title: Separation of bisdioxopiperazine- and vanadate resistance in topoisomerase II.
abstract: Bisdioxopiperazines are inhibitors of topoisomerase II trapping this protein as a closed clamp on DNA with concomitant inhibition of its ATPase activity. Here, we analyse the effects of N-terminal mutations identified in bisdioxopiperazine-resistant cells on ATP hydrolysis by this enzyme. We present data consistent with bisdioxopiperazine resistance arising by two different mechanisms; one involving reduced stability of the N-terminal clamp (the N-gate) and one involving reduced affinity for bisdioxopiperazines. Vanadate is a general inhibitor of type P ATPases and has recently been demonstrated to lock topoisomerase II as a salt-stable closed clamp on DNA analogous to the bisdioxopiperazines. We show that a R162K mutation in human topoisomerase II alpha renders this enzyme highly resistant towards vanadate while having little effect on bisdioxopiperazine sensitivity. The implications of these findings for the mechanism of action of bisdioxopiperazines versus vanadate with topoisomerase II are discussed.
authors.affiliation: Department of Pathology, Diagnostic Centre RH5444, Copenhagen University Hospital, Frederik V's Vej 11, DK-2100 Copenhagen, Denmark.
authors.forename: Tina K
authors.initials: TK
authors.lastname: Sorensen
authors.forename: Morten
authors.initials: M
authors.lastname: Grauslund
authors.forename: Peter B
authors.initials: PB
authors.lastname: Jensen
authors.forename: Maxwell
authors.initials: M
authors.lastname: Sehested
authors.forename: Lars H
authors.initials: LH
authors.lastname: Jensen
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics; D019943:Amino Acid Substitution; D000951:Antigens, Neoplasm / Q000737:chemistry / Q000378:metabolism*; D004247:DNA / Q000494:pharmacology; D004250:DNA Topoisomerases, Type II / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D054659:Diketopiperazines; D004351:Drug Resistance; D006801:Humans; D007700:Kinetics; D010879:Piperazines / Q000494:pharmacology; D011929:Razoxane / Q000031:analogs & derivatives / Q000494:pharmacology*; D059005:Topoisomerase II Inhibitors; D014638:Vanadates / Q000494:pharmacology*
chemical_list: D000951:Antigens, Neoplasm; D004268:DNA-Binding Proteins; D054659:Diketopiperazines; D010879:Piperazines; D059005:Topoisomerase II Inhibitors; C070899:4,4'-(1,2-dimethyl-1,2-ethanediyl)bis-2,6-piperazinedione; D014638:Vanadates; D011929:Razoxane; D004247:DNA; D000251:Adenosine Triphosphatases; D004250:DNA Topoisomerases, Type II; C000283:1,2-bis(3,5-dioxopiperazin-1-yl)ethane