Comparison of aryl hydrocarbon hydroxylase and acetanilide 4-hydroxylase induction by polycyclic aromatic compounds in human and mouse cell lines.
The human MCF-7 and the mouse Hepa-1 cell culture lines were compared for aryl hydrocarbon hydroxylase and acetanilide 4-hydroxylase inducibility by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and benzo[a]anthracene (BA) and TCDD- and BA-specific binding in the cytosol and nucleus. The effective concentration of BA in the growth medium required to induce either enzyme to 50% of its maximally inducible activity (EC50) was the same (5-11 microM) in both MCF-7 and Hepa-1 cells. On the other hand, the EC50 for TCDD in MCF-7 cells (5-25 nM) was more than 40-fold greater than that in Hepa-1 cells (0.4 to 0.6 nM). P1-450- and P3-450-specific mouse cDNA probes were used to quantitate mRNA induction in the Hepa-1 cell line. P1-450 mRNA was induced markedly by TCDD and benzo[a] anthracene, whereas P3-450 mRNA was induced negligibly. A P1-450-specific human cDNA probe was used to quantitate P1-450 mRNA induction in the MCF-7 cell line. Aryl hydrocarbon hydroxylase inducibility by TCDD or BA always paralleled P1-450 mRNA inducibility in either the mouse or human line. Although the cytosolic Ah receptor in Hepa-1 cells was easily detected by sucrose density gradient centrifugation, gel permeation chromatography, and anion-exchange high-performance liquid chromatography, the cytosolic receptor cannot be detected in MCF-7 cells. Following in vivo exposure of cultures to radiolabeled TCDD, the intranuclear concentration of inducer-receptor complex was at least fifty times greater in Hepa-1 than MCF-7 cultures. The complete lack of measurable cytosolic receptor and almost totally absent inducer-receptor complex in the nucleus of MCF-7 cells was, therefore, out of proportion to its capacity for aryl hydrocarbon hydroxylase and acetanilide 4-hydroxylase inducibility. This MCF-7 line should provide an interesting model for a better understanding of the mechanisms of drug-metabolizing enzyme induction by polycyclic aromatic compounds, including the Ah receptor-mediated mechanism.
Jaiswal
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Nebert
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Eisen
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D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000096:biosynthesis*; D001551:Benz(a)Anthracenes / Q000378:metabolism / Q000494:pharmacology; D001943:Breast Neoplasms / Q000201:enzymology; D002460:Cell Line; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis; D004790:Enzyme Induction / Q000187:drug effects; D006801:Humans; D008114:Liver Neoplasms, Experimental / Q000201:enzymology; D051379:Mice; D000072317:Polychlorinated Dibenzodioxins / Q000378:metabolism / Q000494:pharmacology; D011083:Polycyclic Compounds / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis; D018336:Receptors, Aryl Hydrocarbon; D011955:Receptors, Drug / Q000032:analysis
D001551:Benz(a)Anthracenes; D000072317:Polychlorinated Dibenzodioxins; D011083:Polycyclic Compounds; D012333:RNA, Messenger; D018336:Receptors, Aryl Hydrocarbon; D011955:Receptors, Drug; D003577:Cytochrome P-450 Enzyme System; C030935:benz(a)anthracene; D001189:Aryl Hydrocarbon Hydroxylases; C023738:acetanilide hydroxylase