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Bandura JL, Jiang H, Nickerson DW, Edgar BA. The molecular chaperone Hsp90 is required for cell cycle exit in Drosophila melanogaster. PLoS Genet 2013; 9:e1003835. [PMID: 24086162 PMCID: PMC3784567 DOI: 10.1371/journal.pgen.1003835] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 08/13/2013] [Indexed: 11/18/2022] Open
Abstract
The coordination of cell proliferation and differentiation is crucial for proper development. In particular, robust mechanisms exist to ensure that cells permanently exit the cell cycle upon terminal differentiation, and these include restraining the activities of both the E2F/DP transcription factor and Cyclin/Cdk kinases. However, the full complement of mechanisms necessary to restrain E2F/DP and Cyclin/Cdk activities in differentiating cells are not known. Here, we have performed a genetic screen in Drosophila melanogaster, designed to identify genes required for cell cycle exit. This screen utilized a PCNA-miniwhite+ reporter that is highly E2F-responsive and results in a darker red eye color when crossed into genetic backgrounds that delay cell cycle exit. Mutation of Hsp83, the Drosophila homolog of mammalian Hsp90, results in increased E2F-dependent transcription and ectopic cell proliferation in pupal tissues at a time when neighboring wild-type cells are postmitotic. Further, these Hsp83 mutant cells have increased Cyclin/Cdk activity and accumulate proteins normally targeted for proteolysis by the anaphase-promoting complex/cyclosome (APC/C), suggesting that APC/C function is inhibited. Indeed, reducing the gene dosage of an inhibitor of Cdh1/Fzr, an activating subunit of the APC/C that is required for timely cell cycle exit, can genetically suppress the Hsp83 cell cycle exit phenotype. Based on these data, we propose that Cdh1/Fzr is a client protein of Hsp83. Our results reveal that Hsp83 plays a heretofore unappreciated role in promoting APC/C function during cell cycle exit and suggest a mechanism by which Hsp90 inhibition could promote genomic instability and carcinogenesis. Cells must permanently stop dividing when they terminally differentiate for development to occur normally. Maintenance of this postmitotic state is also important, as unscheduled proliferation of differentiated cells can result in cancer. To identify genes important for restraining cell proliferation during terminal differentiation, we performed a genetic screen in Drosophila and found that mutation of Hsp90 caused ectopic cell proliferation in differentiating tissues. Hsp90 is a molecular chaperone that is essential for viability in all eukaryotes and has been shown to facilitate the activity of hundreds of “client” proteins. Indeed, several inhibitors of Hsp90 are currently being tested in clinical trials for use as anti-cancer therapeutics due to their ability to silence multiple client oncoproteins simultaneously. Our data suggest that Hsp90 is necessary to halt cell proliferation during differentiation because the protein Cdh1, which is required for normal cell cycle exit, may be a client of Hsp90. As reduced Cdh1 function results in genomic instability and tumorigenesis, our work highlights the need to design more precisely targeted Hsp90 inhibitors for use as cancer treatments.
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Affiliation(s)
- Jennifer L. Bandura
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- German Cancer Research Center (DKFZ) – Center for Molecular Biology Heidelberg (ZMBH) Alliance, Heidelberg, Germany
| | - Huaqi Jiang
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Derek W. Nickerson
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Bruce A. Edgar
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- German Cancer Research Center (DKFZ) – Center for Molecular Biology Heidelberg (ZMBH) Alliance, Heidelberg, Germany
- * E-mail:
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102
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Zuehlke AD, Wren N, Tenge V, Johnson JL. Interaction of heat shock protein 90 and the co-chaperone Cpr6 with Ura2, a bifunctional enzyme required for pyrimidine biosynthesis. J Biol Chem 2013; 288:27406-27414. [PMID: 23926110 PMCID: PMC3779735 DOI: 10.1074/jbc.m113.504142] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 08/06/2013] [Indexed: 01/16/2023] Open
Abstract
The molecular chaperone heat shock protein 90 (Hsp90) is an essential protein required for the activity and stability of multiple proteins termed clients. Hsp90 cooperates with a set of co-chaperone proteins that modulate Hsp90 activity and/or target clients to Hsp90 for folding. Many of the Hsp90 co-chaperones, including Cpr6 and Cpr7, contain tetratricopeptide repeat (TPR) domains that bind a common acceptor site at the carboxyl terminus of Hsp90. We found that Cpr6 and Hsp90 interacted with Ura2, a protein critical for pyrimidine biosynthesis. Mutation or inhibition of Hsp90 resulted in decreased accumulation of Ura2, indicating it is an Hsp90 client. Cpr6 interacted with Ura2 in the absence of stable Cpr6-Hsp90 interaction, suggesting a direct interaction. However, loss of Cpr6 did not alter the Ura2-Hsp90 interaction or Ura2 accumulation. The TPR domain of Cpr6 was required for Ura2 interaction, but other TPR containing co-chaperones, including Cpr7, failed to interact with Ura2 or rescue CPR6-dependent growth defects. Further analysis suggests that the carboxyl-terminal 100 amino acids of Cpr6 and Cpr7 are critical for specifying their unique functions, providing new information about this important class of Hsp90 co-chaperones.
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Affiliation(s)
- Abbey D Zuehlke
- Department of Biological Sciences, University of Idaho, Moscow, Idaho 83844
| | - Nicholas Wren
- Department of Biological Sciences, University of Idaho, Moscow, Idaho 83844
| | - Victoria Tenge
- Department of Biological Sciences, University of Idaho, Moscow, Idaho 83844
| | - Jill L Johnson
- Department of Biological Sciences, University of Idaho, Moscow, Idaho 83844.
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103
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Blacklock K, Verkhivker GM. Differential modulation of functional dynamics and allosteric interactions in the Hsp90-cochaperone complexes with p23 and Aha1: a computational study. PLoS One 2013; 8:e71936. [PMID: 23977182 PMCID: PMC3747073 DOI: 10.1371/journal.pone.0071936] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 07/10/2013] [Indexed: 12/27/2022] Open
Abstract
Allosteric interactions of the molecular chaperone Hsp90 with a large cohort of cochaperones and client proteins allow for molecular communication and event coupling in signal transduction networks. The integration of cochaperones into the Hsp90 system is driven by the regulatory mechanisms that modulate the progression of the ATPase cycle and control the recruitment of the Hsp90 clientele. In this work, we report the results of computational modeling of allosteric regulation in the Hsp90 complexes with the cochaperones p23 and Aha1. By integrating protein docking, biophysical simulations, modeling of allosteric communications, protein structure network analysis and the energy landscape theory we have investigated dynamics and stability of the Hsp90-p23 and Hsp90-Aha1 interactions in direct comparison with the extensive body of structural and functional experiments. The results have revealed that functional dynamics and allosteric interactions of Hsp90 can be selectively modulated by these cochaperones via specific targeting of the regulatory hinge regions that could restrict collective motions and stabilize specific chaperone conformations. The protein structure network parameters have quantified the effects of cochaperones on conformational stability of the Hsp90 complexes and identified dynamically stable communities of residues that can contribute to the strengthening of allosteric interactions. According to our results, p23-mediated changes in the Hsp90 interactions may provide "molecular brakes" that could slow down an efficient transmission of the inter-domain allosteric signals, consistent with the functional role of p23 in partially inhibiting the ATPase cycle. Unlike p23, Aha1-mediated acceleration of the Hsp90-ATPase cycle may be achieved via modulation of the equilibrium motions that facilitate allosteric changes favoring a closed dimerized form of Hsp90. The results of our study have shown that Aha1 and p23 can modulate the Hsp90-ATPase activity and direct the chaperone cycle by exerting the precise control over structural stability, global movements and allosteric communications in Hsp90.
