1
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Shkedi A, Adkisson M, Schroeder A, Eckalbar WL, Kuo SY, Neckers L, Gestwicki JE. Inhibitor Combinations Reveal Wiring of the Proteostasis Network in Prostate Cancer Cells. J Med Chem 2021; 64:14809-14821. [PMID: 34606726 PMCID: PMC8806517 DOI: 10.1021/acs.jmedchem.1c01342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The protein homeostasis (proteostasis) network is composed of multiple pathways that work together to balance protein folding, stability, and turnover. Cancer cells are particularly reliant on this network; however, it is hypothesized that inhibition of one node might lead to compensation. To better understand these connections, we dosed 22Rv1 prostate cancer cells with inhibitors of four proteostasis targets (Hsp70, Hsp90, proteasome, and p97), either alone or in binary combinations, and measured the effects on cell growth. The results reveal a series of additive, synergistic, and antagonistic relationships, including strong synergy between inhibitors of p97 and the proteasome and striking antagonism between inhibitors of Hsp90 and the proteasome. Based on RNA-seq, these relationships are associated, in part, with activation of stress pathways. Together, these results suggest that cocktails of proteostasis inhibitors might be a powerful way of treating some cancers, although antagonism that blunts the efficacy of both molecules is also possible.
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Affiliation(s)
- Arielle Shkedi
- Department of Pharmaceutical Chemistry and the Institute for Neurodegenerative Disease, University of California San Francisco, San Francisco CA 94158
| | - Michael Adkisson
- Functional Genomics Core, University of California San Francisco, San Francisco, CA 94158
| | - Andrew Schroeder
- Functional Genomics Core, University of California San Francisco, San Francisco, CA 94158
| | - Walter L Eckalbar
- Functional Genomics Core, University of California San Francisco, San Francisco, CA 94158
| | - Szu-Yu Kuo
- Department of Pharmaceutical Chemistry and the Institute for Neurodegenerative Disease, University of California San Francisco, San Francisco CA 94158
| | - Leonard Neckers
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892
| | - Jason E. Gestwicki
- Department of Pharmaceutical Chemistry and the Institute for Neurodegenerative Disease, University of California San Francisco, San Francisco CA 94158
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2
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Rai G, Urban DJ, Mott BT, Hu X, Yang SM, Benavides GA, Johnson MS, Squadrito GL, Brimacombe KR, Lee TD, Cheff DM, Zhu H, Henderson MJ, Pohida K, Sulikowski GA, Dranow DM, Kabir M, Shah P, Padilha E, Tao D, Fang Y, Christov PP, Kim K, Jana S, Muttil P, Anderson T, Kunda NK, Hathaway HJ, Kusewitt DF, Oshima N, Cherukuri M, Davies DR, Norenberg JP, Sklar LA, Moore WJ, Dang CV, Stott GM, Neckers L, Flint AJ, Darley-Usmar VM, Simeonov A, Waterson AG, Jadhav A, Hall MD, Maloney DJ. Pyrazole-Based Lactate Dehydrogenase Inhibitors with Optimized Cell Activity and Pharmacokinetic Properties. J Med Chem 2020; 63:10984-11011. [PMID: 32902275 DOI: 10.1021/acs.jmedchem.0c00916] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Lactate dehydrogenase (LDH) catalyzes the conversion of pyruvate to lactate, with concomitant oxidation of reduced nicotinamide adenine dinucleotide as the final step in the glycolytic pathway. Glycolysis plays an important role in the metabolic plasticity of cancer cells and has long been recognized as a potential therapeutic target. Thus, potent, selective inhibitors of LDH represent an attractive therapeutic approach. However, to date, pharmacological agents have failed to achieve significant target engagement in vivo, possibly because the protein is present in cells at very high concentrations. We report herein a lead optimization campaign focused on a pyrazole-based series of compounds, using structure-based design concepts, coupled with optimization of cellular potency, in vitro drug-target residence times, and in vivo PK properties, to identify first-in-class inhibitors that demonstrate LDH inhibition in vivo. The lead compounds, named NCATS-SM1440 (43) and NCATS-SM1441 (52), possess desirable attributes for further studying the effect of in vivo LDH inhibition.
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Affiliation(s)
- Ganesha Rai
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Daniel J Urban
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Bryan T Mott
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Xin Hu
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Shyh-Ming Yang
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Gloria A Benavides
- Mitochondrial Medicine Laboratory, Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
| | - Michelle S Johnson
- Mitochondrial Medicine Laboratory, Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
| | - Giuseppe L Squadrito
- Mitochondrial Medicine Laboratory, Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
| | - Kyle R Brimacombe
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Tobie D Lee
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Dorian M Cheff
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Hu Zhu
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Mark J Henderson
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Katherine Pohida
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Gary A Sulikowski
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - David M Dranow
- Beryllium Discovery Corp., 7869 Day Road West, Bainbridge Island, Washington 98110, United States
| | - Md Kabir
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Pranav Shah
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Elias Padilha
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Dingyin Tao
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Yuhong Fang
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Plamen P Christov
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Kwangho Kim
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Somnath Jana
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Pavan Muttil
- College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, United States
| | - Tamara Anderson
- College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, United States
| | - Nitesh K Kunda
- College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, United States
| | - Helen J Hathaway
- College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, United States
| | - Donna F Kusewitt
- Dept of Pathology, University of New Mexico Cancer Center, Albuquerque, New Mexico 87131, United States
| | - Nobu Oshima
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, Maryland 20892, United States
| | - Murali Cherukuri
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, Maryland 20892, United States
| | - Douglas R Davies
- Beryllium Discovery Corp., 7869 Day Road West, Bainbridge Island, Washington 98110, United States
| | - Jeffrey P Norenberg
- College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, United States
| | - Larry A Sklar
- Dept of Pathology, University of New Mexico Cancer Center, Albuquerque, New Mexico 87131, United States
| | - William J Moore
- NExT Program Support, Applied/Developmental Research Directorate, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, United States
| | - Chi V Dang
- Abramson Cancer Center, Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.,Ludwig Institute for Cancer Research, New York, New York 10017, United States
| | - Gordon M Stott
- NExT Program Support, Applied/Developmental Research Directorate, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, United States
| | - Leonard Neckers
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, Maryland 20892, United States
| | - Andrew J Flint
- NExT Program Support, Applied/Developmental Research Directorate, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, United States
| | - Victor M Darley-Usmar
- Mitochondrial Medicine Laboratory, Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
| | - Anton Simeonov
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Alex G Waterson
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Ajit Jadhav
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - Matthew D Hall
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
| | - David J Maloney
- National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, United States
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3
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Zuehlke AD, Neckers L. Out with the old: Hsp90 finds amino acid residue more useful than co-chaperone protein. Microb Cell 2017; 4:273-274. [PMID: 28845424 PMCID: PMC5568432 DOI: 10.15698/mic2017.08.586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Redundant functions maintained from single to multi-cellular organisms have made Saccharomyces cerevisiae an important model for the analysis of conserved com-plex cellular processes. Yeast has been especially useful in understanding the regulation and function of the essential molecular chaperone, Heat Shock Protein 90 (Hsp90). Research focused on Hsp90 has determined that it is highly regulated by both co-chaperones and posttranslational modifications. A recent study per-formed by (Zuehlke et al., 2017) demonstrates that the function of one co-chaperone in yeast is replaced by posttranslational modification (PTM) of a single amino acid within Hsp90 in higher eukaryotes.
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Affiliation(s)
- Abbey D Zuehlke
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Leonard Neckers
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD 20892, USA
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4
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Sourbier C, Scroggins BT, Mannes PZ, Liao PJ, Siems K, Wolf D, Beutler JA, Linehan WM, Neckers L. Tonantzitlolone cytotoxicity toward renal cancer cells is PKCθ- and HSF1-dependent. Oncotarget 2016; 6:29963-74. [PMID: 26298773 PMCID: PMC4745775 DOI: 10.18632/oncotarget.4676] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 07/10/2015] [Indexed: 11/25/2022] Open
Abstract
Elucidating the targets and mechanism of action of natural products is strategically important prior to drug development and assessment of potential clinical applications. In this report, we elucidated the main targets and mechanism of action of the natural product tonantzitlolone (TZL) in clear cell renal cell carcinoma (CCRCC). We identified TZL as a dual PKCα and PKCθ activator in vitro, although in CCRCC cells its activity was mostly PKCθ-dependent. Through activation of PKCθ, TZL induced an insulin resistant phenotype by inhibiting IRS1 and the PI3K/Akt pathway. Simultaneously, TZL activated the heat shock factor 1 (HSF1) transcription factor driving glucose dependency. Thus, similar to the selective PKCθ activator englerin A, TZL induces a metabolic catastrophe in CCRCC, starving cells of glucose while simultaneously increasing their glycolytic dependency.
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Affiliation(s)
- Carole Sourbier
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Bradley T Scroggins
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Philip Z Mannes
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Pei-Jyun Liao
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | | | - Dietmar Wolf
- AnalytiCon Discovery GmbH, D-14473 Potsdam, Germany
| | - John A Beutler
- Molecular Targets Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - W Marston Linehan
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Leonard Neckers
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
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5
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Fash DM, Peer CJ, Li Z, Talisman IJ, Hayavi S, Sulzmaier FJ, Ramos JW, Sourbier C, Neckers L, Figg WD, Beutler JA, Chain WJ. Synthesis of a stable and orally bioavailable englerin analogue. Bioorg Med Chem Lett 2016; 26:2641-4. [PMID: 27107948 PMCID: PMC4862412 DOI: 10.1016/j.bmcl.2016.04.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 04/06/2016] [Accepted: 04/07/2016] [Indexed: 12/26/2022]
Abstract
Synthesis of analogues of englerin A with a reduced propensity for hydrolysis of the glycolate moiety led to a compound which possessed the renal cancer cell selectivity of the parent and was orally bioavailable in mice.
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Affiliation(s)
- David M Fash
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, United States
| | - Cody J Peer
- Genitourinary Malignancies Branch, National Cancer Institute, Frederick, MD 21702, United States
| | - Zhenwu Li
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, United States
| | - Ian J Talisman
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, United States
| | - Sima Hayavi
- Developmental Therapeutics Program, National Cancer Institute, Frederick, MD 21702, United States
| | - Florian J Sulzmaier
- The University of Hawaii Cancer Center, 701 Ilalo Street, Honolulu, HI 96813, United States
| | - Joe W Ramos
- The University of Hawaii Cancer Center, 701 Ilalo Street, Honolulu, HI 96813, United States
| | - Carole Sourbier
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, United States
| | - Leonard Neckers
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, United States
| | - W Douglas Figg
- Genitourinary Malignancies Branch, National Cancer Institute, Frederick, MD 21702, United States
| | - John A Beutler
- Molecular Targets Laboratory, National Cancer Institute, Frederick, MD 21702, United States.
| | - William J Chain
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, United States; The University of Hawaii Cancer Center, 701 Ilalo Street, Honolulu, HI 96813, United States.
