1
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Mars JC, Culjkovic-Kraljacic B, Borden KL. eIF4E orchestrates mRNA processing, RNA export and translation to modify specific protein production. Nucleus 2024; 15:2360196. [PMID: 38880976 PMCID: PMC11185188 DOI: 10.1080/19491034.2024.2360196] [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: 02/12/2024] [Accepted: 05/22/2024] [Indexed: 06/18/2024] Open
Abstract
The eukaryotic translation initiation factor eIF4E acts as a multifunctional factor that simultaneously influences mRNA processing, export, and translation in many organisms. Its multifactorial effects are derived from its capacity to bind to the methyl-7-guanosine cap on the 5'end of mRNAs and thus can act as a cap chaperone for transcripts in the nucleus and cytoplasm. In this review, we describe the multifactorial roles of eIF4E in major mRNA-processing events including capping, splicing, cleavage and polyadenylation, nuclear export and translation. We discuss the evidence that eIF4E acts at two levels to generate widescale changes to processing, export and ultimately the protein produced. First, eIF4E alters the production of components of the mRNA processing machinery, supporting a widescale reprogramming of multiple mRNA processing events. In this way, eIF4E can modulate mRNA processing without physically interacting with target transcripts. Second, eIF4E also physically interacts with both capped mRNAs and components of the RNA processing or translation machineries. Further, specific mRNAs are sensitive to eIF4E only in particular mRNA processing events. This selectivity is governed by the presence of cis-acting elements within mRNAs known as USER codes that recruit relevant co-factors engaging the appropriate machinery. In all, we describe the molecular bases for eIF4E's multifactorial function and relevant regulatory pathways, discuss the basis for selectivity, present a compendium of ~80 eIF4E-interacting factors which play roles in these activities and provide an overview of the relevance of its functions to its oncogenic potential. Finally, we summarize early-stage clinical studies targeting eIF4E in cancer.
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Affiliation(s)
- Jean-Clément Mars
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Montréal, QC, Canada
| | - Biljana Culjkovic-Kraljacic
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Montréal, QC, Canada
| | - Katherine L.B. Borden
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Montréal, QC, Canada
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2
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D'Addiego J, Elaldi N, Wand N, Osman K, Bagci BK, Kennedy E, Pektas AN, Hart E, Slack G, Hewson R. Investigating the effect of ribavirin treatment on genetic mutations in Crimean-Congo haemorrhagic fever virus (CCHFV) through next-generation sequencing. J Med Virol 2023; 95:e28548. [PMID: 36734067 DOI: 10.1002/jmv.28548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 01/12/2023] [Accepted: 01/30/2023] [Indexed: 02/04/2023]
Abstract
Crimean-Congo haemorrhagic fever (CCHF) is the most widespread tick-borne viral haemorrhagic fever affecting humans, and yet a licensed drug against the virus (CCHFV) is still not available. While several studies have suggested the efficacy of ribavirin against CCHFV, current literature remains inconclusive. In this study, we have utilised next-generation sequencing to investigate the mutagenic effect of ribavirin on the CCHFV genome during clinical disease. Samples collected from CCHF patients receiving ribavirin treatment or supportive care only at Sivas Cumhuriyet University Hospital, Turkey, were analysed. By comparing the frequency of mutations in each group, we found little evidence of an overall mutagenic effect. This suggests that ribavirin, administered at the acute stages of CCHFV infection (at the World Health Organization-recommended dose) is unable to induce lethal mutagenesis that would cause an extinction event in the CCHFV population and reduce viremia.
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Affiliation(s)
- Jake D'Addiego
- UK Health Security Agency, Salisbury, UK
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Nazif Elaldi
- Department of Infectious Diseases and Clinical Microbiology, Sivas Cumhuriyet University Faculty of Medicine, Sivas, Turkey
| | | | | | - Binnur Koksal Bagci
- Department of Nutrition and Dietetics, Faculty of Health Sciences, Sivas Cumhuriyet University, Sivas, Turkey
| | | | - Ayse Nur Pektas
- Cumhuriyet University Advanced Technology Application and Research Center (CUTAM), Sivas Cumhuriyet University, Sivas, Turkey
| | | | | | - Roger Hewson
- UK Health Security Agency, Salisbury, UK
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
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3
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Sepúlveda CS, García CC, Damonte EB. Inhibitors of Nucleotide Biosynthesis as Candidates for a Wide Spectrum of Antiviral Chemotherapy. Microorganisms 2022; 10:1631. [PMID: 36014049 PMCID: PMC9413629 DOI: 10.3390/microorganisms10081631] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 08/05/2022] [Accepted: 08/08/2022] [Indexed: 11/21/2022] Open
Abstract
Emerging and re-emerging viruses have been a challenge in public health in recent decades. Host-targeted antivirals (HTA) directed at cellular molecules or pathways involved in virus multiplication represent an interesting strategy to combat viruses presently lacking effective chemotherapy. HTA could provide a wide range of agents with inhibitory activity against current and future viruses that share similar host requirements and reduce the possible selection of antiviral-resistant variants. Nucleotide metabolism is one of the more exploited host metabolic pathways as a potential antiviral target for several human viruses. This review focuses on the antiviral properties of the inhibitors of pyrimidine and purine nucleotide biosynthesis, with an emphasis on the rate-limiting enzymes dihydroorotate dehydrogenase (DHODH) and inosine monophosphate dehydrogenase (IMPDH) for which there are old and new drugs active against a broad spectrum of pathogenic viruses.
