Effects of antineoplastic drugs on the post-strand-passage DNA cleavage/religation equilibrium of topoisomerase II

Biochemistry. 1991 Feb 19;30(7):1807-13. doi: 10.1021/bi00221a012.


The post-strand-passage DNA cleavage/religation equilibrium of Drosophila melanogaster topoisomerase II was examined. This was accomplished by including adenyl-5'-yl imidodiphosphate, a nonhydrolyzable ATP analogue which supports strand passage but not enzyme turnover, in assays. Levels of post-strand-passage enzyme-mediated DNA breakage were 3-5 times higher than those generated by topoisomerase II prior to the strand-passage event. This finding correlated with a decrease in the apparent first-order rate of topoisomerase II mediated DNA religation in the post-strand-passage cleavage complex. Since previous studies demonstrated that antineoplastic drugs stabilize the pre-strand-passage cleavage complex of topoisomerase II by impairing the enzyme's ability to religate cleaved DNA [Osheroff, N. (1989) Biochemistry 28, 6157-6160; Robinson, M.J., & Osheroff, N. (1990) Biochemistry 29, 2511-2515], the effects of 4'-(9-acridinylamino)methanesulfon-m-anisidide (m-AMSA) and etoposide on the enzyme's post-strand-passage DNA cleavage complex were characterized. Both drugs stimulated the ability of topoisomerase II to break double-stranded DNA after strand passage. As determined by two independent assay systems, m-AMSA and etoposide stabilized the enzyme's post-strand-passage DNA cleavage complex primarily by inhibiting DNA religation. These results strongly suggest that both the pre- and post-strand-passage DNA cleavage complexes of topoisomerase II serve as physiological targets for these structurally disparate antineoplastic drugs.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenylyl Imidodiphosphate / pharmacology*
  • Amsacrine / pharmacology*
  • Animals
  • DNA / metabolism*
  • DNA Topoisomerases, Type II / metabolism*
  • Drosophila melanogaster / enzymology
  • Etoposide / pharmacology*
  • Hydrolysis
  • Kinetics


  • Amsacrine
  • Adenylyl Imidodiphosphate
  • Etoposide
  • DNA
  • DNA Topoisomerases, Type II