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Affiliation(s)
- Kristin Blacklock
- School of Computational Sciences and Crean School of Health and Life Sciences, Schmid College of Science and Technology, Chapman University, Orange, California, United States of America
| | - Gennady M. Verkhivker
- School of Computational Sciences and Crean School of Health and Life Sciences, Schmid College of Science and Technology, Chapman University, Orange, California, United States of America
- Department of Pharmacology, University of California San Diego, La Jolla, California, United States of America
- * E-mail:
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104
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The fungal Achilles’ heel: targeting Hsp90 to cripple fungal pathogens. Curr Opin Microbiol 2013; 16:377-84. [DOI: 10.1016/j.mib.2013.03.005] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 03/11/2013] [Indexed: 11/24/2022]
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105
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Alarcon SV, Mollapour M, Lee MJ, Tsutsumi S, Lee S, Kim YS, Prince T, Apolo AB, Giaccone G, Xu W, Neckers LM, Trepel JB. Tumor-intrinsic and tumor-extrinsic factors impacting hsp90- targeted therapy. Curr Mol Med 2013; 12:1125-41. [PMID: 22804236 DOI: 10.2174/156652412803306729] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 05/18/2012] [Accepted: 07/07/2012] [Indexed: 01/19/2023]
Abstract
In 1994 the first heat shock protein 90 (Hsp90) inhibitor was identified and Hsp90 was reported to be a target for anticancer therapeutics. In the past 18 years there have been 17 distinct Hsp90 inhibitors entered into clinical trial, and the small molecule Hsp90 inhibitors have been highly valuable as probes of the role of Hsp90 and its client proteins in cancer. Although no Hsp90 inhibitor has achieved regulatory approval, recently there has been significant progress in Hsp90 inhibitor clinical development, and in the past year RECIST responses have been documented in HER2-positive breast cancer and EML4-ALK-positive non-small cell lung cancer. All of the clinical Hsp90 inhibitors studied to date are specific in their target, i.e. they bind exclusively to Hsp90 and two related heat shock proteins. However, Hsp90 inhibitors are markedly pleiotropic, causing degradation of over 200 client proteins and impacting critical multiprotein complexes. Furthermore, it has only recently been appreciated that Hsp90 inhibitors can, paradoxically, cause transient activation of the protein kinase clients they are chaperoning, resulting in initiation of signal transduction and significant physiological events in both tumor and tumor microenvironment. An additional area of recent progress in Hsp90 research is in studies of the posttranslational modifications of Hsp90 itself and Hsp90 co-chaperone proteins. Together, a picture is emerging in which the impact of Hsp90 inhibitors is shaped by the tumor intracellular and extracellular milieu, and in which Hsp90 inhibitors impact tumor and host on a microenvironmental and systems level. Here we review the tumor intrinsic and extrinsic factors that impact the efficacy of small molecules engaging the Hsp90 chaperone machine.
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Affiliation(s)
- S V Alarcon
- Medical Oncology Branch, CCR, NCI, NIH, Bldg 10, Rm 12N230, 10 Center Drive, Bethesda, MD 20816, USA
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106
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WEE1 inhibition and genomic instability in cancer. Biochim Biophys Acta Rev Cancer 2013; 1836:227-35. [PMID: 23727417 DOI: 10.1016/j.bbcan.2013.05.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 05/21/2013] [Accepted: 05/23/2013] [Indexed: 01/23/2023]
Abstract
One of the hallmarks of cancer is genomic instability controlled by cell cycle checkpoints. The G1 and G2 checkpoints allow DNA damage responses, whereas the mitotic checkpoint enables correct seggregation of the sister chromosomes to prevent aneuploidy. Cancer cells often lack a functional G1 arrest and rely on G2 arrest for DNA damage responses. WEE1 kinase is an important regulator of the G2 checkpoint and is overexpressed in various cancer types. Inhibition of WEE1 is a promising strategy in cancer therapy in combination with DNA-damaging agents, especially when cancer cells harbor p53 mutations, as it causes mitotic catastrophy when DNA is not repaired during G2 arrest. Cancer cell response to WEE1 inhibition monotherapy has also been demonstrated in various types of cancer, including p53 wild-type cancers. We postulate that chromosomal instability can explain tumor response to WEE1 monotherapy. Therefore, chromosomal instability may need to be taken into account when determining the most effective strategy for the use of WEE1 inhibitors in cancer therapy.
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107
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Sawarkar R, Paro R. Hsp90@chromatin.nucleus: an emerging hub of a networker. Trends Cell Biol 2013; 23:193-201. [DOI: 10.1016/j.tcb.2012.11.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 11/19/2012] [Accepted: 11/20/2012] [Indexed: 02/06/2023]
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108
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Yano K, Uesono Y, Yoshida S, Kikuchi A, Kashiwazaki J, Mabuchi I, Kikuchi Y. Mih1/Cdc25 is negatively regulated by Pkc1 inSaccharomyces cerevisiae. Genes Cells 2013; 18:425-41. [DOI: 10.1111/gtc.12047] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 02/13/2013] [Indexed: 11/30/2022]
Affiliation(s)
- Kouitiro Yano
- Department of Biological Sciences, Graduate School of Science; The University of Tokyo; 7-3-1 Hongo; Bunkyo-ku; Tokyo; 113-0033; Japan
| | - Yukifumi Uesono
- Department of Biological Sciences, Graduate School of Science; The University of Tokyo; 7-3-1 Hongo; Bunkyo-ku; Tokyo; 113-0033; Japan
| | - Satoshi Yoshida
- Department of Biology and Rosenstiel Basic Biomedical Sciences Research Center; Brandeis University; 415 South Street; Waltham; MA; 02454; USA
| | - Akihiko Kikuchi
- School of Medicine; Nagoya University; Tsurumai; Shouwa-ku; Nagoya; Aichi; 466-8550; Japan
| | - Jun Kashiwazaki
- Department of Life Science, Faculty of Science; Gakushuin University; 1-5-1 Mejiro; Toshima-ku; Tokyo; 171-8588; Japan
| | - Issei Mabuchi
- Department of Life Science, Faculty of Science; Gakushuin University; 1-5-1 Mejiro; Toshima-ku; Tokyo; 171-8588; Japan
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109
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Barrott JJ, Haystead TAJ. Hsp90, an unlikely ally in the war on cancer. FEBS J 2013; 280:1381-96. [PMID: 23356585 PMCID: PMC3815692 DOI: 10.1111/febs.12147] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 01/10/2013] [Accepted: 01/22/2013] [Indexed: 12/25/2022]
Abstract
On the surface heat shock protein 90 (Hsp90) is an unlikely drug target for the treatment of any disease, let alone cancer. Hsp90 is highly conserved and ubiquitously expressed in all cells. There are two major isoforms α and β encoded by distinct genes and together they may constitute 1%-3% of the cellular protein. Deletion of the protein is embryonic lethal and there are no recognized polymorphisms suggesting an association or causal relationship with any human disease. With respect to cancer, the proteins absence from two recent high profile articles, 'Hallmarks of cancer: the next generation' [Hanahan & Weinberg (2011) Cell 144, 646-674] and 'Comprehensive molecular portraits of human breast tumours' [Koboldt et al. (2012) Nature] underlines the perception that it is an unlikely bona fide target to treat this disease. Yet, to date, there are 17 distinct Hsp90 inhibitors in clinical trials for multiple indications in cancer. The protein has been championed for over 20 years by the National Cancer Institute (Bethesda, MD, USA) as a cancer target since the discovery of the antitumor activity of the natural product geldanamycin. This review aims to look at the conundrum of why Hsp90 can even be considered a druggable target for the treatment of cancer. We propose that in contrast to the majority of chemotherapeutics our growing armamentarium of investigational Hsp90 drugs represents an elegant choice that offers real hope in the long-term treatment of certain cancers.
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Affiliation(s)
- Jared J Barrott
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC 27710, USA
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110
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Cloutier P, Coulombe B. Regulation of molecular chaperones through post-translational modifications: decrypting the chaperone code. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:443-54. [PMID: 23459247 DOI: 10.1016/j.bbagrm.2013.02.010] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Revised: 02/15/2013] [Accepted: 02/19/2013] [Indexed: 12/30/2022]
Abstract
Molecular chaperones and their associated cofactors form a group of highly specialized proteins that orchestrate the folding and unfolding of other proteins and the assembly and disassembly of protein complexes. Chaperones are found in all cell types and organisms, and their activity must be tightly regulated to maintain normal cell function. Indeed, deregulation of protein folding and protein complex assembly is the cause of various human diseases. Here, we present the results of an extensive review of the literature revealing that the post-translational modification (PTM) of chaperones has been selected during evolution as an efficient mean to regulate the activity and specificity of these key proteins. Because the addition and reciprocal removal of chemical groups can be triggered very rapidly, this mechanism provides an efficient switch to precisely regulate the activity of chaperones on specific substrates. The large number of PTMs detected in chaperones suggests that a combinatory code is at play to regulate function, activity, localization, and substrate specificity for this group of biologically important proteins. This review surveys the core information currently available as a starting point toward the more ambitious endeavor of deciphering the "chaperone code".
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111
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Dinkova-Kostova AT. The Role of Sulfhydryl Reactivity of Small Molecules for the Activation of the KEAP1/NRF2 Pathway and the Heat Shock Response. SCIENTIFICA 2012; 2012:606104. [PMID: 24278719 PMCID: PMC3820647 DOI: 10.6064/2012/606104] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 11/07/2012] [Indexed: 05/28/2023]
Abstract
The KEAP1/NRF2 pathway and the heat shock response are two essential cytoprotective mechanisms that allow adaptation and survival under conditions of oxidative, electrophilic, and thermal stress by regulating the expression of elaborate networks of genes with versatile protective functions. The two pathways are independently regulated by the transcription factor nuclear factor-erythroid 2 p45-related factor 2 (NRF2) and heat shock factor 1 (HSF1), respectively. The activity of these transcriptional master regulators increases during conditions of stress and also upon encounter of small molecules (inducers), both naturally occurring as well as synthetically produced. Inducers have a common chemical property: the ability to react with sulfhydryl groups. The protein targets of such sulfhydryl-reactive compounds are equipped with highly reactive cysteine residues, which serve as sensors for inducers. The initial cysteine-sensed signal is further relayed to affect the expression of large networks of genes, which in turn can ultimately influence complex cell fate decisions such as life and death. The paper summarizes the multiple lines of experimental evidence demonstrating that the reactivity with sulfhydryl groups is a major determinant of the mechanism of action of small molecule dual activators of the KEAP1/NRF2 pathway and the heat shock response.