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Affiliation(s)
- Claudia Soledad Sepúlveda
- Laboratory of Virology, Biochemistry Department, School of Sciences, University of Buenos Aires (UBA), Ciudad Universitaria, Buenos Aires 1428, Argentina
- Institute of Biochemistry of the School of Sciences (IQUIBICEN), CONICET-UBA, Ciudad Universitaria, Buenos Aires 1428, Argentina
| | - Cybele Carina García
- Laboratory of Virology, Biochemistry Department, School of Sciences, University of Buenos Aires (UBA), Ciudad Universitaria, Buenos Aires 1428, Argentina
- Institute of Biochemistry of the School of Sciences (IQUIBICEN), CONICET-UBA, Ciudad Universitaria, Buenos Aires 1428, Argentina
| | - Elsa Beatriz Damonte
- Laboratory of Virology, Biochemistry Department, School of Sciences, University of Buenos Aires (UBA), Ciudad Universitaria, Buenos Aires 1428, Argentina
- Institute of Biochemistry of the School of Sciences (IQUIBICEN), CONICET-UBA, Ciudad Universitaria, Buenos Aires 1428, Argentina
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4
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Dmitriev SE, Vladimirov DO, Lashkevich KA. A Quick Guide to Small-Molecule Inhibitors of Eukaryotic Protein Synthesis. BIOCHEMISTRY (MOSCOW) 2021; 85:1389-1421. [PMID: 33280581 PMCID: PMC7689648 DOI: 10.1134/s0006297920110097] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Eukaryotic ribosome and cap-dependent translation are attractive targets in the antitumor, antiviral, anti-inflammatory, and antiparasitic therapies. Currently, a broad array of small-molecule drugs is known that specifically inhibit protein synthesis in eukaryotic cells. Many of them are well-studied ribosome-targeting antibiotics that block translocation, the peptidyl transferase center or the polypeptide exit tunnel, modulate the binding of translation machinery components to the ribosome, and induce miscoding, premature termination or stop codon readthrough. Such inhibitors are widely used as anticancer, anthelmintic and antifungal agents in medicine, as well as fungicides in agriculture. Chemicals that affect the accuracy of stop codon recognition are promising drugs for the nonsense suppression therapy of hereditary diseases and restoration of tumor suppressor function in cancer cells. Other compounds inhibit aminoacyl-tRNA synthetases, translation factors, and components of translation-associated signaling pathways, including mTOR kinase. Some of them have antidepressant, immunosuppressive and geroprotective properties. Translation inhibitors are also used in research for gene expression analysis by ribosome profiling, as well as in cell culture techniques. In this article, we review well-studied and less known inhibitors of eukaryotic protein synthesis (with the exception of mitochondrial and plastid translation) classified by their targets and briefly describe the action mechanisms of these compounds. We also present a continuously updated database (http://eupsic.belozersky.msu.ru/) that currently contains information on 370 inhibitors of eukaryotic protein synthesis.
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Affiliation(s)
- S E Dmitriev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia. .,Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, 119234, Russia.,Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia
| | - D O Vladimirov
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, 119234, Russia
| | - K A Lashkevich
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia
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5
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Romagnoli A, Maracci C, D’Agostino M, Teana AL, Marino DD. Targeting mTOR and eIF4E: a feasible scenario in ovarian cancer therapy. CANCER DRUG RESISTANCE (ALHAMBRA, CALIF.) 2021; 4:596-606. [PMID: 35582305 PMCID: PMC9094073 DOI: 10.20517/cdr.2021.20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/22/2021] [Accepted: 04/27/2021] [Indexed: 11/16/2022]
Abstract
Ovarian carcinoma is one of the most common causes for cancer death in women; lack of early diagnosis and acquired resistance to platinum-based chemotherapy account for its poor prognosis and high mortality rate. As with other cancer types, ovarian cancer is characterized by dysregulated signaling pathways and protein synthesis, which together contribute to rapid cellular growth and invasiveness. The mechanistic/mammalian target of rapamycin (mTOR) pathway represents the core of different signaling pathways regulating a number of essential steps in the cell, among which protein synthesis and the eukaryotic initiation factor 4E (eIF4E), the mRNA cap binding protein, is one of its downstream effectors. eIF4E is a limiting factor in translation initiation and its overexpression is a hallmark in many cancers. Because its action is regulated by a number of factors that compete for the same binding site, eIF4E is an ideal target for developing novel antineoplastic drugs. Several inhibitors targeting the mTOR signaling pathway have been designed thus far, however most of these molecules show poor stability and high toxicity in vivo. This minireview explores the possibility of targeting mTOR and eIF4E proteins, thus impacting on translation initiation in ovarian cancer, describing the most promising experimental strategies and specific inhibitors that have been shown to have an effect on other kinds of cancers.
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Affiliation(s)
- Alice Romagnoli
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona 60131, Italy
- New York-Marche Structural Biology Center (NY-MaSBiC), Polytechnic University of Marche, Ancona 60131, Italy
| | - Cristina Maracci
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona 60131, Italy
| | - Mattia D’Agostino
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona 60131, Italy
| | - Anna La Teana
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona 60131, Italy
- New York-Marche Structural Biology Center (NY-MaSBiC), Polytechnic University of Marche, Ancona 60131, Italy
| | - Daniele Di Marino
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona 60131, Italy
- New York-Marche Structural Biology Center (NY-MaSBiC), Polytechnic University of Marche, Ancona 60131, Italy
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6
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Abstract
Inhibiting eukaryotic protein translation with small molecules is emerging as a powerful therapeutic strategy. The advantage of targeting cellular translational machinery is that it is required for the highly proliferative state of many neoplastic cells, replication of certain viruses, and ultimately the expression of a wide variety of protein targets. Although, this approach has been exploited to develop clinical agents, such as homoharringtonine (HHT, 1), used to treat chronic myeloid leukemia (CML), inhibiting components of the translational machinery is often associated with cytotoxic phenotypes. However, recent studies have demonstrated that certain small molecules can inhibit the translation of specific subsets of proteins, leading to lower cytotoxicity, and opening-up therapeutic opportunities for translation inhibitors to be deployed in indications beyond oncology and infectious disease. This review summarizes efforts to develop inhibitors of the eukaryotic translational machinery as therapeutic agents and highlights emerging opportunities for translation inhibitors in the future.
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Affiliation(s)
- Angela Fan
- Department of Discovery Chemistry, Merck & Co., Inc., South San Francisco, California 94080, United States
| | - Phillip P Sharp
- Department of Discovery Chemistry, Merck & Co., Inc., South San Francisco, California 94080, United States
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7
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Smith RCL, Kanellos G, Vlahov N, Alexandrou C, Willis AE, Knight JRP, Sansom OJ. Translation initiation in cancer at a glance. J Cell Sci 2021; 134:jcs248476. [PMID: 33441326 DOI: 10.1242/jcs.248476] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cell division, differentiation and function are largely dependent on accurate proteome composition and regulated gene expression. To control this, protein synthesis is an intricate process governed by upstream signalling pathways. Eukaryotic translation is a multistep process and can be separated into four distinct phases: initiation, elongation, termination and recycling of ribosomal subunits. Translation initiation, the focus of this article, is highly regulated to control the activity and/or function of eukaryotic initiation factors (eIFs) and permit recruitment of mRNAs to the ribosomes. In this Cell Science at a Glance and accompanying poster, we outline the mechanisms by which tumour cells alter the process of translation initiation and discuss how this benefits tumour formation, proliferation and metastasis.
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Affiliation(s)
- Rachael C L Smith
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, G61 1QH, UK
| | - Georgios Kanellos
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
| | - Nikola Vlahov
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
| | | | - Anne E Willis
- MRC Toxicology Unit, University of Cambridge, Cambridge CB2 1QW, UK
| | - John R P Knight
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
| | - Owen J Sansom
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, G61 1QH, UK
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8
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Mohibi S, Chen X, Zhang J. Cancer the'RBP'eutics-RNA-binding proteins as therapeutic targets for cancer. Pharmacol Ther 2019; 203:107390. [PMID: 31302171 DOI: 10.1016/j.pharmthera.2019.07.001] [Citation(s) in RCA: 121] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 07/02/2019] [Indexed: 12/11/2022]
Abstract
RNA-binding proteins (RBPs) play a critical role in the regulation of various RNA processes, including splicing, cleavage and polyadenylation, transport, translation and degradation of coding RNAs, non-coding RNAs and microRNAs. Recent studies indicate that RBPs not only play an instrumental role in normal cellular processes but have also emerged as major players in the development and spread of cancer. Herein, we review the current knowledge about RNA binding proteins and their role in tumorigenesis as well as the potential to target RBPs for cancer therapeutics.
