90-kDa heat shock protein inhibition abrogates the topoisomerase i poison-induced G(2)/M checkpoint in p53-null tumor cells by depleting Chk1 and Wee1 Journal Article


Authors: Tse, A. N.; Sheikh, T. N.; Ho, A.; Chou, T. C.; Schwartz, G. K.
Article Title: 90-kDa heat shock protein inhibition abrogates the topoisomerase i poison-induced G(2)/M checkpoint in p53-null tumor cells by depleting Chk1 and Wee1
Abstract: The G(2)/M cell cycle checkpoint is regulated by a multitude of signaling pathways after genotoxic stress. Herein, we report that treatment with the 90-kDa heat shock protein (Hsp90) molecular chaperone inhibitor 17-allylamino-17-demethoxygeldanamycin (17AAG) selectively abrogates the G (2)/M checkpoint induced by 7-ethyl-10-hydroxycamptothecin (SN-38), an active metabolite of irinotecan, in p53-null compared with p53-intact HCT116 colon cancer cells. The basis for this selectivity can be explained in part by the lack of p21 induction in p53-null cells. In accord with published results, we could show that treatment with 17AAG resulted in depletion of Chk1, a known Hsp90 client protein. In addition, we observed a time- and dose-dependent decrease in Wee1 kinase level, a negative regulator of mitosis, after 17AAG treatment in gastrointestinal cancer cells. Depletion of Wee1 protein preceded mitotic entry induced by 17AAG, and this decrease could be partially rescued by cotreatment with a proteasome inhibitor. Coimmunoprecipitation experiments showed that Hsp90 and Wee1 interacted in whole cells, and 17AAG treatment decreased the degradative half-life of Wee1, indicating that Wee1 is another Hsp90 client in mammalian cells. Knockdown of Chk1 and Wee1 by short interfering RNA each resulted in abrogation of the G(2)/M checkpoint induced by SN-38. The combination of SN-38 and 17AAG was shown to be synergistic in p53-null but not in parental HCT116 cells by median effect/combination index analysis. Taken together, 17AAG specifically inhibits the G(2)/M checkpoint in p53- defective cells by down-regulation of two critical checkpoint kinases, Chk1 and Wee1. Copyright © 2009 The American Society for Pharmacology and Experimental Ther.
Keywords: controlled study; unclassified drug; human cell; dose response; cell cycle protein; metabolism; cell cycle proteins; cell survival; cell cycle; apoptosis; protein kinases; nuclear protein; protein protein interaction; 7 ethyl 10 hydroxycamptothecin; protein; small interfering rna; camptothecin; hct116 cells; drug effect; dose-response relationship, drug; protein tyrosine kinase; protein p53; physiology; time; time factors; nuclear proteins; irinotecan; gene expression regulation; gene expression regulation, neoplastic; drug antagonism; immunoprecipitation; drug derivative; protein induction; tumor suppressor protein p53; tanespimycin; heat shock protein 90; hsp90 heat-shock proteins; cell cycle g2 phase; cell cycle m phase; protein-tyrosine kinases; checkpoint kinase 1; cell cycle regulation; protein p21; protein kinase; drug interactions; benzoquinones; lactams, macrocyclic; g2 phase; dna topoisomerase; cell strain hct116; dna topoisomerases, type i; protein wee1; 17-(allylamino)-17-demethoxygeldanamycin; benzoquinone derivative; macrocyclic lactam; wee1 protein, human; drug interaction
Journal Title: Molecular Pharmacology
Volume: 75
Issue: 1
ISSN: 0026-895X
Publisher: The American Society for Pharmacology and Experimental Therapeutics  
Date Published: 2009-01-01
Start Page: 124
End Page: 133
Language: English
DOI: 10.1124/mol.108.050807
PUBMED: 18820127
PROVIDER: scopus
PMCID: PMC2685054
DOI/URL:
Notes: --- - "Cited By (since 1996): 9" - "Export Date: 30 November 2010" - "CODEN: MOPMA" - "Source: Scopus"
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MSK Authors
  1. Gary Schwartz
    358 Schwartz
  2. Archie Tse
    34 Tse
  3. Alan Loh Ho
    79 Ho
  4. Ting-Chao Chou
    210 Chou
  5. Tahir N Sheikh
    9 Sheikh