Document Detail


Polycyclic aromatic hydrocarbons induce both apoptotic and anti-apoptotic signals in Hepa1c1c7 cells.
MedLine Citation:
PMID:  14729587     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In this study we show that benzo[a]pyrene (B[a]P) and the cyclopenta polycyclic aromatic hydrocarbons (CP-PAH) cyclopenta[c,d]pyrene (CPP), benz[j]aceanthrylene (B[j]A) and benz[l]aceanthrylene (B[l]A) induce apoptosis in Hepa1c1c7 cells, as measured by fluorescence microscopy and flow cytometry. The compounds induced formation of the active form of caspase-3, cleavage of its intracellular substrate, poly(ADP-ribose)polymerase (PARP), and DNA fragmentation. B[j]A was found to be the most potent in inducing apoptosis, followed by B[a]P, CPP and B[l]A. All compounds increased expression of CYP1A1 with relative potencies B[j]A > B[a]P >> CPP > B[l]A, corresponding well with their relative apoptotic responses. alpha-Naphthoflavone (alphaNF), an inhibitor of CYP1A1, reduced the induced apoptosis. B[a]P and CP-PAH exposure also resulted in an accumulation of the tumour suppressor protein p53. No changes were observed in the protein levels of Bax and Bcl-2, whereas the anti-apoptotic Bcl-xl protein was down-regulated, as judged by western blot analysis. Fluorescence microscopic analysis revealed a translocation of p53 to the nucleus and of Bax to the mitochondria. Furthermore, caspase-8 was activated and Bid cleaved. Interestingly, the levels of anti-apoptotic phospho-Bad (Ser155 and Ser112) had a biphasic increase after B[a]P or CPP treatment. Whereas alphaNF markedly reduced the activation of B[a]P to reactive metabolites, as measured by covalent binding to macromolecules, it did not inhibit the up-regulation of phospho-Bad. Neither of the compounds triggered apoptosis in primary cultures of rat lung cells (Clara cells, type 2 cells and lung alveolar macrophages), possibly due to a lack of CYP1A1 induction. In conclusion, B[a]P and the CP-PAH induced apoptotic as well as anti-apoptotic signals in Hepa1c1c7 cells.
Authors:
Anita Solhaug; Magne Refsnes; Marit Låg; Per E Schwarze; Trine Husøy; Jørn A Holme
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2004-01-16
Journal Detail:
Title:  Carcinogenesis     Volume:  25     ISSN:  0143-3334     ISO Abbreviation:  Carcinogenesis     Publication Date:  2004 May 
Date Detail:
Created Date:  2004-04-22     Completed Date:  2004-06-14     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8008055     Medline TA:  Carcinogenesis     Country:  England    
Other Details:
Languages:  eng     Pagination:  809-19     Citation Subset:  IM    
Affiliation:
Division of Environmental Medicine, Norwegian Institute of Public Health, PO Box 4404 Nydalen, N-0403 Oslo, Norway.
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MeSH Terms
Descriptor/Qualifier:
Animals
Apoptosis / drug effects*
Carrier Proteins / metabolism
Caspase 3
Caspases / metabolism
Cells, Cultured
Cytochrome P-450 CYP1A1 / metabolism
Flow Cytometry
Liver Neoplasms / metabolism,  pathology*
Lung / drug effects,  metabolism
Male
Mice
Microscopy, Fluorescence
Poly(ADP-ribose) Polymerases / metabolism
Polycyclic Hydrocarbons, Aromatic / pharmacology*
Proto-Oncogene Proteins / metabolism
Proto-Oncogene Proteins c-bcl-2 / metabolism
Rats
Tumor Suppressor Protein p53 / metabolism
bcl-2-Associated X Protein
bcl-Associated Death Protein
bcl-X Protein
Chemical
Reg. No./Substance:
0/Bad protein, mouse; 0/Bad protein, rat; 0/Bax protein, mouse; 0/Bax protein, rat; 0/Bcl2l1 protein, mouse; 0/Bcl2l1 protein, rat; 0/Carrier Proteins; 0/Polycyclic Hydrocarbons, Aromatic; 0/Proto-Oncogene Proteins; 0/Proto-Oncogene Proteins c-bcl-2; 0/Tumor Suppressor Protein p53; 0/bcl-2-Associated X Protein; 0/bcl-Associated Death Protein; 0/bcl-X Protein; EC 1.14.14.1/Cytochrome P-450 CYP1A1; EC 2.4.2.30/Poly(ADP-ribose) Polymerases; EC 3.4.22.-/Casp3 protein, mouse; EC 3.4.22.-/Casp3 protein, rat; EC 3.4.22.-/Caspase 3; EC 3.4.22.-/Caspases

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