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Wiebel, F.J. ; Cikryt, P.

Dexamethasone-mediated potentiation of P450IA1 induction in H4IIEC3/T hepatoma cells is dependent on a time-consuming process and associated with induction of the Ah receptor.

Chem. Biol. Interact. 76, 307-320 (1990)
DOI
Open Access Green as soon as Postprint is submitted to ZB.
The synergistic effect of dexamethasone (DEX) and polycyclic aromatic hydrocarbons on the induction of cytochrome P450IA1 (P450IA1) was examined in H4IIEC3/T Reuber hepatoma cells. P450IA1 activity was determined by the hydroxylation of benzo[a]pyrene (AHH) and deethylation of 7-ethoxy-resorufin (EROD). The amount of Ah receptors, i.e. the specific cytosolic binding protein of 3-methylcholanthrene or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in H4IIEC3/T cells was characterized and quantitated by high performance gel filtration. Benz[a]anthracene and TCDD induced AHH and EROD activities, respectively, about 20-fold within 4 h. The increase was about 100-fold when cells were pretreated with DEX. The glucocorticoid alone induced P450IA1 activities 3-4-fold. DEX elicited half maximum AHH induction at a concentration of 20 nM in the presence or absence of benz[a]anthracene. Maximal potentiation of AHH induction required treatment with DEX for at least 32 h prior to the exposure to benz[a]anthracene. Treatment of H4IIEC3/T cells with DEX for 20 h caused a 2-3-fold increase in the amount of Ah receptor. The results suggest that the synergistic effect of DEX and polycyclic aromatic hydrocarbons on P450IA1 induction involves a time-consuming process which may consist of the synthesis or modification of a factor, possibly the Ah receptor.
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Publication type Article: Journal article
Document type Scientific Article
Corresponding Author
Keywords Ah Receptor ; Dexamethasone ; H4iiec3 Hepatoma Cells ; P450 (induction Of)
ISSN (print) / ISBN 0009-2797
e-ISSN 1872-7786
Journal Chemico-Biological Interactions
Quellenangaben Volume: 76, Issue: 3, Pages: 307-320 Article Number: , Supplement: ,
Publisher Elsevier
Non-patent literature Publications
Reviewing status Peer reviewed