs (lung, liver, kidney, bladder, colon, spleen, and testis) in lambda/lacZ transgenic mice (Muta Mouse) after intraperitoneal treatment with 3-NBA (25 mg/kg body weight injected once a week for 4 weeks). Increases in MF were found in colon, liver, and bladder, with 7.0-, 4.8-, and 4.1-fold increases above the control value, respectively, whereas no increase in MF was found in lung, kidney, spleen, and testis. Simultaneously, induction of micronuclei in peripheral blood reticulocytes was observed. The sequence alterations in the cll gene recovered from 41 liver mutants from 3-NBA-treated mice were compared with 32 spontaneous mutants from untreated mice. Base substitution mutations predominated for both the 3-NBA-treated (80%) and the untreated (81%) groups. However, the proportion of G:C--〉T:A transversions in the mutants from 3-NBA-treated mice was higher (49% vs. 6%) and the proportion of G:C--〉A:T transitions was lower than those from untreated mice (10% vs. 66%). The increase in MF in the liver was associated with strong DNA binding by 3-NBA, whereas in lung, in which there was no increase in MF, a low level of DNA binding was observed (268.0-282.7 vs. 8.8-15.9 adducts per 10(8) nucleotides). DNA adduct patterns with multiple adduct spots, qualitatively similar to those formed in vitro after activation of 3-NBA with nitroreductases and in vivo in rats, were observed in all tissues examined. Using high-pressure liquid cochromatographic analysis, we confirmed that all major 3-NBA-DNA adducts produced in vivo in mice are derived from reductive metabolites bound to purine bases (70-80% with deoxyguanosine and 20-30% with deoxyadenosine in liver). These results suggest that G:C--〉T:A transversions induced by 3-NBA are caused by misreplication of adducted guanine residues through incorporation of adenine opposite the adduct (A-rule)
    Type of Publication: Journal article published
    PubMed ID: 15065206
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  • 9
    Keywords: CELLS ; IN-VITRO ; human ; IN-VIVO ; VITRO ; LUNG-CANCER ; DNA adducts ; liver ; MICE ; ACTIVATION ; DNA ; kidney ; 3-aminobenzanthrone ; 3-nitrobenzanthrone ; CARCINOGENESIS ; DIESEL EXHAUST ; AIR-POLLUTION ; CONTAMINANT 3-NITROBENZANTHRONE ; P-32-postlabelling ; BINDING ; METABOLITES ; BREAST ; DNA-BINDING ; HUMAN ACETYLTRANSFERASES ; METABOLIC-ACTIVATION ; cytochrome P450 ; V79 CELLS ; RE ; air pollution ; MYELOPEROXIDASE ; ENZYME ; CARCINOGENIC ARISTOLOCHIC ACIDS ; SULFOTRANSFERASES ; reductive activation ; in vivo ; PROSTAGLANDIN-H SYNTHASE
    Abstract: 3-Nitrobenzanthrone (3-NBA) is a suspected human carcinogen found in diesel exhaust and ambient air pollution. The main metabolite of 3-NBA, 3-aminobenzanthrone (3-ABA), was detected in the urine of salt mining workers occupationally exposed to diesel emissions. We evaluated the role of hepatic cytochrome P450 (CYP) enzymes in the activation of 3-ABA in vivo by treating hepatic cytochrome P450 oxidoreductase (POR)-null mice and wild-type littermates intraperitoneally with 0.2 and 2 mg/kg body weight of 3-ABA. Hepatic POR-null mice lack POR-mediated CYP enzyme activity in the liver. Using the P-32-postlabelling method, multiple 3-ABA-derived DNA adducts were observed in liver DNA from wild-type mice, qualitatively similar to those formed in incubations using human hepatic microsomes. The adduct pattern was also similar to those formed by the nitroaromatic counterpart 3-NBA and which derive from reductive metabolites of 3-NBA bound to purine bases in DNA. DNA binding by 3-ABA in the livers of the null mice was undetectable at the lower dose and substantially reduced (by up to 80%), relative to wild-type mice, at the higher dose. These data indicate that POR-mediated CYP enzyme activities are important for the oxidative activation of 3-ABA in livers, confirming recent results indicating that CYP-1A1 and -1A2 are mainly responsible for the metabolic activation of 3-ABA in human hepatic microsomes. No difference in DNA binding was found in kidney and bladder between null and wild-type mice, suggesting that cells in these extrahepatic organs have the metabolic capacity to oxidize 3-ABA to species forming the same 3-ABA-derived DNA adducts, independently from the CYP-mediated oxidation in the liver. We determined that different model peroxidases are able to catalyse DNA adduct formation by 3-ABA in vitro. Horseradish peroxidase (HRP), lactoperoxidase (LPO), myeloperoxidase (MPO), and prostaglandin H synthase (PHS) were all effective in activating 3-ABA in vitro, forming DNA adducts qualitatively similar to those formed in vivo in mice treated with 3-ABA and to those found in DNA reacted with N-hydroxy-3-aminobenzanthrone (N-OH-ABA). Collectively, these results suggest that both CYPs and peroxidases may play an important role in metabolizing 3-ABA to reactive DNA adduct forming species. (c) 2005 Elsevier Ireland Ltd. All rights reserved
    Type of Publication: Journal article published
    PubMed ID: 15885895
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