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Neuwahl J, Neumann CA, Fitz AC, Biermann AD, Magel M, Friedrich A, Sellin L, Stork B, Piekorz RP, Proksch P, Budach W, Jänicke RU, Sohn D. Combined inhibition of class 1-PI3K-alpha and delta isoforms causes senolysis by inducing p21 WAF1/CIP1 proteasomal degradation in senescent cells. Cell Death Dis 2024; 15:373. [PMID: 38811535 PMCID: PMC11136996 DOI: 10.1038/s41419-024-06755-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 05/13/2024] [Accepted: 05/16/2024] [Indexed: 05/31/2024]
Abstract
The targeted elimination of radio- or chemotherapy-induced senescent cells by so-called senolytic substances represents a promising approach to reduce tumor relapse as well as therapeutic side effects such as fibrosis. We screened an in-house library of 178 substances derived from marine sponges, endophytic fungi, and higher plants, and determined their senolytic activities towards DNA damage-induced senescent HCT116 colon carcinoma cells. The Pan-PI3K-inhibitor wortmannin and its clinical derivative, PX-866, were identified to act as senolytics. PX-866 potently induced apoptotic cell death in senescent HCT116, MCF-7 mammary carcinoma, and A549 lung carcinoma cells, independently of whether senescence was induced by ionizing radiation or by chemotherapeutics, but not in proliferating cells. Other Pan-PI3K inhibitors, such as the FDA-approved drug BAY80-6946 (Copanlisib, Aliqopa®), also efficiently and specifically eliminated senescent cells. Interestingly, only the simultaneous inhibition of both PI3K class I alpha (with BYL-719 (Alpelisib, Piqray®)) and delta (with CAL-101 (Idelalisib, Zydelig®)) isoforms was sufficient to induce senolysis, whereas single application of these inhibitors had no effect. On the molecular level, inhibition of PI3Ks resulted in an increased proteasomal degradation of the CDK inhibitor p21WAF1/CIP1 in all tumor cell lines analyzed. This led to a timely induction of apoptosis in senescent tumor cells. Taken together, the senolytic properties of PI3K-inhibitors reveal a novel dimension of these promising compounds, which holds particular potential when employed alongside DNA damaging agents in combination tumor therapies.
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Affiliation(s)
- Judith Neuwahl
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Chantal A Neumann
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Annika C Fitz
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Anica D Biermann
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
- Experimental Nephrology, Clinic for Nephrology, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Maja Magel
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
- Functional Microbiome Research Group, Institute of Medical Microbiology, University Hospital of RWTH, Aachen, Germany
| | - Annabelle Friedrich
- Institute of Molecular Medicine I, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Lorenz Sellin
- Experimental Nephrology, Clinic for Nephrology, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Björn Stork
- Institute of Molecular Medicine I, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Roland P Piekorz
- Institute of Biochemistry and Molecular Biology II, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Peter Proksch
- Institute of Pharmaceutical Biology and Biotechnology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Wilfried Budach
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Reiner U Jänicke
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Dennis Sohn
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
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2
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Proteasome complexes experience profound structural and functional rearrangements throughout mammalian spermatogenesis. Proc Natl Acad Sci U S A 2022; 119:e2116826119. [PMID: 35377789 PMCID: PMC9169623 DOI: 10.1073/pnas.2116826119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
The proteasome is responsible for the homeostasis of intracellular proteins. Here, we describe structural and functional aspects of a poorly characterized proteasome subtype found exclusively in germ cells. The spermatoproteasome was recently shown to be essential for spermatogenesis, a process requiring intense proteolysis. It differs from the constitutive proteasome by only one subunit, α4s, a subunit that replaces its α4 ubiquitous counterpart. In this work, we show how the shift from α4 to α4s regulates proteasome composition, dynamics, interactome, and activity. We reveal a regulation process more complex than previously suggested, which provides the basis for structural and functional studies of the spermatoproteasome. During spermatogenesis, spermatogonia undergo a series of mitotic and meiotic divisions on their path to spermatozoa. To achieve this, a succession of processes requiring high proteolytic activity are in part orchestrated by the proteasome. The spermatoproteasome (s20S) is specific to the developing gametes, in which the gamete-specific α4s subunit replaces the α4 isoform found in the constitutive proteasome (c20S). Although the s20S is conserved across species and was shown to be crucial for germ cell development, its mechanism, function, and structure remain incompletely characterized. Here, we used advanced mass spectrometry (MS) methods to map the composition of proteasome complexes and their interactomes throughout spermatogenesis. We observed that the s20S becomes highly activated as germ cells enter meiosis, mainly through a particularly extensive 19S activation and, to a lesser extent, PA200 binding. Additionally, the proteasome population shifts from c20S (98%) to s20S (>82 to 92%) during differentiation, presumably due to the shift from α4 to α4s expression. We demonstrated that s20S, but not c20S, interacts with components of the meiotic synaptonemal complex, where it may localize via association with the PI31 adaptor protein. In vitro, s20S preferentially binds to 19S and displays higher trypsin- and chymotrypsin-like activities, both with and without PA200 activation. Moreover, using MS methods to monitor protein dynamics, we identified significant differences in domain flexibility between α4 and α4s. We propose that these differences induced by α4s incorporation result in significant changes in the way the s20S interacts with its partners and dictate its role in germ cell differentiation.
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Ha JH, Jayaraman M, Yan M, Dhanasekaran P, Isidoro C, Song YS, Dhanasekaran DN. Identification of GNA12-driven gene signatures and key signaling networks in ovarian cancer. Oncol Lett 2021; 22:719. [PMID: 34429759 PMCID: PMC8371953 DOI: 10.3892/ol.2021.12980] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 07/16/2021] [Indexed: 02/06/2023] Open
Abstract
With the focus on defining the oncogenic network stimulated by lysophosphatidic acid (LPA) in ovarian cancer, the present study sought to interrogate the oncotranscriptome regulated by the LPA-mediated signaling pathway. LPA, LPA-receptor (LPAR) and LPAR-activated G protein 12 α-subunit, encoded by G protein subunit α 12 (GNA12), all serve an important role in ovarian cancer progression. While the general signaling mechanism regulated by LPA/LPAR/GNA12 has previously been characterized, the global transcriptomic network regulated by GNA12 in ovarian cancer pathophysiology remains largely unknown. To define the LPA/LPAR/GNA12-orchestrated oncogenic networks in ovarian cancer, transcriptomic and bioinformatical analyses were conducted using SKOV3 cells, in which the expression of GNA12 was silenced. Array analysis was performed in Agilent SurePrint G3 Human Comparative Genomic Hybridization 8×60 microarray platform. The array results were validated using Kuramochi cells. Gene and functional enrichment analyses were performed using Database for Annotation, Visualization and Integrated Discovery, Search Tool for Retrieval of Interacting Genes and Cytoscape algorithms. The results indicated a paradigm in which GNA12 drove ovarian cancer progression by upregulating a pro-tumorigenic network with AKT1, VEGFA, TGFB1, BCL2L1, STAT3, insulin-like growth factor 1 and growth hormone releasing hormone as critical hub and/or bottleneck nodes. Moreover, GNA12 downregulated a growth-suppressive network involving proteasome 20S subunit (PSM) β6, PSM α6, PSM ATPase 5, ubiquitin conjugating enzyme E2 E1, PSM non-ATPase 10, NDUFA4 mitochondrial complex-associated, NADH:ubiquinone oxidoreductase subunit B8 and anaphase promoting complex subunit 1 as hub or bottleneck nodes. In addition to providing novel insights into the LPA/LPAR/GNA12-regulated oncogenic networks in ovarian cancer, the present study identified several potential nodes in this network that could be assessed for targeted therapy.
