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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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You KS, Yi YW, Cho J, Park JS, Seong YS. Potentiating Therapeutic Effects of Epidermal Growth Factor Receptor Inhibition in Triple-Negative Breast Cancer. Pharmaceuticals (Basel) 2021; 14:589. [PMID: 34207383 PMCID: PMC8233743 DOI: 10.3390/ph14060589] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 06/07/2021] [Accepted: 06/14/2021] [Indexed: 12/13/2022] Open
Abstract
Triple-negative breast cancer (TNBC) is a subset of breast cancer with aggressive characteristics and few therapeutic options. The lack of an appropriate therapeutic target is a challenging issue in treating TNBC. Although a high level expression of epidermal growth factor receptor (EGFR) has been associated with a poor prognosis among patients with TNBC, targeted anti-EGFR therapies have demonstrated limited efficacy for TNBC treatment in both clinical and preclinical settings. However, with the advantage of a number of clinically approved EGFR inhibitors (EGFRis), combination strategies have been explored as a promising approach to overcome the intrinsic resistance of TNBC to EGFRis. In this review, we analyzed the literature on the combination of EGFRis with other molecularly targeted therapeutics or conventional chemotherapeutics to understand the current knowledge and to provide potential therapeutic options for TNBC treatment.
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Affiliation(s)
- Kyu Sic You
- Department of Biochemistry, College of Medicine, Dankook University, Cheonan 31116, Chungcheongnam-do, Korea;
- Graduate School of Convergence Medical Science, Dankook University, Cheonan 3116, Chungcheongnam-do, Korea
| | - Yong Weon Yi
- Department of Nanobiomedical Science, Dankook University, Cheonan 31116, Chungcheongnam-do, Korea; (Y.W.Y.); (J.C.)
| | - Jeonghee Cho
- Department of Nanobiomedical Science, Dankook University, Cheonan 31116, Chungcheongnam-do, Korea; (Y.W.Y.); (J.C.)
| | - Jeong-Soo Park
- Department of Biochemistry, College of Medicine, Dankook University, Cheonan 31116, Chungcheongnam-do, Korea;
| | - Yeon-Sun Seong
- Department of Biochemistry, College of Medicine, Dankook University, Cheonan 31116, Chungcheongnam-do, Korea;
- Graduate School of Convergence Medical Science, Dankook University, Cheonan 3116, Chungcheongnam-do, Korea
- Department of Nanobiomedical Science, Dankook University, Cheonan 31116, Chungcheongnam-do, Korea; (Y.W.Y.); (J.C.)
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3
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Jacobson BA, Ahmad Z, Chen S, Waldusky G, Dillenburg M, Stoian E, Cambron DA, Patel AJ, Patel MR, Wagner CR, Kratzke RA. 4Ei-10 interdiction of oncogenic cap-mediated translation as therapy for non-small cell lung cancer. Invest New Drugs 2021; 39:636-643. [PMID: 33230623 DOI: 10.1007/s10637-020-01036-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 11/18/2020] [Indexed: 11/28/2022]
Abstract
In order to suppress 5' cap-mediated translation a highly available inhibitor of the interaction between the 5' mRNA cap and the eIF4E complex has been developed. 4Ei-10 is a member of the class of ProTide compounds and has elevated membrane permeability and is a strong active chemical antagonist for eIF4E. Once taken up by cells it is converted by anchimeric activation of the lipophilic 2-(methylthio) ethyl protecting group and after that Hint1 P-N bond cleavage to N7-(p-chlorophenoxyethyl) guanosine 5'-monophosphate (7-Cl-Ph-Ethyl-GMP). Using this powerful interaction, it has been demonstrated that 4Ei-10 inhibits non-small cell lung cancer (NSCLC) cell growth. In addition, treatment of NSCLC cells with 4Ei-10 results in suppression of translation and diminished expression of a cohort of cellular proteins important to maintaining the malignant phenotype and resisting apoptosis such as Bcl-2, survivin, and ornithine decarboxylase (ODC). Finally, as a result of targeting the translation of anti-apoptotic proteins, NSCLC cells are synergized to be more sensitive to the existing anti-neoplastic treatment gemcitabine currently used in NSCLC therapy.
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Affiliation(s)
- Blake A Jacobson
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - Zeeshan Ahmad
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | | | | | - Maxwell Dillenburg
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, USA
| | | | | | - Anil J Patel
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - Manish R Patel
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - Carston R Wagner
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, USA
| | - Robert A Kratzke
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA.
- Division of Heme-Onc-Transplant, University of Minnesota Medical School, MMC 480, 420 Delaware St SE, Minneapolis, MN, 55455, USA.
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4
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Ge L, Zhang Y, Zhao X, Wang J, Zhang Y, Wang Q, Yu H, Zhang Y, You Y. EIF2AK2 selectively regulates the gene transcription in immune response and histones associated with systemic lupus erythematosus. Mol Immunol 2021; 132:132-141. [PMID: 33588244 DOI: 10.1016/j.molimm.2021.01.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 01/21/2021] [Accepted: 01/28/2021] [Indexed: 12/13/2022]
Abstract
PKR, also known as EIF2AK2, is an IFN-stimulated gene (ISG) and shows a higher expression in probands with systemic lupus erythematosus (SLE), which is likely responsible for the impaired translational and proliferative responses to mitogens in T cells from SLE patients. In this study, we overexpressed EIF2AK2 in HeLa cells to study EIF2AK2-regulated genes using RNA-seq technology, followed by bioinformatic analysis of target genes of EIF2AK2-regulated transcriptional factors (TFs). Overexpression of EIF2AK2 promotes HeLa cell apoptosis. EIF2AK2 selectively represses the transcription of histone protein genes associated with SLE, immune response genes and TF genes, which was validated by RT-qPCR experiments. Analysis of motifs overrepresented in the promoter regions of EIF2AK2-regulated genes revealed eighteen EIF2AK2-regulated TFs involved in establishing the EIF2AK2 network. Eight out of these predicted EIF2AK2-regulated TFs were further verified by RT-qPCR selectively in both HeLa and Jurkat cells, and most such as HEY2, TFEC, BATF2, GATA3 and ATF3 and FOXO6 are known to regulate immune response. Our results suggest that the dsRNA-dependent kinase EIF2AK2 selectively regulates the transcription of immune response and SLE-associated histone protein genes, and such a selectivity is likely to be operated by EIF2AK2-targeted TFs. The EIF2AK2-TFs axis potentially offers new therapeutic targets for counteracting immunological disease in the future.
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Affiliation(s)
- Lan Ge
- Department of Dermatology, Southwest Hospital, Third Military Medical University(Army Medical University), Chongqing, 400038, China.
| | - Yuhong Zhang
- Laboratory of Human Health and Genome Regulation, ABLife Inc., Wuhan, Hubei 430075, China; Center for Genome Analysis, ABLife Inc., Wuhan, Hubei 430075, China.
| | - Xingwang Zhao
- Department of Dermatology, Southwest Hospital, Third Military Medical University(Army Medical University), Chongqing, 400038, China.
| | - Juan Wang
- Department of Dermatology, Southwest Hospital, Third Military Medical University(Army Medical University), Chongqing, 400038, China.
| | - Yu Zhang
- Center for Genome Analysis, ABLife Inc., Wuhan, Hubei 430075, China.
| | - Qi Wang
- Center for Genome Analysis, ABLife Inc., Wuhan, Hubei 430075, China.
| | - Han Yu
- Laboratory of Human Health and Genome Regulation, ABLife Inc., Wuhan, Hubei 430075, China.
| | - Yi Zhang
- Laboratory of Human Health and Genome Regulation, ABLife Inc., Wuhan, Hubei 430075, China; Center for Genome Analysis, ABLife Inc., Wuhan, Hubei 430075, China.
| | - Yi You
- Department of Dermatology, Southwest Hospital, Third Military Medical University(Army Medical University), Chongqing, 400038, China.
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Minnee E, Faller WJ. Translation initiation and its relevance in colorectal cancer. FEBS J 2021; 288:6635-6651. [PMID: 33382175 PMCID: PMC9291299 DOI: 10.1111/febs.15690] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 12/22/2020] [Accepted: 12/29/2020] [Indexed: 01/08/2023]
Abstract
Protein synthesis is one of the most essential processes in every kingdom of life, and its dysregulation is a known driving force in cancer development. Multiple signaling pathways converge on the translation initiation machinery, and this plays a crucial role in regulating differential gene expression. In colorectal cancer, dysregulation of initiation results in translational reprogramming, which promotes the selective translation of mRNAs required for many oncogenic processes. The majority of upstream mutations found in colorectal cancer, including alterations in the WNT, MAPK, and PI3K\AKT pathways, have been demonstrated to play a significant role in translational reprogramming. Many translation initiation factors are also known to be dysregulated, resulting in translational reprogramming during tumor initiation and/or maintenance. In this review, we outline the role of translational reprogramming that occurs during colorectal cancer development and progression and highlight some of the most critical factors affecting the etiology of this disease.