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6
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Beebe K, Mollapour M, Scroggins B, Prodromou C, Xu W, Tokita M, Taldone T, Pullen L, Zierer BK, Lee MJ, Trepel J, Buchner J, Bolon D, Chiosis G, Neckers L. Posttranslational modification and conformational state of heat shock protein 90 differentially affect binding of chemically diverse small molecule inhibitors. Oncotarget 2014; 4:1065-74. [PMID: 23867252 PMCID: PMC3759666 DOI: 10.18632/oncotarget.1099] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Heat shock protein 90 (Hsp90) is an essential molecular chaperone in eukaryotes that facilitates the conformational maturation and function of a diverse protein clientele, including aberrant and/or over-expressed proteins that are involved in cancer growth and survival. A role for Hsp90 in supporting the protein homeostasis of cancer cells has buoyed interest in the utility of Hsp90 inhibitors as anti-cancer drugs. Despite the fact that all clinically evaluated Hsp90 inhibitors target an identical nucleotide-binding pocket in the N domain of the chaperone, the precise determinants that affect drug binding in the cellular environment remain unclear, and it is possible that chemically distinct inhibitors may not share similar binding preferences. Here we demonstrate that two chemically unrelated Hsp90 inhibitors, the benzoquinone ansamycin geldanamycin and the purine analog PU-H71, select for overlapping but not identical subpopulations of total cellular Hsp90, even though both inhibitors bind to an amino terminal nucleotide pocket and prevent N domain dimerization. Our data also suggest that PU-H71 is able to access a broader range of N domain undimerized Hsp90 conformations than is geldanamycin and is less affected by Hsp90 phosphorylation, consistent with its broader and more potent anti-tumor activity. A more complete understanding of the impact of the cellular milieu on small molecule inhibitor binding to Hsp90 should facilitate their more effective use in the clinic.
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Affiliation(s)
- Kristin Beebe
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
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7
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Yoshida S, Tsutsumi S, Muhlebach G, Sourbier C, Lee MJ, Lee S, Vartholomaiou E, Tatokoro M, Beebe K, Miyajima N, Mohney RP, Chen Y, Hasumi H, Xu W, Fukushima H, Nakamura K, Koga F, Kihara K, Trepel J, Picard D, Neckers L. Molecular chaperone TRAP1 regulates a metabolic switch between mitochondrial respiration and aerobic glycolysis. Proc Natl Acad Sci U S A 2013; 110:E1604-12. [PMID: 23564345 PMCID: PMC3637790 DOI: 10.1073/pnas.1220659110] [Citation(s) in RCA: 190] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
TRAP1 (TNF receptor-associated protein), a member of the HSP90 chaperone family, is found predominantly in mitochondria. TRAP1 is broadly considered to be an anticancer molecular target. However, current inhibitors cannot distinguish between HSP90 and TRAP1, making their utility as probes of TRAP1-specific function questionable. Some cancers express less TRAP1 than do their normal tissue counterparts, suggesting that TRAP1 function in mitochondria of normal and transformed cells is more complex than previously appreciated. We have used TRAP1-null cells and transient TRAP1 silencing/overexpression to show that TRAP1 regulates a metabolic switch between oxidative phosphorylation and aerobic glycolysis in immortalized mouse fibroblasts and in human tumor cells. TRAP1-deficiency promotes an increase in mitochondrial respiration and fatty acid oxidation, and in cellular accumulation of tricarboxylic acid cycle intermediates, ATP and reactive oxygen species. At the same time, glucose metabolism is suppressed. TRAP1-deficient cells also display strikingly enhanced invasiveness. TRAP1 interaction with and regulation of mitochondrial c-Src provide a mechanistic basis for these phenotypes. Taken together with the observation that TRAP1 expression is inversely correlated with tumor grade in several cancers, these data suggest that, in some settings, this mitochondrial molecular chaperone may act as a tumor suppressor.
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Affiliation(s)
| | | | - Guillaume Muhlebach
- Department of Cell Biology, University of Geneva, CH-1211 Geneva 4, Switzerland
| | | | - Min-Jung Lee
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892
| | - Sunmin Lee
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892
| | | | - Manabu Tatokoro
- Urologic Oncology Branch and
- Department of Urology, Tokyo Medical and Dental University, Tokyo 113-8510, Japan; and
| | | | | | | | | | | | | | - Hiroshi Fukushima
- Department of Urology, Tokyo Medical and Dental University, Tokyo 113-8510, Japan; and
| | - Ken Nakamura
- Gladstone Institute of Neurological Disease, University of California at San Francisco School of Medicine, San Francisco, CA 94158
| | - Fumitaka Koga
- Department of Urology, Tokyo Medical and Dental University, Tokyo 113-8510, Japan; and
| | - Kazunori Kihara
- Department of Urology, Tokyo Medical and Dental University, Tokyo 113-8510, Japan; and
| | - Jane Trepel
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892
| | - Didier Picard
- Department of Cell Biology, University of Geneva, CH-1211 Geneva 4, Switzerland
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8
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Kong HS, Lee S, Beebe K, Scroggins B, Gupta G, Lee MJ, Jung YJ, Trepel J, Neckers L. Emetine promotes von Hippel-Lindau-independent degradation of hypoxia-inducible factor-2α in clear cell renal carcinoma. Mol Pharmacol 2010; 78:1072-8. [PMID: 20813864 DOI: 10.1124/mol.110.066514] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Inactivating mutations of the von Hippel-Lindau (VHL) tumor suppressor gene are associated with inherited VHL syndrome, which is characterized by susceptibility to a variety of neoplasms, including central nervous system hemangioblastoma and clear cell renal cell carcinoma (CCRCC). Mutations in the VHL gene are also found in the majority of sporadic clear cell renal carcinoma, the most common malignant neoplasm of the human kidney. Inactivation of VHL ubiquitin ligase is associated with normoxic stabilization of hypoxia-inducible factor-1α and 2-α (HIF-1α and HIF-2α), transcriptional regulators of tumor angiogenesis, invasion, survival, and glucose utilization. HIF-2α has been particularly implicated in the development of CCRCC. Although several inhibitors of HIF-1α have been described, these drugs typically have a minimal affect on HIF-2α. 786-O is a VHL-deficient CCRCC cell line that constitutively expresses only HIF-2α and is therefore suitable for the screening of novel HIF-2α inhibitors. Using this cell line, we have identified emetine as a specific inhibitor of HIF-2α protein stability and transcriptional activity. Without altering HIF-2α mRNA level, emetine rapidly and dramatically down-regulated HIF-2α protein expression in 786-O cells. HIF-2α down-regulation was accompanied by HIF-2α ubiquitination and was reversed by proteasome inhibition. Emetine-induced HIF-2α down-regulation was confirmed in three additional VHL-renal cancer cell lines, was insensitive to the prolyl hydroxylase inhibitor dimethyloxaloyl glycine, and did not require neural precursor cell expressed developmentally down-regulated-8, suggesting that emetine accesses a previously undescribed cullin-independent proteasome degradation pathway for HIF-2α. These data support the use of emetine or structurally related compounds as useful leads for the identification of novel HIF-2α inhibitors.
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Affiliation(s)
- Hye-Sik Kong
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
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9
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Williams H, Krill A, Fowler S, Neckers L, Pinto PA, Ivy P, Srinivasan R, Linehan WM, Bratslavsky G. 993 FEASIBILITY AND OUTCOMES OF PARTIAL NEPHRECTOMY FOLLOWING THERAPY WITH A HEAT SHOCK PROTEIN 90 INHIBITOR. J Urol 2010. [DOI: 10.1016/j.juro.2010.02.1962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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10
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Kawabe M, Mandic M, Taylor J, Vasquez C, Wesa A, Neckers L, Storkus W. HSP90 inhibitor 17-DMAG enhances EphA2+ tumor cell recognition by specific CD8+ T cells (40.27). The Journal of Immunology 2009. [DOI: 10.4049/jimmunol.182.supp.40.27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
EphA2, a member of receptor tyrosine kinases (RTK), is commonly expressed by a broad range of cancer types, where its level of (over)expression correlates with poor clinical outcome. Since tumor cell expressed EphA2 is a non-mutated "self" protein, specific CD8+ T cells are subject to self-tolerance mechanisms and typically exhibit only moderate-to-low functional avidity, rendering them marginally competent to recognize EphA2+ tumor cells in vitro or in vivo. We have recently reported that the ability of specific CD8+ T cells to recognize EphA2+ tumor cells can be augmented after the cancer cells are pretreated with EphA2 agonists that promote proteasomal degradation (Wesa et al., J. Immunol., in press, 2008). In the current study we show that treatment of EphA2+ tumor cells with the HSP90 inhibitor, 17-DMAG, similarly enhances EphA2 degradation by the proteasome, minimally impairs MHC class I antigen presentign machinery, and increases tumor cell recognition by specific CD8+ T cell lines and clones in vitro. These studies suggest that EphA2 represents a novel HSP90 client protein and that the treatment of cancer patients with 17-DMAG-based "pulse" therapy may improve the anti-tumor efficacy of CD8+ T effector cells reactive against EphA2-derived epitopes.
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Affiliation(s)
| | - Maja Mandic
- 2Dermatology, University of Pittsburgh, Pittsburgh, PA
| | | | | | - Amy Wesa
- 2Dermatology, University of Pittsburgh, Pittsburgh, PA
| | | | - Walter Storkus
- 1Immunology
- 4Dermatology, University of Pittsburgh, Pittsburgh, PA
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11
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Kim YS, Alarcon SV, Lee S, Lee MJ, Giaccone G, Neckers L, Trepel JB. Update on Hsp90 inhibitors in clinical trial. Curr Top Med Chem 2009; 9:1479-92. [PMID: 19860730 PMCID: PMC7241864 DOI: 10.2174/156802609789895728] [Citation(s) in RCA: 223] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Accepted: 09/28/2009] [Indexed: 11/22/2022]
Abstract
Twenty-five years ago the first small molecule inhibitors of Hsp90 were identified. In the intervening years there has been dramatic progress in basic scientific understanding of the Hsp90 chaperone machinery and in the role of Hsp90 in malignancy. The first-in-class Hsp90 inhibitor 17-AAG entered into Phase I clinical trials in 1999. There are now 13 Hsp90 inhibitors in clinical trial, representing multiple drug classes, and hundreds of patients have been treated in adult oncology and pediatric oncology trials. This review will provide an overview of the clinical trial results thus far. In addition, pivotal issues in further development of Hsp90 inhibitors as anticancer drugs will be discussed.