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Affiliation(s)
- Ji-Hee Ha
- Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma, OK 73104, USA.,Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma, OK 73104, USA
| | - Muralidharan Jayaraman
- Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma, OK 73104, USA.,Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma, OK 73104, USA
| | - Mingda Yan
- Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma, OK 73104, USA
| | - Padmaja Dhanasekaran
- Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma, OK 73104, USA
| | - Ciro Isidoro
- Laboratory of Molecular Pathology and NanoBioImaging, Department of Health Sciences, University of Eastern Piedmont, I-17-28100 Novara, Italy
| | - Yong-Sang Song
- Department of Obstetrics and Gynecology, Cancer Research Institute, College of Medicine, Seoul National University, Seoul 151-921, Republic of Korea
| | - Danny N Dhanasekaran
- Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma, OK 73104, USA.,Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma, OK 73104, USA
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Potu H, Kandarpa M, Peterson LF, Donato NJ, Talpaz M. Tumor necrosis factor related apoptosis inducing ligand (TRAIL) regulates deubiquitinase USP5 in tumor cells. Oncotarget 2019; 10:5745-5754. [PMID: 31645897 PMCID: PMC6791380 DOI: 10.18632/oncotarget.27196] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 08/22/2019] [Indexed: 01/08/2023] Open
Abstract
The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) pathway has emerged as a cancer therapeutic target. However, clinical trials have proven that most human cancers are resistant to TRAIL. We show that exposure to recombinant TRAIL resulted in the accumulation of ubiquitinated proteins and free ubiquitin polymers, suggesting a link between TRAIL and the ubiquitin (Ub)-proteasome pathway. TRAIL treatment in cancer cells reduced the activity and cleavage of USP5, a deubiquitinase (DUB) previously shown to target unanchored Ub polymers and regulate p53-mediated transcription. TRAIL was effective in suppressing USP5 activity and cleavage in TRAIL-sensitive cells but not resistant cells. Knockdown of USP5 in TRAIL-resistant cells demonstrated that USP5 controls apoptotic responsiveness to TRAIL. USP5 cleavage and ubiquitination were blocked by caspase-8 specific inhibitors. A small-molecule USP5/9× inhibitor (G9) combined with TRAIL enhanced apoptosis and blocked colony growth in highly TRAIL-resistant cell lines. Finally, USP5 protein levels and activity were found to be frequently deregulated in TRAIL-resistant cells. Together, we conclude that activated TRAIL enhances USP5 activity and induces apoptosis in TRAIL-sensitive and -resistant cells. We also suggest that USP5 inhibition may be effective in inducing apoptotic thresholds to enhance responsiveness to TRAIL.
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Affiliation(s)
- Harish Potu
- Department of Internal Medicine, University of Michigan Rogel Cancer Center, Ann Arbor, MI 48109, USA
| | - Malathi Kandarpa
- Department of Internal Medicine, University of Michigan Rogel Cancer Center, Ann Arbor, MI 48109, USA
| | - Luke F Peterson
- Department of Internal Medicine, University of Michigan Rogel Cancer Center, Ann Arbor, MI 48109, USA
| | - Nicholas J Donato
- Center for Scientific Review, National Institutes of Health, Bethesda, MD 20892, USA
| | - Moshe Talpaz
- Department of Internal Medicine, University of Michigan Rogel Cancer Center, Ann Arbor, MI 48109, USA
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The prodomain of caspase-3 regulates its own removal and caspase activation. Cell Death Discov 2019; 5:56. [PMID: 30701088 PMCID: PMC6349851 DOI: 10.1038/s41420-019-0142-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 10/08/2018] [Accepted: 10/16/2018] [Indexed: 12/28/2022] Open
Abstract
Caspase-3 is a cysteine–aspartic acid protease that cleaves cellular targets and executes cell death. Our current understanding is caspase-3 is activated by the cleavage of the interdomain linker and then subsequent cleavage of the N-terminal prodomain. However, previous reports have suggested that removal of the prodomain can result in the constitutive activation of caspase-3, although other studies have not observed this. To address this question in a more physiological setting, we developed an inducible doxycycline system to express a mutant form of caspase-3 that lacks the prodomain (∆28). We found that the removal of the prodomain renders the cells more susceptible to death signals, but the caspase is not constitutively active. To elucidate the regions of the prodomain that regulate activity, we created deletion constructs that remove 10 and 19 N-terminal amino acids. Surprisingly, removal of the first 10 amino acids renders caspase-3 inactive. Following serum withdrawal, the interdomain linker is cleaved, however, the remaining prodomain is not removed. Therefore, there is a specific amino acid or stretch of amino acids within the first 10 that are important for prodomain removal and caspase-3 function. We created different point mutations within the prodomain and found amino acid D9 is vital for caspase-3 function. We hypothesize that an initial cleavage event at D9 is required to allow cleavage at D28 that causes the complete removal of the prodomain allowing for full caspase activation. Together these findings demonstrate a previously unknown role of the prodomain in caspase activation.
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Tang Y, Joo D, Liu G, Tu H, You J, Jin J, Zhao X, Hung MC, Lin X. Linear ubiquitination of cFLIP induced by LUBAC contributes to TNFα-induced apoptosis. J Biol Chem 2018; 293:20062-20072. [PMID: 30361438 DOI: 10.1074/jbc.ra118.005449] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 10/14/2018] [Indexed: 12/17/2022] Open
Abstract
The linear ubiquitin chain assembly complex (LUBAC) regulates NF-κB activation by modifying proteins with linear (M1-linked) ubiquitination chains. Although LUBAC also regulates the apoptosis pathway, the precise mechanism by which LUBAC regulates apoptosis remains not fully defined. Here, we report that LUBAC-mediated M1-linked ubiquitination of cellular FLICE-like inhibitory protein (cFLIP), an anti-apoptotic molecule, contributes to tumor necrosis factor (TNF) α-induced apoptosis. We found that deficiency of RNF31, the catalytic subunit of the LUBAC complex, promoted cFLIP degradation in a proteasome-dependent manner. Moreover, we observed RNF31 directly interact with cFLIP, and LUBAC further conjugated M1-linked ubiquitination chains at Lys-351 and Lys-353 of cFLIP to stabilize cFLIP, thereby protecting cells from TNFα-induced apoptosis. Together, our study identifies a new substrate of LUBAC and reveals a new molecular mechanism through which LUBAC regulates TNFα-induced apoptosis via M1-linked ubiquitination.
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Affiliation(s)
- Yong Tang
- From the Institute for Immunology, Tsinghua University School of Medicine, Beijing 100084, China
| | - Donghyun Joo
- the Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, and
| | - Guangna Liu
- From the Institute for Immunology, Tsinghua University School of Medicine, Beijing 100084, China
| | - Hailin Tu
- From the Institute for Immunology, Tsinghua University School of Medicine, Beijing 100084, China
| | - Jeffrey You
- the Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, and
| | - Jianping Jin
- the Life Science Institute, Zhejiang University, Hangzhou 310058, China
| | - Xueqiang Zhao
- From the Institute for Immunology, Tsinghua University School of Medicine, Beijing 100084, China
| | - Mien-Chie Hung
- the Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, and
| | - Xin Lin
- From the Institute for Immunology, Tsinghua University School of Medicine, Beijing 100084, China,.
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Peng K, Dai Q, Wei J, Shao G, Sun A, Yang W, Lin Q. Stress-induced endocytosis and degradation of epidermal growth factor receptor are two independent processes. Cancer Cell Int 2016; 16:25. [PMID: 27034618 PMCID: PMC4815059 DOI: 10.1186/s12935-016-0301-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 03/24/2016] [Indexed: 12/23/2022] Open
Abstract
Background Epidermal growth factor receptor (EGFR) is an important oncogenic protein in multiple types of cancer. Endocytosis and degradation of epidermal growth factor receptor (EGFR) are two key steps for down-regulation of cell surface level of EGFR and modulation of EGFR signaling. Stress conditions induce ligand-independent endocytosis and degradation of EGFR. However, it is not clear whether stress-induced endocytosis and degradation are consequential or two independent events. Methods Endocytosis and degradation of EGFR in response to stress treatment and effects of the p38 inhibitor, the Caspase-3 inhibitor and the proteasomal inhibitor in cervical cancer HeLa cells were determined using immunoblotting and immunofluorescent staining assays. Results Stress conditions, such as protein biosynthesis inhibition, UV light irradiation, and hyper-osmosis, induced both ligand-independent endocytosis and degradation of EGFR. Stress-induced endocytosis of EGFR relies on p38 kinase activity, while stress-induced degradation of EGFR is catalyzed by Caspase-3 activity. Inhibiting p38 kinase impairs only the endocytosis but not the degradation, while inhibiting Caspase-3 results in the opposite effect to inhibiting p38. Furthermore, proteasomal activity is required for stress-induced degradation of EGFR and cell death, but not for endocytosis. Conclusions The results indicate that stress-induced endocytosis and degradation are two independent events and suggest stress signaling may utilize a double-secure mechanism to down-regulate cell surface EGFR in cancer cells.
