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

Catherine R. Barker, Jane Hamlett, Stephen R. Pennington, Francis Burrows, Karen Lundgren, Rachel Lough, Alastair J M Watson, John R. Jenkins

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35 Citations (Scopus)


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.
Original languageEnglish
Pages (from-to)2685-2693
Number of pages9
JournalInternational Journal of Cancer
Issue number11
Publication statusPublished - 1 Jun 2006

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