title: Effects of nitrated-polycyclic aromatic hydrocarbons and diesel exhaust particle extracts on cell signalling related to apoptosis: possible implications for their mutagenic and carcinogenic effects.
abstract: Nitrated-polycyclic aromatic hydrocarbons (nitro-PAHs) and diesel exhaust particle extracts (DEPE) induced apoptosis in Hepa1c1c7 cells with the following potency: 1,3-dinitropyrene (1,3-DNP)>1-nitropyrene (1-NP) >> DEPE >> 1,8-dinitropyrene (1,8-DNP). The compounds induced cyp1a1, and activated various intracellular signalling pathways related to apoptosis. The CYP inhibitor alpha-naphthoflavone strongly reduced 1,3-DNP-induced cell death, whereas cell death induced by 1-NP was rather increased. Toxic 1,3-DNP and 1-NP were found to induce a concentration-dependent lipid peroxidation. 1,3-DNP caused pro-apoptotic events, including increased phosphorylation and accumulation of p53 in the nucleus, cleavage of bid and of caspases 8 and 3, down-regulation of bcl-x(L) and phosphorylation of p38 and JNK MAPK. Furthermore, 1,3-DNP increased the activation of survival signals including phosphorylation of Akt and inactivation (phosphorylation) of pro-apoptotic bad. Although less potent, rather similar effects were observed following exposure to DEPE, compared to 1-NP. The most important finding was that the most mutagenic and carcinogenic compound tested, 1,8-DNP, induced little (if any) cell death, despite the fact that this compound seemed to give the most DNA damage as judged by DNA adduct formation, increased phosphorylation of p53 and accumulation of cells in S-phase. Immunocytochemical studies revealed that the p53 protein did not accumulate into the nucleus suggesting that 1,8-DNP inactivated the pro-apoptotic function of the p53 protein by a non-mutagenic event. These results suggest that after exposure to 1,8-DNP more cells may survive with DNA damage, thereby increasing its mutagenic and carcinogenic potential.
authors.affiliation: Division of Environmental Medicine, Norwegian Institute of Public Health, Nydalen, N-0403 Oslo, Norway.
authors.forename: Nina E
authors.initials: NE
authors.lastname: Landvik
authors.forename: Morgane
authors.initials: M
authors.lastname: Gorria
authors.forename: Volker M
authors.initials: VM
authors.lastname: Arlt
authors.forename: Nana
authors.initials: N
authors.lastname: Asare
authors.forename: Anita
authors.initials: A
authors.lastname: Solhaug
authors.forename: Dominique
authors.initials: D
authors.lastname: Lagadic-Gossmann
authors.forename: Jørn A
authors.initials: JA
authors.lastname: Holme
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002274:Carcinogens, Environmental / Q000633:toxicity*; D006528:Carcinoma, Hepatocellular; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D018736:DNA Adducts / Q000032:analysis; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D015227:Lipid Peroxidation / Q000187:drug effects; D051379:Mice; D009153:Mutagens / Q000633:toxicity*; D010766:Phosphorylation; D011721:Pyrenes / Q000737:chemistry / Q000145:classification / Q000633:toxicity*; D021281:Quantitative Structure-Activity Relationship; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D001335:Vehicle Emissions / Q000633:toxicity*
chemical_list: D002274:Carcinogens, Environmental; D018736:DNA Adducts; D009153:Mutagens; D011721:Pyrenes; D016159:Tumor Suppressor Protein p53; D001335:Vehicle Emissions; C033310:1,8-dinitropyrene; C033309:1,6-dinitropyrene; C037413:1,3-dinitropyrene; C032668:1-nitropyrene