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mAMSA resistant human topoisomerase IIbeta mutation G465D has reduced ATP hydrolysis activity

Kathryn L Gilroy1, Chrysoula Leontiou, Kay Padget

  • 1The Institute for Cell and Molecular Biosciences, The University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.

Nucleic Acids Research
|March 22, 2006
PubMed

Insights

Researchers identified a new mutation (betaG465D) in human Topoisomerase II, conferring resistance to cancer drugs. This finding sheds light on multi-drug resistance mechanisms and offers new avenues for therapeutic development.

Area of Science:

  • Molecular Biology
  • Biochemistry
  • Genetics

Background:

  • Type II Human DNA Topoisomerases (Topos II) are crucial for DNA replication and transcription.
  • Topos II are key targets for cancer chemotherapy due to their role in DNA damage.
  • Mutations in Topo II can lead to multi-drug resistance in cancer treatment.

Purpose of the Study:

  • To identify mutations conferring resistance to acridine-based chemotherapy drugs using forced molecular evolution.
  • To characterize the functional impact of novel mutations on Topoisomerase II activity and drug response.

Main Methods:

  • Forced molecular evolution to select for drug-resistant Topoisomerase II variants.
  • Biochemical assays to measure ATP affinity, ATP hydrolysis, and DNA decatenation rates.
  • Fluorescence anisotropy technique used with intact human Topoisomerase II for the first time.

Main Results:

  • A novel mutation, betaG465D, was identified and confers cross-resistance to multiple chemotherapy drugs including etoposide, ellipticine, and doxorubicin.
  • The betaG465D mutation significantly decreases ATP affinity and hydrolysis, and alters magnesium requirements for decatenation.
  • A time-dependent decrease in resistance to mAMSA suggests an uncharacterized resistance mechanism.

Conclusions:

  • The betaG465D mutation in Topoisomerase II provides insights into drug resistance mechanisms.
  • Understanding these mutations can inform the development of more effective cancer chemotherapeutics.
  • Novel resistance mechanisms may emerge over time, necessitating continuous research in cancer drug development.

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