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Affiliation(s)
- Ke Peng
- School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, China
| | - Qian Dai
- School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, China
| | - Jing Wei
- School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, China
| | - Genbao Shao
- School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, China
| | - Aiqin Sun
- School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, China
| | - Wannian Yang
- School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, China
| | - Qiong Lin
- School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, China
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Gañán-Gómez I, Estañ-Omaña MC, Sancho P, Aller P, Boyano-Adánez MC. Mechanisms of resistance to apoptosis in the human acute promyelocytic leukemia cell line NB4. Ann Hematol 2014; 94:379-92. [PMID: 25322811 DOI: 10.1007/s00277-014-2237-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 10/07/2014] [Indexed: 12/31/2022]
Abstract
Current frontline therapies have improved overall survival in acute promyelocytic leukemia (APL) patients to exceptional rates; however, relapse is still a problem among high-risk and old patients. Therefore, the development of better and safer therapies continues to be a goal in the treatment of this disease. In the present work, we examined three different pathways that hinder cell death in the APL cell line NB4, shedding light on the mechanisms that underlie resistance to apoptosis in these cells and that might help provide them with a proliferative advantage. We found that the proteasome inhibitor MG-132 specifically induces in NB4 cells an Nrf2-mediated antioxidant response which counteracts mitochondria-dependent apoptosis induced by the lipophilic cation dequalinium. More importantly, we also demonstrated that high basal autophagy levels and the gain-of-function of mutant p53 are intrinsic mechanisms of resistance to apoptosis in this cell line. According to our results, the pharmacological inhibition of autophagy and p53 mutants are useful tools to explore resistance to apoptosis in APL and other types of cancer and could be the bases of new therapeutic approaches that improve the efficiency and allow dose reduction of the current treatments.
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MESH Headings
- Antineoplastic Combined Chemotherapy Protocols/pharmacology
- Antineoplastic Combined Chemotherapy Protocols/therapeutic use
- Antioxidants/metabolism
- Apoptosis/drug effects
- Apoptosis/genetics
- Cell Line, Tumor
- Cell Nucleus/drug effects
- Cell Nucleus/genetics
- Cell Nucleus/metabolism
- Dequalinium/administration & dosage
- Dequalinium/pharmacology
- Dose-Response Relationship, Drug
- Drug Resistance, Neoplasm/genetics
- Gene Expression Regulation, Leukemic/drug effects
- HL-60 Cells
- Humans
- Leukemia, Promyelocytic, Acute/drug therapy
- Leukemia, Promyelocytic, Acute/genetics
- Leukemia, Promyelocytic, Acute/pathology
- Leupeptins/administration & dosage
- Leupeptins/pharmacology
- Protein Transport/drug effects
- Tumor Suppressor Protein p53/metabolism
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Affiliation(s)
- I Gañán-Gómez
- Department of System Biology, Unit of Biochemistry and Molecular Biology, Faculty of Medicine and Health Sciences, University of Alcalá (UAH), Carretera Madrid-Barcelona Km 33.6 s/n, 28871, Alcalá de Henares, Madrid, Spain
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9
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Pietkiewicz S, Sohn D, Piekorz RP, Grether-Beck S, Budach W, Sabapathy K, Jänicke RU. Oppositional regulation of Noxa by JNK1 and JNK2 during apoptosis induced by proteasomal inhibitors. PLoS One 2013; 8:e61438. [PMID: 23593480 PMCID: PMC3623862 DOI: 10.1371/journal.pone.0061438] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Accepted: 03/14/2013] [Indexed: 01/28/2023] Open
Abstract
Proteasome inhibitors (PIs) potently induce apoptosis in a variety of tumor cells, but the underlying mechanisms are not fully elucidated. Comparing PI-induced apoptosis susceptibilities of various mouse embryonic fibroblast (MEF) lines differing in their c-jun N-terminal kinase (JNK) 1 and 2 status, we show that several hallmarks of apoptosis were most rapidly detectable in JNK2-/- cells, whereas they appeared only delayed and severely reduced in their intensities in cells expressing JNK2. Consistent with our finding that PI-induced apoptosis requires de novo protein synthesis, the proteasomal inhibitor MG-132 induced expression of the BH3-only protein Noxa at the transcriptional level in a JNK1-dependent, but JNK2-opposing manner. As the knockdown of Noxa blocked only the rapid PI-induced apoptosis of JNK2-/- cells, but not the delayed death occurring in JNK1-/- and JNK1+/+ cells, our data uncover a novel PI-induced apoptosis pathway that is regulated by the JNK1/2-dependent expression of Noxa. Furthermore, several transcription factors known to modulate Noxa expression including ATF3, ATF4, c-Jun, c-Myc, HIF1α, and p53 were found upregulated following MG-132 exposure. From those, only knockdown of c-Myc rescued JNK2-/- cells from PI-induced apoptosis, however, without affecting expression of Noxa. Together, our data not only show that a rapid execution of PI-induced apoptosis requires JNK1 for upregulation of Noxa via an as yet unknown transcription factor, but also that JNK2 controls this event in an oppositional manner.
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Affiliation(s)
- Sabine Pietkiewicz
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, University of Düsseldorf, Düsseldorf, Germany
| | - Dennis Sohn
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, University of Düsseldorf, Düsseldorf, Germany
| | - Roland P. Piekorz
- Institute for Biochemistry and Molecular Biology II, University of Düsseldorf, Düsseldorf, Germany
| | | | - Wilfried Budach
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, University of Düsseldorf, Düsseldorf, Germany
| | - Kanaga Sabapathy
- Division of Cellular & Molecular Research, Humphrey Oei Institute of Cancer Research, National Cancer Centre, Singapore, Singapore
| | - Reiner U. Jänicke
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, University of Düsseldorf, Düsseldorf, Germany
- * E-mail:
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10
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Martinez-Gamboa L, Lesemann K, Kuckelkorn U, Scheffler S, Ghannam K, Hahne M, Gaber-Elsner T, Egerer K, Naumann L, Buttgereit F, Dörner T, Kloetzel PM, Burmester GR, Faustman DL, Feist E. Gene expression of catalytic proteasome subunits and resistance toward proteasome inhibition of B lymphocytes from patients with primary sjogren syndrome. J Rheumatol 2013; 40:663-73. [PMID: 23504381 DOI: 10.3899/jrheum.120680] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Dysregulation of proteasome subunit β1i expression has been shown in total blood mononuclear cells (PBMC) from patients with primary Sjögren syndrome (pSS), a B cell-driven systemic autoimmune disorder. METHODS Proteasome activation was investigated in sorted blood cells from patients with pSS and controls by measuring transcript levels of constitutive (β1/β2/β5) and corresponding immunoproteasome catalytic subunits (β1i/β2i/β5i) using real-time PCR. At protein level, β1i protein expression was analyzed by immunoblotting. Functional effects of proteasome inhibition on proteolytic activity and induction of apoptosis were also evaluated in cellular subsets. RESULTS The proteasome was found to be activated in pSS, with upregulation of gene expression of catalytic proteasome subunits. Western blot analysis revealed decreased β1i protein expression in pSS B lymphocytes, with decreased protein despite increased messenger RNA (mRNA) levels. After proteasome inhibition in vitro, proteolytic activity was less reduced and resistance to apoptosis was increased in B lymphocytes compared to other cells. CONCLUSION In pSS, catalytic subunits of the proteasome are upregulated at the mRNA level, while dysregulation of subunit β1i is attributed to B lymphocytes. B cell resistance after proteasome inhibition differs from the classical concept of increased susceptibility toward inhibition in activated cells, supporting the novel notion that susceptibility depends on cellular intrinsic factors and on proteasome activation.
