Publication Date:
2016-02-11
Description:
Various types of polycyclic aromatic compounds (PACs) in diesel exhaust particles are thought to contribute to carcinogenesis in mammals. Although the carcinogenicity, mutagenicity and tumour-initiating activity of these compounds have been evaluated, their tumour-promoting activity is unclear. In the present study, to determine the tumour-inducing activity of PACs, including previously known mutagenic compounds in atmospheric environments, a transformation assay for promoting activity mediated by the release of contact inhibition was conducted for six polycyclic aromatic hydrocarbons (PAHs), seven oxygenated PAHs (oxy-PAHs) and seven nitrated PAHs (nitro-PAHs) using mouse embryonic fibroblast cells transfected with the v-Ha- ras gene (Bhas 42 cells). Of these, two PAHs [benzo[ k ]fluoranthene (B[ k ]FA) and benzo[ b ]fluoranthene (B[ b ]FA)], one oxy-PAH [6 H -benzo[ cd ]pyren-6-one (BPO)] and two nitro-PAHs (3-nitro-7 H -benz[ de ]anthracen-7-one and 6-nitrochrysene) were found to exhibit particularly powerful tumour-promoting activity (≥10 foci following exposure to 〈100nM). In addition, clear mRNA expression of CYP1A1, which is associated with aryl hydrocarbon receptor (AhR)-mediated activation, was observed following the exposure of cells to two PAHs (B[ k ]FA and B[ b ]FA) and three oxy-PAHs (1,2-naphthoquinone, 11 H -benzo[ b ]fluoren-11-one and BPO). Further, an HO-1 antioxidant response activation was observed following exposure to B[ k ]FA, B[ b ]FA and BPO, suggesting that the induction of tumour-promoting activity in these compounds is correlated with the dysfunction of signal transduction via AhR-mediated responses and/or oxidative stress responses.
Print ISSN:
0267-8357
Electronic ISSN:
1464-3804
Topics:
Biology
,
Medicine
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