title: A metabolically competent human cell line expressing five cDNAs encoding procarcinogen-activating enzymes: application to mutagenicity testing.
abstract: A human B-lymphoblastoid cell line, designated MCL-5, constitutively expressing human cytochrome P-450 CYP1A1 and also expressing five transfected human cDNAs encoding drug-metabolizing enzymes, has been developed. cDNAs encoding CYP1A2, CYP2A6, and microsomal epoxide hydrolase (mEH) were introduced by using a vector conferring hygromycin B resistance, and cDNAs encoding CYP2E1 and CYP3A4 were introduced by using a vector conferring resistance to 1-histidinol. MCL-5 cells stably expressed all five cDNAs and the native CYP1A1 as determined by measurement of form-specific enzyme activity levels. The mutagenicity of seven model procarcinogens to MCL-5 cells was examined at the hypoxanthine guanine phosphoribosyltransferase (hprt) and thymidine kinase (tk) loci. Exposure to benzo[a]pyrene (BP), 3-methylcholanthrene (3MC), N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), aflatoxin B1, (AFB1), 2-(acetylamino)fluorene (AAF), or benzidine (BZD) induced a statistically significant increase in mutant frequency. Linear interpolation of the concentration of procarcinogen necessary to produce a doubling of the mutant fraction at the hprt locus in MCL-5 cells and the parent AHH-1 cell line revealed that, for each of the chemicals examined, except BZD, MCL-5 cells were significantly more sensitive than the parent AHH-1 cells. The increase in sensitivity to mutagenicity ranged from 3-fold for AAF to greater than 40,000-fold for NDMA. MCL-5 cells have great potential as a screening system for the analysis of human procarcinogen/promutagen activation.
authors.affiliation: Gentest Corporation, Woburn, Massachusetts 01801.
authors.forename: C L
authors.initials: CL
authors.lastname: Crespi
authors.forename: F J
authors.initials: FJ
authors.lastname: Gonzalez
authors.forename: D T
authors.initials: DT
authors.lastname: Steimel
authors.forename: T R
authors.initials: TR
authors.lastname: Turner
authors.forename: H V
authors.initials: HV
authors.lastname: Gelboin
authors.forename: B W
authors.initials: BW
authors.lastname: Penman
authors.forename: R
authors.initials: R
authors.lastname: Langenbach
mesh_terms: D015197:Carcinogenicity Tests; D002273:Carcinogens / Q000378:metabolism*; D002460:Cell Line; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000235:genetics; D004247:DNA / Q000096:biosynthesis*; D004789:Enzyme Activation; D006801:Humans; D015151:Immunoblotting; D008861:Microsomes / Q000201:enzymology; D009152:Mutagenicity Tests / Q000379:methods*; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D002273:Carcinogens; D004247:DNA; D003577:Cytochrome P-450 Enzyme System