Cell killing by monofunctional methylating agents is due mainly to the formation of adducts at the O-6 position of guanine. These methyl adducts are removed from DNA by the O-6-alkylguanine DNA alkyltransferase (OGAT). The mechanism by which O-6-methylguanine (O(6)meG) induces cell death in OGAT-deficient cells requires a functional mismatch repair system (MRS). We have previously reported that depletion of OGAT activity in the human T-cell leukemic jurkat line does not sensitize these cells to the cytotoxic and apoptotic effects of the methylating triazene temozolomide (Tentori et at., 1995). We therefore decided to establish whether the tolerance of Jurkat cells to O(6)meG could be associated with a defect in MRS. The results of mismatch repair complementation studies indicated that jurkat cells are defective in hMutS alpha, a heterodimer of the hMSH2 and hMSH6 proteins. Cytogenetic analysis of two Jurkat clones revealed a deletion in the short arm of chromosome region 2p15-21, indicating an allelic loss of both hMSH2 and hMSH6 genes. DNA sequencing revealed that exon 13 of the second hMSH2 allele contains a base substitution at codon 711,which changes an arginine to a termination codon (CGA-->TGA). in addition, a (C)(8)-->(C)(7) frameshift mutation in codon 1085-1087 of the hMSH6 gene was also found. Although both hMSH2 and hMSH6 transcripts could be detected in Jurkat clones, the respective polypeptides were absent. Taken together, these data indicate that tolerance of Jurkat cells to methylation damage is linked to a loss of functional hMutSa. (C) 1998 Wiley-Liss, Inc.

Levati, L., Marra, G., Lettieri, T., D'Atri, S., Vernole, P., Tentori, L., et al. (1998). Mutation of the mismatch repair gene hMSH2 and hMSH6 in a human T-cell leukemia line tolerant to methylating agents. GENES, CHROMOSOMES & CANCER, 23(2), 159-166.

Mutation of the mismatch repair gene hMSH2 and hMSH6 in a human T-cell leukemia line tolerant to methylating agents

VERNOLE, PATRIZIA;TENTORI, LUCIO;GRAZIANI, GRAZIA
1998-01-01

Abstract

Cell killing by monofunctional methylating agents is due mainly to the formation of adducts at the O-6 position of guanine. These methyl adducts are removed from DNA by the O-6-alkylguanine DNA alkyltransferase (OGAT). The mechanism by which O-6-methylguanine (O(6)meG) induces cell death in OGAT-deficient cells requires a functional mismatch repair system (MRS). We have previously reported that depletion of OGAT activity in the human T-cell leukemic jurkat line does not sensitize these cells to the cytotoxic and apoptotic effects of the methylating triazene temozolomide (Tentori et at., 1995). We therefore decided to establish whether the tolerance of Jurkat cells to O(6)meG could be associated with a defect in MRS. The results of mismatch repair complementation studies indicated that jurkat cells are defective in hMutS alpha, a heterodimer of the hMSH2 and hMSH6 proteins. Cytogenetic analysis of two Jurkat clones revealed a deletion in the short arm of chromosome region 2p15-21, indicating an allelic loss of both hMSH2 and hMSH6 genes. DNA sequencing revealed that exon 13 of the second hMSH2 allele contains a base substitution at codon 711,which changes an arginine to a termination codon (CGA-->TGA). in addition, a (C)(8)-->(C)(7) frameshift mutation in codon 1085-1087 of the hMSH6 gene was also found. Although both hMSH2 and hMSH6 transcripts could be detected in Jurkat clones, the respective polypeptides were absent. Taken together, these data indicate that tolerance of Jurkat cells to methylation damage is linked to a loss of functional hMutSa. (C) 1998 Wiley-Liss, Inc.
1998
Pubblicato
Rilevanza internazionale
Articolo
Sì, ma tipo non specificato
Settore BIO/13 - BIOLOGIA APPLICATA
English
Con Impact Factor ISI
arginine; dna; guanine; guanine derivative; protein; temozolomide; transferase; allele; apoptosis; article; base mispairing; cell killing; chromosome analysis; chromosome deletion; codon; controlled study; dna sequence; drug tolerance; exon; frameshift mutation; gene; gene mutation; human; human cell; immunoblotting; methylation; northern blotting; nucleic acid base substitution; priority journal; reverse transcription polymerase chain reaction; southern blotting; t cell leukemia; Base Pair Mismatch; DNA Methylation; DNA Repair; DNA-Binding Proteins; Drug Resistance, Neoplasm; Humans; Jurkat Cells; Leukemia, T-Cell; Mutation; MutS Homolog 2 Protein; Proto-Oncogene Proteins; Tumor Cells, Cultured
Levati, L., Marra, G., Lettieri, T., D'Atri, S., Vernole, P., Tentori, L., et al. (1998). Mutation of the mismatch repair gene hMSH2 and hMSH6 in a human T-cell leukemia line tolerant to methylating agents. GENES, CHROMOSOMES & CANCER, 23(2), 159-166.
Levati, L; Marra, G; Lettieri, T; D'Atri, S; Vernole, P; Tentori, L; Lacal, Pm; Pagani, E; Bonmassar, E; Jiricny, J; Graziani, G
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/50284
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