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Affiliation(s)
- Emma Minnee
- Division of Oncogenomics, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - William James Faller
- Division of Oncogenomics, Netherlands Cancer Institute, Amsterdam, The Netherlands
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6
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Identification of Cardiac Glycosides as Novel Inhibitors of eIF4A1-Mediated Translation in Triple-Negative Breast Cancer Cells. Cancers (Basel) 2020; 12:cancers12082169. [PMID: 32759815 PMCID: PMC7465665 DOI: 10.3390/cancers12082169] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/23/2020] [Accepted: 08/02/2020] [Indexed: 12/18/2022] Open
Abstract
The eukaryotic translation initiation factor 4F complex (eIF4F) is a potential chemotherapeutic target in triple-negative breast cancer (TNBC). This complex regulates cap-dependent translational initiation and consists of three core proteins: eIF4E, eIF4G, and eIF4A1. In this study, we focus on repositioning compounds as novel inhibitors of eIF4A1-mediated translation. In order to accomplish this goal, a modified synthetic reporter assay was established. More specifically, a (CGG)4 motif, which confers eIF4A dependency, was incorporated into the 5'-leader region of a luciferase-tdTomato lentiviral reporter construct. The Prestwick Chemical Library was then screened in multiple TNBC cell lines by measuring the tdTomato fluorescent intensity. We identified several cardiac glycosides as potential inhibitors of eIF4A1-mediated translation. Based on our studies, we find that cardiac glycosides inhibit the expression of eIF4A1. To identify a potential mechanism by which this was occurring, we utilized the Integrative Library of Integrated Network-Based Cellular Signatures (iLINCS). Our pursuits led us to the discovery that cardiac glycosides also decrease levels of c-MYC. Quantitative PCR confirmed that decreases in c-MYC and eIF4A were occurring at the transcriptional level. As such, disruption of the eIF4A1-c-MYC axis may be a viable approach in the treatment of TNBC. The novel combination of rocaglamide A and digoxin exhibited synergistic anti-cancer activity against TNBC cells in vitro. The findings in this study and others are important for formulating potential combination chemotherapies against eIF4A1 in vivo. Thus, drug repositioning may be one classical approach to successfully target eIF4A1 in TNBC patients.
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Golob-Schwarzl N, Wodlej C, Kleinegger F, Gogg-Kamerer M, Birkl-Toeglhofer AM, Petzold J, Aigelsreiter A, Thalhammer M, Park YN, Haybaeck J. Eukaryotic translation initiation factor 6 overexpression plays a major role in the translational control of gallbladder cancer. J Cancer Res Clin Oncol 2019; 145:2699-2711. [PMID: 31586263 PMCID: PMC6800842 DOI: 10.1007/s00432-019-03030-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 09/16/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND Gallbladder cancer (GBC) is a rare neoplasia of the biliary tract with high mortality rates and poor prognosis. Signs and symptoms of GBC are not specific and often arise at late stage of disease. For this reason, diagnosis is typically made when the cancer is already in advanced stages, and prognosis for survival is less than 5 years in 90% of cases. Biomarkers to monitor disease progression and novel therapeutic alternative targets for these tumors are strongly required. Commonly, dysregulated protein synthesis contributes to carcinogenesis and cancer progression. In this case, protein synthesis directs translation of specific mRNAs, and, in turn, promotes cell survival, invasion, angiogenesis, and metastasis of tumors. In eukaryotes, protein synthesis is regulated at its initiation, which is a rate-limiting step involving eukaryotic translation initiation factors (eIFs). We hypothesize that eIFs represent crossroads in the development of GBC, and might serve as potential biomarkers. The study focus was the role of eIF6 (an anti-association factor for the ribosomal subunits) in GBC. METHODS In human GBC samples, the expression of eIF6 was analyzed biochemically at the protein (immunohistochemistry, immunoblot analyses) and mRNA levels (qRT-PCR). RESULTS High levels of eIF6 correlated with shorter overall survival in biliary tract cancer (BTC) patients (n = 28). Immunohistochemical data from tissue microarrays (n = 114) demonstrated significantly higher expression levels of eIF6 in GBC compared to non-neoplastic tissue. Higher eIF6 expression on protein (immunoblot) and mRNA (qRT-PCR) level was confirmed by analyzing fresh frozen GBC patient samples (n = 14). Depletion of eIF6 (using specific siRNA-mediated knockdown) in Mz-ChA-2 and TFK-1 cell lines inhibited cell proliferation and induced apoptosis. CONCLUSION Our data indicates that eIF6 overexpression plays a major role in the translational control of GBC, and indicates its potential as a new biomarker and therapeutic target in GBC.
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Affiliation(s)
- Nicole Golob-Schwarzl
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Graz, Austria
- Institute of Dermatology and Venerology, Medical University of Graz, Graz, Austria
| | - Christina Wodlej
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Graz, Austria
- Center for Biomarker Research in Medicine, Graz, Austria
| | - Florian Kleinegger
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Graz, Austria
- Department for Biomedical Research, Core Facility Alternative Biomodels and Preclinical Imaging, Medical University of Graz, Graz, Austria
| | - Margit Gogg-Kamerer
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Graz, Austria
| | | | - Johannes Petzold
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Graz, Austria
| | - Ariane Aigelsreiter
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Graz, Austria
| | - Michael Thalhammer
- Department of General Surgery, Medical University of Graz, Graz, Austria
| | - Young Nyun Park
- Department of Pathology, Yonsei University, College of Medicine Soul, Seoul, South Korea
| | - Johannes Haybaeck
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Graz, Austria.
- Center for Biomarker Research in Medicine, Graz, Austria.
- Department of Pathology, Medical Faculty, Otto-von-Guericke-University, Leipziger Straße 44, 39210, Magdeburg, Germany.
- Department of Neuropathology and Molecular Pathology, Medical University of Innsbruck, Innsbruck, Austria.
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8
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Ali EMH, Abdel-Maksoud MS, Oh CH. Thieno[2,3-d]pyrimidine as a promising scaffold in medicinal chemistry: Recent advances. Bioorg Med Chem 2019; 27:1159-1194. [PMID: 30826188 DOI: 10.1016/j.bmc.2019.02.044] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 02/16/2019] [Accepted: 02/20/2019] [Indexed: 12/20/2022]
Abstract
Thienopyrimidine scaffold is a fused heterocyclic ring system that structurally can be considered as adenine, the purine base that is found in both DNA and RNA-bioisosteres. Thienopyrimidines exist in three distinct isomeric forms. The current review discusses thieno[2,3-d]pyrimidine as a one of the opulent heterocycles in drug discovery. Its broad range of medical applications such as anticancer, anti-inflammatory, anti-microbial, and CNS protective agents has inspired us to study its structure-activity relationship (SAR), along with its relevant synthetic strategies. The present review briefly summarizes synthetic approaches for the preparation of thieno[2,3-d]pyrimidine derivatives. In addition, the promising biological activities of this scaffold are also illustrated with explanatory diagrams for their SAR studies.
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Affiliation(s)
- Eslam M H Ali
- Center for Biomaterials, Korea Institute of Science & Technology (KIST), Seoul, Seongbuk-gu 02792, Republic of Korea; Department of Biomolecular Science, University of Science & Technology (UST), Daejeon, Yuseong-gu 34113, Republic of Korea
| | - Mohammed S Abdel-Maksoud
- Medicinal & Pharmaceutical Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Centre (NRC), Dokki, Giza 12622, Egypt
| | - Chang-Hyun Oh
- Center for Biomaterials, Korea Institute of Science & Technology (KIST), Seoul, Seongbuk-gu 02792, Republic of Korea; Department of Biomolecular Science, University of Science & Technology (UST), Daejeon, Yuseong-gu 34113, Republic of Korea.
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9
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Piserà A, Campo A, Campo S. Structure and functions of the translation initiation factor eIF4E and its role in cancer development and treatment. J Genet Genomics 2018; 45:13-24. [DOI: 10.1016/j.jgg.2018.01.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 01/12/2018] [Accepted: 01/15/2018] [Indexed: 12/22/2022]
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10
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Steinberger J, Chu J, Maïga RI, Sleiman K, Pelletier J. Developing anti-neoplastic biotherapeutics against eIF4F. Cell Mol Life Sci 2017; 74:1681-1692. [PMID: 28004147 PMCID: PMC11107644 DOI: 10.1007/s00018-016-2430-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 11/16/2016] [Accepted: 12/01/2016] [Indexed: 02/08/2023]
Abstract
Biotherapeutics have revolutionized modern medicine by providing medicines that would not have been possible with small molecules. With respect to cancer therapies, this represents the current sector of the pharmaceutical industry having the largest therapeutic impact, as exemplified by the development of recombinant antibodies and cell-based therapies. In cancer, one of the most common regulatory alterations is the perturbation of translational control. Among these, changes in eukaryotic initiation factor 4F (eIF4F) are associated with tumor initiation, progression, and drug resistance in a number of settings. This, coupled with the fact that systemic suppression of eIF4F appears well tolerated, indicates that therapeutic agents targeting eIF4F hold much therapeutic potential. Here, we discuss opportunities offered by biologicals for this purpose.