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Affiliation(s)
- Y. S. Kim
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - S. V. Alarcon
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - S. Lee
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - M.-J. Lee
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - G. Giaccone
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - L. Neckers
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - J. B. Trepel
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
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12
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Tsutsumi S, Scroggins B, Koga F, Lee MJ, Trepel J, Felts S, Carreras C, Neckers L. A small molecule cell-impermeant Hsp90 antagonist inhibits tumor cell motility and invasion. Oncogene 2007; 27:2478-87. [PMID: 17968312 DOI: 10.1038/sj.onc.1210897] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Heat shock protein 90 (Hsp90) is a molecular chaperone that maintains function of numerous intracellular signaling nodes utilized by cancer cells for proliferation and survival. Hsp90 is also detected on the plasma membrane of tumor cells and its expression has been suggested to correlate with metastatic potential. Given the abundance and diverse functions of the intracellular pool of this protein, the precise contribution of cell surface Hsp90 to cell motility and tumor metastasis remains to be determined. In this study we utilized the small molecule DMAG-N-oxide, a novel cell-impermeable Hsp90 inhibitor, to specifically examine the role of cell surface Hsp90 in cell motility. We observed that, while not affecting intracellular Hsp90 function, DMAG-N-oxide significantly retarded tumor cell migration and integrin/extracellular matrix-dependent cytoskeletal reorganization. Concomitant with these findings, targeting cell surface Hsp90 significantly inhibited tumor cell motility and invasion in vitro, and had a dramatic impact on melanoma cell lung colonization in vivo. These data indicate that cell surface Hsp90 plays an important role in modulating cancer cell migration that is independent of the function of the intracellular Hsp90 pool, and that small molecule inhibitors of surface Hsp90 may provide a new approach to targeting the metastatic phenotype.
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Affiliation(s)
- S Tsutsumi
- Urologic Oncology Branch, National Cancer Institute, Bethesda, MD 20892-1107, USA
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13
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Kajiguchi T, Chung EJ, Lee S, Stine A, Kiyoi H, Naoe T, Levis MJ, Neckers L, Trepel JB. FLT3 regulates beta-catenin tyrosine phosphorylation, nuclear localization, and transcriptional activity in acute myeloid leukemia cells. Leukemia 2007; 21:2476-84. [PMID: 17851558 DOI: 10.1038/sj.leu.2404923] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Deregulated accumulation of nuclear beta-catenin enhances transcription of beta-catenin target genes and promotes malignant transformation. Recently, acute myeloid leukemia (AML) cells with activating mutations of FMS-like tyrosine kinase-3 (FLT3) were reported to display elevated beta-catenin-dependent nuclear signaling. Tyrosine phosphorylation of beta-catenin has been shown to promote its nuclear localization. Here, we examined the causal relationship between FLT3 activity and beta-catenin nuclear localization. Compared to cells with wild-type FLT3 (FLT3-WT), cells with the FLT3 internal tandem duplication (FLT3-ITD) and tyrosine kinase domain mutation (FLT3-TKD) had elevated levels of tyrosine-phosphorylated beta-catenin. Although beta-catenin was localized mainly in the cytoplasm in FLT3-WT cells, it was primarily nuclear in FLT3-ITD cells. Treatment with FLT3 kinase inhibitors or FLT3 silencing with RNAi decreased beta-catenin tyrosine phosphorylation and nuclear localization. Conversely, treatment of FLT3-WT cells with FLT3 ligand increased tyrosine phosphorylation and nuclear accumulation of beta-catenin. Endogenous beta-catenin co-immunoprecipitated with endogenous activated FLT3, and recombinant activated FLT3 directly phosphorylated recombinant beta-catenin. Finally, FLT3 inhibitor decreased tyrosine phosphorylation of beta-catenin in leukemia cells obtained from FLT3-ITD-positive AML patients. These data demonstrate that FLT3 activation induces beta-catenin tyrosine phosphorylation and nuclear localization, and thus suggest a mechanism for the association of FLT3 activation and beta-catenin oncogeneic signaling in AML.
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Affiliation(s)
- T Kajiguchi
- Urologic Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
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14
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Xu W, Soga S, Beebe K, Lee MJ, Kim YS, Trepel J, Neckers L. Sensitivity of epidermal growth factor receptor and ErbB2 exon 20 insertion mutants to Hsp90 inhibition. Br J Cancer 2007; 97:741-4. [PMID: 17712310 PMCID: PMC2360392 DOI: 10.1038/sj.bjc.6603950] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The mature epidermal growth factor receptor (EGFR) neither associates with nor requires the molecular chaperone heat-shock protein 90 (Hsp90). Mutations in EGFR exons 18, 19, and 21 confer Hsp90 chaperone dependence. In non-small cell lung cancer (NSCLC), these mutations are associated with enhanced sensitivity to EGFR inhibitors in vitro and with clinical response in vivo. Although less prevalent, insertions in EGFR exon 20 have also been described in NSCLC. These mutations, however, confer resistance to EGFR inhibitors. In NSCLC, exon 20 insertions have also been identified in the EGFR family member ErbB2. Here, we examined the sensitivity of exon 20 insertion mutants to an Hsp90 inhibitor currently in the clinic. Our data demonstrate that both EGFR and ErbB2 exon 20 insertion mutants retain dependence on Hsp90 for stability and downstream-signalling capability, and remain highly sensitive to Hsp90 inhibition. Use of Hsp90 inhibitors should be considered in NSCLC harbouring exon 20 insertions in either EGFR or ErbB2.
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Affiliation(s)
- W Xu
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - S Soga
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - K Beebe
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - M-J Lee
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - Y S Kim
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - J Trepel
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - L Neckers
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Building 10/Clinical Research Center, room 1-5940, 9000 Rockville Pike, Bethesda, MD 20892-1107, USA. E-mail:
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15
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Abstract
Hereditary leiomyomatosis and renal cell cancer is a recently described hereditary cancer syndrome in which affected individuals are predisposed to the development of leiomyomas of the skin and uterus. In addition, this clinical entity also can result in the development of biologically aggressive kidney cancer. Affected individuals harbour a germline mutation of the fumarate hydratase (FH) gene, which encodes an enzyme that catalyses conversion of fumarate to malate in the Kreb's cycle. Thus far, proposed mechanisms for carcinogeneis associated with this syndrome include aberrant apoptosis, oxidative stress, and pseudohypoxic drive. At this time, the majority of accumulating data support a role for pseudohypoxic drive in tumour development. The link between FH mutation and pseudohypoxic drive may reside in the biochemical alterations resulting from diminished/absent FH activity. These biochemical derangements may interfere with oxygen homeostasis and result in a cellular environment conducive to tumour formation.
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Affiliation(s)
- S Sudarshan
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 10 Center Drive, Bldg 10 CRC Room 1-5940, Bethesda, MD 20892-1107, USA
| | - W M Linehan
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 10 Center Drive, Bldg 10 CRC Room 1-5940, Bethesda, MD 20892-1107, USA
| | - L Neckers
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 10 Center Drive, Bldg 10 CRC Room 1-5940, Bethesda, MD 20892-1107, USA
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, 10 Center Drive, Bldg 10 CRC Room 1-5940, Bethesda, MD 20892-1107, USA; E-mail:
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16
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Lattouf JB, Srinivasan R, Pinto PA, Linehan WM, Neckers L. Mechanisms of disease: the role of heat-shock protein 90 in genitourinary malignancy. ACTA ACUST UNITED AC 2007; 3:590-601. [PMID: 17088927 DOI: 10.1038/ncpuro0604] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Accepted: 08/14/2006] [Indexed: 12/28/2022]
Abstract
Insight into the molecular biology of cancer has allowed the development of novel therapeutic strategies that target specific oncogenic pathways. Molecular therapeutic strategies are now part of the armamentarium available against urologic malignancy. Among the many targets of interest in urologic cancer, heat-shock protein 90 (HSP90) shows great promise. This molecule has a major role in prostate as well as in renal malignancy. In contrast to other targets, where cancer might escape inhibition via alternative pathways, HSP90 operates at multiple checkpoints in a cancer cell. Its inhibition could, therefore, prove more difficult for neoplastic cells to overcome. Inhibitors of HSP90, such as geldanamycin and its derivatives (17-allylamino-17-demethoxygeldanamycin and 17-dimethylaminoethylamino-17-demethoxygeldanamycin, known as 17AAG and 17DMAG, respectively) are available and have shown activity both in vivo and in vitro. 17AAG is currently being tested for efficacy in humans after having completed phase I trials, while 17DMAG is still in phase I evaluation. Phase II trials of HSP90 inhibitors in urologic malignancy are being conducted in kidney and advanced prostate cancer. Beyond monotherapy, HSP90 inhibitors might also prove to be beneficial in combination therapy with other chemotherapeutic agents in advanced disease. Studies being conducted in prostate cancer will hopefully help to define this potential application better.
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Affiliation(s)
- Jean-Baptiste Lattouf
- Urologic Oncology Branch, National Cancer Institute, Room 1-5942, Building 10 CRC, 9000 Rockville Pike, Bethesda, MD 20892, USA
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17
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Abstract
Heat shock protein 90 (Hsp90) is a molecular chaperone required for the stability and function of a number of conditionally activated and/or expressed signaling proteins, as well as multiple mutated, chimeric, and/or over-expressed signaling proteins, that promote cancer cell growth and/or survival. Hsp90 inhibitors, by interacting specifically with a single molecular target, cause the inactivation, destabilization, and eventual degradation of Hsp90 client proteins, and they have shown promising anti-tumor activity in preclinical model systems. One Hsp90 inhibitor, 17-AAG, has completed Phase I clinical trial and several Phase II trials of this agent are in progress. Hsp90 inhibitors are unique in that, although they are directed toward a specific molecular target, they simultaneously inhibit multiple signaling pathways that frequently interact to promote cancer cell survival. Further, by inhibiting nodal points in multiple overlapping survival pathways utilized by cancer cells, a combination of an Hsp90 inhibitor with standard chemotherapeutic agents may dramatically increase the in vivo efficacy of the standard agent. Hsp90 inhibitors may circumvent the characteristic genetic plasticity that has allowed cancer cells to eventually evade the toxic effects of most molecularly targeted agents. The mechanism-based use of Hsp90 inhibitors, both alone and in combination with other drugs, should be effective toward multiple forms of cancer.
