Lack of induction of o-methylguanine-dna methyltransferase in mammalian cells treated with n-methyl-n' -nitro-n-nitrosoguanidine

R. S. Foote, S. Mitra

Research output: Contribution to journalArticle

51 Scopus citations

Abstract

A synthetic DNA substrate containing O6-methyI(8-3H)guanine was used to assay demethylation of the premutagenic base by O6-methylguanine-DNA methyltransferase in extracts of HeLa cells, Chinese hamster ovary cells and normal rat kidney cells which had been treated with multiple doses of N-methyl-N' -nitro-N-nitrosoguanidine (MNNG). No induction of methyltransferase activity was observed in any of the cell lines tested. Constitutive levels of methyltransferase in cell lines proficient (Mex+) in O6-methylguanine repair were decreased in a dose-dependent fashion by either single or multiple treatments with MNNG over a broad range of dose levels. Recovery of constitutive levels of activity required 24-to 48-h incubation periods. Repair deficient (Mex-) cell lines lacked both constitutive and inducible methyltransferase activity.

Original languageEnglish (US)
Pages (from-to)277-281
Number of pages5
JournalCarcinogenesis
Volume5
Issue number2
DOIs
StatePublished - Feb 1984

ASJC Scopus subject areas

  • Cancer Research

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