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Affiliation(s)
- Jutta Steinberger
- Department of Biochemistry, McGill University, McIntyre Medical Sciences Building, Rm 810, 3655 Drummond St., Montreal, QC, H3G 1Y6, Canada
| | - Jennifer Chu
- Department of Biochemistry, McGill University, McIntyre Medical Sciences Building, Rm 810, 3655 Drummond St., Montreal, QC, H3G 1Y6, Canada
| | - Rayelle Itoua Maïga
- Department of Biochemistry, McGill University, McIntyre Medical Sciences Building, Rm 810, 3655 Drummond St., Montreal, QC, H3G 1Y6, Canada
| | - Katia Sleiman
- Department of Biochemistry, McGill University, McIntyre Medical Sciences Building, Rm 810, 3655 Drummond St., Montreal, QC, H3G 1Y6, Canada
| | - Jerry Pelletier
- Department of Biochemistry, McGill University, McIntyre Medical Sciences Building, Rm 810, 3655 Drummond St., Montreal, QC, H3G 1Y6, Canada.
- The Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, QC, H3G 1Y6, Canada.
- Department of Oncology, McGill University, Montreal, QC, H3G 1Y6, Canada.
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11
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Attar-Schneider O, Drucker L, Gottfried M. Migration and epithelial-to-mesenchymal transition of lung cancer can be targeted via translation initiation factors eIF4E and eIF4GI. J Transl Med 2016; 96:1004-15. [PMID: 27501049 DOI: 10.1038/labinvest.2016.77] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 05/18/2016] [Accepted: 06/20/2016] [Indexed: 02/06/2023] Open
Abstract
Metastasis underlies cancer morbidity and accounts for disease progression and significant death rates generally and in non-small cell lung cancer (NSCLC) particularly. Therefore, it is critically important to understand the molecular events that regulate metastasis. Accumulating data portray a central role for protein synthesis, particularly translation initiation (TI) factors eIF4E and eIF4G in tumorigenesis and patients' survival. We have published that eIF4E/eIF4GI activities and consequently NSCLC cell migration are modulated by bone-marrow mesenchymal stem cell secretomes, suggesting a role for TI in metastasis. Here, we aimed to expand our understanding of the TI factors significance to NSCLC characteristics, particularly epithelial-to-mesenchymal transition (EMT) and migration, supportive of metastasis. In a model of NSCLC cell lines (H1299, H460), we inhibited eIF4E/eIF4GI's expressions (siRNA, ribavirin) and assessed NSCLC cell lines' migration (scratch), differentiation (EMT, immunoblotting), and expression of select microRNAs (qPCR). Initially, we determined an overexpression of several TI factors (eIF4E, eIF4GI, eIF4B, and DHX29) and their respective targets in NSCLC compared with normal lung samples (70-350%↑, P<0.05). Knockdown (KD) of eIF4E/eIF4GI in NSCLC cell lines (70%↓, P<0.05) also manifested in decreased target levels (ERα, SMAD5, NFkB, CyclinD1, c-MYC, and HIF1α) (20-50%↓, P<0.05). eIF4E/eIF4GI KD also attenuated cell migration (60-75%↓, P<0.05), EMT promoters (15-90%↓, P<0.05), and enhanced EMT suppressors (30-380%↑, P<0.05). The importance of eIF4E KD to NSCLC phenotype was further corroborated with its inhibitor, ribavirin. Changes in expression of essential microRNAs implicated in NSCLC cell migration concluded the study (20-100%, P<0.05). In summary, targeting eIF4E/eIF4GI reduces migration and EMT, both essential for metastasis, thereby underscoring the potential of TI targeting in NSCLC therapy, especially the already clinically employed agents (ribavirin/4EGI). Comparison of these findings with previously reported effects of eIF4E/eIF4GI KD in multiple myeloma suggests a collective role for these TI factors in cancer progression.
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Affiliation(s)
- Oshrat Attar-Schneider
- Lung Cancer Research Laboratory, Lung Cancer Unit, Meir Medical Center, Kfar Saba, Israel.,Oncogenetic Laboratory, Meir Medical Center, Kfar Saba, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Liat Drucker
- Oncogenetic Laboratory, Meir Medical Center, Kfar Saba, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Maya Gottfried
- Lung Cancer Research Laboratory, Lung Cancer Unit, Meir Medical Center, Kfar Saba, Israel.,Oncology Department, Lung Cancer Unit, Meir Medical Center, Kfar Saba, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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12
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Wang J, Ma L, Tang X, Zhang X, Qiao Y, Shi Y, Xu Y, Wang Z, Yu Y, Sun F. Doxorubicin induces apoptosis by targeting Madcam1 and AKT and inhibiting protein translation initiation in hepatocellular carcinoma cells. Oncotarget 2016; 6:24075-91. [PMID: 26124182 PMCID: PMC4695171 DOI: 10.18632/oncotarget.4373] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 05/30/2015] [Indexed: 12/27/2022] Open
Abstract
Doxorubicin (Doxo) is one of the most widely used chemotherapeutic drugs for patients with hepatocellular carcinoma (HCC). Doxo is a DNA intercalating drug that inhibits topoisomerase II. Thereby Doxo has the ability to block DNA replication and induce apoptosis. However, the other targets and mechanisms through which Doxo induces apoptosis to treat HCC still remain unknown. Here, we identified Mucosal vascular addressin cell adhesion molecule 1 (Madcam1) as a potential Doxo target because Madcam1 overexpression suppressed, while Madcam1 depletion stimulated Doxo-induced apoptosis. Furthermore, we first revealed that Doxo can induce apoptosis by blocking protein translation initiation. In contrast, Madcam1 activated protein translation through an opposite mechanism. We also found de-phosphorylation of AKT may be an important pro-apoptotic event that is triggered by Doxo-induced Madcam1 down-regulation. Finally, we revealed that Madcam1 promoted increased AKT phosphorylation, which is essential for maintaining the sensitivity of HCC cells to Doxo treatment. Taken together, we uncovered a potential mechanism for Doxo-induced apoptosis in HCC treatment through targeting Madcam1 and AKT and blocking protein translation initiation.
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Affiliation(s)
- Jiayi Wang
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital of Tongji University, Shanghai, China.,Translation Medicine of High Institute, Tongji University, Shanghai, China
| | - Lifang Ma
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital of Tongji University, Shanghai, China
| | - Xun Tang
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital of Tongji University, Shanghai, China
| | - Xiao Zhang
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital of Tongji University, Shanghai, China
| | - Yongxia Qiao
- School of Public Health, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Yuling Shi
- Department of Dermatology, Shanghai Tenth People's Hospital of Tongji University, Shanghai, China
| | - Yanfeng Xu
- Department of Pharmacy, Shanghai Municipal Hospital of Traditional Chinese Medicine affiliated to Shanghai TCM University, Shanghai, China
| | - Zhongyong Wang
- Medical Examination Centre, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, China
| | - Yongchun Yu
- Shanghai Municipal Hospital of Traditional Chinese Medicine affiliated to Shanghai TCM University, Shanghai, China
| | - Fenyong Sun
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital of Tongji University, Shanghai, China
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13
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Aspen Cancer Conference Fellows. Toxicol Pathol 2016. [DOI: 10.1080/01926230490882358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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14
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Dabbah M, Attar-Schneider O, Zismanov V, Tartakover Matalon S, Lishner M, Drucker L. Multiple myeloma cells promote migration of bone marrow mesenchymal stem cells by altering their translation initiation. J Leukoc Biol 2016; 100:761-770. [DOI: 10.1189/jlb.3a1115-510rr] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 04/26/2016] [Indexed: 12/26/2022] Open
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15
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Csizmok V, Follis AV, Kriwacki RW, Forman-Kay JD. Dynamic Protein Interaction Networks and New Structural Paradigms in Signaling. Chem Rev 2016; 116:6424-62. [PMID: 26922996 DOI: 10.1021/acs.chemrev.5b00548] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Understanding signaling and other complex biological processes requires elucidating the critical roles of intrinsically disordered proteins (IDPs) and regions (IDRs), which represent ∼30% of the proteome and enable unique regulatory mechanisms. In this review, we describe the structural heterogeneity of disordered proteins that underpins these mechanisms and the latest progress in obtaining structural descriptions of conformational ensembles of disordered proteins that are needed for linking structure and dynamics to function. We describe the diverse interactions of IDPs that can have unusual characteristics such as "ultrasensitivity" and "regulated folding and unfolding". We also summarize the mounting data showing that large-scale assembly and protein phase separation occurs within a variety of signaling complexes and cellular structures. In addition, we discuss efforts to therapeutically target disordered proteins with small molecules. Overall, we interpret the remodeling of disordered state ensembles due to binding and post-translational modifications within an expanded framework for allostery that provides significant insights into how disordered proteins transmit biological information.