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Affiliation(s)
- L Neckers
- Urologic Oncology Branch, National Cancer Institute, Rockville MD, 20850, USA.
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18
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Wei MH, Toure O, Glenn GM, Pithukpakorn M, Neckers L, Stolle C, Choyke P, Grubb R, Middelton L, Turner ML, Walther MM, Merino MJ, Zbar B, Linehan WM, Toro JR. Novel mutations in FH and expansion of the spectrum of phenotypes expressed in families with hereditary leiomyomatosis and renal cell cancer. J Med Genet 2005; 43:18-27. [PMID: 15937070 PMCID: PMC2564499 DOI: 10.1136/jmg.2005.033506] [Citation(s) in RCA: 226] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
BACKGROUND Hereditary leiomyomatosis and renal cell cancer (HLRCC; OMIM 605839) is the predisposition to develop smooth muscle tumours of the skin and uterus and/or renal cancer and is associated with mutations in the fumarate hydratase gene (FH). Here we characterise the clinical and genetic features of 21 new families and present the first report of two African-American families with HLRCC. METHODS Using direct sequencing analysis we identified FH germline mutations in 100% (21/21) of new families with HLRCC. RESULTS We identified 14 germline FH mutations (10 missense, one insertion, two nonsense, and one splice site) located along the entire length of the coding region. Nine of these were novel, with six missense (L89S, R117G, R190C, A342D, S376P, Q396P), one nonsense (S102X), one insertion (111insA), and one splice site (138+1G>C) mutation. Four unrelated families had the R58X mutation and five unrelated families the R190H mutation. Of families with HLRCC, 62% (13/21) had renal cancer and 76% (16/21) cutaneous leiomyomas. Of women FH mutation carriers from 16 families, 100% (22/22) had uterine fibroids. Our study shows that expression of cutaneous manifestations in HLRCC ranges from absent to mild to severe cutaneous leiomyomas. FH mutations were associated with a spectrum of renal tumours. No genotype-phenotype correlations were identified. CONCLUSIONS In combination with our previous report, we identify 31 different germline FH mutations in 56 families with HLRCC (20 missense, eight frameshifts, two nonsense, and one splice site). Our FH mutation detection rate is 93% (52/56) in families suspected of HLRCC.
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Affiliation(s)
- M-H Wei
- Genetic Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD 20892, USA
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19
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Yuan X, Xu W, Neckers L. 84 Regulation of the oncogenic x-protein of hepatitis B by cellular chaperones. EJC Suppl 2004. [DOI: 10.1016/s1359-6349(04)80092-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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20
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Isaacs J, Jung Y, Lee S, Torres-Cabala C, Merino M, Trepel J, Zbar B, Toro J, Linehan M, Neckers L. 343 Novel role of fumarate in antagonizing VHL function. EJC Suppl 2004. [DOI: 10.1016/s1359-6349(04)80350-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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21
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Mimnaugh E, Xu W, Scroggins B, Yuan X, Prince T, Hartson S, Vos M, Neckers L. 60 Geldanamycin combined with bortezomib interferes with the ER-associated protein degradation function of valosin-containing protein. EJC Suppl 2004. [DOI: 10.1016/s1359-6349(04)80068-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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22
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Isaacs J, Neckers L. 164 Targeting oncogenic Eph proteins with Hsp90 inhibitors. EJC Suppl 2004. [DOI: 10.1016/s1359-6349(04)80172-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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23
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Abstract
The cellular prion protein PrPc is of crucial importance for the development of neurodegenerative diseases called transmissible spongiform encephalopathies. We investigated if the function of members of the HSP90 family is required for the integrity of the normal, nonpathogenic prion protein called PrPc. Eukaryotic cells were treated with the structurally unrelated HSP90-inhibitors geldanamycin (GA) or radicicol (RC). In either case the cellular prion protein was induced and exhibited faster migrating bands on western blot analysis, whereas geldampicin (GE), an analog of GA known not to bind to HSP90, had no effect. Ongoing protein and messenger RNA synthesis during treatment were found to be necessary for the appearance of these bands. Cotreatment with tunicamycin abrogated any effect of HSP90 inhibitors on the cellular prion protein. Finally, enzymatic deglycosylation with peptide:N-glycosidase F of the normal prion protein as well as the variant induced by benzoquinone ansamycins resulted in very similar band patterns. These experiments indicate that either altered glycosylation, or a change in conformation, or both are involved in the induction of faster migrating bands by HSP90 inhibitors. Thus the inhibition of the function of members of the HSP90 family of molecular chaperones results in profound changes in the physicochemical properties of PrPc.
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Affiliation(s)
- H-J Ochel
- Otto-von-Guericke-University, Medical Faculty, Clinic for Radiation Therapy, Radiobiological Laboratory, Leipziger Str. 44, 39120 Magdeburg, Germany.
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24
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Nakamura M, Matsuo T, Stauffer J, Neckers L, Thiele CJ. Retinoic acid decreases targeting of p27 for degradation via an N-myc-dependent decrease in p27 phosphorylation and an N-myc-independent decrease in Skp2. Cell Death Differ 2003; 10:230-9. [PMID: 12700651 DOI: 10.1038/sj.cdd.4401125] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Poor prognosis neuroblastoma (NB) tumors are marked by amplification and overexpression of N-myc. Retinoic acid (RA) decreases N-myc levels and induces cell cycle arrest in vitro and increases event-free survival in advanced stage NB patients. In this study, we investigated the mechanism(s) by which RA regulates cell cycle and how N-myc affects NB cell cycle progression. Constitutive N-myc overexpression stimulates increases in cyclin E-dependent kinase activity and decreases in p27 resulting in increased DNA synthesis. N-myc regulates p27 levels through an increase in targeting of p27 to the proteasome via cyclin E kinase-dependent phosphorylation of p27 and its ubiquitination. N-myc also stimulates an increase in proteasome activity. In RA-treated cells in which N-myc levels decline as p27 levels increase, degradation of p27 is also decreased. However, RA does not affect the activity of proteasome. The decrease in the degradation of p27 in RA-treated cells is due in part to a decrease in the N-myc stimulated phosphorylation of p27. However, RA also decreases Skp2 levels thus impairing the ability of p27 to be ubiquitinated. Thus, RA induces both N-myc-dependent and -independent mechanisms to minimize the degradation of p27 and arrest NB cell growth.
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Affiliation(s)
- M Nakamura
- Cell and Molecular Biology Section, Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
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25
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Li QQ, Yunmbam MK, Zhong X, Yu JJ, Mimnaugh EG, Neckers L, Reed E. Lactacystin enhances cisplatin sensitivity in resistant human ovarian cancer cell lines via inhibition of DNA repair and ERCC-1 expression. Cell Mol Biol (Noisy-le-grand) 2002; 47 Online Pub:OL61-72. [PMID: 11936875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Cisplatin is among the most effective chemotherapeutic agents in the treatment of human ovarian cancer. The cytotoxicity of cisplatin results primarily from its ability to bind covalently to DNA and prevent DNA replication and transcription. The ubiquitin-proteasome pathway plays important roles in a broad array of basic cellular processes. Lactacystin is a selective inhibitor of the proteasome that can inhibit the ubiquitin pathway. However, the effect of lactacystin on DNA repair and the antitumor activity of cisplatin in ovarian cancer have not been evaluated. We report in this work that lactacystin, at concentrations that do not appear harmful, increased cisplatin toxicity in three resistant human ovarian carcinoma cell lines. In addition, lactacystin significantly enhanced DNA platination and decreased DNA repair of cisplatin-DNA adducts in these cell lines, as measured by atomic absorption spectrometry. Furthermore, Northem blot analysis and in vitro nuclear transcript elongation assay demonstrated that lactacystin dramatically reduced the steady-state mRNA expression and the rate of transcription of the DNA repair gene ERCC-1 in these cells. These observations indicate that proteasome inhibition has impact on nucleotide excision repair in several ways: i/ the normal ERCC-1 message upregulation is suppressed; ii/ cisplatin-DNA adduct repair is inhibited, and iii/ DNA platination, as well as cisplatin cytotoxicity, is enhanced.
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Affiliation(s)
- Q Q Li
- Medical Ovarian Cancer Section, Developmental Therapeutics Department, Medicine Branch, Division of Clinical Sciences, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
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26
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Mimnaugh EG, Kayastha G, McGovern NB, Hwang SG, Marcu MG, Trepel J, Cai SY, Marchesi VT, Neckers L. Caspase-dependent deubiquitination of monoubiquitinated nucleosomal histone H2A induced by diverse apoptogenic stimuli. Cell Death Differ 2001; 8:1182-96. [PMID: 11753566 DOI: 10.1038/sj.cdd.4400924] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2000] [Revised: 04/11/2001] [Accepted: 02/06/2001] [Indexed: 11/09/2022] Open
Abstract
Enzymatic deubiquitination of mono-ubiquitinated nucleosomal histone H2A (uH2A) and H2B (uH2B) is closely associated with mitotic chromatin condensation, although the function of this histone modification in cell division remains ambiguous. Here we show that rapid and extensive deubiquitination of nucleosomal uH2A occurs in Jurkat cells undergoing apoptosis initiated by anti-Fas activating antibody, staurosporine, etoposide, doxorubicin and the proteasome inhibitor, N-acetyl-leucyl-leucyl-norlucinal. These diverse apoptosis inducers also promoted the accumulation of slowly migrating, high molecular weight ubiquitinated proteins and depleted the cellular pool of unconjugated ubiquitin. In apoptotic cells, ubiquitin was cleaved from uH2A subsequent to the appearance of plasma membrane blebbing, and deubiquitination of uH2A closely coincided with the onset of nuclear pyknosis and chromatin condensation. Nucleosomal uH2A deubiquitination, poly (ADP-ribose)polymerase (PARP) cleavage and chromatin condensation were prevented in cells challenged with apoptosis inducers by pretreatment with the pan-caspase inhibitor, zVAD-fmk, or by over-expressing anti-apoptotic Bcl-xL protein. These results implicate a connection between caspase cascade activation and nucleosomal uH2A deubiquitination. Transient transfection of 293 cells with the gene encoding Ubp-M, a human deubiquitinating enzyme, promoted uH2A deubiquitination, while an inactive mutated Ubp-M enzyme did not. However, Ubp-M-promoted deubiquitination of uH2A was insufficient to initiate apoptosis in these cells. We conclude that uH2A deubiquitination is a down-stream consequence of procaspase activation and that unscheduled cleavage of ubiquitin from uH2A is a consistent feature of the execution phase of apoptosis rather than a determining or initiating apoptogenic event. Nucleosomal uH2A deubiquitination may function as a cellular sensor of stress in situations like apoptosis through which cells attempt to preserve genomic integrity.
