O6-methylguanine-DNA methyltransferase in human normal and tumor tissue from brain, lung, and ovary.
The resistance of human tumor strains in culture to cell killing by alkylating nitrosoureas is correlated with their levels of the DNA repair activity O6-methylguanine-DNA methyltransferase. Strains with the Mer- phenotype have no activity and are extremely sensitive. However, the relationship between the sensitivity of human tumors in vivo and transferase levels is not known, and even the existence of Mer- human tumors in vivo has been questioned. In this study 73 human tumor and normal tissue samples from brain, lung, and ovary were assayed for transferase levels and methylpurine glycosylase activity. For each organ, transferase levels varied over 100-fold, and Mer- tumors were detected in each group. There was no correlation between transferase and glycosylase levels, indicating that the absence of transferase in some tumor samples was not an artifact due to necrosis or inactivation of enzymes in the extract.
Citron
M
M
Long Island Jewish Medical Center, New Hyde Park, New York 11042.
Decker
R
R
Chen
S
S
Schneider
S
S
Graver
M
M
Kleynerman
L
L
Kahn
L B
LB
White
A
A
Schoenhaus
M
M
Yarosh
D
D
D001426:Bacterial Proteins / Q000378:metabolism*; D001921:Brain / Q000201:enzymology*; D001932:Brain Neoplasms / Q000201:enzymology*; D029968:Escherichia coli Proteins; D005260:Female; D006801:Humans; D007700:Kinetics; D008168:Lung / Q000201:enzymology*; D008175:Lung Neoplasms / Q000201:enzymology*; D019853:O(6)-Methylguanine-DNA Methyltransferase; D010051:Ovarian Neoplasms / Q000201:enzymology*; D010053:Ovary / Q000201:enzymology*; D012016:Reference Values; D014157:Transcription Factors
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D014157:Transcription Factors; C045675:Ada protein, E coli; D019853:O(6)-Methylguanine-DNA Methyltransferase