The topoisomerase II–Hsp90 complex: A new chemotherapeutic target?

Authors

  • Catherine R. Barker,

    1. The Henry Wellcome Laboratory of Molecular and Cellular Gastroenterology, Division of Gastroenterology, School of Clinical Sciences, The University of Liverpool, Liverpool, United Kingdom
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  • Jane Hamlett,

    1. Department of Anatomy and Cell Biology, University of Liverpool, Liverpool, United Kingdom
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  • Stephen R. Pennington,

    1. Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
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  • Francis Burrows,

    1. Department of Biology, Conforma Therapeutics Corporation, San Diego, CA, USA
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  • Karen Lundgren,

    1. Department of Biology, Conforma Therapeutics Corporation, San Diego, CA, USA
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  • Rachel Lough,

    1. Department of Biology, Conforma Therapeutics Corporation, San Diego, CA, USA
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  • Alastair J.M. Watson,

    1. The Henry Wellcome Laboratory of Molecular and Cellular Gastroenterology, Division of Gastroenterology, School of Clinical Sciences, The University of Liverpool, Liverpool, United Kingdom
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  • John R. Jenkins

    Corresponding author
    1. The Henry Wellcome Laboratory of Molecular and Cellular Gastroenterology, Division of Gastroenterology, School of Clinical Sciences, The University of Liverpool, Liverpool, United Kingdom
    • The Henry Wellcome Laboratory of Molecular and Cellular Gastroenterology, Division of Gastroenterology, School of Clinical Sciences, The University of Liverpool, Crown Street, Liverpool L69 3BX, UK
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    • Fax: 44-151-794-6825


Abstract

The modulation of DNA topology by topoisomerase II plays a crucial role during chromosome condensation and segregation in mitosis and has thus become a highly attractive target for chemotherapeutic drugs. However, these drugs are highly toxic, and so new approaches are required. One such strategy is to target topoisomerase II-interacting proteins. Here we report the identification of potential topoisomerase II-associated proteins using immunoprecipitation, followed by 1-D and 2-D gel electrophoresis and MALDI-TOF mass spectrometry. A total of 23 proteins were identified and, of these, 17 were further validated as topoisomerase IIα-associated proteins by coimmunoprecipitation and Western blot. Six of the interacting proteins were cellular chaperones, including 3 members of the heat shock protein-90 (Hsp90) family, and so the effect of Hsp90 modulation on the antitumor activity of topoisomerase II drugs was tested using the sulforhodamine B assay, clonogenic assays and a xenograft model. The Hsp90 inhibitors geldanamycin, 17-AAG (17-allylamino-17-demethoxygeldanamycin) and radicicol significantly enhanced the activity of the topoisomerase II poisons etoposide and mitoxantrone in vitro and in vivo. Thus, our method of identifying topoisomerase II-interacting proteins appears to be effective, and at least 1 novel topoisomerase IIα-associated protein, Hsp90, may represent a valid drug target in the context of topoisomerase II-directed chemotherapy. © 2005 Wiley-Liss, Inc.

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