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Affiliation(s)
- Shakur Mohibi
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, United States
| | - Xinbin Chen
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, United States
| | - Jin Zhang
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, United States.
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9
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Nyström K, Waldenström J, Tang KW, Lagging M. Ribavirin: pharmacology, multiple modes of action and possible future perspectives. Future Virol 2019. [DOI: 10.2217/fvl-2018-0166] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ribavirin is a unique guanosine analog with broad-spectrum activity against many RNA and DNA viruses. In addition to its mutational properties, ribavirin exerts extensive perturbation of cellular and viral gene expression. Furthermore, recent advances indicate that the impact of ribavirin on divergent cellular and viral pathways may be concentration dependent. This review aims at providing an overview of the pharmacology and multiple modes of action of ribavirin as well as pointing to possible novel future uses.
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Affiliation(s)
- Kristina Nyström
- Department of Infectious Diseases/Virology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Västra Götaland Region, Sweden
| | - Jesper Waldenström
- Department of Infectious Diseases/Virology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Västra Götaland Region, Sweden
| | - Ka-Wei Tang
- Department of Infectious Diseases/Virology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Västra Götaland Region, Sweden
| | - Martin Lagging
- Department of Infectious Diseases/Virology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Västra Götaland Region, Sweden
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10
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Uttam S, Wong C, Price TJ, Khoutorsky A. eIF4E-Dependent Translational Control: A Central Mechanism for Regulation of Pain Plasticity. Front Genet 2018; 9:470. [PMID: 30459806 PMCID: PMC6232926 DOI: 10.3389/fgene.2018.00470] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 09/24/2018] [Indexed: 01/04/2023] Open
Abstract
Translational control of gene expression has emerged as a key mechanism in regulating different forms of long-lasting neuronal plasticity. Maladaptive plastic reorganization of peripheral and spinal nociceptive circuits underlies many chronic pain states and relies on new gene expression. Accordingly, downregulation of mRNA translation in primary afferents and spinal dorsal horn neurons inhibits tissue injury-induced sensitization of nociceptive pathways, supporting a central role for translation dysregulation in the development of persistent pain. Translation is primarily regulated at the initiation stage via the coordinated activity of translation initiation factors. The mRNA cap-binding protein, eukaryotic translation initiation factor 4E (eIF4E), is involved in the recruitment of the ribosome to the mRNA cap structure, playing a central role in the regulation of translation initiation. eIF4E integrates inputs from the mTOR and ERK signaling pathways, both of which are activated in numerous painful conditions to regulate the translation of a subset of mRNAs. Many of these mRNAs are involved in the control of cell growth, proliferation, and neuroplasticity. However, the full repertoire of eIF4E-dependent mRNAs in the nervous system and their translation regulatory mechanisms remain largely unknown. In this review, we summarize the current evidence for the role of eIF4E-dependent translational control in the sensitization of pain circuits and present pharmacological approaches to target these mechanisms. Understanding eIF4E-dependent translational control mechanisms and their roles in aberrant plasticity of nociceptive circuits might reveal novel therapeutic targets to treat persistent pain states.
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Affiliation(s)
- Sonali Uttam
- Department of Anesthesia, McGill University, Montreal, QC, Canada
| | - Calvin Wong
- Department of Anesthesia, McGill University, Montreal, QC, Canada
| | - Theodore J. Price
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
- Center for Advanced Pain Studies, The University of Texas at Dallas, Richardson, TX, United States
| | - Arkady Khoutorsky
- Department of Anesthesia, McGill University, Montreal, QC, Canada
- Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC, Canada
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11
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VENTURI V, MASEK T, POSPISEK M. A Blood Pact: the Significance and Implications of eIF4E on Lymphocytic Leukemia. Physiol Res 2018. [DOI: 10.33549/physiolres.933696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Elevated levels of eukaryotic initiation factor 4E (eIF4E) are implicated in neoplasia, with cumulative evidence pointing to its role in the etiopathogenesis of hematological diseases. As a node of convergence for several oncogenic signaling pathways, eIF4E has attracted a great deal of interest from biologists and clinicians whose efforts have been targeting this translation factor and its biological circuits in the battle against leukemia. The role of eIF4E in myeloid leukemia has been ascertained and drugs targeting its functions have found their place in clinical trials. Little is known, however, about the pertinence of eIF4E to the biology of lymphocytic leukemia and a paucity of literature is available in this regard that prospectively evaluates the topic to guide practice in hematological cancer. A comprehensive analysis on the significance of eIF4E translation factor in the clinical picture of leukemia arises, therefore, as a compelling need. This review presents aspects of eIF4E involvement in the realm of the lymphoblastic leukemia status; translational control of immunological function via eIF4E and the state-of-the-art in drugs will also be outlined.
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Affiliation(s)
| | | | - M. POSPISEK
- Department of Genetics and Microbiology, Faculty of Science, Charles University, Prague, Czech Republic
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12
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Antiviral Drug Ribavirin Targets Thyroid Cancer Cells by Inhibiting the eIF4E-β-Catenin Axis. Am J Med Sci 2017; 354:182-189. [DOI: 10.1016/j.amjms.2017.03.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 03/13/2017] [Accepted: 03/14/2017] [Indexed: 11/18/2022]
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13
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Todt D, Walter S, Brown RJP, Steinmann E. Mutagenic Effects of Ribavirin on Hepatitis E Virus-Viral Extinction versus Selection of Fitness-Enhancing Mutations. Viruses 2016; 8:E283. [PMID: 27754363 PMCID: PMC5086615 DOI: 10.3390/v8100283] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 09/30/2016] [Accepted: 10/06/2016] [Indexed: 12/11/2022] Open
Abstract
Hepatitis E virus (HEV), an important agent of viral hepatitis worldwide, can cause severe courses of infection in pregnant women and immunosuppressed patients. To date, HEV infections can only be treated with ribavirin (RBV). Major drawbacks of this therapy are that RBV is not approved for administration to pregnant women and that the virus can acquire mutations, which render the intra-host population less sensitive or even resistant to RBV. One of the proposed modes of action of RBV is a direct mutagenic effect on viral genomes, inducing mismatches and subsequent nucleotide substitutions. These transition events can drive the already error-prone viral replication beyond an error threshold, causing viral population extinction. In contrast, the expanded heterogeneous viral population can facilitate selection of mutant viruses with enhanced replication fitness. Emergence of these mutant viruses can lead to therapeutic failure. Consequently, the onset of RBV treatment in chronically HEV-infected individuals can result in two divergent outcomes: viral extinction versus selection of fitness-enhanced viruses. Following an overview of RNA viruses treated with RBV in clinics and a summary of the different antiviral modes of action of this drug, we focus on the mutagenic effect of RBV on HEV intrahost populations, and how HEV is able to overcome lethal mutagenesis.