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Affiliation(s)
- Albena T. Dinkova-Kostova
- Jacqui Wood Cancer Centre, Division of Cancer Research, Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, James Arrott Drive, Dundee DD1 9SY, UK
- Department of Pharmacology and Molecular Sciences and Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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112
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Genest O, Reidy M, Street TO, Hoskins JR, Camberg JL, Agard DA, Masison DC, Wickner S. Uncovering a region of heat shock protein 90 important for client binding in E. coli and chaperone function in yeast. Mol Cell 2012; 49:464-73. [PMID: 23260660 DOI: 10.1016/j.molcel.2012.11.017] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 09/28/2012] [Accepted: 11/13/2012] [Indexed: 10/27/2022]
Abstract
The heat shock protein 90 (Hsp90) family of heat shock proteins is an abundantly expressed and highly conserved family of ATP-dependent molecular chaperones. Hsp90 facilitates remodeling and activation of hundreds of proteins. In this study, we developed a screen to identify Hsp90-defective mutants in E. coli. The mutations obtained define a region incorporating residues from the middle and C-terminal domains of E. coli Hsp90. The mutant proteins are defective in chaperone activity and client binding in vitro. We constructed homologous mutations in S. cerevisiae Hsp82 and identified several that caused defects in chaperone activity in vivo and in vitro. However, the Hsp82 mutant proteins were less severely defective in client binding to a model substrate than the corresponding E. coli mutant proteins. Our results identify a region in Hsp90 important for client binding in E. coli Hsp90 and suggest an evolutionary divergence in the mechanism of client interaction by bacterial and yeast Hsp90.
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Affiliation(s)
- Olivier Genest
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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113
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Leach MD, Klipp E, Cowen LE, Brown AJP. Fungal Hsp90: a biological transistor that tunes cellular outputs to thermal inputs. Nat Rev Microbiol 2012; 10:693-704. [PMID: 22976491 DOI: 10.1038/nrmicro2875] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Heat shock protein 90 (HSP90) is an essential, abundant and ubiquitous eukaryotic chaperone that has crucial roles in protein folding and modulates the activities of key regulators. The fungal Hsp90 interactome, which includes numerous client proteins such as receptors, protein kinases and transcription factors, displays a surprisingly high degree of plasticity that depends on environmental conditions. Furthermore, although fungal Hsp90 levels increase following environmental challenges, Hsp90 activity is tightly controlled via post-translational regulation and an autoregulatory loop involving heat shock transcription factor 1 (Hsf1). In this Review, we discuss the roles and regulation of fungal Hsp90. We propose that Hsp90 acts as a biological transistor that modulates the activity of fungal signalling networks in response to environmental cues via this Hsf1-Hsp90 autoregulatory loop.
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Affiliation(s)
- Michelle D Leach
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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114
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Hong DS, Banerji U, Tavana B, George GC, Aaron J, Kurzrock R. Targeting the molecular chaperone heat shock protein 90 (HSP90): lessons learned and future directions. Cancer Treat Rev 2012. [PMID: 23199899 DOI: 10.1016/j.ctrv.2012.10.001] [Citation(s) in RCA: 198] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Due to the critical role of heat shock protein 90 (HSP90) in regulating the stability, activity and intracellular sorting of its client proteins involved in multiple oncogenic processes, HSP90 inhibitors are promising therapeutic agents for cancer treatment. In cancer cells, HSP90 client proteins play a major role in oncogenic signal transduction (i.e., mutant epidermal growth factor receptor), angiogenesis (i.e., vascular endothelial growth factor), anti-apoptosis (i.e., AKT), and metastasis (i.e., matrix metalloproteinase 2 and CD91), processes central to maintaining the cancer phenotype. Thus, HSP90 has emerged as a viable target for antitumor drug development, and several HSP90 inhibitors have transitioned to clinical trials. HSP90 inhibitors include geldanamycin and its derivatives (i.e., tanespimycin, alvespimycin, IPI-504), synthetic and small molecule inhibitors (i.e., AUY922, AT13387, STA9090, MPC3100), other inhibitors of HSP90 and its isoforms (i.e., shepherdin and 5'-N-ethylcarboxamideadenosine). With more than 200 "client" proteins, many of them meta-stable and oncogenic, HSP90 inhibition can affect an array of tumors. Here we review the molecular structure of HSP90, structural features of HSP90 inhibition, pharmacodynamic effects and tumor responses in clinical trials of HSP90 inhibitors. We also discuss lessons learned from completed clinical trials of HSP90 inhibitors, and future directions for these promising therapeutic agents.
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Affiliation(s)
- David S Hong
- Department of Investigational Cancer Therapeutics, Division of Cancer Medicine, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA.
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115
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Armstrong H, Wolmarans A, Mercier R, Mai B, LaPointe P. The co-chaperone Hch1 regulates Hsp90 function differently than its homologue Aha1 and confers sensitivity to yeast to the Hsp90 inhibitor NVP-AUY922. PLoS One 2012; 7:e49322. [PMID: 23166640 PMCID: PMC3498168 DOI: 10.1371/journal.pone.0049322] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 10/10/2012] [Indexed: 12/23/2022] Open
Abstract
Hsp90 is a dimeric ATPase responsible for the activation or maturation of a specific set of substrate proteins termed 'clients'. This molecular chaperone acts in the context of a structurally dynamic and highly regulated cycle involving ATP, co-chaperone proteins and clients. Co-chaperone proteins regulate conformational transitions that may be impaired in mutant forms of Hsp90. We report here that the in vivo impairment of commonly studied Hsp90 variants harbouring the G313S or A587T mutation are exacerbated by the co-chaperone Hch1p. Deletion of HCH1, but not AHA1, mitigates the temperature sensitive phenotype and high sensitivity to Hsp90 inhibitor drugs observed in Saccharomyces cerevisiae that express either of these two Hsp90 variants. Moreover, the deletion of HCH1 results in high resistance to Hsp90 inhibitors in yeast that express wildtype Hsp90. Conversely, the overexpression of Hch1p greatly increases sensitivity to Hsp90 inhibition in yeast expressing wildtype Hsp90. We conclude that despite the similarity between these two co-chaperones, Hch1p and Aha1p regulate Hsp90 function in distinct ways and likely independent of their roles as ATPase stimulators. We further conclude that Hch1p plays a critical role in regulating Hsp90 inhibitor drug sensitivity in yeast.
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Affiliation(s)
- Heather Armstrong
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Annemarie Wolmarans
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Rebecca Mercier
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - BaoChan Mai
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Paul LaPointe
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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116
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Giessrigl B, Krieger S, Rosner M, Huttary N, Saiko P, Alami M, Messaoudi S, Peyrat JF, Maciuk A, Gollinger M, Kopf S, Kazlauskas E, Mazal P, Szekeres T, Hengstschläger M, Matulis D, Jäger W, Krupitza G. Hsp90 stabilizes Cdc25A and counteracts heat shock-mediated Cdc25A degradation and cell-cycle attenuation in pancreatic carcinoma cells. Hum Mol Genet 2012; 21:4615-27. [PMID: 22843495 DOI: 10.1093/hmg/dds303] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Pancreas cancer cells escape most treatment options. Heat shock protein (Hsp)90 is frequently over-expressed in pancreas carcinomas and protects a number of cell-cycle regulators such as the proto-oncogene Cdc25A. We show that inhibition of Hsp90 with geldanamycin (GD) destabilizes Cdc25A independent of Chk1/2, whereas the standard drug for pancreas carcinoma treatment, gemcitabine (GEM), causes Cdc25A degradation through the activation of Chk2. Both agents applied together additively inhibit the expression of Cdc25A and the proliferation of pancreas carcinoma cells thereby demonstrating that both Cdc25A-destabilizing/degrading pathways are separated. The role of Hsp90 as stabilizer of Cdc25A in pancreas carcinoma cells is further supported by two novel synthetic inhibitors 4-tosylcyclonovobiocic acid and 7-tosylcyclonovobiocic acid and specific Hsp90AB1 (Hsp90β) shRNA. Our data show that targeting Hsp90 reduced the resistance of pancreas carcinoma cells to treatment with GEM.
