title: 17-AAG, an Hsp90 inhibitor, causes kinetochore defects: a novel mechanism by which 17-AAG inhibits cell proliferation.
abstract: The Hsp90 inhibitor 17-allylaminogeldanamycin (17-AAG), which is currently in clinical trials, is thought to exert antitumor activity by simultaneously targeting several oncogenic signaling pathways. Here we report a novel mechanism by which 17-AAG inhibits cell proliferation, and we provide the first evidence that HSP90 is required for the assembly of kinetochore protein complexes in humans. 17-AAG caused delocalization of several kinetochore proteins including CENP-I and CENP-H but excluding CENP-B and CENP-C. Consistently, 17-AAG induced a mitotic arrest that depends on the spindle checkpoint and induced misalignment of chromosomes and aneuploidy. We found that HSP90 associates with SGT1 (suppressor of G2 allele of skp1; SUGT1) in human cells and that depletion of SGT1 sensitizes HeLa cells to 17-AAG. Overexpression of SGT1 restored the localization of specific kinetochore proteins and chromosome alignment in cells treated with 17-AAG. Biochemical and genetic results suggest that HSP90, through its interaction with SGT1 (SUGT1), is required for kinetochore assembly. Furthermore, time-course experiments revealed that transient treatment with 17-AAG between late S and G2/M phases causes substantial delocalization of CENP-H and CENP-I, a finding that strongly suggests that HSP90 participates in kinetochore assembly in a cell cycle-dependent manner.
authors.affiliation: Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, TN 38105-2794, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Niikura
authors.forename: S
authors.initials: S
authors.lastname: Ohta
authors.forename: K J
authors.initials: KJ
authors.lastname: Vandenbeldt
authors.forename: R
authors.initials: R
authors.lastname: Abdulle
authors.forename: B F
authors.initials: BF
authors.lastname: McEwen
authors.forename: K
authors.initials: K
authors.lastname: Kitagawa
mesh_terms: D016227:Benzoquinones; D018797:Cell Cycle Proteins / Q000502:physiology; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects*; D006131:Growth Inhibitors / Q000494:pharmacology*; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors*; D006367:HeLa Cells; D006801:Humans; D018386:Kinetochores / Q000187:drug effects*; D047029:Lactams, Macrocyclic; D034741:RNA, Small Interfering / Q000494:pharmacology; D017828:Rifabutin / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D016227:Benzoquinones; D018797:Cell Cycle Proteins; D006131:Growth Inhibitors; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D034741:RNA, Small Interfering; C490164:SUGT1 protein, human; D017828:Rifabutin; C112765:tanespimycin