Decreased nuclear matrix DNA topoisomerase II in human leukemia cells resistant to VM-26 and m-AMSA

Biochemistry. 1990 May 1;29(17):4235-41. doi: 10.1021/bi00469a028.


CEM leukemia cells selected for resistance to VM-26 (CEM/VM-1) are cross-resistant to various other DNA topoisomerase II inhibitors but not to Vinca alkaloids. Since DNA topoisomerase II is a major protein of the nuclear matrix, we asked if alterations in nuclear matrix topoisomerase II might be important in this form of multidrug resistance. Pretreatment of drug-sensitive CEM cells for 2 h with either 5 microM VM-26 or 3 microM m-AMSA reduced the specific activity of newly replicated DNA on the nuclear matrix by 75 and 50%, respectively, relative to that of the bulk DNA. However, neither VM-26 nor m-AMSA affected the relative specific activity of nascent DNA isolated from the nuclear matrices of drug-resistant CEM/VM-1 cells. The decatenating and unknotting activities of DNA topoisomerase II were 6- and 7-fold lower, respectively, in the nuclear matrix preparations from the CEM/VM-1 cells compared to parental CEM cells. Western blot analysis revealed that the amount of immunoreactive topoisomerase II in the nuclear matrices of the CEM/VM-1 cells was decreased 3.2-fold relative to that in CEM cells, but there was no significant difference in the amount of enzyme present in the nonmatrix (1.5 M salt soluble) fractions of nuclei from these cell lines. Increasing the NaCl concentration used in the matrix isolation procedure from 0.2 to 1.8 M resulted in a progressive decrease in the specific activity of topoisomerase II in matrices of CEM/VM-1 but not CEM cells, which suggested that the association of the enzyme with the matrix is altered in the resistant cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

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

MeSH terms

  • Amsacrine / analogs & derivatives*
  • Amsacrine / pharmacology
  • Animals
  • Antineoplastic Agents
  • Cell Nucleus / drug effects
  • Cell Nucleus / enzymology*
  • Crithidia / drug effects
  • Crithidia / enzymology*
  • DNA / metabolism
  • DNA Topoisomerases, Type II / genetics
  • DNA Topoisomerases, Type II / metabolism*
  • Drug Resistance
  • Humans
  • Leukemia / enzymology*
  • Podophyllotoxin / analogs & derivatives*
  • Teniposide / pharmacology*
  • Tumor Cells, Cultured


  • Antineoplastic Agents
  • Amsacrine
  • 4'-(9-acridinylamino)methanesulfon-o-anisidide
  • DNA
  • Teniposide
  • DNA Topoisomerases, Type II
  • Podophyllotoxin