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Topoisomerase levels determine chemotherapy response in vitro and in vivo

Darren J Burgess1, Jason Doles, Lars Zender

  • 1Cold Spring Harbor Laboratory and Howard Hughes Medical Institute, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.

Proceedings of the National Academy of Sciences of the United States of America
|June 25, 2008
PubMed

Insights

Chemotherapy resistance in cancer can stem from varying topoisomerase levels. This study reveals how targeting topoisomerase 1 (Top1) and topoisomerase 2A (Top2A) impacts drug response, offering new strategies for cancer treatment.

Area of Science:

  • Oncology
  • Molecular Biology
  • Genetics

Background:

  • Topoisomerase poisons are crucial chemotherapy agents for treating malignancies.
  • Tumor refractoriness and acquired resistance limit the efficacy of these drugs.
  • Understanding the genetic basis of heterogeneous responses is vital for improving cancer therapy.

Purpose of the Study:

  • To explore the genetic determinants of heterogeneous responses to topoisomerase poisons.
  • To identify genetic factors influencing resistance and sensitivity to chemotherapy.
  • To investigate strategies for enhancing the effectiveness of topoisomerase poisons.

Main Methods:

  • Utilized a pool-based RNA interference (RNAi) screening approach.
  • Employed a well-characterized mouse model of lymphoma for in vitro and in vivo studies.
  • Conducted targeted RNAi experiments to assess specific topoisomerase gene functions.

Main Results:

  • Topoisomerase 2A (Top2A) expression levels significantly determine response to doxorubicin.
  • Suppression of Top2A confers resistance to doxorubicin, while Top1 suppression confers resistance to camptothecin.
  • Top1 suppression hypersensitizes cancer cells to doxorubicin, and relapsed lymphomas show altered topoisomerase levels.

Conclusions:

  • Pooled shRNA screens are effective for identifying genetic determinants of chemotherapy response.
  • Altered topoisomerase levels in relapsed lymphomas contribute to treatment resistance.
  • Modulating topoisomerase levels presents a potential strategy to improve topoisomerase poison efficacy in cancer treatment.

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