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Affiliation(s)
- Benedikt Giessrigl
- 1Institute of Clinical Pathology, Medical University of Vienna, General Hospital of Vienna, Waehringer Guertel 18-20, Vienna A-1090, Austria
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117
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Robbins N, Leach MD, Cowen LE. Lysine deacetylases Hda1 and Rpd3 regulate Hsp90 function thereby governing fungal drug resistance. Cell Rep 2012; 2:878-88. [PMID: 23041319 PMCID: PMC3607219 DOI: 10.1016/j.celrep.2012.08.035] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 06/26/2012] [Accepted: 08/30/2012] [Indexed: 12/03/2022] Open
Abstract
The molecular chaperone Hsp90 is a hub of protein homeostasis and regulatory circuitry. Hsp90 function is regulated by posttranslational modifications including acetylation in mammals; however, whether this regulation is conserved remains unknown. In fungi, Hsp90 governs the evolution of drug resistance by stabilizing signal transducers. Here, we establish that pharmacological inhibition of lysine deacetylases (KDACs) blocks the emergence and maintenance of Hsp90-dependent resistance to the most widely deployed antifungals, the azoles, in the human fungal pathogen Candida albicans and the model yeast Saccharomyces cerevisiae. S. cerevisiae Hsp90 is acetylated on lysine 27 and 270, and key KDACs for drug resistance are Hda1 and Rpd3. Compromising KDACs alters stability and function of Hsp90 client proteins, including the drug-resistance regulator calcineurin. Thus, we establish acetylation as a mechanism of posttranslational control of Hsp90 function in fungi, functional redundancy between KDACs Hda1 and Rpd3, as well as a mechanism governing fungal drug resistance with broad therapeutic potential.
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Affiliation(s)
- Nicole Robbins
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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118
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Lokeshwar VB. Wee1-Hsp90 inhibitor combination treatment: molecular therapy with potentially broad applicability. Cell Cycle 2012; 11:3722-3. [PMID: 22983000 PMCID: PMC3495812 DOI: 10.4161/cc.22119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Vinata B Lokeshwar
- Division of Urology Research, Department of Urology and Cell Biology, University of Miami Miller School of Medicine, Miami, FL, USA.
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119
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Iwai A, Bourboulia D, Mollapour M, Jensen-Taubman S, Lee S, Donnelly AC, Yoshida S, Miyajima N, Tsutsumi S, Smith AK, Sun D, Wu X, Blagg BS, Trepel JB, Stetler-Stevenson WG, Neckers L. Combined inhibition of Wee1 and Hsp90 activates intrinsic apoptosis in cancer cells. Cell Cycle 2012; 11:3649-55. [PMID: 22935698 DOI: 10.4161/cc.21926] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Heat shock protein 90 (Hsp90) is an essential, evolutionarily conserved molecular chaperone. Cancer cells rely on Hsp90 to chaperone mutated and/or activated oncoproteins, and its involvement in numerous signaling pathways makes it an attractive target for drug development. Surprisingly, however, the impact of Hsp90 inhibitors on cancer cells is frequently cytostatic in nature, and efforts to enhance the antitumor activity of Hsp90 inhibitors in the clinic remain a significant challenge. In agreement with previous data obtained using Wee1 siRNA, we show that dual pharmacologic inhibition of Wee1 tyrosine kinase and Hsp90 causes cancer cells to undergo apoptosis in vitro and in vivo. Gene expression profiling revealed that induction of the intrinsic apoptotic pathway by this drug combination coincided with transcriptional downregulation of Survivin and Wee1, an outcome not seen in cells treated separately with either agent. At the translational level, expression of these two proteins, as well as activated Akt, was completely abrogated. These data support the hypothesis that Wee1 inhibition sensitizes cancer cells to Hsp90 inhibitors; they establish combined Wee1/Hsp90 inhibition as a novel therapeutic strategy; and they provide a mechanistic rationale for enhancing the pro-apoptotic activity of Hsp90 inhibitors.
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Affiliation(s)
- Aki Iwai
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
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120
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H2B Tyr37 phosphorylation suppresses expression of replication-dependent core histone genes. Nat Struct Mol Biol 2012; 19:930-7. [PMID: 22885324 DOI: 10.1038/nsmb.2356] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 07/09/2012] [Indexed: 01/12/2023]
Abstract
Histone gene transcription is actively downregulated after completion of DNA synthesis to avoid overproduction. However, the precise mechanistic details of the cessation of histone mRNA synthesis are not clear. We found that histone H2B phosphorylation at Tyr37 occurs upstream of histone cluster 1, Hist1, during the late S phase. We identified WEE1 as the kinase that phosphorylates H2B at Tyr37. Loss of expression or inhibition of WEE1 kinase abrogated H2B Tyr37 phosphorylation with a concomitant increase in histone transcription in yeast and mammalian cells. H2B Tyr37 phosphorylation excluded binding of the transcriptional coactivator NPAT and RNA polymerase II and recruited the histone chaperone HIRA upstream of the Hist1 cluster. Taken together, our data show a previously unknown and evolutionarily conserved function for WEE1 kinase as an epigenetic modulator that marks chromatin with H2B Tyr37 phosphorylation, thereby inhibiting the transcription of multiple histone genes to lower the burden on the histone mRNA turnover machinery.
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121
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122
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Desjardins F, Delisle C, Gratton JP. Modulation of the cochaperone AHA1 regulates heat-shock protein 90 and endothelial NO synthase activation by vascular endothelial growth factor. Arterioscler Thromb Vasc Biol 2012; 32:2484-92. [PMID: 22859491 DOI: 10.1161/atvbaha.112.256008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Vascular endothelial growth factor (VEGF) signaling to endothelial NO synthase (eNOS) plays a central role in angiogenesis. In endothelial cells (ECs), heat-shock protein 90 (Hsp90) is also a regulator of eNOS activity. Our study is designed to determine whether modulation of the activator of Hsp90 ATPase 1 (AHA1) regulates the function of Hsp90 in ECs. METHODS AND RESULTS We show that eNOS phosphorylation on Ser-1179 after VEGF stimulation is significantly reduced in ECs transfected with a small interfering RNA against AHA1. Accordingly, VEGF-stimulated NO production, endothelial permeability, cell migration, and EC invasion in Matrigel implants in mice are reduced in small interfering RNA against AHA1-treated conditions. Furthermore, the induction of eNOS association with Hsp90 after VEGF stimulation is decreased in AHA1-downregulated cells. We also demonstrate that modulation of Hsp90 activity by AHA1 regulates phosphorylation of Hsp90 on Tyr-300. Interestingly, the association of AHA1 with Hsp90 is increased after c-Src-mediated phosphorylation of Hsp90 on Tyr-300. Finally, we show that overexpression of AHA1 in ECs promotes association of eNOS and Hsp90, phosphorylation of Ser-1179 of eNOS, increases NO production, and cell migration. CONCLUSIONS These results reveal that modulation of Hsp90 activity by AHA1 regulates VEGF signaling to eNOS and angiogenesis.
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123
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C-terminal phosphorylation of Hsp70 and Hsp90 regulates alternate binding to co-chaperones CHIP and HOP to determine cellular protein folding/degradation balances. Oncogene 2012; 32:3101-10. [PMID: 22824801 DOI: 10.1038/onc.2012.314] [Citation(s) in RCA: 151] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Heat shock proteins Hsp90 and Hsp70 facilitate protein folding but can also direct proteins for ubiquitin-mediated degradation. The mechanisms regulating these opposite activities involve Hsp binding to co-chaperones including CHIP and HOP at their C-termini. We demonstrated that the extreme C-termini of Hsp70 and Hsp90 contain phosphorylation sites targeted by kinases including CK1, CK2 and GSK3-β in vitro. The phosphorylation of Hsp90 and Hsp70 prevents binding to CHIP and thus enhances binding to HOP. Highly proliferative cells contain phosphorylated chaperones in complex with HOP and phospho-mimetic and non-phosphorylable Hsp mutant proteins show that phosphorylation is directly associated with increased proliferation rate. We also demonstrate that primary human cancers contain high levels of phosphorylated chaperones and show increased levels of HOP protein and mRNA. These data identify C-terminal phosphorylation of Hsp70 and Hsp90 as a switch for regulating co-chaperone binding and indicate that cancer cells possess an elevated protein folding environment by the concerted action of co-chaperone expression and chaperone modifications. In addition to identifying the pathway responsible for regulating chaperone-mediated protein folding/degradation balances in normal cells, the data provide novel mechanisms to account for the aberrant chaperone activities observed in human cancer cells and have implications for the application of anti-chaperone therapies in cancer treatment.
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124
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Dixit A, Verkhivker GM. Probing molecular mechanisms of the Hsp90 chaperone: biophysical modeling identifies key regulators of functional dynamics. PLoS One 2012; 7:e37605. [PMID: 22624053 PMCID: PMC3356286 DOI: 10.1371/journal.pone.0037605] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Accepted: 04/24/2012] [Indexed: 12/26/2022] Open
Abstract
Deciphering functional mechanisms of the Hsp90 chaperone machinery is an important objective in cancer biology aiming to facilitate discovery of targeted anti-cancer therapies. Despite significant advances in understanding structure and function of molecular chaperones, organizing molecular principles that control the relationship between conformational diversity and functional mechanisms of the Hsp90 activity lack a sufficient quantitative characterization. We combined molecular dynamics simulations, principal component analysis, the energy landscape model and structure-functional analysis of Hsp90 regulatory interactions to systematically investigate functional dynamics of the molecular chaperone. This approach has identified a network of conserved regions common to the Hsp90 chaperones that could play a universal role in coordinating functional dynamics, principal collective motions and allosteric signaling of Hsp90. We have found that these functional motifs may be utilized by the molecular chaperone machinery to act collectively as central regulators of Hsp90 dynamics and activity, including the inter-domain communications, control of ATP hydrolysis, and protein client binding. These findings have provided support to a long-standing assertion that allosteric regulation and catalysis may have emerged via common evolutionary routes. The interaction networks regulating functional motions of Hsp90 may be determined by the inherent structural architecture of the molecular chaperone. At the same time, the thermodynamics-based "conformational selection" of functional states is likely to be activated based on the nature of the binding partner. This mechanistic model of Hsp90 dynamics and function is consistent with the notion that allosteric networks orchestrating cooperative protein motions can be formed by evolutionary conserved and sparsely connected residue clusters. Hence, allosteric signaling through a small network of distantly connected residue clusters may be a rather general functional requirement encoded across molecular chaperones. The obtained insights may be useful in guiding discovery of allosteric Hsp90 inhibitors targeting protein interfaces with co-chaperones and protein binding clients.
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Affiliation(s)
- Anshuman Dixit
- Department of Pharmaceutical Chemistry, School of Pharmacy, The University of Kansas, Lawrence, Kansas, United States of America
| | - Gennady M. Verkhivker
- School of Computational Sciences and Crean School of Health and Life Sciences, Schmid College of Science and Technology, Chapman University, Orange, California, United States of America
- Department of Pharmacology, University of California San Diego, La Jolla, California, United States of America
- * E-mail:
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125
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Soroka J, Buchner J. Mechanistic aspects of the Hsp90 phosphoregulation. Cell Cycle 2012; 11:1870-1. [PMID: 22544316 DOI: 10.4161/cc.20418] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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126
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Hughes PF, Barrott JJ, Carlson DA, Loiselle DR, Speer BL, Bodoor K, Rund LA, Haystead TAJ. A highly selective Hsp90 affinity chromatography resin with a cleavable linker. Bioorg Med Chem 2012; 20:3298-305. [PMID: 22520629 DOI: 10.1016/j.bmc.2012.03.043] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 03/14/2012] [Accepted: 03/21/2012] [Indexed: 10/28/2022]
Abstract
Over 200 proteins have been identified that interact with the protein chaperone Hsp90, a recognized therapeutic target thought to participate in non-oncogene addiction in a variety of human cancers. However, defining Hsp90 clients is challenging because interactions between Hsp90 and its physiologically relevant targets involve low affinity binding and are thought to be transient. Using a chemo-proteomic strategy, we have developed a novel orthogonally cleavable Hsp90 affinity resin that allows purification of the native protein and is quite selective for Hsp90 over its immediate family members, GRP94 and TRAP 1. We show that the resin can be used under low stringency conditions for the rapid, unambiguous capture of native Hsp90 in complex with a native client. We also show that the choice of linker used to tether the ligand to the insoluble support can have a dramatic effect on the selectivity of the affinity media.
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Affiliation(s)
- Philip F Hughes
- Department of Pharmacology and Cancer Biology, C119 LSRC, Research Drive, Duke University, Durham, NC 27710, United States
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127
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Mollapour M, Neckers L. Post-translational modifications of Hsp90 and their contributions to chaperone regulation. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1823:648-55. [PMID: 21856339 PMCID: PMC3226900 DOI: 10.1016/j.bbamcr.2011.07.018] [Citation(s) in RCA: 228] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 07/21/2011] [Accepted: 07/27/2011] [Indexed: 12/20/2022]
Abstract
Molecular chaperones, as the name suggests, are involved in folding, maintenance, intracellular transport, and degradation of proteins as well as in facilitating cell signaling. Heat shock protein 90 (Hsp90) is an essential eukaryotic molecular chaperone that carries out these processes in normal and cancer cells. Hsp90 function in vivo is coupled to its ability to hydrolyze ATP and this can be regulated by co-chaperones and post-translational modifications. In this review, we explore the varied roles of known post-translational modifications of cytosolic and nuclear Hsp90 (phosphorylation, acetylation, S-nitrosylation, oxidation and ubiquitination) in fine-tuning chaperone function in eukaryotes. This article is part of a Special Issue entitled: Heat Shock Protein 90 (HSP90).
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Affiliation(s)
- Mehdi Mollapour
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Len Neckers
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD 20892, USA
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128
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Prodromou C. The 'active life' of Hsp90 complexes. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1823:614-23. [PMID: 21840346 PMCID: PMC3793855 DOI: 10.1016/j.bbamcr.2011.07.020] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 07/27/2011] [Accepted: 07/29/2011] [Indexed: 12/02/2022]
Abstract
Hsp90 forms a variety of complexes differing both in clientele and co-chaperones. Central to the role of co-chaperones in the formation of Hsp90 complexes is the delivery of client proteins and the regulation of the ATPase activity of Hsp90. Determining the mechanisms by which co-chaperones regulate Hsp90 is essential in understanding the assembly of these complexes and the activation and maturation of Hsp90's clientele. Mechanistically, co-chaperones alter the kinetics of the ATP-coupled conformational changes of Hsp90. The structural changes leading to the formation of a catalytically active unit involve all regions of the Hsp90 dimer. Their complexity has allowed different orthologues of Hsp90 to evolve kinetically in slightly different ways. The interaction of the cytosolic Hsp90 with a variety of co-chaperones lends itself to a complex set of different regulatory mechanisms that modulate Hsp90's conformation and ATPase activity. It also appears that the conformational switches of Hsp90 are not necessarily coupled under all circumstances. Here, I described different co-chaperone complexes and then discuss in detail the mechanisms and role that specific co-chaperones play in this. I will also discuss emerging evidence that post-translational modifications also affect the ATPase activity of Hsp90, and thus complex formation. Finally, I will present evidence showing how Hsp90's active site, although being highly conserved, can be altered to show resistance to drug binding, but still maintain ATP binding and ATPase activity. Such changes are therefore unlikely to significantly alter Hsp90's interactions with client proteins and co-chaperones. This article is part of a Special Issue entitled: Heat Shock Protein 90 (HSP90).
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129
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Thr90 phosphorylation of Hsp90α by protein kinase A regulates its chaperone machinery. Biochem J 2012; 441:387-97. [PMID: 21919888 DOI: 10.1042/bj20110855] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Hsp90 (heat-shock protein 90) is one of the most important molecular chaperones in eukaryotes. Hsp90 facilitates the maturation, activation or degradation of its client proteins. It is now well accepted that both ATP binding and co-chaperone association are involved in regulating the Hsp90 chaperone machinery. However, other factors such as post-translational modifications are becoming increasingly recognized as being involved in this process. Recent studies have reported that phosphorylation of Hsp90 plays an unanticipated role in this process. In the present study, we systematically investigated the impact of phosphorylation of a single residue (Thr90) of Hsp90α (pThr90-Hsp90α) on its chaperone machinery. We demonstrate that protein kinase A specifically phosphorylates Hsp90α at Thr90, and that the pThr9090-Hsp90α level is significantly elevated in proliferating cells. Thr90 phosphorylation affects the binding affinity of Hsp90α to ATP. Subsequent examination of the interactions of Hsp90α with co-chaperones reveals that Thr90 phosphorylation specifically regulates the association of a subset of co-chaperones with Hsp90α. The Hsp90α T90E phosphor-mimic mutant exhibits increased association with Aha1 (activator of Hsp90 ATPase homologue 1), p23, PP5 (protein phosphatase 5) and CHIP (C-terminus of Hsp70-interacting protein), and decreased binding affinity with Hsp70, Cdc37 (cell division cycle 37) and Hop [Hsc70 (heat-shock cognate protein 70)/Hsp90-organizing protein], whereas its interaction with FKBP52 (FK506-binding protein 4) is only moderately affected. Moreover, we find that the ability of the T90E mutant to form complexes with its clients, such as Src, Akt or PKCγ (protein kinase Cγ), is dramatically impaired, suggesting that phosphorylation affects its chaperoning activity. Taken together, the results of the present study demonstrate that Thr90 phosphorylation is actively engaged in the regulation of the Hsp90α chaperone machinery and should be a generic determinant for the cycling of Hsp90α chaperone function.
