Lack of induction of O6-methylguanine-DNA methyltransferase in mammalian cells treated with N-methyl-N' -nitro-N-nitrosoguanidine
- 1 February 1984
- journal article
- research article
- Published by Oxford University Press (OUP) in Carcinogenesis: Integrative Cancer Research
- Vol. 5 (2) , 277-281
- https://doi.org/10.1093/carcin/5.2.277
Abstract
A synthetic DNA substrate containing O 6 -methyI(8- 3 H)guanine was used to assay demethylation of the premutagenic base by O 6 -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 O 6 -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.This publication has 0 references indexed in Scilit: