title: Induction by xenobiotics of phase I and phase II enzyme activities in the human keratinocyte cell line NCTC 2544.
abstract: This study analyses the expression and induction of several drug-metabolising enzyme activities involved in either phase I or phase II biotransformations in NCTC 2544 human keratinocytes. The phase I activities 7-ethoxycoumarin O-deethylase (ECOD), 7-ethoxyresorufin O-deethylase (EROD) and 7-pentoxyresorufin O-depenthylase (PROD) were easily detectable in basal conditions. During incubations lasting up to 144 h in the presence of the classical cytochrome P450 inducers beta-naphthoflavone (BNF), 3-methylcholanthrene (MC) and phenobarbital (PB), a considerable and significant increase in all the three activities was observed. PROD activity was induced up to 4.5-fold after 96 h in the presence of PB. The MC-induced ECOD and EROD activities were also dose-dependently inhibited by alpha-naphothflavone, which was given to the cells during the incubation with CYP 1A1 inducers. Also the PB-induced PROD activity was decreased by the simultaneous addition of the CYP 2B inhibitor metyrapone. Both cytochrome P450 inhibitors were used at non-cytotoxic concentrations. The phase II enzymes glutathione S-transferase, aldehyde dehydrogenase and quinone reductase were all highly expressed and inducible by MC. The exposure (24 h) of the cells to four hair dyes used in cosmetic formulations resulted in a marked increase in ECOD activity. All data give sustained evidence for the suitability of NCTC 2544 cell line to skin toxicology studies.
authors.affiliation: Department of Experimental Medicine, General Pathology Division, University of Genoa, Via L.B. Alberti, 2, 16132, Genova, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Gelardi
authors.forename: F
authors.initials: F
authors.lastname: Morini
authors.forename: F
authors.initials: F
authors.lastname: Dusatti
authors.forename: S
authors.initials: S
authors.lastname: Penco
authors.forename: M
authors.initials: M
authors.lastname: Ferro
mesh_terms: D001571:Benzoflavones / Q000494:pharmacology; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction; D006801:Humans; D008658:Inactivation, Metabolic; D015603:Keratinocytes / Q000187:drug effects* / Q000201:enzymology; D008748:Methylcholanthrene / Q000494:pharmacology; D008797:Metyrapone / Q000494:pharmacology; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D010634:Phenobarbital / Q000494:pharmacology; D015262:Xenobiotics / Q000378:metabolism* / Q000494:pharmacology; D019324:beta-Naphthoflavone / Q000494:pharmacology
chemical_list: D001571:Benzoflavones; D015262:Xenobiotics; D008748:Methylcholanthrene; C011512:alpha-naphthoflavone; D019324:beta-Naphthoflavone; D010088:Oxidoreductases; D010634:Phenobarbital; D008797:Metyrapone