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130
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Soroka J, Wandinger S, Mäusbacher N, Schreiber T, Richter K, Daub H, Buchner J. Conformational Switching of the Molecular Chaperone Hsp90 via Regulated Phosphorylation. Mol Cell 2012; 45:517-28. [DOI: 10.1016/j.molcel.2011.12.031] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 09/26/2011] [Accepted: 12/05/2011] [Indexed: 11/26/2022]
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131
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da Silva VCH, Ramos CHI. The network interaction of the human cytosolic 90 kDa heat shock protein Hsp90: A target for cancer therapeutics. J Proteomics 2012; 75:2790-802. [PMID: 22236519 DOI: 10.1016/j.jprot.2011.12.028] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 12/18/2011] [Accepted: 12/19/2011] [Indexed: 10/14/2022]
Abstract
In the cell, proteins interact within a network in which a small number of proteins are highly connected nodes or hubs. A disturbance in the hub proteins usually has a higher impact on the cell physiology than a disturbance in poorly connected nodes. In eukaryotes, the cytosolic Hsp90 is considered to be a hub protein as it interacts with molecular chaperones and co-chaperones, and has key regulatory proteins as clients, such as transcriptional factors, protein kinases and hormone receptors. The large number of Hsp90 partners suggests that Hsp90 is involved in very important functions, such as signaling, proteostasis and epigenetics. Some of these functions are dysregulated in cancer, making Hsp90 a potential target for therapeutics. The number of Hsp90 interactors appears to be so large that a precise answer to the question of how many proteins interact with this chaperone has no definitive answer yet, not even if the question refers to specific Hsp90s as one of the human cytosolic forms. Here we review the major chaperones and co-chaperones that interact with cytosolic Hsp90s, highlighting the latest findings regarding client proteins and the role that posttranslational modifications have on the function and interactions of these molecular chaperones. This article is part of a Special Issue entitled: Proteomics: The clinical link.
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Affiliation(s)
- Viviane C H da Silva
- Institute of Chemistry, University of Campinas-UNICAMP. P.O. Box 6154, 13083-970, Campinas, SP, Brazil
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132
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Abstract
Heat shock protein (Hsp) 90 is an ATP-dependent molecular chaperone that is exploited by malignant cells to support activated oncoproteins, including many cancer-associated kinases and transcription factors, and it is essential for oncogenic transformation. Originally viewed with skepticism, Hsp90 inhibitors are now being actively pursued by the pharmaceutical industry, with 17 agents having entered clinical trials. Investigators established Hsp90's druggability using the natural products geldanamycin and radicicol, which mimic the unusual ATP structure adopted in the chaperone's N-terminal nucleotide-binding pocket and cause potent and selective blockade of ATP binding/hydrolysis, inhibit chaperone function, deplete oncogenic clients, and show antitumor activity. Preclinical data obtained with these natural products have heightened interest in Hsp90 as a drug target, and 17-allylamino-17-demethoxygeldanamycin (17-AAG, tanespimycin) has shown clinical activity (as defined by Response Evaluation Criteria in Solid Tumors) in HER2+ breast cancer. Many optimized synthetic, small-molecule Hsp90 inhibitors from diverse chemotypes are now in clinical trials. Here, we review the discovery and development of Hsp90 inhibitors and assess their potential. There has been significant learning from studies of the basic biology of Hsp90, as well as translational drug development involving this chaperone, enhanced by the use of Hsp90 inhibitors as chemical probes. Success will likely lie in treating cancers that are addicted to particular driver oncogene products (e.g., HER2, ALK, EGFR, and BRAF) that are sensitive Hsp90 clients, as well as malignancies (especially multiple myeloma) in which buffering of proteotoxic stress is critical for survival. We discuss approaches for enhancing the effectiveness of Hsp90 inhibitors and highlight new chaperone and stress-response pathway targets, including HSF1 and Hsp70.
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Affiliation(s)
- Len Neckers
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike Bldg. 10/CRC, Room 1-5940, Bethesda, MD 20892-1107 USA
| | - Paul Workman
- Signal Transduction and Molecular Pharmacology Team, Cancer Research UK Cancer Therapeutics Unit, Division of Cancer Therapeutics, The Institute of Cancer Research, Haddow Laboratories, 15 Cotswold Road, Sutton SM2 5NG UK
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Abstract
Hsp90 is a highly abundant and ubiquitous molecular chaperone which plays an essential role in many cellular processes including cell cycle control, cell survival, hormone and other signalling pathways. It is important for the cell's response to stress and is a key player in maintaining cellular homeostasis. In the last ten years, it has become a major therapeutic target for cancer, and there has also been increasing interest in it as a therapeutic target in neurodegenerative disorders, and in the development of anti-virals and anti-protozoan infections. The focus of this review is the structural and mechanistic studies which have been performed in order to understand how this important chaperone acts on a wide variety of different proteins (its client proteins) and cellular processes. As with many of the other classes of molecular chaperone, Hsp90 has a critical ATPase activity, and ATP binding and hydrolysis known to modulate the conformational dynamics of the protein. It also uses a host of cochaperones which not only regulate the ATPase activity and conformational dynamics but which also mediate interactions with Hsp90 client proteins. The system is also regulated by post-translational modifications including phosphorylation and acetylation. This review discusses all these aspects of Hsp90 structure and function.
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134
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Abstract
A common need for microbial cells is the ability to respond to potentially toxic environmental insults. Here we review the progress in understanding the response of the yeast Saccharomyces cerevisiae to two important environmental stresses: heat shock and oxidative stress. Both of these stresses are fundamental challenges that microbes of all types will experience. The study of these environmental stress responses in S. cerevisiae has illuminated many of the features now viewed as central to our understanding of eukaryotic cell biology. Transcriptional activation plays an important role in driving the multifaceted reaction to elevated temperature and levels of reactive oxygen species. Advances provided by the development of whole genome analyses have led to an appreciation of the global reorganization of gene expression and its integration between different stress regimens. While the precise nature of the signal eliciting the heat shock response remains elusive, recent progress in the understanding of induction of the oxidative stress response is summarized here. Although these stress conditions represent ancient challenges to S. cerevisiae and other microbes, much remains to be learned about the mechanisms dedicated to dealing with these environmental parameters.
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135
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Senn H, Shapiro RS, Cowen LE. Cdc28 provides a molecular link between Hsp90, morphogenesis, and cell cycle progression in Candida albicans. Mol Biol Cell 2011; 23:268-83. [PMID: 22090345 PMCID: PMC3258172 DOI: 10.1091/mbc.e11-08-0729] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The molecular chaperone Hsp90 regulates morphogenesis of the leading human fungal pathogen Candida albicans. Hsp90 inhibition induces filaments with a delay in mitotic exit mediated by the checkpoint protein Bub2. Hsp90 depletion destabilizes the cyclin-dependent kinase Cdc28, providing a link between Hsp90, cell cycle regulation, and morphogenesis. The trimorphic fungus Candida albicans is the leading cause of systemic candidiasis, a disease with poor prognosis affecting immunocompromised individuals. The capacity of C. albicans to transition between morphological states is a key determinant of its ability to cause life-threatening infection. Recently the molecular chaperone heat shock protein 90 (Hsp90) was implicated as a major regulator of temperature-dependent C. albicans morphogenesis; compromising Hsp90 function induces filamentation and relieves repression of Ras1–protein kinase A (PKA) signaling, although the mechanism involved remains unknown. Here we demonstrate that filaments generated by compromise of Hsp90 function are neither pseudohyphae nor hyphae but closely resemble filaments formed in response to cell cycle arrest. Closer examination revealed that these filaments exhibit a delay in mitotic exit mediated by the checkpoint protein Bub2. Furthermore, Hsp90 inhibition also led to a distinct morphology with defects in cytokinesis. We found that the cyclin-dependent kinase Cdc28 was destabilized in response to depletion of Hsp90 and that Cdc28 physically interacts with Hsp90, implicating this major cell cycle regulator as a novel Hsp90 client protein in C. albicans. Taken together, our results suggest that Hsp90 is instrumental in the regulation of cell division during yeast-form growth in C. albicans and exerts its major effects during late cell cycle events.
