title: Two independent amsacrine-resistant human myeloid leukemia cell lines share an identical point mutation in the 170 kDa form of human topoisomerase II.
abstract: Cloning and sequencing of cDNA segments of human TOP2 gene encoding the 170 kDa form of human DNA topoisomerase II show that Arg486 of the enzyme has been mutated to a lysine in the enzyme from two human leukemia cell lines HL-60/AMSA and KBM-3/AMSA, which were independently selected for resistance to the antitumor drug amsacrine (4'-[9-acridinylamino]-methanesulfon-m-anisidide, mAMSA). Sequence identity comparisons between eukaryotic DNA topoisomerase II and bacterial gyrase (bacterial DNA topoisomerase II) indicate that the position of the common mutation observed in mAMSA-resistant human TOP2 corresponds to that of the point mutation nal-31 in the Escherichia coli gyrase B gene, which confers resistance to nalidixic acid. Because mAMSA and nalidixic acid are known to act on their respective targets by a common mechanism of trapping the covalent enzyme-DNA intermediates, these results provide strong evidence that the 170 kDa form of human DNA topoisomerase II is a major cellular target of mAMSA, and that Arg486 of this enzyme is involved in mAMSA-mediated trapping of the covalent enzyme-DNA complex.
authors.affiliation: Division of Laboratory Medicine, University of Texas M. D. Anderson Cancer Center, Houston 77030.
authors.forename: M S
authors.initials: MS
authors.lastname: Lee
authors.forename: J C
authors.initials: JC
authors.lastname: Wang
authors.forename: M
authors.initials: M
authors.lastname: Beran
mesh_terms: D000595:Amino Acid Sequence; D000677:Amsacrine / Q000494:pharmacology*; D004252:DNA Mutational Analysis; D004250:DNA Topoisomerases, Type II / Q000235:genetics*; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D015183:Restriction Mapping; D059005:Topoisomerase II Inhibitors; D014407:Tumor Cells, Cultured
chemical_list: D059005:Topoisomerase II Inhibitors; D000677:Amsacrine; D004250:DNA Topoisomerases, Type II