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A metabolically competent human cell line expressing five cDNAs encoding procarcinogen-activating enzymes: application to mutagenicity testing.

C L Crespi·F J Gonzalez·D T Steimel·T R Turner·H V Gelboin·B W Penman·R Langenbach
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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.

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Carcinogenicity TestsCarcinogensCell LineCytochrome P-450 Enzyme SystemDNAEnzyme ActivationHumansImmunoblottingMicrosomesMutagenicity TestsTransfectionTumor Cells, CulturedJournal ArticleResearch Support, U.S. Gov't, P.H.S.

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C L Crespi, F J Gonzalez, D T Steimel, T R Turner, H V Gelboin, B W Penman, R Langenbach. A metabolically competent human cell line expressing five cDNAs encoding procarcinogen-activating enzymes: application to mutagenicity testing.. https://doi.org/10.1021/tx00023a013

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