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Affiliation(s)
- E G Mimnaugh
- Tumor Cell Biology Section, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
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27
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Yunmbam MK, Li QQ, Mimnaugh EG, Kayastha GL, Yu JJ, Jones LN, Neckers L, Reed E. Effect of the proteasome inhibitor ALLnL on cisplatin sensitivity in human ovarian tumor cells. Int J Oncol 2001; 19:741-8. [PMID: 11562749 DOI: 10.3892/ijo.19.4.741] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Small molecules suppressing proteasome function inhibit the post-translational ubiquitination of selected proteins. Ubiquitin H2A is an example of an abundant chromatin-associated protein that is known to be ubiquitinated, which is important for several proteins involved in the repair of DNA damage. We therefore studied the effect of the proteasome inhibitor, N-acetyl leucyl-leucyl norlucinal (ALLnL), on cisplatin sensitivity in three human ovarian tumor cell lines. The proteasome inhibitor ALLnL was administered for 4 h before cells were subsequently exposed to cisplatin for 1 h. Our results showed that ALLnL, at its respective IC20 concentration, increased cellular sensitivity to cisplatin in an additive manner in human ovarian cancer A2780, A2780/CP70, and OVCAR3 cells. We also demonstrated that ALLnL caused a 50% increase in total cellular accumulation of cisplatin, and reduced the rate of cisplatin efflux by about 50%. In addition, DNA damage levels were increased after ALLnL treatment. By contrast, DNA repair was inhibited 2 to 3-fold in ALLnL-pretreated cells, as compared to the controls. Furthermore, our study showed that ALLnL deubiquitinated nucleosomal histone H2A in these cells in a concentration-dependent fashion, as assessed by Western blot analysis. These data suggest that sublethal levels of exposure to agents that inhibit proteasome function may alter the subcellular pharmacology of platinum in human ovarian carcinoma cells.
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Affiliation(s)
- M K Yunmbam
- Medical Ovarian Cancer Section, Developmental Therapeutics Department, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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28
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Agnew EB, Wilson RH, Grem JL, Neckers L, Bi D, Takimoto CH. Measurement of the novel antitumor agent 17-(allylamino)-17-demethoxygeldanamycin in human plasma by high-performance liquid chromatography. J Chromatogr B Biomed Sci Appl 2001; 755:237-43. [PMID: 11393709 DOI: 10.1016/s0378-4347(01)00113-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A sensitive HPLC assay has been developed to determine the concentration of 17-(allylamino)-17-demethoxygeldanamycin (AAG) in human plasma over the concentration range of 12.5 to 2,500 nM (7.33 to 1,465 ng/mL). After the addition of 1,000 nM geldanamycin as the internal standard, 1 mL samples of human plasma were subjected to solid-phase extraction, via Bond-Elut C18 cartridges, followed by analysis using an isocratic reversed-phase HPLC assay with UV detection. A Phenomenex Kingsorb, 3 micron, C18, 150x4.60 mm column and a Phenomenex Security Guard pre-column, C18 (ODS, Octadecyl), were used to achieve separation. AAG and GM were monitored at 334 and 308 nm, respectively, on a Hewlett-Packard 1050 Diode-Array Detector. The mobile phase, run at a flow-rate of 1 mL/min, was composed of 50% (v/v) 25 mM sodium phosphate (pH 3.00) with 10 mM triethylamine and 50% acetonitrile. HPLC effectively resolved AAG with retention times of 14.60 +/- 0.54 min and the internal standard geldanamycin at 10.72+/-0.38 min (n = 15). This assay was able to measure plasma concentrations of AAG, the lower limit of quantitation being 12.5 nM, at a starting dose of 10 mg/m2 infused intravenously over 1 h in a Phase I clinical trial in adult patients with solid tumors.
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Affiliation(s)
- E B Agnew
- Developmental Therapeutics Department, Medicine Branch, Division of Clinical Sciences, National Cancer Institute, Bethesda, MD 20889, USA
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Xu W, Mimnaugh E, Rosser MF, Nicchitta C, Marcu M, Yarden Y, Neckers L. Sensitivity of mature Erbb2 to geldanamycin is conferred by its kinase domain and is mediated by the chaperone protein Hsp90. J Biol Chem 2001; 276:3702-8. [PMID: 11071886 DOI: 10.1074/jbc.m006864200] [Citation(s) in RCA: 300] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ErbB receptors are a family of ligand-activated tyrosine kinases that play a central role in proliferation, differentiation, and oncogenesis. ErbB2 is overexpressed in >25% of breast and ovarian cancers and is correlated with poor prognosis. Although ErbB2 and ErbB1 are highly homologous, they respond quite differently to geldanamycin (GA), an antibiotic that is a specific inhibitor of the chaperone protein Hsp90. Thus, although both mature and nascent ErbB2 proteins are down-regulated by GA, only nascent ErbB1 is sensitive to the drug. To reveal the underlying mechanism behind these divergent responses, we made a chimeric receptor (ErbB1/2) composed of the extracellular and transmembrane domains of ErbB1 and the intracellular domain of ErbB2. The ErbB1/2 protein is functional since its kinase activity was stimulated by epidermal growth factor. The sensitivity of ErbB1/2 to GA was similar to that of ErbB2 and unlike that of ErbB1, indicating that the intracellular domain of the chimera confers GA sensitivity. This finding also suggests that the GA sensitivity of mature ErbB2 depends on cytosolic Hsp90, rather than Grp94, a homolog of Hsp90 that is restricted to the lumen of the endoplasmic reticulum, although both chaperones bind to and are inhibited by GA. Lack of Grp94 involvement in mediating ErbB2 sensitivity to GA is further suggested by the fact that a GA derivative with low affinity for Grp94 efficiently depleted ErbB2 protein in treated cells. To localize the specific region of ErbB2 that confers GA sensitivity, we made truncated receptors with progressive deletions of the cytoplasmic domain and tested the GA sensitivity of these molecules. We found that ErbB2 constructs containing an intact kinase domain retained GA sensitivity, whereas those lacking the kinase domain (ErbB2/DK) lost responsiveness to GA completely. Hsp90 co-immunoprecipitated with all ErbB2 constructs that were sensitive to GA, but not with ErbB2/DK or ErbB1. Both tyrosine-phosphorylated and non-phosphorylated ErbB2 proteins were similarly sensitive to GA, as was a kinase-dead ErbB2 mutant. These data suggest that Hsp90 uniquely stabilizes ErbB2 via interaction with its kinase domain and that GA stimulates ErbB2 degradation secondary to disruption of ErbB2/Hsp90 association.
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Affiliation(s)
- W Xu
- Department of Cell and Cancer Biology, Medicine Branch, NCI, National Institutes of Health, Rockville, Maryland 20850, USA
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Casibang M, Purdom S, Jakowlew S, Neckers L, Zia F, Ben-Av P, Hla T, You L, Jablons DM, Moody TW. Prostaglandin E2 and vasoactive intestinal peptide increase vascular endothelial cell growth factor mRNAs in lung cancer cells. Lung Cancer 2001; 31:203-12. [PMID: 11165399 DOI: 10.1016/s0169-5002(00)00168-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The effects of prostaglandin E2 (PGE2) and vasoactive intestinal peptide (VIP) on vascular endothelial cell growth factor (VEGF) mRNAs were investigated using lung cancer cells. By RT-PCR, VEGF(121), VEGF(165), and VEGF(189), but not VEGF(206) isoforms were detected in all lung cancer cell lines and biopsy specimens examined. By Northern blot, VEGF mRNA was detected in all small cell lung cancer (SCLC) and non-SCLC (NSCLC) cell lines examined. PGE2, VIP and forskolin caused increased VEGF expression in a time- and concentration-dependent manner using NSCLC cell line NCI-H157. Approximately 1 microM PGE2, 0.1 microM VIP and 50 microM forskolin caused cAMP elevation, 64-, 33- and 128-fold, respectively, using NCI-H157 cells after 5 min. The increase in cAMP caused by PGE(2) and VIP was reversed by somatostatin (SST). Also 1 microM PGE2, 0.1 microM VIP and 50 microM forskolin increased the VEGF mRNA 2.0-, 1.5- and 2.3-fold, respectively, after 4 h. The increase in VEGF mRNA caused by PGE2, VIP and forskolin was inhibited by H-89, a protein kinase A inhibitor. A VIP receptor antagonist, VIPhybrid, inhibited the increase in cAMP and VEGF mRNA caused by VIP. By ELISA, VEGF was detected in the conditioned media exposed to the lung cancer cell lines. These results suggest that VEGF synthesis in and secretion from lung cancer cells can be regulated by agents, which cause adenylyl cyclase activation.
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Affiliation(s)
- M Casibang
- Medicine Branch, National Cancer Institute, CCBD, BLDG. KWC, Rm. 300, 9610 Medical Center Drive, Rockville, MD 20850, USA
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31
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Mimnaugh EG, Yunmbam MK, Li Q, Bonvini P, Hwang SG, Trepel J, Reed E, Neckers L. Prevention of cisplatin-DNA adduct repair and potentiation of cisplatin-induced apoptosis in ovarian carcinoma cells by proteasome inhibitors. Biochem Pharmacol 2000; 60:1343-54. [PMID: 11008128 DOI: 10.1016/s0006-2952(00)00455-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Histones H2A and H2B are known to be reversibly post-translationally modified by ubiquitination. We previously observed in cultured tumor cells that proteasome inhibition stabilizes polyubiquitinated proteins, depletes unconjugated ubiquitin, and thereby promotes the deubiquitination of nucleosomal histones in chromatin. Provocative indirect evidence suggests that histone ubiquitination/deubiquitination cycles alter chromatin structure, which may limit accessibility of DNA repair proteins to damaged sites. In the present study, we focused on the relationship between the ubiquitination status of histone H2A, the structure of chromatin, and the efficiency of nucleotide excision repair (NER) of cisplatin-DNA adducts in human ovarian carcinoma cells exposed to the antitumor drug cisplatin. Pretreating cells with the proteasome inhibitor lactacystin (LC) or N-acetyl-leucyl-leucyl-norleucinal (ALLnL) induced deubiquitination of ubiquitinated histone H2A (uH2A) and concomitantly promoted chromatin condensation, increased the extent of cisplatin-DNA adducts, and diminished NER-dependent repair of cisplatin-DNA lesions, compared with control cells treated with cisplatin alone. Both proteasome inhibitors also prevented the increase in ERCC-1 mRNA expression that occurs in cells exposed to cisplatin. Cells treated with the combination of ALLnL and cisplatin underwent apoptosis, as indicated by caspase-dependent poly(ADP-ribose) polymerase (PARP) cleavage, more quickly than cells treated with either agent alone. Additionally, the combination of ALLnL and cisplatin potently increased p53 levels in cell lysates and stimulated the binding of p53 to chromatin. Together, these observations suggest that proteasome inhibition may be exploited therapeutically for its potential to sensitize ovarian tumor cells to cisplatin.