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Affiliation(s)
- Lorena Martinez-Gamboa
- Rheumatology Research Laboratory, Department of Rheumatology and Clinical Immunology, Charite Universitätsmedizin Berlin, Germany.
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de Wilt LHAM, Kroon J, Jansen G, de Jong S, Peters GJ, Kruyt FAE. Bortezomib and TRAIL: a perfect match for apoptotic elimination of tumour cells? Crit Rev Oncol Hematol 2012; 85:363-72. [PMID: 22944363 DOI: 10.1016/j.critrevonc.2012.08.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 07/13/2012] [Accepted: 08/06/2012] [Indexed: 01/11/2023] Open
Abstract
Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is a cytokine that selectively eradicates tumour cells via specific cell surface receptors and is intensively explored for use as a novel anticancer approach. To enhance the efficacy of TRAIL receptor agonists the proteasome inhibitor bortezomib is one of the most potent sensitizers. Here we review the main mechanisms underlying bortezomib-dependent TRAIL sensitization, including stimulation of apoptosis by increasing expression of TRAIL receptors, reduction of cFLIP and enhancement of caspase 8 activation, and modulation of Bcl-2 family proteins and inhibitor of apoptosis proteins (IAPs). Concomitantly, pro-survival signals are suppressed such as elicited by NF-κB and Akt. The different preclinical tumour models explored with this combination, including primary tumour (stem) cells, stroma co-culture and mice models, are discussed, as well as possible hurdles for clinical activity. Collectively, anticipating a solid rationale for bortezomib-TRAIL combination and very promising preclinical results, its clinical activity remains to be demonstrated.
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Affiliation(s)
- L H A M de Wilt
- Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands
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Laussmann MA, Passante E, Hellwig CT, Tomiczek B, Flanagan L, Prehn JHM, Huber HJ, Rehm M. Proteasome inhibition can impair caspase-8 activation upon submaximal stimulation of apoptotic tumor necrosis factor-related apoptosis inducing ligand (TRAIL) signaling. J Biol Chem 2012; 287:14402-11. [PMID: 22408249 DOI: 10.1074/jbc.m111.304378] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) can induce extrinsic apoptosis, resulting in caspase-8 activation, but may also initiate transcription-dependent prosurvival signaling. Proteasome inhibitors were suggested to promote TRAIL signal transduction through the death-inducing signaling complex (DISC) by modulating the relative abundance of core DISC components, thereby enhancing caspase-8 activation and apoptosis. To test this hypothesis, we quantified the changes in DISC protein levels as an early consequence of proteasome inhibition in HeLa cervical cancer cells and, based on these data, mathematically modeled the proapoptotic TRAIL signaling toward caspase-8 activation. Modeling results surprisingly suggested that caspase-8 activation might be delayed in presence of proteasome inhibitors, in particular at submaximal TRAIL doses. Subsequent FRET-based single cell time-lapse imaging at conditions where transcription dependent prosurvival signaling was blocked confirmed this hypothesis: caspase-8 activity was delayed by hours in the presence of proteasome inhibitors epoxomicin or bortezomib. Corresponding delays were detected for effector caspase processing and cell death. Contrary to current models, we therefore provide evidence that synergies between TRAIL and proteasome inhibitors do not result from changes in the levels of core DISC signaling proteins.
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Affiliation(s)
- Maike A Laussmann
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, Dublin 2, Ireland
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13
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Rena Hesse A, Hagemeier K, Lürbke A, Held J, Friedman H, Peterson A, Brück W, Kuhlmann T. XIAP protects oligodendrocytes against cell death in vitro but has no functional role in toxic demyelination. Glia 2011; 60:271-80. [DOI: 10.1002/glia.21261] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 09/12/2011] [Accepted: 10/05/2011] [Indexed: 12/13/2022]
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14
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Hörnle M, Peters N, Thayaparasingham B, Vörsmann H, Kashkar H, Kulms D. Caspase-3 cleaves XIAP in a positive feedback loop to sensitize melanoma cells to TRAIL-induced apoptosis. Oncogene 2010; 30:575-87. [PMID: 20856198 DOI: 10.1038/onc.2010.434] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Successful treatment of melanoma is still challenging, because metastasis remain chemoresistant and radioresistant. Accordingly, combinational treatments involving death ligands are mandatory. In a recent study from our lab, the majority out of 18 melanoma cell lines remained resistant against treatment with the death ligand TRAIL (tumor necrosis factor related apoptosis inducing ligand). Resistance was shown to be mainly due to incomplete processing of caspase-3 into catalytically inactive p21 by binding of the anti-apoptotic protein X-linked inhibitor of apoptosis protein (XIAP). Co-irradiation with sub-lethal ultraviolet (UV) B caused depletion of XIAP resulting in synergistic sensitization of all but two melanoma cell lines to TRAIL. We show here the XIAP depletion to essentially require initial caspase-mediated cleavage, which promotes proteasomal degradation of XIAP. Utilizing specific caspase inhibitors and small interfering RNA-mediated knockdown, we further identified caspase-3 to be responsible for performing the initial cleavage of XIAP after UVB treatment. Additional evidence suggests an accelerated mitochondrial outer membrane permeabilization in response to co-treatment with TRAIL and UVB, which directs the release of XIAP antagonizing factors including Smac. Distraction of XIAP consequently liberates caspase-3 to autocatalytically process into active p17. Activated caspase-3 cleaves XIAP and further enhances its activation in a positive regulatory feedback loop. The molecular mechanism discovered here appears to have broader implications, because cleavage of XIAP was also shown to accompany cisplatin-induced sensitization of melanoma cells to TRAIL.
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Affiliation(s)
- M Hörnle
- Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, Baden-Württemberg, Germany
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15
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Interaction with Sug1 enables Ipaf ubiquitination leading to caspase 8 activation and cell death. Biochem J 2010; 427:91-104. [PMID: 20085538 DOI: 10.1042/bj20091349] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Activation of initiator caspases is dependent on interacting proteins, and Ipaf [ICE (interleukin-1beta-converting enzyme)-protease activating factor] {NLRC4 [NLR (Nod-like receptor) family CARD (caspase activation and recruitment domain)-containing 4]} an inflammasome component, is involved in caspase 1 activation and apoptosis. Investigating the mechanisms of Ipaf activation, we found that the C-terminal LRR (leucine-rich repeat) domain of Ipaf, through intramolecular interaction, negatively regulates its apoptosis-inducing function. In A549 lung carcinoma cells, expression of Ac-Ipaf (LRR-domain-deleted Ipaf) induced cell death that was dependent on caspase 8, but not on caspase 1. A yeast two-hybrid screen using Ac-Ipaf as bait identified human Sug1 (suppressor of gal 1), a component of the 26S proteasome, as an interacting protein. In mammalian cells Sug1 interacts and co-localizes with Ipaf. Sug1 binds to amino acids 91-253 of Ipaf, which is also the region that the LRR domain binds to. It potentiates cell death induced by Ipaf and Ac-Ipaf, and co-expression of Sug1 and Ipaf induces caspase-8-dependent cell death. Cellular complexes formed by Ipaf and Sug1 contain caspase 8. Expression of Ac-Ipaf or co-expression of Sug1 with Ipaf results in the formation of cytoplasmic aggregates and caspase 8 activation. Sug1 co-expression enabled modification of Ipaf by ubiquitination. Tagging ubiquitin molecules to Ipaf led to aggregate formation, enhanced caspase 8 interaction and activation, resulting in induction of cell death. Using RNAi (RNA interference) and dominant-negative approaches, we have shown that cell death induced by Ac-Ipaf expression or by treatment with TNF-alpha (tumour necrosis factor alpha) or doxorubicin is dependent on Sug1. Our results suggest a role for ubiquitination of Ipaf that is enabled by its interaction with Sug1, leading to caspase 8 activation and cell death.
