Keywords:
CANCER
;
CELLS
;
EXPRESSION
;
IN-VIVO
;
LUNG-CANCER
;
DNA adducts
;
RISK
;
GENE
;
LINES
;
ACTIVATION
;
DNA
;
3-aminobenzanthrone
;
3-nitrobenzanthrone
;
AIR
;
CARCINOGENESIS
;
CYP1A2
;
CYTO-TOXIC METABOLITES
;
DIESEL EXHAUST
;
DNA ADDUCT FORMATION
;
ENVIRONMENTAL CONTAMINANT 3-NITROBENZANTHRONE
;
GENETIC POLYMORPHISMS
;
HETEROCYCLIC AMINES
;
HETEROLOGOUS EXPRESSION
;
HUMAN CYTOSOLIC SULFOTRANSFERASES
;
IONS
;
metabolic activation
;
NAT : SULT
;
nitro-PAH
;
P-32- postlabeling
;
PHENOL SULFOTRANSFERASES
;
POSTLABELING ANALYSIS
Abstract:
3-Nitrobenzanthrone (3-NBA) is a potent mutagen and suspected human carcinogen identified in diesel exhaust and ambient air pollution. 3-Aminobenzanthrone (3-ABA), 3- acetylaminobenzanthrone (3-Ac-ABA) and N-acetyl-N-hydroxy-3- aminobenzanthrone (N-Ac-N-OH-ABA) have been identified as 3-NBA metabolites. Recently we found that 3-NBA and its metabolites (3-ABA, 3-Ac-ABA and N-Ac-N-OH-ABA) form the same DNA adducts in vivo in rats. In order to investigate whether human cytochrome P450 (CYP) enzymes (i.e., CYPIA2), human N,O- acetyltransferases (NATs) and sulfotransferases (SULTs) contribute to the metabolic activation of 3-NBA and its metabolites we developed a panel of Chinese hamster V79MZ-hIA2 derived cell lines expressing human CYPIA2 in conjunction with human NATI, NAT2, SULTIAI or SULTIA2, respectively. Cells were treated with 0.01, 0.1 or I muM 3-NBA, or its metabolites (3- ABA, 3-Ac-ABA and N-Ac-N-OH-ABA). Using both enrichment versions of the P-32-postlabeling assay, nuclease P I digestion and butanol extraction, essentially 4 major and 2 minor DNA adducts were detected in the appropriate cell lines with all 4 compounds. The major ones were identical to those detected in rat tissue; the adducts lack an N-acetyl group. Human CYPIA2 was required for the metabolic activation of 3-ABA and 3-Ac-ABA (probably via N-oxidation) and enhanced the activity of 3-NBA (probably via nitroreduction). The lack of acetylated adducts suggests N-deacetylation of 3-Ac-ABA and N-Ac-N-OH-ABA. Thus, N-hydroxy-3-aminobenzanthrone (N-OH-ABA) appears to be a common intermediate for the formation of the electrophilic arylnitrenium ions capable of reacting with DNA. Human NAT I and NAT2 as well as human SULTIAI and SULTIA2 strongly contributed to the high genotoxicity of 3-NBA and its metabolites. Moreover, N,O-acetyltransfer reactions catalyzed by human NATs leading to the corresponding N-acetoxyester may be important in the bioactivation of N-Ac-N-OH-ABA. As human exposure to 3-NBA is likely to occur primarily via the respiratory tract, expression of CYPs, NATs and SULTs in respiratory tissues may contribute significantly and specifically to the metabolic activation of 3-NBA and its metabolites. Consequently, polymorphisms in these genes could be important determinants of lung cancer risk from 3-NBA
Type of Publication:
Journal article published
Deep Link:
http://www.dkfz.de/cgi-bin/sel?http://www.dkfz.de/PublicationManager/Show/ShowJournal.aspx%3fpublishedId=21
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