KINETICS OF O6-METHYLGUANINE REPAIR IN HUMAN NORMAL AND ATAXIA TELANGIECTASIA CELL-LINES AND CORRELATION OF REPAIR CAPACITY WITH CELLULAR-SENSITIVITY TO METHYLATING AGENTS
- 1 January 1981
- journal article
- research article
- Vol. 41 (12), 5114-5120
Abstract
Human lymphoblastoid cell lines from normal individuals and from patients with ataxia telangiectasia were either proficient or deficient in their ability to repair the mutagenic DNA adduct O6-methylguanine that is induced by methylating carcinogens. There was no relationship between the capacity to repair O6-methylguanine and the ataxia telangiectasia phenotype. Time-course studies done following a short pulse (2 min) of alkylation with 0.5 .mu.g of N-[3H]methyl-N''-nitro-N-nitrosoguanidine per ml revealed that the repair of O6-methylguanine in human lymphoblastoid lines proficient in this ability is a rapid process which proceeds with a t1/2 of 10-15 min. Lymphoblastoid lines with deficient capacity to repair this DNA adduct were hypersensitive to the cytotoxic effect of the methylating carcinogens N-methyl-N''-nitro-N-nitrosoguanidine, N-methyl-N-nitrosourea and methyl methanesulfonate, and this hypersensitivity was correlated with the relative amount of O6-methylguanine induced by each of the 3 chemicals. This was taken as an indication of the lethality of unrepaired O6-methylguanine. The extent of DNA repair synthesis induced by the 3 carcinogens was the same in cell lines proficient and deficient in O6-methylguanine repair, indicating no major deficiency in an excision repair pathway in the hypersensitive cell lines.This publication has 19 references indexed in Scilit:
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