title: Local base sequence preferences for DNA cleavage by mammalian topoisomerase II in the presence of amsacrine or teniposide.
abstract: Several classes of antitumor drugs are known to stabilize topoisomerase complexes in which the enzyme is covalently bound to a terminus of a DNA strand break. The DNA cleavage sites generally are different for each class of drugs. We have determined the DNA sequence locations of a large number of drug-stimulated cleavage sites of topoisomerase II, and find that the results provide a clue to the possible structure of the complexes and the origin of the drug-specific differences. Cleavage enhancements by VM-26 and amsacrine (m-AMSA), which are representative of different classes of topoisomerase II inhibitors, have strong dependence on bases directly at the sites of cleavage. The preferred bases were C at the 3' terminus for VM-26 and A at the 5' terminus for m-AMSA. Also, a region of dyad symmetry of 12 to 16 base pairs was detected about the enzyme cleavage positions. These results are consistent with those obtained with doxorubicin, although in the case of doxorubicin, cleavage requires the presence of an A at the 3' terminus of at least one the pair of breaks that constitute a double-strand cleavage (Capranico et al., Nucleic Acids Res., 1990, 18: 6611). These findings suggest that topoisomerase II inhibitors may stack with one or the other base pair flanking the enzyme cleavage sites.
authors.affiliation: Laboratory of Molecular Pharmacology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
authors.forename: Y
authors.initials: Y
authors.lastname: Pommier
authors.forename: G
authors.initials: G
authors.lastname: Capranico
authors.forename: A
authors.initials: A
authors.lastname: Orr
authors.forename: K W
authors.initials: KW
authors.lastname: Kohn
mesh_terms: D000677:Amsacrine / Q000494:pharmacology*; D001483:Base Sequence; D001665:Binding Sites / Q000187:drug effects / Q000235:genetics; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004279:DNA, Viral / Q000378:metabolism*; D004317:Doxorubicin / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D013539:Simian virus 40 / Q000235:genetics; D013713:Teniposide / Q000494:pharmacology*
chemical_list: D004279:DNA, Viral; D000677:Amsacrine; D004317:Doxorubicin; D013713:Teniposide; D004250:DNA Topoisomerases, Type II