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Affiliation(s)
- Daniel Todt
- Institute of Experimental Virology, Twincore-Centre for Experimental and Clinical Infection Research, a Joint Venture between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research, 30625 Hannover, Germany.
| | - Stephanie Walter
- Institute of Experimental Virology, Twincore-Centre for Experimental and Clinical Infection Research, a Joint Venture between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research, 30625 Hannover, Germany.
| | - Richard J P Brown
- Institute of Experimental Virology, Twincore-Centre for Experimental and Clinical Infection Research, a Joint Venture between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research, 30625 Hannover, Germany.
| | - Eike Steinmann
- Institute of Experimental Virology, Twincore-Centre for Experimental and Clinical Infection Research, a Joint Venture between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research, 30625 Hannover, Germany.
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14
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Borden KLB. The eukaryotic translation initiation factor eIF4E wears a "cap" for many occasions. ACTA ACUST UNITED AC 2016; 4:e1220899. [PMID: 28090419 PMCID: PMC5173310 DOI: 10.1080/21690731.2016.1220899] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 07/12/2016] [Accepted: 08/02/2016] [Indexed: 01/11/2023]
Abstract
The eukaryotic translation initiation factor eIF4E plays important roles in controlling the composition of the proteome. Indeed, dysregulation of eIF4E is associated with poor prognosis cancers. The traditional view has been that eIF4E acts solely in translation. However, over the last ∼25 years, eIF4E was found in the nucleus where it acts in mRNA export and in the last ∼10 years, eIF4E was found in cytoplasmic processing bodies (P-bodies) where it functions in mRNA sequestration and stability. The common biochemical thread for these activities is the ability of eIF4E to bind the 7-methylguanosine cap on the 5′ end of mRNAs. Recently, the possibility that eIF4E directly binds some mRNA elements independently of the cap has also been raised. Importantly, the effects of eIF4E are not genome-wide with a subset of transcripts targeted depending on the presence of specific mRNA elements and context-dependent regulatory factors. Indeed, eIF4E governs RNA regulons through co-regulating the expression of groups of transcripts acting in the same biochemical pathways. In addition, studies over the past ∼15 years indicate that there are multiple strategies that regulatory factors employ to modulate eIF4E activities in context-dependent manners. This perspective focuses on these new findings and incorporates them into a broader model for eIF4E function.
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Affiliation(s)
- Katherine L B Borden
- Department of Pathology and Cell Biology, Institute of Research in Immunology and Cancer (IRIC), Université de Montréal , Montreal, Québec, Canada
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15
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Roch FF, Hinterkörner G, Menke J, Tang GQ, Cusack S, Butzendobler B, Buschmann H, Datta K, Wolkerstorfer A. An RNA Hybridization Assay for Screening Influenza A Virus Polymerase Inhibitors Using the Entire Ribonucleoprotein Complex. Assay Drug Dev Technol 2016; 13:488-506. [PMID: 26461433 DOI: 10.1089/adt.2015.668] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Novel antiviral drugs, which are less prone to resistance development, are desirable alternatives to the currently approved drugs for the treatment of potentially serious influenza virus infections. The viral polymerase is highly conserved and serves as an attractive target for antiviral drugs since potent inhibitors would directly stop viral replication at an early stage. Recent structural studies on the functional domains of the heterotrimeric influenza polymerase, which comprises subunits PA, PB1, and PB2, opened the way to a structure-based approach for optimizing inhibitors of viral replication. These strategies, however, are limited by the use of isolated protein fragments instead of employing the entire ribonucleoprotein complex (RNP), which represents the functional form of the influenza polymerase in infected cells. In this study, we have established a screening assay for efficient and reliable analysis of potential influenza polymerase inhibitors of various molecular targets such as monoselective polymerase inhibitors targeting the endonuclease site, the cap-binding domain, and the polymerase active site, respectively. By utilizing whole viral RNPs and a radioactivity-free endpoint detection with the capability for efficient compound screening while offering high-content information on potential inhibitors to drive medicinal chemistry program in a reliable manner, this biochemical assay provides significant advantages over the currently available conventional assays. We propose that this assay can eventually be adapted for coinstantaneous analysis and subsequent optimization of two or more different chemical scaffold classes targeting multiple active sites within the polymerase complex, thus enabling the evaluation of drug combinations and characterization of molecules with dual functionality.
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Affiliation(s)
| | | | - John Menke
- 2 Virology Discovery, Hoffmann-La Roche, Inc. , Nutley, New Jersey
| | - Guo-Qing Tang
- 2 Virology Discovery, Hoffmann-La Roche, Inc. , Nutley, New Jersey
| | - Stephen Cusack
- 3 Grenoble Outstation, European Molecular Biology Laboratory , Grenoble, France
| | | | | | - Kausiki Datta
- 2 Virology Discovery, Hoffmann-La Roche, Inc. , Nutley, New Jersey
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16
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Abstract
The translation initiation factor eIF4E mediates a rate-limiting process that drives selective translation of many oncongenic proteins such as cyclin D1, survivin and VEGF, thereby contributing to tumour growth, metastasis and therapy resistance. As an essential regulatory hub in cancer signalling network, many oncogenic signalling pathways appear to converge on eIF4E. Therefore, targeting eIF4E-mediated cap-dependent translation is considered a promising anticancer strategy. This paper reviews the strategies that can be used to target eIF4E, highlighting agents that target eIF4E activity at each distinct level.
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Cencic R, Pelletier J. Hippuristanol - A potent steroid inhibitor of eukaryotic initiation factor 4A. ACTA ACUST UNITED AC 2016; 4:e1137381. [PMID: 27335721 DOI: 10.1080/21690731.2015.1137381] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 12/08/2015] [Accepted: 12/24/2015] [Indexed: 01/02/2023]
Abstract
Protein synthesis and its regulatory signaling pathways play essential roles in the initiation and maintenance of the cancer phenotype. Insight obtained over the last 3 decades on the mechanisms regulating translation in normal and transformed cells have revealed that perturbed control in cancer cells may offer an Achilles' heel for the development of novel anti-neoplastic agents. Several small molecule inhibitors have been identified and characterized that target translation initiation - more specifically, the rate-limiting step where ribosomes are recruited to mRNA templates. Among these, hippuristanol, a polyhydroxysteroid from the gorgonian Isis hippuris has been found to inhibit translation initiation by blocking the activity of eukaryotic initiation factor (eIF) 4A, an essential RNA helicase involved in this process. Herein, we highlight the biological properties of this compound, its potential development as an anti-cancer agent, and its use to validate eIF4A as an anti-neoplastic target.