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Affiliation(s)
- E G Mimnaugh
- Tumor Cell Biology Section, Cell and Cancer Biology Department, Medicine Branch, National Cancer Institute, NIH, 20892, Bethesda, MD 20892, USA.
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Garayoa M, Martínez A, Lee S, Pío R, An WG, Neckers L, Trepel J, Montuenga LM, Ryan H, Johnson R, Gassmann M, Cuttitta F. Hypoxia-inducible factor-1 (HIF-1) up-regulates adrenomedullin expression in human tumor cell lines during oxygen deprivation: a possible promotion mechanism of carcinogenesis. Mol Endocrinol 2000. [PMID: 10847587 DOI: 10.1210/me.14.6.848] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Little is known about the molecular mechanisms that control adrenomedullin (AM) production in human cancers. We demonstrate here that the expression of AM mRNA in a variety of human tumor cell lines is highly induced in a time-dependent manner by reduced oxygen tension (1% O2) or exposure to hypoxia mimetics such as desferrioxamine mesylate (DFX) or CoCl2. This AM expression seems to be under hypoxia-inducible factor-1 (HIF-1) transcriptional regulation, since HIF-1alpha and HIF-1beta knockout mouse cell lines had an ablated or greatly reduced hypoxia AM mRNA induction. Similarly, inhibition or enhancement of HIF-1 activity in human tumor cells showed an analogous modulation of AM mRNA. Under hypoxic conditions, immunohistochemical analysis of tumor cell lines revealed elevated levels of AM and HIF-1alpha as compared with normoxia, and we also found an increase of immunoreactive AM in the conditioned medium of tumor cells analyzed by RIA. AM mRNA stabilization was shown to be partially responsible for the hypoxic up-regulated expression of AM. In addition, we have identified several putative hypoxia response elements (HREs) in the human AM gene, and reporter studies with selected HREs were capable of enhancing luciferase expression after exposure to DFX. Furthermore, transient coexpression of HIF-1alpha resulted in an augmented transactivation of the reporter gene after DFX treatment. Given that most solid human tumors have focal hypoxic areas and that AM functions as a mitogen, angiogenic factor, and apoptosis-survival factor, our findings implicate the HIF-1/AM link as a possible promotion mechanism of carcinogenesis.
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Affiliation(s)
- M Garayoa
- Department of Cell and Cancer Biology, National Cancer Institute, National Institutes of Health Bethesda, Maryland 20892, USA.
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Garayoa M, Martínez A, Lee S, Pío R, An WG, Neckers L, Trepel J, Montuenga LM, Ryan H, Johnson R, Gassmann M, Cuttitta F. Hypoxia-inducible factor-1 (HIF-1) up-regulates adrenomedullin expression in human tumor cell lines during oxygen deprivation: a possible promotion mechanism of carcinogenesis. Mol Endocrinol 2000; 14:848-62. [PMID: 10847587 DOI: 10.1210/mend.14.6.0473] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Little is known about the molecular mechanisms that control adrenomedullin (AM) production in human cancers. We demonstrate here that the expression of AM mRNA in a variety of human tumor cell lines is highly induced in a time-dependent manner by reduced oxygen tension (1% O2) or exposure to hypoxia mimetics such as desferrioxamine mesylate (DFX) or CoCl2. This AM expression seems to be under hypoxia-inducible factor-1 (HIF-1) transcriptional regulation, since HIF-1alpha and HIF-1beta knockout mouse cell lines had an ablated or greatly reduced hypoxia AM mRNA induction. Similarly, inhibition or enhancement of HIF-1 activity in human tumor cells showed an analogous modulation of AM mRNA. Under hypoxic conditions, immunohistochemical analysis of tumor cell lines revealed elevated levels of AM and HIF-1alpha as compared with normoxia, and we also found an increase of immunoreactive AM in the conditioned medium of tumor cells analyzed by RIA. AM mRNA stabilization was shown to be partially responsible for the hypoxic up-regulated expression of AM. In addition, we have identified several putative hypoxia response elements (HREs) in the human AM gene, and reporter studies with selected HREs were capable of enhancing luciferase expression after exposure to DFX. Furthermore, transient coexpression of HIF-1alpha resulted in an augmented transactivation of the reporter gene after DFX treatment. Given that most solid human tumors have focal hypoxic areas and that AM functions as a mitogen, angiogenic factor, and apoptosis-survival factor, our findings implicate the HIF-1/AM link as a possible promotion mechanism of carcinogenesis.
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Affiliation(s)
- M Garayoa
- Department of Cell and Cancer Biology, National Cancer Institute, National Institutes of Health Bethesda, Maryland 20892, USA.
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Abstract
Heat shock protein 90 is one of the most abundant cellular proteins. Although its functions are still being characterized, it appears to serve as a chaperone for a growing list of cell signaling proteins, including many tyrosine and serine/threonine kinases, involved in proliferation and/or survival. The benzoquinone ansamycin geldanamycin has been shown to bind to Hsp90 and to specifically inhibit this chaperone's function, resulting in client protein destabilization. Its ability to simultaneously stimulate depletion of multiple oncogenic proteins suggests that geldanamycin, or other molecules capable of targeting Hsp90 in cancer cells, may be of clinical benefit.
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Affiliation(s)
- L Neckers
- Department of Cell and Cancer Biology, Medicine Branch, National Cancer Institute, Rockville, MD, USA
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35
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Lewis J, Devin A, Miller A, Lin Y, Rodriguez Y, Neckers L, Liu ZG. Disruption of hsp90 function results in degradation of the death domain kinase, receptor-interacting protein (RIP), and blockage of tumor necrosis factor-induced nuclear factor-kappaB activation. J Biol Chem 2000; 275:10519-26. [PMID: 10744744 DOI: 10.1074/jbc.275.14.10519] [Citation(s) in RCA: 259] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The death domain kinase, receptor interacting protein (RIP), is one of the major components of the tumor necrosis factor receptor 1 (TNFR1) complex and plays an essential role in tumor necrosis factor (TNF)-mediated nuclear factor kappaB (NF-kappaB) activation. The activation of NF-kappaB protects cells against TNF-induced apoptosis. Heat-shock proteins (Hsps) are chaperone molecules that confer protein stability and help to restore protein native folding following heat shock and other stresses. The most abundant Hsp, Hsp90, is also involved in regulating the stability and function of a number of cell-signaling molecules. Here we report that RIP is a novel Hsp90-associated kinase and that disruption of Hsp90 function by its specific inhibitor, geldanamycin (GA), selectively causes RIP degradation and the subsequent inhibition of TNF-mediated IkappaB kinase and NF-kappaB activation. MG-132, a specific proteasome inhibitor, abrogated GA-induced degradation of RIP but failed to restore the activation of IkappaB kinase by TNF, perhaps because, in the presence of GA and MG-132, RIP accumulated in a detergent-insoluble subcellular fraction. Most importantly, the degradation of RIP sensitizes cells to TNF-induced apoptosis. These data indicate that Hsp90 plays an important role in TNF-mediated NF-kappaB activation by modulating the stability and solubility of RIP. Thus, inhibition of NF-kappaB activation by GA may be a critical component of the anti-tumor activity of this drug.
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Affiliation(s)
- J Lewis
- Department of Cell and Cancer Biology, Medicine Branch, Division of Clinical Sciences, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA
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Bonvini P, Hwang SG, el-Gamil M, Robbins P, Neckers L, Trepel J. Melanoma cell lines contain a proteasome-sensitive, nuclear cytoskeleton-associated pool of beta-catenin. Ann N Y Acad Sci 2000; 886:208-11. [PMID: 10667221 DOI: 10.1111/j.1749-6632.1999.tb09418.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- P Bonvini
- Department of Cell and Cancer Biology, Medicine Branch, National Cancer Institute, National Institutes of Health, Rockville, Maryland 20850, USA.
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37
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Bonvini P, Hwang SG, El-Gamil M, Robbins P, Kim JS, Trepel J, Neckers L. Nuclear beta-catenin displays GSK-3beta- and APC-independent proteasome sensitivity in melanoma cells. Biochim Biophys Acta 2000; 1495:308-18. [PMID: 10699468 DOI: 10.1016/s0167-4889(99)00162-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Colon carcinoma and melanoma cells containing either a deletion of the adenomatous polyposis coli tumor suppressor protein (APC) or mutation of the site in beta-catenin phosphorylated by glycogen synthase kinase-3beta (GSK-3beta) display elevated levels of detergent-soluble beta-catenin due to insensitivity of the cytosolic protein to proteasome-dependent degradation. In this study, we have examined the effect of beta-catenin mutation (S37F) or APC loss on the proteasome sensitivity of additional subcellular beta-catenin pools in melanoma cells. In contrast to detergent-soluble beta-catenin, the detergent-insoluble protein remains proteasome-sensitive irrespective of S37F mutation or APC status. This insoluble component appears associated primarily with nuclear cytoskeletal elements. In addition, DNase I treatment solubilized a portion of detergent-insoluble beta-catenin, suggesting that this fraction also contains chromatin-associated protein, and correlating with a proteasome-sensitive elevation in beta-catenin-stimulated reporter activity. Since the detergent-insoluble nuclear component of beta-catenin displays GSK-3beta- and APC-independent proteasome sensitivity, distinct from the soluble nuclear and cytosolic pools of this protein, regulation of beta-catenin proteasome sensitivity and the contribution of this process to beta-catenin function may be more complex than previously appreciated.
