title: Levels of O6-methylguanine acceptor protein in extracts of human breast tumor tissues.
abstract: We have measured the abilities of extracts of tissues from human breast tumors to demethylate adducts of O6-meG in exogenous DNA by transfer of the methyl group to an acceptor protein. The results have shown that all 21 specimens examined (including 5 non-neoplastic, 11 malignant tumors and 5 benign growth) contained significant amounts of O6-meG acceptor activity, removing on average 221.1 +/- 2.1 (SEM) fmol O6-meG per mg protein or 10.07 +/- 0.98 (SEM) fmol O6-megG per microgram DNA in the extracts. There were also wide interindividual variations, which were not age-dependent, and there were no significant differences between the non-neoplastic and neoplastic tissues obtained from individuals with benign or with malignant disease. It was estimated that the average number of O6-meG acceptor molecules per cell in normal human breast tissues was calculated as 46,000 +/- 7000 (SEM).
authors.affiliation: Institute of Biophysics, Academia Sinica, Beijing, China.
authors.forename: E H
authors.initials: EH
authors.lastname: Cao
authors.forename: X J
authors.initials: XJ
authors.lastname: Fan
authors.forename: X H
authors.initials: XH
authors.lastname: Yuan
authors.forename: S M
authors.initials: SM
authors.lastname: Xin
authors.forename: Y Y
authors.initials: YY
authors.lastname: Liu
authors.forename: H T
authors.initials: HT
authors.lastname: Yu
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D004260:DNA Repair; D004273:DNA, Neoplasm / Q000378:metabolism; D005260:Female; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D006147:Guanine; C008449:O-(6)-methylguanine