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Affiliation(s)
- Regina Cencic
- Department of Biochemistry, McGill University , Montreal, Québec, Canada
| | - Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, Québec, Canada; The Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, Québec, Canada; Department of Oncology, McGill University, Montreal, Québec, Canada
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18
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Pelletier J, Graff J, Ruggero D, Sonenberg N. Targeting the eIF4F translation initiation complex: a critical nexus for cancer development. Cancer Res 2015; 75:250-63. [PMID: 25593033 DOI: 10.1158/0008-5472.can-14-2789] [Citation(s) in RCA: 267] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Elevated protein synthesis is an important feature of many cancer cells and often arises as a consequence of increased signaling flux channeled to eukaryotic initiation factor 4F (eIF4F), the key regulator of the mRNA-ribosome recruitment phase of translation initiation. In many cellular and preclinical models of cancer, eIF4F deregulation results in changes in translational efficiency of specific mRNA classes. Importantly, many of these mRNAs code for proteins that potently regulate critical cellular processes, such as cell growth and proliferation, enhanced cell survival and cell migration that ultimately impinge on several hallmarks of cancer, including increased angiogenesis, deregulated growth control, enhanced cellular survival, epithelial-to-mesenchymal transition, invasion, and metastasis. By being positioned as the molecular nexus downstream of key oncogenic signaling pathways (e.g., Ras, PI3K/AKT/TOR, and MYC), eIF4F serves as a direct link between important steps in cancer development and translation initiation. Identification of mRNAs particularly responsive to elevated eIF4F activity that typifies tumorigenesis underscores the critical role of eIF4F in cancer and raises the exciting possibility of developing new-in-class small molecules targeting translation initiation as antineoplastic agents.
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Affiliation(s)
- Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, Québec, Canada. The Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, Québec, Canada. Department of Oncology, McGill University, Montreal, Québec, Canada.
| | - Jeremy Graff
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana
| | - Davide Ruggero
- School of Medicine and Department of Urology, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, California
| | - Nahum Sonenberg
- Department of Biochemistry, McGill University, Montreal, Québec, Canada. The Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, Québec, Canada
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19
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Abstract
Dysregulation of mRNA translation is a frequent feature of neoplasia. Many oncogenes and tumour suppressors affect the translation machinery, making aberrant translation a widespread characteristic of tumour cells, independent of the genetic make-up of the cancer. Therefore, therapeutic agents that target components of the protein synthesis apparatus hold promise as novel anticancer drugs that can overcome intra-tumour heterogeneity. In this Review, we discuss the role of translation in cancer, with a particular focus on the eIF4F (eukaryotic translation initiation factor 4F) complex, and provide an overview of recent efforts aiming to 'translate' these results to the clinic.
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20
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Karaki S, Andrieu C, Ziouziou H, Rocchi P. The Eukaryotic Translation Initiation Factor 4E (eIF4E) as a Therapeutic Target for Cancer. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2015; 101:1-26. [PMID: 26572974 PMCID: PMC7185574 DOI: 10.1016/bs.apcsb.2015.09.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cancer cells depend on cap-dependent translation more than normal tissue. This explains the emergence of proteins involved in the cap-dependent translation as targets for potential anticancer drugs. Cap-dependent translation starts when eIF4E binds to mRNA cap domain. This review will present eIF4E's structure and functions. It will also expose the use of eIF4E as a therapeutic target in cancer.
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Affiliation(s)
- Sara Karaki
- INSERM, U1068, CRCM, Marseille, France,Institut Paoli-Calmettes, Marseille, France,Aix-Marseille University, Marseille, France,CNRS, UMR7258, Marseille, France
| | - Claudia Andrieu
- INSERM, U1068, CRCM, Marseille, France,Institut Paoli-Calmettes, Marseille, France,Aix-Marseille University, Marseille, France,CNRS, UMR7258, Marseille, France
| | - Hajer Ziouziou
- INSERM, U1068, CRCM, Marseille, France,Institut Paoli-Calmettes, Marseille, France,Aix-Marseille University, Marseille, France,CNRS, UMR7258, Marseille, France
| | - Palma Rocchi
- INSERM, U1068, CRCM, Marseille, France,Institut Paoli-Calmettes, Marseille, France,Aix-Marseille University, Marseille, France,CNRS, UMR7258, Marseille, France,Corresponding author:
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21
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Akcakanat A, Hong DS, Meric-Bernstam F. Targeting translation initiation in breast cancer. ACTA ACUST UNITED AC 2014; 2:e28968. [PMID: 26779407 PMCID: PMC4705830 DOI: 10.4161/trla.28968] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 04/09/2014] [Accepted: 04/22/2014] [Indexed: 12/23/2022]
Abstract
Over the past 20 years, a better understanding of cancer biology, screening for early detection, improved adjuvant treatment, and targeted therapies have decreased the rate of breast cancer deaths. However, resistance to treatment is common, and new approaches are needed. Deregulation of translation initiation is associated with the commencement and progression of cancer. Often, translation initiation factors are overexpressed and the related signaling pathways activated in human tumors. Recently, a significant number of inhibitors that target translation factors and pathways have become available. These inhibitors are being tested alone or in combination with chemotherapeutic agents in clinical trials. The results are varied, and it is not yet clear which drug treatments most effectively inhibit tumor growth. This review highlights the pathways and downstream effects of the activation of translation and discusses targeting the control of translation initiation as a therapeutic approach in cancer, focusing on breast cancer clinical trials.
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Affiliation(s)
- Argun Akcakanat
- Department of Investigational Cancer Therapeutics; Houston, TX USA
| | - David S Hong
- Department of Investigational Cancer Therapeutics; Houston, TX USA
| | - Funda Meric-Bernstam
- Department of Investigational Cancer Therapeutics; Houston, TX USA; Department of Surgical Oncology; The University of Texas MD Anderson Cancer Center; Houston, TX USA
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22
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Bitterman PB, Polunovsky VA. Attacking a nexus of the oncogenic circuitry by reversing aberrant eIF4F-mediated translation. Mol Cancer Ther 2013; 11:1051-61. [PMID: 22572598 DOI: 10.1158/1535-7163.mct-11-0530] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Notwithstanding their genetic complexity, different cancers share a core group of perturbed pathways converging upon a few regulatory nodes that link the intracellular-signaling network with the basic metabolic machinery. The clear implication of this view for cancer therapy is that instead of targeting individual genetic alterations one by one, the next generation of cancer therapeutics will target critical hubs in the cancer network. One such hub is the translation-initiation complex eIF4F, which integrates several cancer-related pathways into a self-amplifying signaling system. When hyperactivated by apical oncogenic signals, the eIF4F-driven translational apparatus selectively switches the translational repertoire of a cell toward malignancy. This central integrative role of pathologically activated eIF4F has motivated the development of small-molecule inhibitors to correct its function. A genome-wide, systems-level means to objectively evaluate the pharmacologic response to therapeutics targeting eIF4F remains an unmet challenge.