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Affiliation(s)
- P Bonvini
- Department of Cell and Cancer Biology, Medicine Branch, NCI, NIH, 9610 Medical Center Drive, Suite 300, Rockville, MD 20850, USA
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Abstract
BACKGROUND Heat shock protein 90 (Hsp90) interacts with and stabilizes several oncogenic protein kinases (e.g., p185(erbB2), p60(v-src), and Raf-1) and is required for the stability and dominant-negative function of mutated p53 protein. Two unrelated antibiotics, geldanamycin and radicicol, bind specifically to an atypical nucleotide-binding pocket of Hsp90, a site that shares homology with the adenosine triphosphate (ATP)-binding domain of bacterial DNA gyrase B. This interaction leads to destabilization of proteins that interact with Hsp90. Since the nucleotide-binding site of gyrase B is targeted by coumarin antibiotics (e.g., novobiocin), we investigated whether these drugs can also interact with Hsp90 and affect its activity. METHODS We used immobilized novobiocin, geldanamycin, or radicicol to isolate either endogenous Hsp90 from cell lysates or Hsp90 deletion fragments translated in vitro. Effects of the coumarin antibiotics novobiocin, chlorobiocin, and coumermycin A1 on several proteins interacting with Hsp90 were assessed in vitro and in vivo. RESULTS Hsp90 binding to immobilized novobiocin was competed by soluble coumarins and ATP but not by geldanamycin or radicicol. A carboxy-terminal Hsp90 fragment bound immobilized novobiocin but not immobilized geldanamycin, while a geldanamycin-binding amino-terminal fragment did not bind novobiocin. All three coumarins markedly reduced cellular levels of p185(erbB2), p60(v-src), Raf-1, and mutated p53. Furthermore, novobiocin reduced Raf-1 levels in the spleens of mice treated with the drug. CONCLUSIONS These coumarin antibiotics, particularly novobiocin, represent a first-generation alternative to other Hsp90-targeting drugs that are not as well tolerated. Novobiocin's unique interaction with Hsp90 identifies an additional site on this protein amenable to pharmacologic interference with small molecules.
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Affiliation(s)
- M G Marcu
- Department of Cell and Cancer Biology, Medicine Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20850, USA
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Neckers L. Effects of geldanamycin and other naturally occurring small molecule antagonists of heat shock protein 90 on HER2 protein expression. Breast Dis 2000; 11:49-59. [PMID: 15687592 DOI: 10.3233/bd-1999-11105] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
Several natural product antibiotics, including herbimycin, geldanamycin, and radicicol, bind to an amino terminal nucleotide binding pocket in the heat shock protein Hsp90. Drug binding alters the conformation of Hsp90 and interferes with its ability to chaperone a distinct group of "client" proteins, including a number of transmembrane and soluble tyrosine and serine/threonine kinases. Prominent among the kinases dependent on Hsp90 is the ErbB family member HER2, which is frequently overexpressed in adenocarcinoma and is associated with a poor prognosis and resistance to chemotherapy. Disruption of Hsp90 function promotes the proteasome-dependent and ubiquitin-mediated degradation of HER2, making small molecule chaperone antagonists exciting candidates for clinical development.
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Affiliation(s)
- L Neckers
- Department of Cell and Cancer Biology, Medicine Branch, National Cancer Institute, Rockville, MD 20850, USA.
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Abstract
Ubiquitination of key cellular proteins involved in signal transduction, gene transcription and cell-cycle regulation usually condemns those proteins to proteasomal or lysosomal degradation. Additionally, cycles of reversible ubiquitination regulate the function of certain proteins in a manner analogous to phosphorylation. In this short review we describe the current methodology for measuring ubiquitin and ubiquitination, provide examples which illustrate how various techniques have been used to study protein ubiquination, alert the readers of pitfalls to avoid, and offer guidelines to investigators newly interested in this novel post-translational protein modification.
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Affiliation(s)
- E G Mimnaugh
- Tumor Cell Biology Section, Medicine Branch, National Cancer Institute, National Institutes of Health, Key West Center, Rockville, MD 20850, USA.
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Abstract
FAK is a nonreceptor tyrosine kinase involved in adhesion-mediated signal transduction whose level of expression is related to the invasiveness of malignant tumors. In seeking strategies to downregulate FAK, we treated various cell lines in vitro with the benzoquinone ansamycin geldanamycin (GA) which was previously described as a tyrosine kinase inhibitor, but recently has been shown to exert its effects by interfering with the chaperone function of members of the hsp90 family of heat-shock proteins. We evaluated the effects of benzoquinone ansamycins on FAK steady-state protein level and FAK half-life in breast and prostate carcinoma, Ewing's sarcoma, and 3T3 fibroblasts. Our data demonstrate that GA stimulates the proteolytic degradation of FAK in all cell lines examined and markedly reduces the half-life of newly synthesized FAK protein without significantly altering the level of FAK mRNA. These data demonstrate FAK to be another tyrosine kinase sensitive to the destabilizing effects of benzoquinone ansamycins and further show that small molecule-mediated pharmacologic modulation of FAK protein level is a feasible approach to the interdiction of FAK function.
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Affiliation(s)
- H J Ochel
- Medicine Branch, National Cancer Institute, Rockville, Maryland, 20850, USA
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42
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Abstract
p53 is required for hypoxia-induced apoptosis in vivo, although the mechanism by which this occurs is not known. Conversely, induction of the hypoxia-inducible factor-1 (HIF-1) transactivator stimulates transcription of a number of genes crucial to survival of the hypoxic state. Here we demonstrate that p53 represses HIF-1-stimulated transcription. Although higher levels of p53 are required to inhibit HIF than are necessary to transcriptionally activate p53 target genes, these levels of p53 are similar to those that stimulate cleavage of poly(ADP-ribose) polymerase, an early event in apoptosis. Transfection of full-length p300 stimulates both p53-dependent and HIF-dependent transcription but does not relieve p53-mediated inhibition of HIF. In contrast, a p300 fragment, which binds to p53 but not to HIF-1, prevents p53-dependent repression of HIF activity. Transcriptionally inactive p53, mutated in its DNA binding domain, retains the ability to block HIF transactivating activity, whereas a transcriptionally inactive double point mutant defective for p300 binding does not inhibit HIF. Finally, depletion of doxorubicin-induced endogenous p53 by E6 protein attenuates doxorubicin-stimulated inhibition of HIF, suggesting that a p53 level sufficient for HIF inhibition can be achieved in vivo. These data support a model in which stoichiometric binding of p53 to a HIF/p300 transcriptional complex mediates inhibition of HIF activity.
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Affiliation(s)
- M V Blagosklonny
- Department of Experimental Therapeutics, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Mimnaugh EG, Chen HY, Davie JR, Celis JE, Neckers L. Rapid deubiquitination of nucleosomal histones in human tumor cells caused by proteasome inhibitors and stress response inducers: effects on replication, transcription, translation, and the cellular stress response. Biochemistry 1997; 36:14418-29. [PMID: 9398160 DOI: 10.1021/bi970998j] [Citation(s) in RCA: 143] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The proteasome inhibitors, lactacystin and N-acetyl-leucyl-leucyl-norlucinal, caused a rapid and near-complete loss of approximately 22-23-kDa ubiquitinated nucleoproteins, which we have identified as monoubiquitinated nucleosomal histones H2A and H2B by immunological and two-dimensional electrophoretic techniques. In human SKBr3 breast tumor cells, depletion of monoubiquitinated histones by the proteasome inhibitors coincided with the accumulation of high molecular weight ubiquitinated proteins in both nucleoprotein and cytosolic fractions and decreased unconjugated ubiquitin in the cytosol, without changes in the nonubiquitinated core histones. Unconjugated ubiquitin was not detected in isolated tumor cell nuclei. A similar loss in monoubiquitinated histones occurred in cells harboring a defective, temperature-sensitive mutation of the ubiquitin-activating E1 enzyme, after these cells were elevated from 33 degrees C to the non-permissive temperature of 39 degrees C. DNA replication and RNA transcription were decreased by the proteasome inhibitors most strongly after 90% of the ubiquitin had been removed from ubiquitinated histones H2A and H2B, suggesting a relationship between the nucleosomal histone ubiquitin status and the processing of genetic information. Interestingly, although both proteasome inhibitors caused a generalized decrease in methionine incorporation into proteins, they strongly induced the synthesis of the hsp72 and hsp90 stress proteins. Finally, treating cells with heat-shock at 43 degrees C, with stress response-provoking chemicals or with several other proteasome inhibitors caused ubiquitinated proteins to accumulate, depleted free ubiquitin, and concomitantly decreased nucleosomal monoubiquitinated histones. These results suggest that deubiquitination of nucleosomal histones H2A and H2B may play a previously unrecognized role in the cellular stress response, as well as in the processing of chromatin, and emphasize the important role of the proteasome in cellular homeostasis.
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Affiliation(s)
- E G Mimnaugh
- Department of Cancer and Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Whitesell L, Sutphin P, An WG, Schulte T, Blagosklonny MV, Neckers L. Geldanamycin-stimulated destabilization of mutated p53 is mediated by the proteasome in vivo. Oncogene 1997; 14:2809-16. [PMID: 9190897 DOI: 10.1038/sj.onc.1201120] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Mutation of the tumor suppressor gene p53 is the most common genetic abnormality detected in human cancers. Wild type p53 is a short-lived protein with very low basal intracellular levels. Most mutated forms of the protein, however, display markedly increased intracellular levels as an essential feature of their positive transforming activity. In this report, we have used selective inhibitors of the 20S proteasome to demonstrate that processing of p53 by ubiquitination and proteasome-mediated degradation is impaired by commonly occuring mutations of the protein. We found that this impairment of p53 turnover can be reversed by treatment of tumor cells with the benzoquinone ansamycin, geldanamycin, leading to a marked reduction in intracellular p53 levels. Finally, using cells which over-express a mutant p53 protein, we were able to demonstrate that restoration of proteasome-mediated degradation by geldanamycin is accompanied by p53 polyubiquitination. Although much remains to be learned about the mechanisms involved, our data demonstrate that selective de-stabilization of mutant transforming proteins such as p53 can be achieved pharmacologically with agents such as geldanamycin which modify the function of molecular chaperone proteins within tumor cells.
