title: A Genetically engineered cell-based system for detecting metabolism-mediated toxicity.
abstract: Xenobiotics undergoing bioactivation by CYP450 enzymes form reactive metabolites that may exert direct metabolism-mediated toxicity. An in vitro model was developed to study the direct toxic effects that follow the metabolic activation of chemicals. The model uses monolayer cultures of genetically engineered NIH-3T3 or V79 cells that express individual human or rat CYP450 isoforms, respectively. Following exposure to 1,3-dichloropropanol or cyclophosphamide, basal cytotoxicity endpoints, including neutral red uptake and Alamar Blue( reduction were used to assess changes in cell number and functional viability resulting from the formation of metabolites. Cell lines that express cytochrome P450 enzymes metabolised the test compounds, leading to increased toxicity compared with that observed in the control cell line. The use of specific inhibitors confirmed that the formation of reactive metabolites was CYP450-isoform dependent. These results indicate that a panel of genetically engineered cell lines expressing various cytochrome P450 enzyme isoforms can be used to reveal measurable metabolising capabilities, and could become a useful tool for the detection and possible determination of CYP450 isoforms in human liver metabolism-mediated toxicity.
authors.affiliation: ECVAM, Institute for Health & Consumer Protection, European Commission Joint Research Centre, 21020 Ispra (VA), Italy.
authors.forename: S
authors.initials: S
authors.lastname: Bull
authors.forename: I
authors.initials: I
authors.lastname: Langezaal
authors.forename: R
authors.initials: R
authors.lastname: Clothier
authors.forename: S
authors.initials: S
authors.lastname: Coecke
mesh_terms: D016475:3T3 Cells / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D000826:Animal Testing Alternatives; D000818:Animals; D001711:Biotransformation; D002470:Cell Survival / Q000187:drug effects; D004396:Coloring Agents / Q000378:metabolism; D003520:Cyclophosphamide / Q000633:toxicity; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D004050:Ditiocarb / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005818:Genetic Engineering; D005978:Glutathione / Q000172:deficiency / Q000378:metabolism; D006801:Humans; D051379:Mice; D009499:Neutral Red / Q000378:metabolism; D010078:Oxazines; D010084:Oxidation-Reduction; D020033:Protein Isoforms; D051381:Rats; D014162:Transfection; D014966:Xanthenes; D015262:Xenobiotics / Q000493:pharmacokinetics* / Q000633:toxicity*; D000517:alpha-Chlorohydrin / Q000031:analogs & derivatives* / Q000633:toxicity
chemical_list: D004396:Coloring Agents; D004791:Enzyme Inhibitors; D010078:Oxazines; D020033:Protein Isoforms; D014966:Xanthenes; D015262:Xenobiotics; C033489:1,3-dichloro-2-propanol; C005843:resazurin; D009499:Neutral Red; D003520:Cyclophosphamide; D003577:Cytochrome P-450 Enzyme System; D000517:alpha-Chlorohydrin; D004050:Ditiocarb; D005978:Glutathione