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Affiliation(s)
- Veronika Csizmok
- Molecular Structure & Function, The Hospital for Sick Children , Toronto, ON M5G 0A4, Canada
| | - Ariele Viacava Follis
- Department of Structural Biology, St. Jude Children's Research Hospital , Memphis, Tennessee 38105, United States
| | - Richard W Kriwacki
- Department of Structural Biology, St. Jude Children's Research Hospital , Memphis, Tennessee 38105, United States.,Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Sciences Center , Memphis, Tennessee 38163, United States
| | - Julie D Forman-Kay
- Molecular Structure & Function, The Hospital for Sick Children , Toronto, ON M5G 0A4, Canada.,Department of Biochemistry, University of Toronto , Toronto, ON M5S 1A8, Canada
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16
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eIF4E and eIF4GI have distinct and differential imprints on multiple myeloma's proteome and signaling. Oncotarget 2015; 6:4315-29. [PMID: 25717031 PMCID: PMC4414192 DOI: 10.18632/oncotarget.3008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 12/21/2014] [Indexed: 12/20/2022] Open
Abstract
Accumulating data indicate translation plays a role in cancer biology, particularly its rate limiting stage of initiation. Despite this evolving recognition, the function and importance of specific translation initiation factors is unresolved. The eukaryotic translation initiation complex eIF4F consists of eIF4E and eIF4G at a 1:1 ratio. Although it is expected that they display interdependent functions, several publications suggest independent mechanisms. This study is the first to directly assess the relative contribution of eIF4F components to the expressed cellular proteome, transcription factors, microRNAs, and phenotype in a malignancy known for extensive protein synthesis-multiple myeloma (MM). Previously, we have shown that eIF4E/eIF4GI attenuation (siRNA/Avastin) deleteriously affected MM cells' fate and reduced levels of eIF4E/eIF4GI established targets. Here, we demonstrated that eIF4E/eIF4GI indeed have individual influences on cell proteome. We used an objective, high throughput assay of mRNA microarrays to examine the significance of eIF4E/eIF4GI silencing to several cellular facets such as transcription factors, microRNAs and phenotype. We showed different imprints for eIF4E and eIF4GI in all assayed aspects. These results promote our understanding of the relative contribution and importance of eIF4E and eIF4GI to the malignant phenotype and shed light on their function in eIF4F translation initiation complex.
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17
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Lee HE, Nam JS, Shin JA, Hong IS, Yang IH, You MJ, Cho SD. Convallaria keiskei as a novel therapeutic alternative for salivary gland cancer treatment by targeting myeloid cell leukemia-1. Head Neck 2015; 38 Suppl 1:E761-70. [PMID: 25914292 DOI: 10.1002/hed.24096] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/16/2015] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Various chemotherapeutic agents have been used largely for the treatment of salivary gland cancer. However, results are disappointing, and these agents can cause some serious side effects. Therefore, recent studies have focused on the possible roles of natural products to overcome these limitations. METHODS Salivary gland cancer cells treated with or without Convallaria keiskei (MECK) for 24 hours. Apoptotic changes were evaluated by live/dead assay, immunoblotting, and expression levels of caspase-3 and B-cell lymphoma-2 family member. RESULTS MECK significantly inhibited salivary gland cancer growth. At the molecular level, MECK dramatically reduced myeloid cell leukemia-1 (Mcl-1) in a translation-dependent manner and thereby induced apoptosis through Bax/Bid. Furthermore, we found that Mcl-1 could be a potential therapeutic target of MECK-induced apoptosis and its stability is regulated by extracellular signal-regulated kinases 1/2 (ERK1/2) signaling CONCLUSION MECK can be used as a safe and efficient therapeutic alternative for the treatment of salivary gland cancer. © 2015 Wiley Periodicals, Inc. Head Neck 38: E761-E770, 2016.
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Affiliation(s)
- Haeng-Eun Lee
- Department of Oral Pathology, School of Dentistry and Institute of Biodegradable Material, Institute of Oral Bioscience, Brain Korea 21 Project, Chonbuk National University, Jeonju, Republic of Korea
| | - Jeong-Seok Nam
- Laboratory of Tumor Suppressor, Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, South Korea.,Department of Molecular Medicine, School of Medicine, Gachon University, Incheon, South Korea
| | - Ji-Ae Shin
- Department of Oral Pathology, School of Dentistry and Institute of Biodegradable Material, Institute of Oral Bioscience, Brain Korea 21 Project, Chonbuk National University, Jeonju, Republic of Korea
| | - In-Sun Hong
- Laboratory of Tumor Suppressor, Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, South Korea.,Department of Molecular Medicine, School of Medicine, Gachon University, Incheon, South Korea
| | - In-Hyoung Yang
- Department of Oral Pathology, School of Dentistry and Institute of Biodegradable Material, Institute of Oral Bioscience, Brain Korea 21 Project, Chonbuk National University, Jeonju, Republic of Korea
| | - Myung-Jo You
- Laboratory of Veterinary Parasitology, College of Veterinary Medicine and Bio-Safety Research Centre, Chonbuk National University, Jeonju, Republic of Korea
| | - Sung-Dae Cho
- Department of Oral Pathology, School of Dentistry and Institute of Biodegradable Material, Institute of Oral Bioscience, Brain Korea 21 Project, Chonbuk National University, Jeonju, Republic of Korea
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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: 265] [Impact Index Per Article: 29.4] [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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eIF4E is an adverse prognostic marker of melanoma patient survival by increasing melanoma cell invasion. J Invest Dermatol 2015; 135:1358-1367. [PMID: 25562667 DOI: 10.1038/jid.2014.552] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 12/01/2014] [Accepted: 12/11/2014] [Indexed: 12/26/2022]
Abstract
Human cutaneous melanoma is a devastating skin cancer because of its invasive nature and high metastatic potential. We used tissue microarray to study the role of human eukaryotic translation initiation factor 4E (eIF4E) in melanoma progression in 448 melanocytic lesions and found that high eIF4E expression was significantly increased in primary melanomas compared with dysplastic nevi (P<0.001), and further increased in metastatic melanomas (P<0.001). High eIF4E expression was associated with melanoma thickness (P=0.046), and poor overall and disease-specific 5-year survival of all, and primary melanoma patients, especially those with tumors ≥1 mm thick. Multivariate Cox regression analysis revealed that eIF4E is an independent prognostic marker. eIF4E knockdown (KD) in melanoma cells resulted in a significant increase in apoptosis (sub-G1 populations) and decrease in cell proliferation, and also resulted in downregulation of mesenchymal markers and upregulation of E-cadherin. In addition, eIF4E KD led to a decrease in melanoma cell invasion, matrix metalloproteinase-2 expression and activity, c-myc and BCL2 expression, and an increase in cleaved PARP and cleaved caspase-3 expression and chemosensitivity. Taken together, our data suggest that the eIF4E may promote melanoma cell invasion and metastasis, and may also serve as a promising prognostic marker and a potential therapeutic target for melanoma.
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21
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Avdulov S, Herrera J, Smith K, Peterson M, Gomez-Garcia JR, Beadnell TC, Schwertfeger KL, Benyumov AO, Manivel JC, Li S, Bielinsky AK, Yee D, Bitterman PB, Polunovsky VA. eIF4E threshold levels differ in governing normal and neoplastic expansion of mammary stem and luminal progenitor cells. Cancer Res 2014; 75:687-97. [PMID: 25524901 DOI: 10.1158/0008-5472.can-14-2571] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Translation initiation factor eIF4E mediates normal cell proliferation, yet induces tumorigenesis when overexpressed. The mechanisms by which eIF4E directs such distinct biologic outputs remain unknown. We found that mouse mammary morphogenesis during pregnancy and lactation is accompanied by increased cap-binding capability of eIF4E and activation of the eIF4E-dependent translational apparatus, but only subtle oscillations in eIF4E abundance. Using a transgenic mouse model engineered so that lactogenic hormones stimulate a sustained increase in eIF4E abundance in stem/progenitor cells of lactogenic mammary epithelium during successive pregnancy/lactation cycles, eIF4E overexpression increased self-renewal, triggered DNA replication stress, and induced formation of premalignant and malignant lesions. Using complementary in vivo and ex vivo approaches, we found that increasing eIF4E levels rescued cells harboring oncogenic c-Myc or H-RasV12 from DNA replication stress and oncogene-induced replication catastrophe. Our findings indicate that distinct threshold levels of eIF4E govern its biologic output in lactating mammary glands and that eIF4E overexpression in the context of stem/progenitor cell population expansion can initiate malignant transformation by enabling cells to evade DNA damage checkpoints activated by oncogenic stimuli. Maintaining eIF4E levels below its proneoplastic threshold is an important anticancer defense in normal cells, with important implications for understanding pregnancy-associated breast cancer.
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Affiliation(s)
- Svetlana Avdulov
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Jeremy Herrera
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Karen Smith
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Mark Peterson
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | | | - Thomas C Beadnell
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota
| | - Kathryn L Schwertfeger
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota. Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Alexey O Benyumov
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - J Carlos Manivel
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota
| | - Shunan Li
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Anja-Katrin Bielinsky
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota. Departament of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - Douglas Yee
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota. Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Peter B Bitterman
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota. Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota.
| | - Vitaly A Polunovsky
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota. Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota.