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Zhang X, Zou T, Rao JN, Liu L, Xiao L, Wang PY, Cui YH, Gorospe M, Wang JY. Stabilization of XIAP mRNA through the RNA binding protein HuR regulated by cellular polyamines. Nucleic Acids Res 2009; 37:7623-37. [PMID: 19825980 PMCID: PMC2794158 DOI: 10.1093/nar/gkp755] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Revised: 08/26/2009] [Accepted: 08/27/2009] [Indexed: 12/23/2022] Open
Abstract
The X chromosome-linked inhibitor of apoptosis protein (XIAP) is the most potent intrinsic caspase inhibitor and plays an important role in the maintenance of intestinal epithelial integrity. The RNA binding protein, HuR, regulates the stability and translation of many target transcripts. Here, we report that HuR associated with both the 3'-untranslated region and coding sequence of the mRNA encoding XIAP, stabilized the XIAP transcript and elevated its expression in intestinal epithelial cells. Ectopic HuR overexpression or elevated cytoplasmic levels of endogenous HuR by decreasing cellular polyamines increased [HuR/XIAP mRNA] complexes, in turn promoting XIAP mRNA stability and increasing XIAP protein abundance. Conversely, HuR silencing in normal and polyamine-deficient cells rendered the XIAP mRNA unstable, thus reducing the steady state levels of XIAP. Inhibition of XIAP expression by XIAP silencing or by HuR silencing reversed the resistance of polyamine-deficient cells to apoptosis. Our findings demonstrate that HuR regulates XIAP expression by stabilizing its mRNA and implicates HuR-mediated XIAP in the control of intestinal epithelial apoptosis.
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Affiliation(s)
- Xian Zhang
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore Veterans Affairs Medical Center, Department of Pathology, University of Maryland School of Medicine and Laboratory of Cellular and Molecular Biology, National Institute on Aging-IRP, NIH, Baltimore, MD 21224, USA
| | - Tongtong Zou
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore Veterans Affairs Medical Center, Department of Pathology, University of Maryland School of Medicine and Laboratory of Cellular and Molecular Biology, National Institute on Aging-IRP, NIH, Baltimore, MD 21224, USA
| | - Jaladanki N. Rao
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore Veterans Affairs Medical Center, Department of Pathology, University of Maryland School of Medicine and Laboratory of Cellular and Molecular Biology, National Institute on Aging-IRP, NIH, Baltimore, MD 21224, USA
| | - Lan Liu
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore Veterans Affairs Medical Center, Department of Pathology, University of Maryland School of Medicine and Laboratory of Cellular and Molecular Biology, National Institute on Aging-IRP, NIH, Baltimore, MD 21224, USA
| | - Lan Xiao
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore Veterans Affairs Medical Center, Department of Pathology, University of Maryland School of Medicine and Laboratory of Cellular and Molecular Biology, National Institute on Aging-IRP, NIH, Baltimore, MD 21224, USA
| | - Peng-Yuan Wang
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore Veterans Affairs Medical Center, Department of Pathology, University of Maryland School of Medicine and Laboratory of Cellular and Molecular Biology, National Institute on Aging-IRP, NIH, Baltimore, MD 21224, USA
| | - Yu-Hong Cui
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore Veterans Affairs Medical Center, Department of Pathology, University of Maryland School of Medicine and Laboratory of Cellular and Molecular Biology, National Institute on Aging-IRP, NIH, Baltimore, MD 21224, USA
| | - Myriam Gorospe
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore Veterans Affairs Medical Center, Department of Pathology, University of Maryland School of Medicine and Laboratory of Cellular and Molecular Biology, National Institute on Aging-IRP, NIH, Baltimore, MD 21224, USA
| | - Jian-Ying Wang
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore Veterans Affairs Medical Center, Department of Pathology, University of Maryland School of Medicine and Laboratory of Cellular and Molecular Biology, National Institute on Aging-IRP, NIH, Baltimore, MD 21224, USA
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Costes S, Vandewalle B, Tourrel-Cuzin C, Broca C, Linck N, Bertrand G, Kerr-Conte J, Portha B, Pattou F, Bockaert J, Dalle S. Degradation of cAMP-responsive element-binding protein by the ubiquitin-proteasome pathway contributes to glucotoxicity in beta-cells and human pancreatic islets. Diabetes 2009; 58:1105-15. [PMID: 19223597 PMCID: PMC2671045 DOI: 10.2337/db08-0926] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Accepted: 02/10/2009] [Indexed: 01/09/2023]
Abstract
OBJECTIVE In type 2 diabetes, chronic hyperglycemia is detrimental to beta-cells, causing apoptosis and impaired insulin secretion. The transcription factor cAMP-responsive element-binding protein (CREB) is crucial for beta-cell survival and function. We investigated whether prolonged exposure of beta-cells to high glucose affects the functional integrity of CREB. RESEARCH DESIGN AND METHODS INS-1E cells and rat and human islets were used. Gene expression was analyzed by RT-PCR and Western blotting. Apoptosis was detected by cleaved caspase-3 emergence, DNA fragmentation, and electron microscopy. RESULTS Chronic exposure of INS-1E cells and rat and human islets to high glucose resulted in decreased CREB protein expression, phosphorylation, and transcriptional activity associated with apoptosis and impaired beta-cell function. High-glucose treatment increased CREB polyubiquitination, while treatment of INS-1E cells with the proteasome inhibitor MG-132 prevented the decrease in CREB content. The emergence of apoptosis in INS-1E cells with decreased CREB protein expression knocked down by small interfering RNA suggested that loss of CREB protein content induced by high glucose contributes to beta-cell apoptosis. Loading INS-1E cells or human islets with a cell-permeable peptide mimicking the proteasomal targeting sequence of CREB blocked CREB degradation and protected INS-1E cells and human islets from apoptosis induced by high glucose. The insulin secretion in response to glucose and the insulin content were preserved in human islets exposed to high glucose and loaded with the peptide. CONCLUSIONS These studies demonstrate that the CREB degradation by the ubiquitin-proteasome pathway contributes to beta-cell dysfunction and death upon glucotoxicity and provide new insight into the cellular mechanisms of glucotoxicity.