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Affiliation(s)
- Peter B Bitterman
- Department of Medicine, University of Minnesota, Minneapolis, MN 55455, USA
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23
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Picard-Jean F, Bougie I, Shuto S, Bisaillon M. The immunosuppressive agent mizoribine monophosphate is an inhibitor of the human RNA capping enzyme. PLoS One 2013; 8:e54621. [PMID: 23349942 PMCID: PMC3547949 DOI: 10.1371/journal.pone.0054621] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 12/13/2012] [Indexed: 11/18/2022] Open
Abstract
Mizoribine monophosphate (MZP) is a specific inhibitor of the cellular inosine-5′-monophosphate dehydrogenase (IMPDH), the enzyme catalyzing the rate-limiting step of de novo guanine nucleotide biosynthesis. MZP is a highly potent antagonistic inhibitor of IMPDH that blocks the proliferation of T and B lymphocytes that use the de novo pathway of guanine nucleotide synthesis almost exclusively. In the present study, we investigated the ability of MZP to directly inhibit the human RNA capping enzyme (HCE), a protein harboring both RNA 5′-triphosphatase and RNA guanylyltransferase activities. HCE is involved in the synthesis of the cap structure found at the 5′ end of eukaryotic mRNAs, which is critical for the splicing of the cap-proximal intron, the transport of mRNAs from the nucleus to the cytoplasm, and for both the stability and translation of mRNAs. Our biochemical studies provide the first insight that MZP can inhibit the formation of the RNA cap structure catalyzed by HCE. In the presence of MZP, the RNA 5′-triphosphatase activity appears to be relatively unaffected while the RNA guanylyltransferase activity is inhibited, indicating that the RNA guanylyltransferase activity is the main target of MZP inhibition. Kinetic studies reveal that MZP is a non-competitive inhibitor that likely targets an allosteric site on HCE. Mizoribine also impairs mRNA capping in living cells, which could account for the global mechanism of action of this therapeutic agent. Together, our study clearly demonstrates that mizoribine monophosphate inhibits the human RNA guanylyltransferase in vitro and impair mRNA capping in cellulo.
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Affiliation(s)
- Frédéric Picard-Jean
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Isabelle Bougie
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Satoshi Shuto
- Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Martin Bisaillon
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada
- * E-mail:
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24
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Garvie CW. Solution-based approach to study binding to the eIF4E cap-binding site using CD spectroscopy. Anal Biochem 2012; 434:166-71. [PMID: 23219983 DOI: 10.1016/j.ab.2012.11.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 11/21/2012] [Accepted: 11/26/2012] [Indexed: 01/04/2023]
Abstract
The eukaryotic initiation factor 4E (eIF4E) is the key component of the translational initiation complex that recruits mRNA by binding to a unique "cap" structure located at the 5' end of the mRNA. Overexpression of eIF4E has been implicated in the development of cancer, potentially as a result of increasing the cellular levels of proteins involved in processes that include proliferation and regulation of apoptosis. As a result, the cap-binding site of eIF4E has become a target for the development of anti-cancer therapeutics. The structure of eIF4E bound to the cap mimic 7-methyl-GDP revealed that two tryptophans from different loops in eIF4E sandwiched the 7-methylguanine group between them. This interaction gives rise to a strong exciton coupling signal between the two tryptophans that can be visualized by CD spectroscopy. eIF4E is a challenging protein to work with because of a propensity to aggregate under conditions used in biophysical techniques. CD spectroscopy provides a gentle, solution-based approach to study binding to the cap-binding site of eIF4E. Evidence is provided that the exciton coupling signal can be used to both qualitatively and quantitatively analyze the binding of cap analogs to eIF4E.
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Affiliation(s)
- Colin W Garvie
- Discovery Technology, Hoffmann-La Roche Inc., 340 Kingsland Street, Nutley, NJ 07110, USA.
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25
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Jia Y, Polunovsky V, Bitterman PB, Wagner CR. Cap-dependent translation initiation factor eIF4E: an emerging anticancer drug target. Med Res Rev 2012; 32:786-814. [PMID: 22495651 PMCID: PMC7168506 DOI: 10.1002/med.21260] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cancer cells tend to be more highly dependent on cap‐dependent translation than normal tissues. Thus, proteins involved in the initiation of cap‐dependent translation have emerged as potential anti‐cancer drug targets. Cap‐dependent translation is initiated by the binding of the factor eIF4E to the cap domain of mRNA. Detailed x‐ray crystal and NMR structures are available for eIF4E in association with cap‐analogs, as well as domains of other initiation factors. This review will summarize efforts to design potential antagonist of eIF4E that could be used as new pharmacological tools and anti‐cancer agents and. Insights drawn from these studies should aid in the design of future inhibitors of eIF4E dependent translation initiation. © 2012 Wiley Periodicals, Inc. Med Res Rev., 32, No. 4, 786‐814, 2012
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Affiliation(s)
- Yan Jia
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
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26
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Abstract
Protein synthesis is a complex, tightly regulated process in eukaryotic cells and its deregulation is a hallmark of many cancers. Translational control occurs primarily at the rate-limiting initiation step, where ribosomal subunits are recruited to template mRNAs through the concerted action of several eukaryotic initiation factors (eIFs). One factor that interacts with both the mRNA and ribosomes, and appears limiting for translation is eIF4F, a complex composed of the cap-binding protein, eIF4E; the scaffold protein, eIF4G; and the ATP-dependent DEAD-box helicase, eIF4A. eIF4E appears to play an important role in tumor initiation and progression since its overexpression can cooperate with oncogenes to accelerate transformation in cell lines and animal models, and its levels are elevated in many human cancers. This, therefore, represents a vulnerability for transformed cells, and presents an opportunity for therapeutic intervention. In this review, we discuss approaches for targeting eIF4F activity.