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22
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Bitterman PB, Polunovsky VA. eIF4E-mediated translational control of cancer incidence. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:774-80. [PMID: 25263391 DOI: 10.1016/j.bbagrm.2014.09.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Revised: 09/03/2014] [Accepted: 09/10/2014] [Indexed: 11/16/2022]
Abstract
Mitogen activated translation initiation factor eIF4E mediates normal cell proliferation, yet induces tumorigenesis when deregulated and overexpressed. It remains unknown, how activated eIF4E directs such distinct biological outputs. Our experimental data provide evidence that distinct threshold levels of eIF4E govern its biological output in lactating mammary glands and that eIF4E overexpression in the context of cell population expansion can initiate malignant transformation by enabling cells to evade DNA damage checkpoints caused by hyperproliferative oncogenic stimuli. These findings point at the cellular level of eIF4E as an important sensor for normal or pro-neoplastic propagation of cells. Here, we describe a model that links the pro-neoplastic function of eIF4F to its ability to disable oncogene-activated tumor surveillance programs; and propose a novel therapeutic strategy for cancer prevention based upon targeting aberrant eIF4E with safe doses of small-molecule antagonists to ensure the maintenance of eIF4E levels below the pro-neoplastic threshold. This article is part of a Special Issue entitled: Translation and Cancer.
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Affiliation(s)
- Peter B Bitterman
- Department of Medicine, University of Minnesota, 420 Delaware Street S.E., MMC 276, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, 420 Delaware Street S.E., MMC 276, Minneapolis, MN 55455, USA.
| | - Vitaly A Polunovsky
- Department of Medicine, University of Minnesota, 420 Delaware Street S.E., MMC 276, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, 420 Delaware Street S.E., MMC 276, Minneapolis, MN 55455, USA.
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23
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Pettersson F, del Rincon SV, Miller WH. Eukaryotic translation initiation factor 4E as a novel therapeutic target in hematological malignancies and beyond. Expert Opin Ther Targets 2014; 18:1035-48. [DOI: 10.1517/14728222.2014.937426] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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24
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Jacobson BA, Thumma SC, Jay-Dixon J, Patel MR, Dubear Kroening K, Kratzke MG, Etchison RG, Konicek BW, Graff JR, Kratzke RA. Targeting eukaryotic translation in mesothelioma cells with an eIF4E-specific antisense oligonucleotide. PLoS One 2013; 8:e81669. [PMID: 24260583 PMCID: PMC3832430 DOI: 10.1371/journal.pone.0081669] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 10/17/2013] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Aberrant cap-dependent translation is implicated in tumorigenesis in multiple tumor types including mesothelioma. In this study, disabling the eIF4F complex by targeting eIF4E with eIF4E-specific antisense oligonucleotide (4EASO) is assessed as a therapy for mesothelioma. METHODS Mesothelioma cells were transfected with 4EASO, designed to target eIF4E mRNA, or mismatch-ASO control. Cell survival was measured in mesothelioma treated with 4EASO alone or combined with either gemcitabine or pemetrexed. Levels of eIF4E, ODC, Bcl-2 and β-actin were assessed following treatment. Binding to a synthetic cap-analogue was used to study the strength of eIF4F complex activation following treatment. RESULTS eIF4E level and the formation of eIF4F cap-complex decreased in response to 4EASO, but not mismatch control ASO, resulting in cleavage of PARP indicating apoptosis. 4EASO treatment resulted in dose dependent decrease in eIF4E levels, which corresponded to cytotoxicity of mesothelioma cells. 4EASO resulted in decreased levels of eIF4E in non-malignant LP9 cells, but this did not correspond to increased cytotoxicity. Proteins thought to be regulated by cap-dependent translation, Bcl-2 and ODC, were decreased upon treatment with 4EASO. Combination therapy of 4EASO with pemetrexed or gemcitabine further reduced cell number. CONCLUSION 4EASO is a novel drug that causes apoptosis and selectively reduces eIF4E levels, eIF4F complex formation, and proliferation of mesothelioma cells. eIF4E knockdown results in decreased expression of anti-apoptotic and pro-growth proteins and enhances chemosensitivity.
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Affiliation(s)
- Blake A. Jacobson
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Saritha C. Thumma
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Joseph Jay-Dixon
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Manish R. Patel
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - K. Dubear Kroening
- Department of Biological Sciences, University of Wisconsin-Fox Valley, Menasha, Wisconsin, United States of America
| | - Marian G. Kratzke
- Research Service, Minneapolis Veterans Affairs Medical Center, Minneapolis, Minnesota, United States of America
| | - Ryan G. Etchison
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Bruce W. Konicek
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Jeremy R. Graff
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Robert A. Kratzke
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota, United States of America
- * E-mail:
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25
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Carroll M, Borden KLB. The oncogene eIF4E: using biochemical insights to target cancer. J Interferon Cytokine Res 2013; 33:227-38. [PMID: 23472659 DOI: 10.1089/jir.2012.0142] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The eukaryotic translation initiation factor eIF4E is overexpressed in many human malignancies where it is typically a harbinger of poor prognosis. eIF4E is positioned as a nexus in post-transcriptional gene expression. To carry out these functions, eIF4E needs to bind the m(7)G cap moiety on mRNAs. It plays critical roles in mRNA translation, mRNA export, and most likely in mRNA stability as well. Through these activities, eIF4E coordinately modulates the expression of many transcripts involved in proliferation and survival. eIF4E function is controlled by interactions with protein cofactors in concert with many signaling pathways, including Ras, Mnk, Erk, MAPK, PI3K, mTOR, and Akt. This review describes the eIF4E activity and provides several examples of cellular control mechanisms. Further, we describe some therapeutic strategies in preclinical and clinical development.
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Affiliation(s)
- Martin Carroll
- Division of Hematology and Oncology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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26
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Hariri F, Arguello M, Volpon L, Culjkovic-Kraljacic B, Nielsen TH, Hiscott J, Mann KK, Borden KLB. The eukaryotic translation initiation factor eIF4E is a direct transcriptional target of NF-κB and is aberrantly regulated in acute myeloid leukemia. Leukemia 2013; 27:2047-55. [PMID: 23467026 DOI: 10.1038/leu.2013.73] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 02/22/2013] [Accepted: 02/26/2013] [Indexed: 12/11/2022]
Abstract
The eukaryotic translation initiation factor eIF4E is a potent oncogene elevated in many cancers, including the M4 and M5 subtypes of acute myeloid leukemia (AML). Although eIF4E RNA levels are elevated 3- to 10-fold in M4/M5 AML, the molecular underpinnings of this dysregulation were unknown. Here, we demonstrate that EIF4E is a direct transcriptional target of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) that is dysregulated preferentially in M4 and M5 AML. In primary hematopoietic cells and in cell lines, eIF4E levels are induced by NF-κB activating stimuli. Pharmacological or genetic inhibition of NF-κB represses this activation. The endogenous human EIF4E promoter recruits p65 and cRel to evolutionarily conserved κB sites in vitro and in vivo following NF-κB activation. Transcriptional activation is demonstrated by recruitment of p300 to the κB sites and phosphorylated Pol II to the coding region. In primary AML specimens, generally we observe that substantially more NF-κB complexes associate with eIF4E promoter elements in M4 and M5 AML specimens examined than in other subtypes or unstimulated normal primary hematopoietic cells. Consistently, genetic inhibition of NF-κB abrogates eIF4E RNA levels in this same population. These findings provide novel insights into the transcriptional control of eIF4E and a novel molecular basis for its dysregulation in at least a subset of M4/M5 AML specimens.
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Affiliation(s)
- F Hariri
- Department of Pathology and Cell Biology, Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montreal, Quebec, Canada
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27
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Cap-dependent mRNA translation and the ubiquitin-proteasome system cooperate to promote ERBB2-dependent esophageal cancer phenotype. Cancer Gene Ther 2012; 19:609-18. [PMID: 22767218 DOI: 10.1038/cgt.2012.39] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Pathological post-transcriptional control of the proteome composition is a central feature of malignancy. Two steps in this pathway, eIF4F-driven cap-dependent mRNA translation and the ubiquitin-proteasome system (UPS), are deregulated in most if not all cancers. We tested a hypothesis that eIF4F is aberrantly activated in human esophageal adenocarcinoma (EAC) and requires elevated rates of protein turnover and proteolysis and thereby activated UPS for its pro-neoplastic function. Here, we show that 80% of tumors and cell lines featuring amplified ERBB2 display an aberrantly activated eIF4F. Direct genetic targeting of the eIF4F in ERBB2-amplified EAC cells with a constitutively active form of the eIF4F repressor 4E-BP1 decreased colony formation and proliferation and triggered apoptosis. In contrast, suppression of m-TOR-kinase activity towards 4E-BP1with rapamycin only modestly inhibited eIF4F-driven cap-dependent translation and EAC malignant phenotype; and promoted feedback activation of other cancer pathways. Our data show that co-treatment with 2 FDA-approved agents, the m-TOR inhibitor rapamycin and the proteasome inhibitor bortezomib, leads to strong synergistic growth-inhibitory effects. Moreover, direct targeting of eIF4F with constitutively active 4E-BP1 is significantly more potent in collaboration with bortezomib than rapamycin. These data support the hypothesis that a finely tuned balance between eIF4F-driven protein synthesis and proteasome-mediated protein degradation is required for the maintenance of ERBB2-mediated EAC malignant phenotype. Altogether, our study supports the development of pharmaceuticals to directly target eIF4F as most efficient strategy; and provides a clear rationale for the clinical evaluation of combination therapy with m-TOR inhibitors and bortezomib for EAC treatment.
