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Published on: December 2, 2022

Atypical multidrug resistance may be associated with catalytically active mutants of human DNA topoisomerase II alpha

Y Okada1, A Tosaka, Y Nimura

  • 1The First Department of Surgery, Nagoya University School of Medicine, Nagoya, 466-8550, Japan.

Gene
|July 27, 2001
PubMed

Insights

Two DNA topoisomerase II alpha (TOP2 alpha) mutants, K798L and K798P, confer resistance to etoposide, doxorubicin, and mAMSA. These mutants exhibit intrinsic resistance in vitro, suggesting a mechanism for atypical multidrug resistance in vivo.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Genetics

Background:

  • Atypical drug resistance in human cells is linked to DNA topoisomerase II alpha (TOP2 alpha) dysfunction.
  • Previous studies identified TOP2 alpha mutants with altered catalytic activity or nuclear localization impacting drug resistance.

Purpose of the Study:

  • To investigate the drug resistance mechanisms of two etoposide-resistant human TOP2 alpha mutants, K798L and K798P.
  • To determine if these mutants confer resistance to other chemotherapy drugs, specifically doxorubicin and mAMSA.

Main Methods:

  • Utilized a yeast strain (ISE2, rad52, top2-4) to assess in vivo drug resistance of TOP2 alpha mutants at non-permissive temperatures.
  • Purified recombinant TOP2 alpha mutants (K798L, K798P) for in vitro characterization.
  • Measured drug resistance by quantifying the accumulation of cleavable DNA complexes.

Main Results:

  • The K798L and K798P TOP2 alpha mutants demonstrated resistance to etoposide, doxorubicin, and mAMSA in vivo.
  • Purified mutant proteins showed 8- to 12-fold increased resistance to etoposide and doxorubicin, and 2-fold resistance to amsacrine compared to wild-type TOP2 alpha in vitro.
  • These findings suggest intrinsic resistance of the mutants to these drugs.

Conclusions:

  • The K798L and K798P mutations in human TOP2 alpha confer resistance to multiple chemotherapy drugs, including etoposide, doxorubicin, and mAMSA.
  • The observed in vitro intrinsic resistance of these mutants is likely responsible for the atypical multidrug resistant phenotype observed in vivo.
  • These findings provide insights into the molecular mechanisms underlying drug resistance in TOP2 alpha-targeting cancer therapies.

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