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Affiliation(s)
- Safia Costes
- Institut National de la Santé et de la Recherche Médicale (INSERM), U661, Equipe Avenir, Institut de Génomique Fonctionnelle, Montpellier, France
- Centre National de la Recherche Scientifique (CNRS), UMR5203, Université Montpellier (IFR3), Montpellier, France
| | | | | | - Christophe Broca
- Institut National de la Santé et de la Recherche Médicale (INSERM), U661, Equipe Avenir, Institut de Génomique Fonctionnelle, Montpellier, France
- Centre National de la Recherche Scientifique (CNRS), UMR5203, Université Montpellier (IFR3), Montpellier, France
| | - Nathalie Linck
- Institut National de la Santé et de la Recherche Médicale (INSERM), U661, Equipe Avenir, Institut de Génomique Fonctionnelle, Montpellier, France
- Centre National de la Recherche Scientifique (CNRS), UMR5203, Université Montpellier (IFR3), Montpellier, France
| | - Gyslaine Bertrand
- Institut National de la Santé et de la Recherche Médicale (INSERM), U661, Equipe Avenir, Institut de Génomique Fonctionnelle, Montpellier, France
- Centre National de la Recherche Scientifique (CNRS), UMR5203, Université Montpellier (IFR3), Montpellier, France
| | | | | | | | - Joel Bockaert
- Institut National de la Santé et de la Recherche Médicale (INSERM), U661, Equipe Avenir, Institut de Génomique Fonctionnelle, Montpellier, France
- Centre National de la Recherche Scientifique (CNRS), UMR5203, Université Montpellier (IFR3), Montpellier, France
| | - Stéphane Dalle
- Institut National de la Santé et de la Recherche Médicale (INSERM), U661, Equipe Avenir, Institut de Génomique Fonctionnelle, Montpellier, France
- Centre National de la Recherche Scientifique (CNRS), UMR5203, Université Montpellier (IFR3), Montpellier, France
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Nguyen-Khuong T, White MY, Hung TT, Seeto S, Thomas ML, Fitzgerald AM, Martucci CE, Luk S, Pang SF, Russell PJ, Walsh BJ. Alterations to the protein profile of bladder carcinoma cell lines induced by plant extract MINA-05 in vitro. Proteomics 2009; 9:1883-92. [PMID: 19294694 DOI: 10.1002/pmic.200700839] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2007] [Indexed: 11/08/2022]
Abstract
Bladder cancer (BLCa) is a severe urological cancer of both men and women that commonly recurs and once invasive, is difficult to treat. MINA-05 (CK Life Sciences Int'l, Hong Kong) is a derivative of complex botanical extracts, shown to reduce cellular proliferation of bladder and prostate carcinomas. We tested the effects of MINA-05 against human BLCa cell sublines, B8, B8-RSP-GCK, B8-RSP-LN and C3, from a transitional cell carcinoma, grade IV, to determine the molecular targets of treatment by observing the cellular protein profile. Cells were acclimatised for 48 h then treated for 72 h with concentrations of MINA-05 reflecting 1/2 IC(50), IC(50) and 2 x IC(50) (n = 3) or with vehicle, (0.5% DMSO). Dose-dependant changes in protein abundance were detected and characterised using 2-dimensional electrophoresis and MS. We identified 10 proteins that underwent changes in abundance, pI and/or molecular mass in response to treatment. MINA-05 was shown to influence proteins across numerous functional classes including cytoskeletal proteins, energy metabolism proteins, protein degradation proteins and tumour suppressors, suggesting a global impact on these cell lines. This study implies that the ability of MINA-05 to retard cellular proliferation is attributed to its ability to alter cell cycling, metabolism, protein degradation and the cancer cell environment.
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BCL-XL regulates TNF-alpha-mediated cell death independently of NF-kappaB, FLIP and IAPs. Cell Res 2008; 18:1020-36. [PMID: 18591962 DOI: 10.1038/cr.2008.76] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Upon activation, tumor necrosis factor alpha (TNF-alpha) receptor can engage apoptotic or survival pathways. Inhibition of macromolecular synthesis is known to sensitize cells to TNF-alpha-induced cell death. It is believed that this sensitization is due to the transcriptional blockade of genes regulated by NF-kappaB. Nevertheless, such evidence has remained elusive in the nervous system. Here, we show that TNF-alpha cannot normally induce apoptosis in PC12 cells or cortical neurons. However, cells treated with Actinomycin D (ActD) become susceptible to TNF-alpha-induced cell death through the activation of caspase-8, generation of tBid and activation of caspase-9 and -3. Analysis of several proteins involved in TNF-alpha receptor signaling showed no significant downregulation of NF-kappaB target genes, such as IAPs or FLIP, under such conditions. However, Bcl-x(L) protein levels, but not those of Bcl-2, Bax and Bak, are reduced by ActD or TNF-alpha/ActD treatments. Moreover, Bcl-x(L) overexpression fully protects cells against TNF-alpha/ActD-induced cell death. When endogenous levels of Bcl-x(L) are specifically downregulated by lentiviral-based RNAi, cells no longer require ActD to be sensitive to TNF-alpha-triggered apoptosis. Furthermore, Bcl-x(L) downregulation does not affect TNF-alpha-mediated NF-kappaB activation. Altogether, our results demonstrate that Bcl-x(L), and not Bcl-2, FLIP or IAPs, acts as the endogenous regulator of neuronal resistance/sensitivity to TNF-alpha-induced apoptosis in an NF-kappaB-independent manner.
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20
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Haimerl F, Erhardt A, Sass G, Tiegs G. Down-regulation of the de-ubiquitinating enzyme ubiquitin-specific protease 2 contributes to tumor necrosis factor-alpha-induced hepatocyte survival. J Biol Chem 2008; 284:495-504. [PMID: 19001362 DOI: 10.1074/jbc.m803533200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tumor necrosis factor-alpha (TNFalpha) stimulation of hepatocytes induces either cell survival or apoptosis, which seems to be regulated by the ubiquitin-proteasome system. Here we investigated the role of TNFalpha-induced down-modulation of the de-ubiquitinating enzyme USP2 for hepatocyte survival. Inhibition of hepatocyte apoptosis by pre-treatment with TNFalpha (TNFalpha tolerance) was analyzed in the mouse model of galactosamine/TNFalpha-induced liver injury and in actinomycin D/TNFalpha-treated primary mouse hepatocytes. The role of USP2 for TNFalpha-induced hepatocyte survival was studied using small interference RNA or an expression clone. Injection of mice or preincubation of hepatocytes with TNFalpha caused a rapid down-regulation of hepatic USP2-41kD, the predominant USP2 isoform in the liver. In vitro an artificial knockdown of USP2 inhibited actinomycin D/TNFalpha-induced hepatocyte apoptosis, which was associated with elevated levels of the anti-apoptotic protein c-Flip(L/S) and a concomitant decrease of cellular levels of the ubiquitinligase Itch, a negative regulator of c-Flip. USP2-41kD overexpression abrogated TNFalpha tolerance in vitro, prevented accumulation of c-Flip(L/S) and resulted in elevated levels of Itch. Accordingly, c-Flip(L/S) protein levels were elevated in livers of TNFalpha-tolerant mice, which correlated to a switch from JNK and ERK to p38 signaling after galactosamine/TNF re-challenge. Our results indicate that TNFalpha-induced USP2 down-regulation is an effective cytoprotective mechanism in hepatocytes. Hence, USP2 could be a novel pharmacological target, and specific USP2 inhibitors might be potential candidates for the treatment of inflammation-related apoptotic liver damage.
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Affiliation(s)
- Florian Haimerl
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Erlangen-Nuremberg, Erlangen D-91054 and the Division of Experimental Immunology and Hepatology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg D-20246, Germany
| | - Annette Erhardt
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Erlangen-Nuremberg, Erlangen D-91054 and the Division of Experimental Immunology and Hepatology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg D-20246, Germany
| | - Gabriele Sass
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Erlangen-Nuremberg, Erlangen D-91054 and the Division of Experimental Immunology and Hepatology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg D-20246, Germany
| | - Gisa Tiegs
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Erlangen-Nuremberg, Erlangen D-91054 and the Division of Experimental Immunology and Hepatology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg D-20246, Germany; Institute of Experimental and Clinical Pharmacology and Toxicology, University of Erlangen-Nuremberg, Erlangen D-91054 and the Division of Experimental Immunology and Hepatology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg D-20246, Germany.
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Thayaparasingham B, Kunz A, Peters N, Kulms D. Sensitization of melanoma cells to TRAIL by UVB-induced and NF-κB-mediated downregulation of xIAP. Oncogene 2008; 28:345-62. [DOI: 10.1038/onc.2008.397] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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van Hees HWH, Li YP, Ottenheijm CAC, Jin B, Pigmans CJC, Linkels M, Dekhuijzen PNR, Heunks LMA. Proteasome inhibition improves diaphragm function in congestive heart failure rats. Am J Physiol Lung Cell Mol Physiol 2008; 294:L1260-8. [PMID: 18424622 DOI: 10.1152/ajplung.00035.2008] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In congestive heart failure (CHF), diaphragm weakness is known to occur and is associated with myosin loss and activation of the ubiquitin-proteasome pathway. The effect of modulating proteasome activity on myosin loss and diaphragm function is unknown. The present study investigated the effect of in vivo proteasome inhibition on myosin loss and diaphragm function in CHF rats. Coronary artery ligation was used as an animal model for CHF. Sham-operated rats served as controls. Animals were treated with the proteasome inhibitor bortezomib (intravenously) or received saline (0.9%) injections. Force generating capacity, cross-bridge cycling kinetics, and myosin content were measured in diaphragm single fibers. Proteasome activity, caspase-3 activity, and MuRF-1 and MAFbx mRNA levels were determined in diaphragm homogenates. Proteasome activities in the diaphragm were significantly reduced by bortezomib. Bortezomib treatment significantly improved diaphragm single fiber force generating capacity (approximately 30-40%) and cross-bridge cycling kinetics (approximately 20%) in CHF. Myosin content was approximately 30% higher in diaphragm fibers from bortezomib-treated CHF rats than saline. Caspase-3 activity was decreased in diaphragm homogenates from bortezomib-treated rats. CHF increased MuRF-1 and MAFbx mRNA expression in the diaphragm, and bortezomib treatment diminished this rise. The present study demonstrates that treatment with a clinically used proteasome inhibitor improves diaphragm function by restoring myosin content in CHF.