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28
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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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29
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Bitterman PB, Polunovsky VA. Translational control of cell fate: from integration of environmental signals to breaching anticancer defense. Cell Cycle 2012; 11:1097-107. [PMID: 22356766 DOI: 10.4161/cc.11.6.19610] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Despite their genetic diversity, different cancers manifest common features at the protein pathway level. They share a core group of perturbed pathways that converge upon a few regulatory hubs linking the cellular signaling network with the basic metabolic machinery. Available evidence indicates that one such hub is the eIF4F-mediated cap-dependent mRNA translation initiation apparatus, whose integrity is required for physiological control of growth, proliferation and viability. However, when hyperactivated by upstream oncogenic signaling, eIF4F selectively stimulates the translation of a group of mRNAs required for cancer genesis and progression. Here, we describe a model that links the pro-neoplastic function of eIF4F to its ability to disable oncogene-activated tumor surveillance programs and propose a novel therapeutic strategy for cancer based upon targeting aberrant eIF4F with small-molecule antagonists.
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Affiliation(s)
- Peter B Bitterman
- Department of Medicine and Masonic Cancer Center, University of Minnesota; Minneapolis, MN, USA
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30
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Seki N, Takasu T, Sawada S, Nakata M, Nishimura R, Segawa Y, Shibakuki R, Hanafusa T, Eguchi K. Prognostic significance of expression of eukaryotic initiation factor 4E and 4E binding protein 1 in patients with pathological stage I invasive lung adenocarcinoma. Lung Cancer 2011; 70:329-34. [PMID: 20621385 DOI: 10.1016/j.lungcan.2010.03.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2009] [Revised: 01/13/2010] [Accepted: 03/11/2010] [Indexed: 01/21/2023]
Abstract
BACKGROUND Both eukaryotic initiation factor 4E (eIF4E) and eIF4E binding protein 1 (4E-BP1) are involved in the malignant progression of human cancers. However, the role of eIF4E and 4E-BP1 expression as prognostic markers has not been evaluated concurrently in any human cancers. METHODS The expression of eIF4E and 4E-BP1 was semiquantitatively examined with immunohistochemical staining in 80 patients with pathological stage I invasive lung adenocarcinoma. RESULTS The 10-year survival rate was significantly lower for patients with high eIF4E expression (64.0% [n=36]) than for patients with low eIF4E expression (89.9% [n=44], P=0.024), and in patients with high eIF4E expression the 10-year survival rate was lower for patients with low 4E-BP1 expression (39.0% [n=12]) than for patients with high 4E-BP1 expression (85.2% [n=24], P=0.036). In patients with low eIF4E expression, the 10-year survival rate was lower for patients with low 4E-BP1 expression (87.6% [n=36]) than for patients with high 4E-BP1 expression (100% [n=8]), but statistical analysis was impossible because all patients with high 4E-BP1 expression were censored. Unfavorable prognostic factors for survival were age greater than 65 years (P=0.015), pathological stage IB disease (P=0.045), high eIF4E expression (P=0.008), and low 4E-BP1 expression (P=0.007). CONCLUSIONS Both eIF4E and 4E-BP1 are potential new prognostic factors for survival and stratification in patients with pathological stage I lung adenocarcinoma. The eIF4E and 4E-BP1 status may provide a basis for individualized therapy.
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Affiliation(s)
- Nobuhiko Seki
- Division of Medical Oncology, Department of Internal Medicine, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan.
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Borden KLB, Culjkovic-Kraljacic B. Ribavirin as an anti-cancer therapy: acute myeloid leukemia and beyond? Leuk Lymphoma 2011; 51:1805-15. [PMID: 20629523 DOI: 10.3109/10428194.2010.496506] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Ribavirin was discovered nearly 40 years ago as a broad-spectrum antiviral drug. Recent data suggest that ribavirin may also be an effective cancer therapy. In this case, ribavirin targets an oncogene, the eukaryotic translation initiation factor eIF4E, elevated in approximately 30% of cancers including many leukemias and lymphomas. Specifically, ribavirin impedes eIF4E mediated oncogenic transformation by acting as an inhibitor of eIF4E. In a phase II clinical trial, ribavirin treatment led to substantial clinical benefit in patients with poor-prognosis acute myeloid leukemia (AML). Here molecular targeting of eIF4E correlated with clinical response. Ribavirin also targets a key enzyme in the guanosine biosynthetic pathway, inosine monophosphate dehydrogenase (IMPDH), and also modulates immunity. Parallels with known antiviral mechanisms could be informative; however, after 40 years, these are not entirely clear. The antiviral effects of ribavirin appear cell-type specific. This variation likely arises for many reasons, including cell specific variations in ribavirin metabolism as well as virus specific factors. Thus, it seems that the mechanisms for ribavirin action in cancer therapy may also vary in terms of the cancer/tissue under study. Here we review the anticancer activities of ribavirin and discuss the possible utility of incorporating ribavirin into diverse cancer therapeutic regimens.
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Affiliation(s)
- Katherine L B Borden
- Institute of Research in Immunology and Cancer (IRIC), Department of Pathology and Cell Biology, Université de Montréal, Montreal, QC, Canada.
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Topisirovic I, Svitkin YV, Sonenberg N, Shatkin AJ. Cap and cap-binding proteins in the control of gene expression. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 2:277-98. [PMID: 21957010 DOI: 10.1002/wrna.52] [Citation(s) in RCA: 280] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The 5' mRNA cap structure is essential for efficient gene expression from yeast to human. It plays a critical role in all aspects of the life cycle of an mRNA molecule. Capping occurs co-transcriptionally on the nascent pre-mRNA as it emerges from the RNA exit channel of RNA polymerase II. The cap structure protects mRNAs from degradation by exonucleases and promotes transcription, polyadenylation, splicing, and nuclear export of mRNA and U-rich, capped snRNAs. In addition, the cap structure is required for the optimal translation of the vast majority of cellular mRNAs, and it also plays a prominent role in the expression of eukaryotic, viral, and parasite mRNAs. Cap-binding proteins specifically bind to the cap structure and mediate its functions in the cell. Two major cellular cap-binding proteins have been described to date: eukaryotic translation initiation factor 4E (eIF4E) in the cytoplasm and nuclear cap binding complex (nCBC), a nuclear complex consisting of a cap-binding subunit cap-binding protein 20 (CBP 20) and an auxiliary protein cap-binding protein 80 (CBP 80). nCBC plays an important role in various aspects of nuclear mRNA metabolism such as pre-mRNA splicing and nuclear export, whereas eIF4E acts primarily as a facilitator of mRNA translation. In this review, we highlight recent findings on the role of the cap structure and cap-binding proteins in the regulation of gene expression. We also describe emerging regulatory pathways that control mRNA capping and cap-binding proteins in the cell.
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Affiliation(s)
- Ivan Topisirovic
- Department of Biochemistry and Goodman Cancer Centre, McGill University, Montréal, QC, Canada
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Samad N, Younes A. Temsirolimus in the treatment of relapsed or refractory mantle cell lymphoma. Onco Targets Ther 2010; 3:167-78. [PMID: 20856791 PMCID: PMC2939769 DOI: 10.2147/ott.s8147] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2010] [Indexed: 01/08/2023] Open
Abstract
Mantle cell lymphoma (MCL) is a rare and aggressive subtype of lymphoma associated with a poor prognosis. Chemotherapy is the mainstay of frontline treatment for patients with this disease. Despite high response rates to combination chemotherapy regimens, the majority of patients relapse within a few years of treatment. Therefore, finding efficacious treatments for relapsed or refractory disease has become a growing area of clinical research. The mammalian target of rapamycin (mTOR) is responsible for integrating cell signals from growth factors, hormones, and nutrients and communicating energy status. Scientific research on aberrant molecular pathways in cancer has revealed that several proteins along the mTOR pathway may be upregulated in this and other types of lymphoma. Temsirolimus is the first mTOR inhibitor that has shown clinical efficacy in treating MCL that has relapsed after frontline treatments.
