title: The topoisomerase II-Hsp90 complex: a new chemotherapeutic target?
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 IIalpha-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 IIalpha-associated protein, Hsp90, may represent a valid drug target in the context of topoisomerase II-directed chemotherapy.
authors.affiliation: The Henry Wellcome Laboratory of Molecular and Cellular Gastroenterology, Division of Gastroenterology, School of Clinical Sciences, The University of Liverpool, Liverpool, United Kingdom.
authors.forename: Catherine R
authors.initials: CR
authors.lastname: Barker
authors.forename: Jane
authors.initials: J
authors.lastname: Hamlett
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Pennington
authors.forename: Francis
authors.initials: F
authors.lastname: Burrows
authors.forename: Karen
authors.initials: K
authors.lastname: Lundgren
authors.forename: Rachel
authors.initials: R
authors.lastname: Lough
authors.forename: Alastair J M
authors.initials: AJ
authors.lastname: Watson
authors.forename: John R
authors.initials: JR
authors.lastname: Jenkins
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology; D000818:Animals; D016227:Benzoquinones; D001943:Breast Neoplasms / Q000473:pathology; D018196:Carcinoma, Adenosquamous / Q000473:pathology; D003110:Colonic Neoplasms / Q000188:drug therapy; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D018841:HSP90 Heat-Shock Proteins / Q000032:analysis* / Q000502:physiology*; D006801:Humans; D047468:Immunoprecipitation; D047029:Lactams, Macrocyclic; D007783:Lactones / Q000494:pharmacology; D018942:Macrolides; D051379:Mice; D008819:Mice, Nude; D018832:Molecular Chaperones; D009369:Neoplasms / Q000188:drug therapy; D011485:Protein Binding; D011809:Quinones / Q000494:pharmacology; D017828:Rifabutin / Q000031:analogs & derivatives / Q000494:pharmacology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured
chemical_list: D016227:Benzoquinones; D004791:Enzyme Inhibitors; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D007783:Lactones; D018942:Macrolides; D018832:Molecular Chaperones; D011809:Quinones; D017828:Rifabutin; C112765:tanespimycin; D004250:DNA Topoisomerases, Type II; C035359:monorden; C001277:geldanamycin