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27
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McCarty MF. mTORC1 activity as a determinant of cancer risk--rationalizing the cancer-preventive effects of adiponectin, metformin, rapamycin, and low-protein vegan diets. Med Hypotheses 2011; 77:642-8. [PMID: 21862237 DOI: 10.1016/j.mehy.2011.07.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 06/09/2011] [Accepted: 07/01/2011] [Indexed: 02/07/2023]
Abstract
Increased plasma levels of adiponectin, metformin therapy of diabetes, rapamycin administration in transplant patients, and lifelong consumption of low-protein plant-based diets have all been linked to decreased risk for various cancers. These benefits may be mediated, at least in part, by down-regulated activity of the mTORC1 complex, a key regulator of protein translation. By boosting the effective availability of the translation initiator eIF4E, mTORC1 activity promotes the translation of a number of "weak" mRNAs that code for proteins, often up-regulated in cancer, that promote cellular proliferation, invasiveness, and angiogenesis, and that abet cancer promotion and chemoresistance by opposing apoptosis. Measures which inhibit eIF4E activity, either directly or indirectly, may have utility not only for cancer prevention, but also for the treatment of many cancers in which eIF4E drives malignancy. Since eIF4E is overexpressed in many cancers, strategies which target eIF4E directly--some of which are now being assessed clinically--may have the broadest efficacy in this regard. Many of the "weak" mRNAs coding for proteins that promote malignant behavior or chemoresistance are regulated transcriptionally by NF-kappaB and/or Stat3, which are active in a high proportion of cancers; thus, regimens concurrently targeting eIF4E, NF-kappaB, and Stat3 may suppress these proteins at both the transcriptional and translational levels, potentially achieving a very marked reduction in their expression.
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Affiliation(s)
- Mark F McCarty
- NutriGuard Research, 1051 Hermes Ave., Encinitas, CA 92024, United States.
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28
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McCarty MF. Metformin may antagonize Lin28 and/or Lin28B activity, thereby boosting let-7 levels and antagonizing cancer progression. Med Hypotheses 2011; 78:262-9. [PMID: 22129484 DOI: 10.1016/j.mehy.2011.10.041] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 10/26/2011] [Indexed: 12/15/2022]
Abstract
Cancer cells with stem cell characteristics are harbored by most tumors, and are characterized by epithelial-mesenchymal transition (EMT) - which promotes invasive growth and metastasis - chemoresistance, and the capacity to reconstitute new tumors. Hence, the control or destruction of cancer stem cells should be a major goal of cancer management. The let-7 family of microRNAs has cancer suppressor activity, and recent evidence suggests that markedly reduced levels of let-7 are not only a typical feature of cancer stem cells, but may be largely responsible for cancer stemness. It is therefore particularly intriguing that metformin, a diabetes drug thought to have potential in the prevention and treatment of cancer, has recently been found to oppose cancer cell stemness, to markedly potentiate chemotherapeutic control of cancer in mouse xenograft models, and to notably boost let-7a levels in cancer stem cells. It is proposed that this latter effect of metformin may reflect AMPK-mediated inhibition of the expression or activity of Lin28/Lin28A, proteins which act post-transcriptionally to decrease the levels of all let-7 family members. The transcription of Lin28B is promoted by NF-kappaB and by Myc; hence, practical measures which antagonize NF-kappaB or Myc activity may complement the utility of metformin for boosting let-7 expression and controlling cancer stemness; salsalate, antioxidants, tyrosine kinase and cox-2 inhibitors, ribavirin, vitamin D, gamma-secretase inhibitors (when available), and parenteral curcumin may have some utility in this regard. Although the impact of histone deacetylase inhibitors on let-7 expression has not been assessed, there is reason to suspect that these drugs might complement let-7's impact on chemoresistance, EMT, and stemness. Multifocal strategies centering on metformin may have considerable potential for reversing cancer stemness and rendering advanced cancers more susceptible to long term control.
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Affiliation(s)
- Mark F McCarty
- NutriGuard Research, 1051 Hermes Ave., Encinitas, CA 92024, USA.
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29
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Tremblay-Létourneau M, Despins S, Bougie I, Bisaillon M. Virtual high-throughput screening identifies mycophenolic acid as a novel RNA capping inhibitor. PLoS One 2011; 6:e24806. [PMID: 21935470 PMCID: PMC3174198 DOI: 10.1371/journal.pone.0024806] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 08/18/2011] [Indexed: 12/25/2022] Open
Abstract
The RNA guanylyltransferase (GTase) is involved in the synthesis of the m7Gppp-RNA cap structure found at the 5′ end of eukaryotic mRNAs. GTases are members of the covalent nucleotidyl transferase superfamily, which also includes DNA and RNA ligases. GTases catalyze a two-step reaction in which they initially utilize GTP as a substrate to form a covalent enzyme-GMP intermediate. The GMP moiety is then transferred to the diphosphate end of the RNA transcript in the second step of the reaction to form the Gppp-RNA structure. In the current study, we used a combination of virtual database screening, homology modeling, and biochemical assays to search for novel GTase inhibitors. Using this approach, we demonstrate that mycophenolic acid (MPA) can inhibit the GTase reaction by preventing the catalytic transfer of the GMP moiety onto an acceptor RNA. As such, MPA represents a novel type of inhibitor against RNA guanylyltransferases that inhibits the second step of the catalytic reaction. Moreover, we show that the addition of MPA to S. cerevisiae cells leads to a reduction of capped mRNAs. Finally, biochemical assays also demonstrate that MPA can inhibit DNA ligases through inhibition of the second step of the reaction. The biological implications of these findings for the MPA-mediated inhibition of members of the covalent nucleotidyl superfamily are discussed.
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Affiliation(s)
- Maude Tremblay-Létourneau
- RNA Group, Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Simon Despins
- RNA Group, Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Isabelle Bougie
- RNA Group, Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Martin Bisaillon
- RNA Group, Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada
- * E-mail:
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30
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Abstract
A challenge in cancer therapy is to selectively target activities that are essential for survival of malignant cells while sparing normal cells. Translational control represents a potential anti-neoplastic target because it is exerted by major signaling pathways that are often usurped in cancers. Herein we describe approaches being developed that target eukaryotic initiation factor (eIF) 4F, a heterotrimeric complex that integrates multiple signaling inputs to the translation apparatus.
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31
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Abstract
The AKT signalling pathway is a major regulator of protein synthesis that impinges on multiple cellular processes frequently altered in cancer, such as proliferation, cell growth, survival, and angiogenesis. AKT controls protein synthesis by regulating the multistep process of mRNA translation at every stage from ribosome biogenesis to translation initiation and elongation. Recent studies have highlighted the ability of oncogenic AKT to drive cellular transformation by altering gene expression at the translational level. Oncogenic AKT signalling leads to both global changes in protein synthesis as well as specific changes in the translation of select mRNAs. New and developing technologies are significantly advancing our ability to identify and functionally group these translationally controlled mRNAs into gene networks based on their modes of regulation. How oncogenic AKT activates ribosome biogenesis, translation initiation, and translational elongation to regulate these translational networks is an ongoing area of research. Currently, the majority of therapeutics targeting translational control are focused on blocking translation initiation through inhibition of eIF4E hyperactivity. However, it will be important to determine whether combined inhibition of ribosome biogenesis, translation initiation, and translation elongation can demonstrate improved therapeutic efficacy in tumours driven by oncogenic AKT.
