Introduction of cytochrome P450IA2 metabolic capability into cell lines genetically matched for DNA repair proficiency/deficiency

Larry H. Thompson, Rebekah W. Wu, James S. Felton

Research output: Contribution to journalArticle

31 Scopus citations

Abstract

We introduced into the CHO cell line the cDNA of the mouse cytochrome P3450 (P450IA2) gene, which oxidizes aromatic amines. A cDNA clone of P3450 was transfected into mutant UV5 cells, which is defective in nucleotide excision repair. Expression of the P3450 cDNA was measured using 9000 × g supernatant (S9) fractions from CHO cells to evaluate Salmonella TA1538 mutagenicity with the mutagen 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). The P3450-expressing clone UV5P3 was reverted to repair proficiency using ethyl methanesulfonate to obtain the UV-resistant clone 5P3R2. which maintained the same level of P3450 protein activity as UV5P3. These genetically similar cell lines were compared for toxicity and mutation induction at the aprt locus. With 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (the most prevalent mutagen found in fried beef) the differential sensitivity due to repair deficiency/proficiency was ≈40-fold, and with IQ there were smaller, but significant, differences in sensitivity. These genotoxic effects occurred at doses that were ≈10 times lower than those that previously gave similar effects in S9-mediated assays. Thus, these cell lines should be valuable for genotoxicity analysis as well as important for assessing DNA repair when evaluating compounds that undergo metabolic activation.

Original languageEnglish (US)
Pages (from-to)3827-3831
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume88
Issue number9
StatePublished - 1991
Externally publishedYes

Keywords

  • Beef mutagens
  • CHO cells
  • Mutagen sensitivity
  • Mutagenesis testing

ASJC Scopus subject areas

  • General
  • Genetics

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