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Affiliation(s)
- Hieronymus W H van Hees
- Deptartment of Pulmonary Diseases, Radboud University Medical Centre, Nijmegen, The Netherlands.
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Wickliffe KE, Leppla SH, Moayeri M. Killing of macrophages by anthrax lethal toxin: involvement of the N-end rule pathway. Cell Microbiol 2008; 10:1352-62. [PMID: 18266992 DOI: 10.1111/j.1462-5822.2008.01131.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Macrophages from certain inbred mouse strains are rapidly killed (< 90 min) by anthrax lethal toxin (LT). LT cleaves cytoplasmic MEK proteins at 20 min and induces caspase-1 activation in sensitive macrophages at 50-60 min, but the mechanism of LT-induced death is unknown. Proteasome inhibitors block LT-mediated caspase-1 activation and can protect against cell death, indicating that the degradation of at least one cellular protein is required for LT-mediated cell death. Proteins can be degraded by the proteasome via the N-end rule, in which a protein's stability is determined by its N-terminal residue. Using amino acid derivatives that act as inhibitors of this pathway, we show that the N-end rule is required for LT-mediated caspase-1 activation and cell death. We also found that bestatin methyl ester, an aminopeptidase inhibitor protects against LT in vitro and in vivo and that the different inhibitors of the protein degradation pathway act synergistically in protecting against LT. We identify c-IAP1, a mammalian member of the inhibitor of apoptosis protein (IAP) family, as a novel N-end rule substrate degraded in macrophages treated with LT. We also show that LT-induced c-IAP1 degradation is independent of the IAP-antagonizing proteins Smac/DIABLO and Omi/HtrA2, but dependent on caspases.
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Affiliation(s)
- Katherine E Wickliffe
- Bacterial Toxins and Therapeutics Section, Laboratory of Bacterial Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Konstantinova IM, Tsimokha AS, Mittenberg AG. Role of proteasomes in cellular regulation. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 267:59-124. [PMID: 18544497 DOI: 10.1016/s1937-6448(08)00602-3] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The 26S proteasome is the key enzyme of the ubiquitin-dependent pathway of protein degradation. This energy-dependent nanomachine is composed of a 20S catalytic core and associated regulatory complexes. The eukaryotic 20S proteasomes demonstrate besides several kinds of peptidase activities, the endoribonuclease, protein-chaperone and DNA-helicase activities. Ubiquitin-proteasome pathway controls the levels of the key regulatory proteins in the cell and thus is essential for life and is involved in regulation of crucial cellular processes. Proteasome population in the cell is structurally and functionally heterogeneous. These complexes are subjected to tightly organized regulation, particularly, to a variety of posttranslational modifications. In this review we will summarize the current state of knowledge regarding proteasome participation in the control of cell cycle, apoptosis, differentiation, modulation of immune responses, reprogramming of these particles during these processes, their heterogeneity and involvement in the main levels of gene expression.
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Abstract
The proteasome inhibitor bortezomib has been approved as a cytostatic drug for the therapy of multiple myeloma, and is currently being tested in clinical trials for a variety of other malignancies. At the same time, a growing number of animal studies suggest that proteasome inhibitors may also prove to be valuable remedies for the treatment of non-tumorous diseases. In this review, we will revisit the current applications of proteasome inhibitors in clinical research according to the cellular effects of proteasome inhibitors as poisons, which induce apoptosis, or as remedies, which modulate cellular function and protect from cell death. We postulate that the correct distinction of a poison from a remedy depends on cell type and on the degree of proteasome inhibition. Dose-dependent and differential inhibition of the proteasome may affect specific sets of substrates, thereby conferring substrate specificity. According to this idea, we suggest that inhibition of the proteasome to a defined degree may offer a promising tool in achieving desired therapeutic effects in various diseases.
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Affiliation(s)
- Silke Meiners
- Universitätsmedizin Berlin, Charité, Medizinische Klinik mit Schwerpunkt Kardiologie und Angiologie, Germany.
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26
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Yang C, Kaushal V, Shah SV, Kaushal GP. Mcl-1 is downregulated in cisplatin-induced apoptosis, and proteasome inhibitors restore Mcl-1 and promote survival in renal tubular epithelial cells. Am J Physiol Renal Physiol 2007; 292:F1710-7. [PMID: 17311906 DOI: 10.1152/ajprenal.00505.2006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mcl-1 is an antiapoptotic member of the Bcl-2 family that plays an important role in cell survival. We demonstrate that proteasome-dependent regulation of Mcl-1 plays a critical role in renal tubular epithelial cell injury from cisplatin. Protein levels of Mcl-1 rapidly declined in a time-dependent manner following cisplatin treatment of LLC-PK1cells. However, mRNA levels of Mcl-1 were not altered following cisplatin treatment. Expression of other antiapoptotic members of the Bcl-2 family such as Bcl-2 and BclxL was not affected by cisplatin treatment. Cisplatin-induced loss of Mcl-1 occurs at the same time as the mitochondrial release of cytochrome c, activation of caspase-3, and initiation of apoptosis. Treatment of cells with cycloheximide, a protein synthesis inhibitor, revealed rapid turnover of Mcl-1. In addition, treatment with cycloheximide in the presence or absence of cisplatin demonstrated that cisplatin-induced loss of Mcl-1 results from posttranslational degradation rather than transcriptional inhibition. Overexpression of Mcl-1 protected cells from cisplatin-induced caspase-3 activation and apoptosis. Preincubating cells with the proteasome inhibitor MG-132 or lactacystin not only restored cisplatin-induced loss of Mcl-1 but also resulted in an accumulation of Mcl-1 that exceeded basal levels; however, Bcl-2 and BclxL levels did not change in response to MG-132 or lactacystin. The proteasome inhibitors effectively blocked cisplatin-induced mitochondrial release of cytochrome c, caspase-3 activation, and apoptosis. These studies suggest that proteasome regulation of Mcl-1 is crucial in the cisplatin-induced apoptosis via the mitochondrial apoptotic pathway and that Mcl-1 is an important therapeutic target in cisplatin injury to renal tubular epithelial cells.
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Affiliation(s)
- Cheng Yang
- Department of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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27
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Fu NY, Sukumaran SK, Yu VC. Inhibition of ubiquitin-mediated degradation of MOAP-1 by apoptotic stimuli promotes Bax function in mitochondria. Proc Natl Acad Sci U S A 2007; 104:10051-6. [PMID: 17535899 PMCID: PMC1877986 DOI: 10.1073/pnas.0700007104] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The multidomain proapoptotic protein Bax of the Bcl-2 family is a central regulator for controlling the release of apoptogenic factors from mitochondria. Recent evidence suggests that the Bax-associating protein MOAP-1 may act as an effector for promoting Bax function in mitochondria. Here, we report that MOAP-1 protein is rapidly up-regulated by multiple apoptotic stimuli in mammalian cells. MOAP-1 is a short-lived protein (t(1/2) approximately 25 min) that is constitutively degraded by the ubiquitin-proteasome system. Induction of MOAP-1 by apoptotic stimuli ensues through inhibition of its polyubiquitination process. Elevation of MOAP-1 levels sensitizes cells to apoptotic stimuli and promotes recombinant Bax-mediated cytochrome c release from isolated mitochondria. Mitochondria depleted of short-lived proteins by cycloheximide (CHX) become resistant to Bax-mediated cytochrome c release. Remarkably, incubation of these mitochondria with in vitro-translated MOAP-1 effectively restores the cytochrome c releasing effect of recombinant Bax. We propose that apoptotic stimuli can facilitate the proapoptotic function of Bax in mitochondria through stabilization of MOAP-1.