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Affiliation(s)
- L Whitesell
- Department of Pediatrics, Steele Memorial Children's Research Center, University of Arizona, Tucson 85724, USA
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Kyle E, Neckers L, Takimoto C, Curt G, Bergan R. Genistein-induced apoptosis of prostate cancer cells is preceded by a specific decrease in focal adhesion kinase activity. Mol Pharmacol 1997; 51:193-200. [PMID: 9203623 DOI: 10.1124/mol.51.2.193] [Citation(s) in RCA: 132] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Genistein (5,7,4'-trihydroxyisoflavone), an isoflavinoid found in soy beans, has been identified as potentially causal for the low incidence of metastatic prostate cancer (PCa) in certain countries. Although genistein-induced PCa cell adhesion has been identified as a possible causative mechanism, direct growth inhibition by genistein has been reported and also could be causal. If in vivo growth inhibition was significant, then growth inhibition should occur at concentrations attained with dietary consumption, the mechanism of growth inhibition should be relevant to PCa, and genistein (a broad-spectrum in vitro protein-tyrosine kinase inhibitor) should have relatively specific kinase inhibitory effects in vivo. These considerations were investigated by measuring growth inhibitory activity in a variety of PCa cell lines. Growth inhibitory effects were shown not to occur with concentrations below the low micromolar range (i.e., 3 logs above that attained in serum). In-depth mechanistic studies with the PC3-M metastatic variant cell line demonstrated that growth inhibition was independent of genistein's estrogenic effects. Genistein was shown to decrease the viability of nonadherent cells, suggesting a lack of dependence on cell adhesion for growth inhibition. However, important molecular and kinetic differences between genistein's effects on growth in adherent versus nonadherent cells were identified. Specific suppression of focal adhesion kinase activity (without global decreases in phosphotyrosine) was shown to precede induction of apoptosis, which was responsible for growth inhibition in adherent cells. These findings do not support an in vivo growth inhibitory role by genistein consumed in quantities associated with a soy-based diet. They do, however, identify genistein as a potential therapeutic agent for PCa and as a tool with which to study the control of apoptosis in PCa.
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Affiliation(s)
- E Kyle
- Clinical Pharmacology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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Abstract
Ewing's sarcoma family of tumors (EFT) contain reciprocal translocations, of which approximately 90% occur between the long arm of chromosomes 11 and 22,t(11;22)(q24;q12) resulting in the formation of chimeric proteins generated by a fusion of the EWS and FLI-1 genes. To determine if EWS-FLI-1 protein is responsible for the Ewing sarcoma phenotype we have used sequence-specific antisense oligodeoxynucleotides (ODN) to block its expression. We have evaluated a series of antisense ODN directed toward the breakpoint region in an effort to prevent translation of the fusion messenger RNA. ODN were first evaluated in a cell-free in vitro translation system. Exogenously added RNase H was found to be required for translation inhibition. ODN that showed complete inhibition of translation were electroporated into TC-32 cells, a EFT cell line. Fusion protein and EWS protein levels were evaluated by Western blot analysis. A 40-60% decrease in the fusion protein was observed in TC-32 cells with antisense ODN directed toward the breakpoint region. Cell viability was reduced with antisense sequences in TC-32 cells but not in a prostate cancer cell line. Since inhibition of t(11:22) gene product is correlated to effects on cell viability reduction of the fusion protein may thus offer insight into the biology of EFT.
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Affiliation(s)
- J A Toretsky
- Pediatric Branch, National Cancer Institute, Bethesda, MD 20892, USA
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An WG, Schnur RC, Neckers L, Blagosklonny MV. Depletion of p185erbB2, Raf-1 and mutant p53 proteins by geldanamycin derivatives correlates with antiproliferative activity. Cancer Chemother Pharmacol 1997; 40:60-4. [PMID: 9137531 DOI: 10.1007/s002800050626] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
PURPOSE Recently, it has been shown that geldanamycin (GA), a benzoquinone ansamycin, is able to deplete mutant p53, p185erbB2 and Raf-1 proteins in cancer cells. However, the relationship between these activities of GA and its antiproliferative activity is not clear. Here we investigated the effects of 28 GA derivatives in SKBr3, a human breast cancer cell line. METHODS We performed Western blot analysis of Raf-1, p185erbB2 and mutant p53 proteins following drug treatment and correlated these findings with the cytotoxicity of the various GA derivatives. RESULTS We found that downregulation of Raf-1, p185erbB2 and mutant p53 proteins was correlated. Thus, a drug that was active against one oncoprotein was equally active against the two others. Inactive derivatives were identified by their inability to downregulate these oncoproteins, even at a high dose (2 microM). These inactive drugs also had no or minimal antiproliferative activity (IC50 > 3 microM). All other analogs (at a concentration of 2 microM) downregulated p53, p185erbB2, and Raf-1, and also displayed cytotoxicity (IC50 in the range 6-600 nM). This category of drugs was further divided into more- and less-active agents by testing at lower doses (40 nM). The drugs that remained active against their molecular targets had an IC50 for antiproliferative activity of less than 40 nM. Maximal effects on mutant p53, p185erbB2 and Raf-1 were observed at doses that were 4-5 times greater than the cytotoxic IC50. CONCLUSIONS These findings suggest that GA and its derivatives are cytostatic/cytotoxic at concentrations that also downregulate Raf-1, p185erbB2 and mutant p53, and raise the possibility that depletion of these proteins and the antiproliferative activities of GA have a common mechanism.
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Affiliation(s)
- W G An
- Clinical Pharmacology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, USA
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Blagosklonny MV, Giannakakou P, el-Deiry WS, Kingston DG, Higgs PI, Neckers L, Fojo T. Raf-1/bcl-2 phosphorylation: a step from microtubule damage to cell death. Cancer Res 1997; 57:130-5. [PMID: 8988053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Recent studies have shown that paclitaxel leads to activation of Raf-1 kinase and have suggested that this activation is essential for bcl-2 phosphorylation and apoptosis. In the present study, we demonstrate that, in addition to paclitaxel, other agents that interact with tubulin and microtubules also induce Raf-1/bcl-2 phosphorylation, whereas DNA-damaging drugs, antimetabolites, and alkylating agents do not. Activation of Raf-1 kinase by paclitaxel is linked to tubulin polymerization; the effect is blunted in paclitaxel-resistant cells, the tubulin of which does not polymerize following the addition of paclitaxel. In contrast, vincristine and vinblastine, drugs to which the paclitaxel-resistant cells retain sensitivity were able to bring about Raf-1 phosphorylation. The requirement for disruption of microtubules in this signaling cascade was strengthened further using paclitaxel analogues by demonstrating a correlation between tubulin polymerization, Raf-1/bcl-2 phosphorylation, and cytotoxicity. Inhibition of RNA or protein synthesis prevents Raf-1 activation and bcl-2 phosphorylation, suggesting that an intermediate protein(s) acts upstream of Raf-1 in this microtubule damage-activating pathway. A model is proposed that envisions a pathway of Raf-1 activation and bcl-2 phosphorylation following disruption of microtubular architecture, serving a role similar to p53 induction following DNA damage.
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Affiliation(s)
- M V Blagosklonny
- Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia 19104, USA
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Mimnaugh EG, Chavany C, Neckers L. Polyubiquitination and proteasomal degradation of the p185c-erbB-2 receptor protein-tyrosine kinase induced by geldanamycin. J Biol Chem 1996; 271:22796-801. [PMID: 8798456 DOI: 10.1074/jbc.271.37.22796] [Citation(s) in RCA: 317] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Treatment of SKBr3 human breast carcinoma cells with the benzoquinoid ansamycin, geldanamycin, rapidly depletes p185c-erbB-2 protein-tyrosine kinase. Loss of p185c-erbB-2 is initiated by disruption of a heteromeric complex between p185c-erbB-2 and the 94-kDa glucose-regulated protein, GRP94, to which geldanamycin binds avidly. Here we report that within minutes of exposure to geldanamycin, mature p185c-erbB-2 becomes polyubiquitinated. Treatment of cells with the specific proteasome proteolytic inhibitor, lactacystin, blocked geldanamycin-induced degradation of p185c-erbB-2 and enhanced the accumulation of polyubiquitinated p185c-erbB-2. Following geldanamycin and lactacystin treatment, a higher molecular weight form of p185c-erbB-2, which likely represents ubiquitin-p185c-erbB-2 conjugates, was detected by anti-p185c-erbB-2 immunoblotting. Nascent p185c-erbB-2 synthesized in the presence of geldanamycin is incompletely glycosylated and remains sequestered in the endoplasmic reticulum. While this immature form of the protein is not ubiquitinated in the presence of geldanamycin, its marked, drug-induced instability is nonetheless antagonized by lactacystin. Thus, the rapid depletion of mature p185c-erbB-2 caused by geldanamycin and the marked, drug-stimulated decrease in half-life of the newly synthesized protein are both mediated by the proteasome, although only the former phenomenon involves polyubiquitination.
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Affiliation(s)
- E G Mimnaugh
- Clinical Pharmacology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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Bergan R, Kyle E, Nguyen P, Trepel J, Ingui C, Neckers L. Genistein-stimulated adherence of prostate cancer cells is associated with the binding of focal adhesion kinase to beta-1-integrin. Clin Exp Metastasis 1996; 14:389-98. [PMID: 8878413 DOI: 10.1007/bf00123398] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The isoflavinoid genistein is a protein-tyrosine kinase inhibitor which has been identified as a putative cancer prevention agent. Its consumption is associated with a low incidence of clinical metastatic prostate cancer in the face of a sustained high incidence of organ-confined prostate cancer. We therefore undertook studies to examine genistein's effect upon cell adhesion as one possible mechanism by which it could be acting as an antimetastatic agent. A morphogenic analysis revealed that genistein caused cell flattening in a variety of cell lines: PC3-M, PC3, and DU-145 prostate carcinoma cells, as well as MCF-7 breast carcinoma cells. Mechanistic studies focused on the highly metastatic PC3-M cell line, and revealed that cell flattening was accompanied by an increase in cell adhesion. Further investigations demonstrated that focal adhesion kinase (FAK) accumulated in areas of focal cell attachment, and that this accumulation occurred only when cells were actively undergoing genistein-mediated morphologic change. Concurrent formation of a complex between the cell attachment molecule, beta-1-integrin, and FAK was shown to occur, and to correlate with transient activation of FAK activity. Genistein is presented as a novel investigative tool for use in the study of molecular events involved in the process of cell adhesion.
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Affiliation(s)
- R Bergan
- Clinical Pharmacology Branch, National Cancer Institute, National Institutes of Health, Bethesda 20892, MD, USA
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