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Affiliation(s)
- A C Hsieh
- Department of Urology, School of Medicine, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, Helen Diller Family Cancer Research Building, Room 386, 1450 3rd Street, San Francisco, CA 94158-3110, USA
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32
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33
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Hsieh AC, Ruggero D. Targeting eukaryotic translation initiation factor 4E (eIF4E) in cancer. Clin Cancer Res 2010; 16:4914-20. [PMID: 20702611 DOI: 10.1158/1078-0432.ccr-10-0433] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Recent advances in understanding the role of eukaryotic translation initiator factor 4E (eIF4E) in tumorigenesis and cancer progression have generated significant interest in therapeutic agents that indirectly or directly target aberrant activation of eIF4E in cancer. Here, we address the general function of eIF4E in translation initiation and cancer, present evidence supporting its role in cancer initiation and progression, and highlight emerging therapeutics that efficiently target hyperactivated eIF4E. In doing so, we also highlight the major differences between these therapeutics that may influence their mechanism of action.
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Affiliation(s)
- Andrew C Hsieh
- Department of Urology, Helen Diller Family Comprehensive Cancer Center, School of Medicine, University of California, San Francisco, San Francisco, California, USA
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34
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Abd-El-Aziz AS, Carraher CE, Pittman CU, Zeldin M. Cisplatin Derivatives as Antiviral Agents. INORGANIC AND ORGANOMETALLIC MACROMOLECULES 2008. [PMCID: PMC7121272 DOI: 10.1007/978-0-387-72947-3_8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The use of polymeric derivatives of cisplatin as antiviral drugs is reviewed. Some of these drugs inhibit a wide variety of both RNA and DNA viruses including those responsible for herpes, common colds, chickenpox, and smallpox. The desirability of polymeric drugs is described as is the mode(s) of action of cisplatin itself. A description of viruses and methods of combating viruses is presented. Included is a review of current antiviral agents as well as modes of action of these antiviral agents.
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Affiliation(s)
- Alaa S. Abd-El-Aziz
- The University of British Columbia, Okanagan, 3333 University Way, V1V 1V7 Kelowna, British Columbia Canada
| | - Charles E. Carraher
- Department of Chemistry & Biochemistry, Florida Atlantic University, 777 Glades Rd., 33431 Boca Raton, Florida USA
| | - Charles U. Pittman
- Department of Chemistry, Mississippi State University, 39762 Mississippi State, Mississippi USA
| | - Martel Zeldin
- Department of Chemistry, University of Richmond, 28 Westhampton Way, 23173 Richmond, Virginia USA
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35
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Abstract
The nucleoside analogue ribavirin has antiviral activity against many distinct viruses both in vitro and in vivo. Five distinct mechanisms have been proposed to explain the antiviral properties of ribavirin. These include both indirect mechanisms (inosine monophosphate dehydrogenase inhibition, immunomodulatory effects) and direct mechanisms (interference with RNA capping, polymerase inhibition, lethal mutagenesis). Recent concerns about bioterrorism have renewed interest in exploring the antiviral activity of ribavirin against unique viruses. In this paper, we review the proposed mechanisms of action with emphasis on recent discoveries, as well as the implications of ribavirin resistance. Evidence exists to support each of the five proposed mechanisms of action, and distinct virus/host combinations may preferentially favour one or more of these mechanisms during antiviral therapy. Copyright © 2005 John Wiley & Sons, Ltd.
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Affiliation(s)
- Jason D. Graci
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Craig E. Cameron
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
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Kentsis A, Volpon L, Topisirovic I, Soll CE, Culjkovic B, Shao L, Borden KLB. Further evidence that ribavirin interacts with eIF4E. RNA (NEW YORK, N.Y.) 2005; 11:1762-6. [PMID: 16251386 PMCID: PMC1370864 DOI: 10.1261/rna.2238705] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
This commentary discusses the recent reports in RNA by Yan and colleagues and Westman and colleagues of the apparent failure of ribavirin to bind to recombinant eIF4E and inhibit 7-methyl guanosine cap-dependent exogenous mRNA translation of cell extracts in vitro. Measuring binding by using affinity chromatography of matrix-immobilized proteins and by using protein emission fluorescence spectroscopy in the presence of nucleotide ligands, as well as limitations of using cell extracts for the assessment of mechanisms of mRNA translation are discussed. Possible reasons for the discordant findings of Yan and colleagues and Westman and colleagues are suggested, and direct observation of the specific binding of ribavirin to eIF4E by using mass spectrometry is presented.
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Affiliation(s)
- Alex Kentsis
- Mount Sinai School of Medicine, New York University, New York, NY 10029, USA
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Westman B, Beeren L, Grudzien E, Stepinski J, Worch R, Zuberek J, Jemielity J, Stolarski R, Darzynkiewicz E, Rhoads RE, Preiss T. The antiviral drug ribavirin does not mimic the 7-methylguanosine moiety of the mRNA cap structure in vitro. RNA (NEW YORK, N.Y.) 2005; 11:1505-13. [PMID: 16131589 PMCID: PMC1370834 DOI: 10.1261/rna.2132505] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The eukaryotic initiation factor eIF4E binds the mRNA 5' cap structure and has a central role during translational initiation. eIF4E and the mechanisms to control its activity have oncogenic properties and thus have become targets for anticancer drug development. A recent study (Kentsis et al. 2004) presented evidence that the antiviral nucleoside ribavirin and its phosphorylated derivatives were structural mimics of the mRNA cap, high-affinity ligands for eIF4E, and potent repressors of eIF4E-mediated cell transformation and tumor growth. Based on these findings, we tested ribavirin, ribavirin triphosphate (RTP), and the dinucleotide RpppG for their ability to inhibit translation in vitro. Surprisingly, the ribavirin-based compounds did not affect translation at concentrations where canonical cap analogs efficiently block cap-dependent translation. Using a set of reporter mRNAs that are translated via either cap-dependent or viral internal ribosome entry sites (IRES)-dependent initiation, we found that these ribavirin-containing compounds did inhibit translation at high (millimolar) concentrations, but there was no correlation of this inhibition with an eIF4E requirement for translation. The addition of a ribavirin-containing cap to mRNA did not stimulate translation. Fluorescence titration experiments with eIF4E and the nuclear cap-binding complex CBC indicated affinities for RTP and RpppG that were two to four orders of magnitude lower than those of m(7)GTP and m(7)GpppG. We conclude that, at least with respect to translation, ribavirin does not act in vitro as a functional mimic of the mRNA cap.
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Affiliation(s)
- Belinda Westman
- Molecular Genetics Program, Victor Chang Cardiac Research Institute, Darlinghurst, Sydney, NSW 2010, Australia
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