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Affiliation(s)
- Nai Yang Fu
- Institute of Molecular and Cell Biology, 61 Biopolis Drive (Proteos), Singapore 138673
| | - Sunil K. Sukumaran
- Institute of Molecular and Cell Biology, 61 Biopolis Drive (Proteos), Singapore 138673
| | - Victor C. Yu
- Institute of Molecular and Cell Biology, 61 Biopolis Drive (Proteos), Singapore 138673
- *To whom correspondence should be addressed. E-mail:
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28
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Li W, Zhang X, Olumi AF. MG-132 Sensitizes TRAIL-Resistant Prostate Cancer Cells by Activating c-Fos/c-Jun Heterodimers and Repressing c-FLIP(L). Cancer Res 2007; 67:2247-55. [PMID: 17332355 DOI: 10.1158/0008-5472.can-06-3793] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent because it induces apoptosis in cancer cells but not in normal cells. Unfortunately, some cancer cells develop resistance to TRAIL-induced apoptosis. Therefore, it is clinically relevant to determine the molecular mechanisms that differentiate between TRAIL-sensitive and TRAIL-resistant tumors. Previously, we have shown that the antiapoptotic molecule cellular-FLICE-inhibitory protein long isoform [c-FLIP(L)] is necessary and sufficient to maintain resistance to TRAIL-induced apoptosis. We have found that c-FLIP(L) is transcriptionally regulated by the activator protein-1 (AP-1) family member protein c-Fos. Here, we report that MG-132, a small-molecule inhibitor of the proteasome, sensitizes TRAIL-resistant prostate cancer cells by inducing c-Fos and repressing c-FLIP(L). c-Fos, which is activated by MG-132, negatively regulates c-FLIP(L) by direct binding to the putative promoter region of the c-FLIP(L) gene. In addition to activating c-Fos, MG-132 activates another AP-1 family member, c-Jun. We show that c-Fos heterodimerizes with c-Jun to repress transcription of c-FLIP(L). Therefore, MG-132 sensitizes TRAIL-resistant prostate cancer cells by activating the AP-1 family members c-Fos and c-Jun, which, in turn, repress the antiapoptotic molecule c-FLIP(L).
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Affiliation(s)
- Wenhua Li
- Division of Urologic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA
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29
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Liu WH, Hsiao HW, Tsou WI, Lai MZ. Notch inhibits apoptosis by direct interference with XIAP ubiquitination and degradation. EMBO J 2007; 26:1660-9. [PMID: 17318174 PMCID: PMC1829378 DOI: 10.1038/sj.emboj.7601611] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Accepted: 01/25/2007] [Indexed: 01/15/2023] Open
Abstract
The physiological activity of Notch is a function of its ability to increase survival in many cell types. Several pathways have been shown to contribute to the survival effect of Notch, but the exact mechanism of Notch action is not completely understood. Here we identified that the regulation of cell survival by Notch intracellular domain could partly be attributed to a selective increase of X-linked inhibitor of apoptosis protein (XIAP). We further found that Notch intracellular domain inhibited the degradation of XIAP during apoptosis. The transactivation domain of Notch interacted directly with the RING region of XIAP to block the binding of E2 and prevent the in vivo and in vitro ubiquitination of XIAP. This antiapoptotic activity of Notch was abolished when XIAP was knocked down. Our results reveal a novel mechanism for Notch-selective suppression of apoptosis through an increase in the stability of a key antiapoptotic protein, XIAP.
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Affiliation(s)
- Wen-Hsien Liu
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, ROC
| | - Huey-Wen Hsiao
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, ROC
- Graduate Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Wen-I Tsou
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, ROC
| | - Ming-Zong Lai
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, ROC
- Graduate Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, ROC
- Graduate Institute of Immunology, National Taiwan University, Taipei, Taiwan, ROC
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan, ROC. Tel.: +886 2 2789 9236; Fax: +886 2 2782 6085; E-mail:
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30
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Sohn D, Essmann F, Schulze-Osthoff K, Jänicke RU. p21 blocks irradiation-induced apoptosis downstream of mitochondria by inhibition of cyclin-dependent kinase-mediated caspase-9 activation. Cancer Res 2007; 66:11254-62. [PMID: 17145870 DOI: 10.1158/0008-5472.can-06-1569] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The role of the cyclin-dependent kinase (CDK) inhibitor p21 as a mediator of p53-induced growth arrest is well established. In addition, recent data provide strong evidence for new emerging functions of p21, including a role as a modulator of apoptosis. The mechanisms, however, by which p21 interferes with the death machinery, especially following ionizing radiation (IR), are largely unknown. Here, we report that IR induced caspase-9 and caspase-3 activation and subsequent apoptosis only in p21-deficient colon carcinoma cells, whereas similar treated wild-type cells were permanently arrested in the G(2)-M phase, correlating with the induction of cellular senescence. Interestingly, activation of the mitochondrial pathway, including caspase-2 processing, depolarization of the outer mitochondrial membrane, and cytochrome c release, was achieved by IR in both cell lines, indicating that p21 inhibits an event downstream of mitochondria but preceding caspase-9 activation. IR-induced p21 protein expression was restricted to the nucleus, and no evidence for a mitochondrial or cytoplasmic association was found. In addition, p21 did neither interact with caspase-3 or caspase-9, suggesting that these events are not required for the observed protection. Consistent with this assumption, we found that CDK inhibitors potently abrogated IR-induced caspase processing and activation without affecting mitochondrial events. In addition, in vitro caspase activation assays yielded higher caspase-3 activities in extracts of irradiated p21-deficient cells compared with extracts of similar treated wild-type cells. Thus, our results strongly indicate that p21 protects cells from IR-induced apoptosis by suppression of CDK activity that seems to be required for activation of the caspase cascade downstream of the mitochondria.
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Affiliation(s)
- Dennis Sohn
- Institute of Molecular Medicine, University of Düsseldorf, Düsseldorf, Germany
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31
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Finnberg N, El-Deiry WS. Selective TRAIL-Induced Apoptosis in Dysplastic Neoplasia of the Colon May Lead to New Neoadjuvant or Adjuvant Therapies. Clin Cancer Res 2006; 12:4132-6. [PMID: 16857782 DOI: 10.1158/1078-0432.ccr-06-0567] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Niklas Finnberg
- Laboratory of Molecular Oncology and Cell Cycle Regulation, Department of Medicine, the Abramson Comprehensive Cancer Center, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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32
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Schmitz I, Meyer C, Schulze-Osthoff K. CD95 ligand mediates T-cell receptor-induced apoptosis of a CD4+ CD8+ double positive thymic lymphoma. Oncogene 2006; 25:7587-96. [PMID: 16767155 DOI: 10.1038/sj.onc.1209741] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Tumors in the thymus can be of different cellular origin. Among the most common tumors are thymoma and lymphoma, which are derived from transformed thymic epithelial cells and transformed lymphocytes, respectively. Thymic lymphoma and their response to apoptotic stimuli are poorly characterized. Here, we analyse apoptosis events in the thymic lymphoma cell line Thy278, which expresses cell surface antigens characteristic of immature double positive thymocytes. Upon T-cell receptor (TCR)/CD3 stimulation, Thy278 cells die by apoptosis, similar as primary thymocytes during negative selection. Caspases are crucial for deletion of both Thy278 cells and normal thymocytes. Moreover, we show that deletion of primary thymocytes and Thy278 cells upon CD3 stimulation is considerably impaired by neutralizing CD95L antibody. Thus, our results not only demonstrate that TCR-induced apoptosis is still functional in transformed thymocytes, but also suggest that Thy278 cells are a helpful model for the molecular analysis of negative selection.
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Affiliation(s)
- I Schmitz
- Institute of Molecular Medicine, University of Düsseldorf, Düsseldorf, Germany.
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