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Oyarzabal J, Zarich N, Albarran MI, Palacios I, Urbano-Cuadrado M, Mateos G, Reymundo I, Rabal O, Salgado A, Corrionero A, Fominaya J, Pastor J, Bischoff JR. Discovery of Mitogen-Activated Protein Kinase-Interacting Kinase 1 Inhibitors by a Comprehensive Fragment-Oriented Virtual Screening Approach. J Med Chem 2010; 53:6618-28. [DOI: 10.1021/jm1005513] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Julen Oyarzabal
- Experimental Therapeutics Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernandez Almagro 3, 28029 Madrid, Spain
| | - Natasha Zarich
- Experimental Therapeutics Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernandez Almagro 3, 28029 Madrid, Spain
| | - María Isabel Albarran
- Experimental Therapeutics Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernandez Almagro 3, 28029 Madrid, Spain
| | - Irene Palacios
- Experimental Therapeutics Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernandez Almagro 3, 28029 Madrid, Spain
| | - Manuel Urbano-Cuadrado
- Experimental Therapeutics Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernandez Almagro 3, 28029 Madrid, Spain
| | - Genoveva Mateos
- Experimental Therapeutics Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernandez Almagro 3, 28029 Madrid, Spain
| | - Isabel Reymundo
- Experimental Therapeutics Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernandez Almagro 3, 28029 Madrid, Spain
| | - Obdulia Rabal
- Experimental Therapeutics Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernandez Almagro 3, 28029 Madrid, Spain
| | - Antonio Salgado
- Experimental Therapeutics Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernandez Almagro 3, 28029 Madrid, Spain
| | - Ana Corrionero
- Experimental Therapeutics Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernandez Almagro 3, 28029 Madrid, Spain
| | - Jesús Fominaya
- Experimental Therapeutics Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernandez Almagro 3, 28029 Madrid, Spain
| | - Joaquin Pastor
- Experimental Therapeutics Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernandez Almagro 3, 28029 Madrid, Spain
| | - James R. Bischoff
- Experimental Therapeutics Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernandez Almagro 3, 28029 Madrid, Spain
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Xu X, Vatsyayan J, Gao C, Bakkenist CJ, Hu J. Sumoylation of eIF4E activates mRNA translation. EMBO Rep 2010; 11:299-304. [PMID: 20224576 PMCID: PMC2854592 DOI: 10.1038/embor.2010.18] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Revised: 01/22/2010] [Accepted: 01/25/2010] [Indexed: 01/08/2023] Open
Abstract
Eukaryotic translation initiation factor 4E (eIF4E) is the cap-binding protein that binds the 5' cap structure of cellular messenger RNAs (mRNAs). Despite the obligatory role of eIF4E in cap-dependent mRNA translation, how the translation activity of eIF4E is controlled remains largely undefined. Here, we report that mammalian eIF4E is regulated by SUMO1 (small ubiquitin-related modifier 1) conjugation. eIF4E sumoylation promotes the formation of the active eIF4F translation initiation complex and induces the translation of a subset of proteins that are essential for cell proliferation and preventing apoptosis. Furthermore, disruption of eIF4E sumoylation inhibits eIF4E-dependent protein translation and abrogates the oncogenic and antiapoptotic functions associated with eIF4E. These data indicate that sumoylation is a new fundamental regulatory mechanism of protein synthesis. Our findings suggest further that eIF4E sumoylation might be important in promoting human cancers.
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Affiliation(s)
- Xiang Xu
- Department of Pharmacology and Chemical Biology, University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, 5117 Centre Avenue, Suite 2.42D, Pittsburgh, Pennsylvania 15213, USA
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Robert F, Pelletier J. Translation initiation: a critical signalling node in cancer. Expert Opin Ther Targets 2009; 13:1279-93. [PMID: 19705976 DOI: 10.1517/14728220903241625] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Mammalian target of rapamycin (mTOR) is a master regulator of translation initiation that controls the recruitment of ribosomes to mRNA templates in response to intracellular and extracellular cues. Evidence suggests that mTOR and its direct downstream targets, S6K and eIF4E/4E-BP, play significant roles in oncogenesis, and that inhibiting this pathway holds promise as an anti-proliferative approach. Recent genome-wide analyses of mutations in human cancers indicate that transformed cells activate a handful of processes and signalling pathways that are major contributors to their phenotype. Here we review the current literature implicating mTOR and translation initiation downstream of many of these various signalling pathways and processes usurped in human cancers. This review highlights the widespread activation of mTOR/eIF4E following acquisition of oncogenic lesions and its implication in promoting the transformation phenotype and indicates that targeting the control of translation initiation makes logical sense as a broad-acting therapeutic approach.
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Affiliation(s)
- Francis Robert
- Department of Biochemistry and Goodman cancer centre, McGill University, McIntyre Medical Sciences Building, Room 810, 3655 Promenade Sir William Osler, Montreal, Quebec, H3G 1Y6, Canada
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Understanding and Targeting the Eukaryotic Translation Initiation Factor eIF4E in Head and Neck Cancer. JOURNAL OF ONCOLOGY 2009; 2009:981679. [PMID: 20049173 PMCID: PMC2798714 DOI: 10.1155/2009/981679] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2009] [Accepted: 09/30/2009] [Indexed: 01/08/2023]
Abstract
The eukaryotic translation initiation factor eIF4E is elevated in about 30% of human malignancies including HNSCC where its levels correlate with poor prognosis. Here, we discuss the biochemical and molecular underpinnings of the oncogenic potential of eIF4E. Studies in human leukemia specimens, and later in a mouse model of prostate cancer, strongly suggest that cells with elevated eIF4E develop an oncogene dependency to it, making them more sensitive to targeting eIF4E than normal cells. We describe several strategies that have been suggested for eIF4E targeting in the clinic: the use of a small molecule antagonist of eIF4E (ribavirin), siRNA or antisense oligonucleotide strategies, suicide gene therapy, and the use of a tissue-targeting 4EBP fusion peptide. The first clinical trial targeting eIF4E indicates that ribavirin effectively targets eIF4E in poor prognosis leukemia patients and more importantly leads to striking clinical responses including complete and partial remissions. Finally, we discuss the relevance of these findings to HNSCC.
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Abstract
Translational control is an important but relatively unappreciated mechanism that regulates levels of protein products. In addition to a global translational control that regulates the cell's response to external stimuli such as growth factors, cytokines, stress, and viral infections, selective translational control has recently been demonstrated to affect many genes related to growth and apoptotic processes. Translational infidelity has recently been suggested as a new mechanism of T cell dysregulation in SLE. This review discusses current data on translational control of T cell biology and the central aspect of translational control in the signalling pathway leading to T cell proliferation, apoptotic response, and cytokine production. The utility for global analysis by genomics to study translational control of T cell gene expression is also discussed.
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Affiliation(s)
- Laura Beretta
- Department of Microbiology and Immunology, University of Michigan, Medical School, Ann Arbor, 48109-0620, USA.
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39
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Chen X, Wang Y, Li J, Jiang A, Cheng Y, Zhang W. Mitochondrial proteome during salt stress-induced programmed cell death in rice. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2009; 47:407-15. [PMID: 19217306 DOI: 10.1016/j.plaphy.2008.12.021] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Revised: 12/29/2008] [Accepted: 12/31/2008] [Indexed: 05/19/2023]
Abstract
It has been shown that mitochondria play a pivotal role in plant programmed cell death (PCD). Previous study established a salt stress-induced PCD model in rice (Oryza sativa L. cv. WYJ 8th) root tip cells, demonstrated by DNA laddering, cytochrome c release, and TUNEL positive reaction. In this study, the role of mitochondria during the early phase of PCD (2h-PCD) was analyzed in rice roots. After 2h-PCD induction, the integrity of mitochondria decreased slightly, consistent with a small release of cytochrome c. 2h-PCD partially inhibited electron transport, resulting in oxidative burst in mitochondria. However, ATP production maintained constant. Mitochondria proteome were analyzed by two-dimensional IEF/SDS-PAGE before and after 2h-PCD induction, and eight PCD-related proteins were identified. Among them, four proteins were up-regulated after PCD induction, which included glycoside hydrolase, mitochondrial heat shock protein 70, 20S proteasome subunit, and Cu/Zn-superoxide dismutase, and four were down-regulated, namely ATP synthase beta subunit, cytochrome c oxidase subunit 6b, S-adenosylmethionine synthetase 2, and transcription initiation factor eIF-3 epsilon. These results suggested that ATP synthase may not be the major producer of ATP in mitochondria during the early stage of PCD in rice. Glycoside hydrolase may be involved in ETC impairment and ROS burst, and mitochondrial HSP70 is a potential candidate for PCD regulation. The possible roles of other proteins on PCD initiation were also discussed.