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Affiliation(s)
- Heather Senn
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
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136
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Mechanisms of Resistance to Hsp90 Inhibitor Drugs: A Complex Mosaic Emerges. Pharmaceuticals (Basel) 2011; 4:1400-1422. [PMID: 27721330 PMCID: PMC4060131 DOI: 10.3390/ph4111400] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 10/04/2011] [Accepted: 10/17/2011] [Indexed: 01/07/2023] Open
Abstract
The molecular chaperone Hsp90 holds great promise as a cancer drug target, despite some of the initial clinical trials of Hsp90 inhibitor drugs having not lived up to expectation. Effective use of these drugs will benefit greatly from a much more detailed understanding of the factors that contribute to resistance, whether intrinsic or acquired. We review how cell culture studies have revealed a number of different mechanisms whereby cells can be rendered less susceptible to the effects of Hsp90 inhibitor treatment. A major influence is Hsp90 inhibition causing strong induction of the heat shock response, a stress response that increases cellular levels of prosurvival chaperones such as Hsp27 and Hsp70. Another problem seems to be that these inhibitors do not always access the Hsp90 proteins of the mitochondrion, forms of Hsp90 that—in cancer cells—are operating to suppress apoptosis. It should be possible to overcome these drawbacks through the appropriate drug redesign or with the combinatorial use of an Hsp90 inhibitor with a drug that targets either heat shock factor or the chaperone Hsp70. Still though, cells will often differ in the key antiapoptotic versus proapoptotic activities that are dependent on Hsp90, in the key steps in their apoptotic pathways responsive to Hsp90 inhibition or Hsp70 level, as well as the extents to which their survival is dependent on oncogenic tyrosine kinases that are clients of Hsp90. A systems approach will therefore often be required in order to establish the most prominent effects of Hsp90 inhibition in each type of cancer cell.
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137
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Mollapour M, Tsutsumi S, Kim YS, Trepel J, Neckers L. Casein kinase 2 phosphorylation of Hsp90 threonine 22 modulates chaperone function and drug sensitivity. Oncotarget 2011; 2:407-17. [PMID: 21576760 PMCID: PMC3248188 DOI: 10.18632/oncotarget.272] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The molecular chaperone Heat Shock Protein 90 (Hsp90) is essential for the function of various oncoproteins that are vital components of multiple signaling networks regulating cancer cell proliferation, survival, and metastasis. Hsp90 chaperone function is coupled to its ATPase activity, which can be inhibited by natural products such as the ansamycin geldanamycin (GA) and the resorcinol radicicol (RD). These compounds have served as templates for development of numerous natural product Hsp90 inhibitors. More recently, second generation, fully synthetic Hsp90 inhibitors, based on a variety of chemical scaffolds, have also been synthesized. Together, 18 natural product and synthetic Hsp90 inhibitors have entered clinical trial in cancer patients. To successfully develop Hsp90 inhibitors for oncology indications it is important to understand the factors that influence the susceptibility of Hsp90 to these drugs in vivo. We recently reported that Casein Kinase 2 phosphorylates a conserved threonine residue (T22) in helix-1 of the yeast Hsp90 N-domain both in vitro and in vivo. Phosphorylation of this residue reduces ATPase activity and affects Hsp90 chaperone function. Here, we present additional data demonstrating that ATP binding but not N-domain dimerization is a prerequisite for T22 phosphorylation. We also provide evidence that T22 is an important determinant of Hsp90 inhibitor sensitivity in yeast and we show that T22 phosphorylation status contributes to drug sensitivity in vivo.
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Affiliation(s)
- Mehdi Mollapour
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA.
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138
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HSP90 functions in the circadian clock through stabilization of the client F-box protein ZEITLUPE. Proc Natl Acad Sci U S A 2011; 108:16843-8. [PMID: 21949396 DOI: 10.1073/pnas.1110406108] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The autoregulatory loops of the circadian clock consist of feedback regulation of transcription/translation circuits but also require finely coordinated cytoplasmic and nuclear proteostasis. Although protein degradation is important to establish steady-state levels, maturation into their active conformation also factors into protein homeostasis. HSP90 facilitates the maturation of a wide range of client proteins, and studies in metazoan clocks implicate HSP90 as an integrator of input or output. Here we show that the Arabidopsis circadian clock-associated F-box protein ZEITLUPE (ZTL) is a unique client for cytoplasmic HSP90. The HSP90-specific inhibitor geldanamycin and RNAi-mediated depletion of cytoplasmic HSP90 reduces levels of ZTL and lengthens circadian period, consistent with ztl loss-of-function alleles. Transient transfection of artificial microRNA targeting cytoplasmic HSP90 genes similarly lengthens period. Proteolytic targets of SCF(ZTL), TOC1 and PRR5, are stabilized in geldanamycin-treated seedlings, whereas the levels of closely related clock proteins, PRR3 and PRR7, are unchanged. An in vitro holdase assay, typically used to demonstrate chaperone activity, shows that ZTL can be effectively bound, and aggregation prevented, by HSP90. GIGANTEA, a unique stabilizer of ZTL, may act in the same pathway as HSP90, possibly linking these two proteins to a similar mechanism. Our findings establish maturation of ZTL by HSP90 as essential for proper function of the Arabidopsis circadian clock. Unlike metazoan systems, HSP90 functions here within the core oscillator. Additionally, F-box proteins as clients may place HSP90 in a unique and more central role in proteostasis.
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139
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Li J, Soroka J, Buchner J. The Hsp90 chaperone machinery: conformational dynamics and regulation by co-chaperones. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1823:624-35. [PMID: 21951723 DOI: 10.1016/j.bbamcr.2011.09.003] [Citation(s) in RCA: 368] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Revised: 09/07/2011] [Accepted: 09/08/2011] [Indexed: 11/24/2022]
Abstract
Hsp90 is a dimeric molecular chaperone required for the activation and stabilization of numerous client proteins many of which are involved in essential cellular processes like signal transduction pathways. This activation process is regulated by ATP-induced large conformational changes, co-chaperones and posttranslational modifications. For some co-chaperones, a detailed picture on their structures and functions exists, for others their contributions to the Hsp90 system is still unclear. Recent progress on the conformational dynamics of Hsp90 and how co-chaperones affect the Hsp90 chaperone cycle significantly increased our understanding of the gearings of this complex molecular machinery. This article is part of a Special Issue entitled: Heat Shock Protein 90 (Hsp90).
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Affiliation(s)
- Jing Li
- Technische Universitat, Munchen, Germany
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140
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Abstract
The ubiquitous molecular chaperone Hsp90 makes up 1-2% of cytosolic proteins and is required for viability in eukaryotes. Hsp90 affects the folding and activation of a wide variety of substrate proteins including many involved in signaling and regulatory processes. Some of these substrates are implicated in cancer and other diseases, making Hsp90 an attractive drug target. Structural analyses have shown that Hsp90 is a highly dynamic and flexible molecule that can adopt a wide variety of structurally distinct states. One driving force for these rearrangements is the intrinsic ATPase activity of Hsp90, as seen with other chaperones. However, unlike other chaperones, studies have shown that the ATPase cycle of Hsp90 is not conformationally deterministic. That is, rather than dictating the conformational state, ATP binding and hydrolysis only shift the equilibria between a pre-existing set of conformational states. For bacterial, yeast and human Hsp90, there is a conserved three-state (apo-ATP-ADP) conformational cycle; however; the equilibria between states are species specific. In eukaryotes, cytosolic co-chaperones regulate the in vivo dynamic behavior of Hsp90 by shifting conformational equilibria and affecting the kinetics of structural changes and ATP hydrolysis. In this review, we discuss the structural and biochemical studies leading to our current understanding of the conformational dynamics of Hsp90, as well as the roles that nucleotide, co-chaperones, post-translational modification and substrates play. This view of Hsp90's conformational dynamics was enabled by the use of multiple complementary structural methods including, crystallography, small-angle X-ray scattering (SAXS), electron microscopy, Förster resonance energy transfer (FRET) and NMR. Finally, we discuss the effects of Hsp90 inhibitors on conformation and the potential for developing small molecules that inhibit Hsp90 by disrupting the conformational dynamics.
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Affiliation(s)
- Kristin A Krukenberg
- Department of Biochemistry and Biophysics, The Howard Hughes Medical Institute, University of California, San Francisco, CA 94158, USA
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141
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PosthumaDeBoer J, Würdinger T, Graat HCA, van Beusechem VW, Helder MN, van Royen BJ, Kaspers GJL. WEE1 inhibition sensitizes osteosarcoma to radiotherapy. BMC Cancer 2011; 11:156. [PMID: 21529352 PMCID: PMC3103478 DOI: 10.1186/1471-2407-11-156] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 04/29/2011] [Indexed: 11/18/2022] Open
Abstract
Background The use of radiotherapy in osteosarcoma (OS) is controversial due to its radioresistance. OS patients currently treated with radiotherapy generally are inoperable, have painful skeletal metastases, refuse surgery or have undergone an intralesional resection of the primary tumor. After irradiation-induced DNA damage, OS cells sustain a prolonged G2 cell cycle checkpoint arrest allowing DNA repair and evasion of cell death. Inhibition of WEE1 kinase leads to abrogation of the G2 arrest and could sensitize OS cells to irradiation induced cell death. Methods WEE1 expression in OS was investigated by gene-expression data analysis and immunohistochemistry of tumor samples. WEE1 expression in OS cell lines and human osteoblasts was investigated by Western blot. The effect of WEE1 inhibition on the radiosensitivity of OS cells was assessed by cell viability and caspase activation analyses after combination treatment. The presence of DNA damage was visualized using immunofluorescence microscopy. Cell cycle effects were investigated by flow cytometry and WEE1 kinase regulation was analyzed by Western blot. Results WEE1 expression is found in the majority of tested OS tissue samples. Small molecule drug PD0166285 inhibits WEE1 kinase activity. In the presence of WEE1-inhibitor, irradiated cells fail to repair their damaged DNA, and show higher levels of caspase activation. The inhibition of WEE1 effectively abrogates the irradiation-induced G2 arrest in OS cells, forcing the cells into premature, catastrophic mitosis, thus enhancing cell death after irradiation treatment. Conclusion We show that PD0166285, a small molecule WEE1 kinase inhibitor, can abrogate the G2 checkpoint in OS cells, pushing them into mitotic catastrophe and thus sensitizing OS cells to irradiation-induced cell death. This suggests that WEE1 inhibition may be a promising strategy to enhance the radiotherapy effect in patients with OS.
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Affiliation(s)
- Jantine PosthumaDeBoer
- Department of Orthopaedic Surgery, VU University Medical Center, 1007 MB Amsterdam, the Netherlands
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142
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Mollapour M, Tsutsumi S, Truman AW, Xu W, Vaughan CK, Beebe K, Konstantinova A, Vourganti S, Panaretou B, Piper PW, Trepel JB, Prodromou C, Pearl LH, Neckers L. Threonine 22 phosphorylation attenuates Hsp90 interaction with cochaperones and affects its chaperone activity. Mol Cell 2011; 41:672-81. [PMID: 21419342 PMCID: PMC3062913 DOI: 10.1016/j.molcel.2011.02.011] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 12/10/2010] [Accepted: 01/07/2011] [Indexed: 12/30/2022]
Abstract
Heat shock protein 90 (Hsp90) is an essential molecular chaperone whose activity is regulated not only by cochaperones but also by distinct posttranslational modifications. We report here that casein kinase 2 phosphorylates a conserved threonine residue (T22) in α helix-1 of the yeast Hsp90 N-domain both in vitro and in vivo. This α helix participates in a hydrophobic interaction with the catalytic loop in Hsp90's middle domain, helping to stabilize the chaperone's ATPase-competent state. Phosphomimetic mutation of this residue alters Hsp90 ATPase activity and chaperone function and impacts interaction with the cochaperones Aha1 and Cdc37. Overexpression of Aha1 stimulates the ATPase activity, restores cochaperone interactions, and compensates for the functional defects of these Hsp90 mutants.
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Affiliation(s)
- Mehdi Mollapour
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Shinji Tsutsumi
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Andrew W. Truman
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | - Wanping Xu
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Cara K. Vaughan
- Institute of Structural and Molecular Biology, School of Crystallography, Birkbeck College, London, UK
| | - Kristin Beebe
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Anna Konstantinova
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Srinivas Vourganti
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Barry Panaretou
- Pharmaceutical Science Division, King's College London, London, UK
| | - Peter W. Piper
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | - Jane B. Trepel
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | | | - Laurence H. Pearl
- Genome Damage and Stability Centre, The University of Sussex, Brighton, UK
| | - Len Neckers
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD 20892, USA
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Patel HJ, Modi S, Chiosis G, Taldone T. Advances in the discovery and development of heat-shock protein 90 inhibitors for cancer treatment. Expert Opin Drug Discov 2011; 6:559-587. [PMID: 22400044 DOI: 10.1517/17460441.2011.563296] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION: Over the last 15 - 20 years, targeted anticancer strategies have focused on therapies aimed at abrogating a single malignant protein. Agents that are directed towards the inhibition of a single oncoprotein have resulted in a number of useful drugs in the treatment of cancers (i.e., Gleevec, BCR-ABL; Tarceva and Iressa, EGFR). However, such a strategy relies on the notion that a cancer cell is dependent on a single signaling pathway for its survival. The possibility that a cancer cell may mutate or switch its dependence to another signaling pathway can result in the ineffectiveness of such agents. Recent advances in the biology of heat-shock protein 90 (Hsp90) have revealed intimate details into the complexity of the chaperoning process that Hsp90 is engaged in and, at the same time, have offered those involved in drug discovery several unique ways to interfere in this process. AREAS COVERED: This review provides the current understanding of the chaperone cycle of Hsp90 and presents the multifaceted approaches used by researchers in the discovery of potential Hsp90 drugs. It discusses the phenotypic outcomes in cancer cells on Hsp90 inhibition by these several approaches and also addresses several distinctions observed among direct Hsp90 ATP-pocket competitors providing commentary on the potential biological outcomes as well as the clinical relevance of such features. EXPERT OPINION: The significantly different phenotypic outcomes observed from Hsp90 inhibition by the many inhibitors developed suggest that the clinical development of Hsp90 inhibitors would be better served by careful consideration of the pharmacokinetic/pharmacodynamic properties of individual candidates rather than a generic approach directed towards the target.
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Affiliation(s)
- Hardik J Patel
- Sloan Kettering Institute, Department of Molecular Pharmacology and Chemistry, NY, USA
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144
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Abstract
Heat shock protein 90 (Hsp90) was the focus of a recent meeting in the Swiss Alps, where the Hsp90 community met to discuss the operation and functions of this ubiquitous and essential molecular chaperone.
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Affiliation(s)
- Cara K Vaughan
- Cara K. Vaughan is at the Institute of Structural Molecular Biology, Birkbeck College, London, UK
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145
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Gymnastics of Molecular Chaperones. Mol Cell 2010; 39:321-31. [DOI: 10.1016/j.molcel.2010.07.012] [Citation(s) in RCA: 253] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 06/14/2010] [Accepted: 07/09/2010] [Indexed: 11/20/2022]
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146
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Abstract
The molecular chaperone heat shock protein 90 (HSP90) has been used by cancer cells to facilitate the function of numerous oncoproteins, and it can be argued that cancer cells are 'addicted' to HSP90. However, although recent reports of the early clinical efficacy of HSP90 inhibitors are encouraging, the optimal use of HSP90-targeted therapeutics will depend on understanding the complexity of HSP90 regulation and the degree to which HSP90 participates in both neoplastic and normal cellular physiology.
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Affiliation(s)
- Jane Trepel
- Medical Oncology Branch Center for Cancer Research, National Cancer Institute, Building 10, room 1-5940, 9000 Rockville Pike, Bethesda, MD 20892, USA
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147
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Abstract
Heat Shock Protein 90 (Hsp90) is an essential molecular chaperone in eukaryotic cells, and it maintains the functional conformation of a subset of proteins that are typically key components of multiple regulatory and signaling networks mediating cancer cell proliferation, survival, and metastasis. It is possible to selectively inhibit Hsp90 using natural products such as geldanamycin (GA) or radicicol (RD), which have served as prototypes for development of synthetic Hsp90 inhibitors. These compounds bind within the ADP/ATP-binding site of the Hsp90 N-terminal domain to inhibit its ATPase activity. As numerous N-terminal domain inhibitors are currently undergoing extensive clinical evaluation, it is important to understand the factors that may modulate in vivo susceptibility to these drugs. We recently reported that Wee1Swe1-mediated, cell cycle-dependent, tyrosine phosphorylation of Hsp90 affects GA binding and impacts cancer cell sensitivity to Hsp90 inhibition. This phosphorylation also affects Hsp90 ATPase activity and its ability to chaperone a selected group of clients, comprised primarily of protein kinases. Wee1 regulates the G2/M transition. Here we present additional data demonstrating that tyrosine phosphorylation of Hsp90 by Wee1Swe1 is important for Wee1Swe1 association with Hsp90 and for Wee1Swe1 stability. Yeast expressing non-phosphorylatable yHsp90-Y24F, like swe1∆ yeast, undergo premature nuclear division that is insensitive to G2/M checkpoint arrest. These findings demonstrate the importance of Hsp90 phosphorylation for proper cell cycle regulation.
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Affiliation(s)
- Mehdi Mollapour
- Urologic Oncology Branch; Center for Cancer Research; National Cancer Institute; Bethesda, MD USA
| | - Shinji Tsutsumi
- Urologic Oncology Branch; Center for Cancer Research; National Cancer Institute; Bethesda, MD USA
| | - Len Neckers
- Urologic Oncology Branch; Center for Cancer Research; National Cancer Institute; Bethesda, MD USA
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148
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Abstract
Heat shock protein 90 (HSP90) is a highly conserved molecular chaperone that facilitates the maturation of a wide range of proteins (known as clients). Clients are enriched in signal transducers, including kinases and transcription factors. Therefore, HSP90 regulates diverse cellular functions and exerts marked effects on normal biology, disease and evolutionary processes. Recent structural and functional analyses have provided new insights on the transcriptional and biochemical regulation of HSP90 and the structural dynamics it uses to act on a diverse client repertoire. Comprehensive understanding of how HSP90 functions promises not only to provide new avenues for therapeutic intervention, but to shed light on fundamental biological questions.
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