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Affiliation(s)
- Xi Chen
- Department of Biochemistry and Molecular Biology, Nanjing Agricultural University, Weigang, China
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40
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Cencic R, Carrier M, Galicia-Vázquez G, Bordeleau ME, Sukarieh R, Bourdeau A, Brem B, Teodoro JG, Greger H, Tremblay ML, Porco JA, Pelletier J. Antitumor activity and mechanism of action of the cyclopenta[b]benzofuran, silvestrol. PLoS One 2009; 4:e5223. [PMID: 19401772 PMCID: PMC2671147 DOI: 10.1371/journal.pone.0005223] [Citation(s) in RCA: 232] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2009] [Accepted: 03/19/2009] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Flavaglines are a family of natural products from the genus Aglaia that exhibit anti-cancer activity in vitro and in vivo and inhibit translation initiation. They have been shown to modulate the activity of eIF4A, the DEAD-box RNA helicase subunit of the eukaryotic initiation factor (eIF) 4F complex, a complex that stimulates ribosome recruitment during translation initiation. One flavagline, silvestrol, is capable of modulating chemosensitivity in a mechanism-based mouse model. METHODOLOGY/PRINCIPAL FINDINGS Among a number of flavagline family members tested herein, we find that silvestrol is the more potent translation inhibitor among these. We find that silvestrol impairs the ribosome recruitment step of translation initiation by affecting the composition of the eukaryotic initiation factor (eIF) 4F complex. We show that silvestrol exhibits significant anticancer activity in human breast and prostate cancer xenograft models, and that this is associated with increased apoptosis, decreased proliferation, and inhibition of angiogenesis. We demonstrate that targeting translation by silvestrol results in preferential inhibition of weakly initiating mRNAs. CONCLUSIONS/SIGNIFICANCE Our results indicate that silvestrol is a potent anti-cancer compound in vivo that exerts its activity by affecting survival pathways as well as angiogenesis. We propose that silvestrol mediates its effects by preferentially inhibiting translation of malignancy-related mRNAs. Silvestrol appears to be well tolerated in animals.
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MESH Headings
- Animals
- Antineoplastic Agents, Phytogenic/chemistry
- Antineoplastic Agents, Phytogenic/pharmacology
- Base Sequence
- Breast Neoplasms/drug therapy
- Breast Neoplasms/genetics
- Breast Neoplasms/pathology
- Cell Line, Tumor
- Cells, Cultured
- Eukaryotic Initiation Factor-4E/metabolism
- Female
- Humans
- Male
- Mice
- Mice, Nude
- Neoplasm Transplantation
- Neovascularization, Pathologic/prevention & control
- Prostatic Neoplasms/drug therapy
- Prostatic Neoplasms/genetics
- Prostatic Neoplasms/pathology
- Protein Biosynthesis/drug effects
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Neoplasm/genetics
- RNA, Neoplasm/metabolism
- Transplantation, Heterologous
- Triterpenes/chemistry
- Triterpenes/pharmacology
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Affiliation(s)
- Regina Cencic
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Marilyn Carrier
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | | | | | - Rami Sukarieh
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Annie Bourdeau
- Sunnybrook Health Sciences Centre and the Department of Immunology, University of Toronto, Toronto, Ontario, Canada
| | - Brigitte Brem
- Comparative Phytochemistry Department, Institute of Botany, University of Vienna, Vienna, Austria
| | - Jose G. Teodoro
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
- Goodman Cancer Center, McGill University, Montreal, Quebec, Canada
| | - Harald Greger
- Comparative Phytochemistry Department, Institute of Botany, University of Vienna, Vienna, Austria
| | - Michel L. Tremblay
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
- Goodman Cancer Center, McGill University, Montreal, Quebec, Canada
| | - John A. Porco
- Department of Chemistry, Center for Chemical Methodology and Library Development, Boston University, Boston, Massachusetts, United States of America
| | - Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
- Goodman Cancer Center, McGill University, Montreal, Quebec, Canada
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Graff JR, Konicek BW, Lynch RL, Dumstorf CA, Dowless MS, McNulty AM, Parsons SH, Brail LH, Colligan BM, Koop JW, Hurst BM, Deddens JA, Neubauer BL, Stancato LF, Carter HW, Douglass LE, Carter JH. eIF4E activation is commonly elevated in advanced human prostate cancers and significantly related to reduced patient survival. Cancer Res 2009; 69:3866-73. [PMID: 19383915 DOI: 10.1158/0008-5472.can-08-3472] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Elevated eukaryotic translation initiation factor 4E (eIF4E) function induces malignancy in experimental models by selectively enhancing translation of key malignancy-related mRNAs (c-myc and BCL-2). eIF4E activation may reflect increased eIF4E expression or phosphorylation of its inhibitory binding proteins (4E-BP). By immunohistochemical analyses of 148 tissues from 89 prostate cancer patients, we now show that both eIF4E expression and 4E-BP1 phosphorylation (p4E-BP1) are increased significantly, particularly in advanced prostate cancer versus benign prostatic hyperplasia tissues. Further, increased eIF4E and p4E-BP1 levels are significantly related to reduced patient survival, whereas uniform 4E-BP1 expression is significantly related to better patient survival. Both immunohistochemistry and Western blotting reveal that elevated eIF4E and p4E-BP1 are evident in the same prostate cancer tissues. In two distinct prostate cancer cell models, the progression to androgen independence also involves increased eIF4E activation. In these prostate cancer cells, reducing eIF4E expression with an eIF4E-specific antisense oligonucleotide currently in phase I clinical trials robustly induces apoptosis, regardless of cell cycle phase, and reduces expression of the eIF4E-regulated proteins BCL-2 and c-myc. Collectively, these data implicate eIF4E activation in prostate cancer and suggest that targeting eIF4E may be attractive for prostate cancer therapy.
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Affiliation(s)
- Jeremy R Graff
- Lilly Research Labs, Eli Lilly and Company, Indianapolis, Indiana 46285, USA.
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42
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Gao X, Xing D. Molecular mechanisms of cell proliferation induced by low power laser irradiation. J Biomed Sci 2009; 16:4. [PMID: 19272168 PMCID: PMC2644974 DOI: 10.1186/1423-0127-16-4] [Citation(s) in RCA: 301] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Accepted: 01/12/2009] [Indexed: 02/07/2023] Open
Abstract
Low power laser irradiation (LPLI) promotes proliferation of multiple cells, which (especially red and near infrared light) is mainly through the activation of mitochondrial respiratory chain and the initiation of cellular signaling. Recently, the signaling proteins involved in LPLI-induced proliferation merit special attention, some of which are regulated by mitochondrial signaling. Hepatocyte growth factor receptor (c-Met), a member of tyrosine protein kinase receptors (TPKR), is phosphorylated during LPLI-induced proliferation, but tumor necrosis factor alpha (TNF-alpha) receptor has not been affected. Activated TPKR could activate its downstream signaling elements, like Ras/Raf/MEK/ERK, PI3K/Akt/eIF4E, PI3K/Akt/eNOS and PLC-gamma/PKC pathways. Other two pathways, DeltaPsim/ATP/cAMP/JNK/AP-1 and ROS/Src, are also involved in LPLI-induced proliferation. LPLI-induced cell cycle progression can be regulated by the activation or elevated expressions of cell cycle-specific proteins. Furthermore, LPLI induces the synthesis or release of many molecules, like growth factors, interleukins, inflammatory cytokines and others, which are related to promotive effects of LPLI.
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Affiliation(s)
- Xuejuan Gao
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, South China Normal University, Guangzhou 510631, PR China
| | - Da Xing
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, South China Normal University, Guangzhou 510631, PR China
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43
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Bordeleau ME, Robert F, Gerard B, Lindqvist L, Chen SMH, Wendel HG, Brem B, Greger H, Lowe SW, Porco JA, Pelletier J. Therapeutic suppression of translation initiation modulates chemosensitivity in a mouse lymphoma model. J Clin Invest 2008; 118:2651-60. [PMID: 18551192 DOI: 10.1172/jci34753] [Citation(s) in RCA: 189] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Accepted: 05/07/2008] [Indexed: 01/20/2023] Open
Abstract
Disablement of cell death programs in cancer cells contributes to drug resistance and in some cases has been associated with altered translational control. As eukaryotic translation initiation factor 4E (eIF4E) cooperates with c-Myc during lymphomagenesis, induces drug resistance, and is a genetic modifier of the rapamycin response, we have investigated the effect of dysregulation of the ribosome recruitment phase of translation initiation on tumor progression and chemosensitivity. eIF4E is a subunit of eIF4F, a complex that stimulates ribosome recruitment during translation initiation by delivering the DEAD-box RNA helicase eIF4A to the 5' end of mRNAs. eIF4A is thought to prepare a ribosome landing pad on mRNA templates for incoming 40S ribosomes (and associated factors). Using small molecule screening, we found that cyclopenta[b]benzofuran flavaglines, a class of natural products, modulate eIF4A activity and inhibit translation initiation. One member of this class of compounds, silvestrol, was able to enhance chemosensitivity in a mouse lymphoma model in which carcinogenesis is driven by phosphatase and tensin homolog (PTEN) inactivation or elevated eIF4E levels. These results establish that targeting translation initiation can restore drug sensitivity in vivo and provide an approach to modulating chemosensitivity.
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44
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Tan K, Culjkovic B, Amri A, Borden KLB. Ribavirin targets eIF4E dependent Akt survival signaling. Biochem Biophys Res Commun 2008; 375:341-5. [PMID: 18706892 DOI: 10.1016/j.bbrc.2008.07.163] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Accepted: 07/30/2008] [Indexed: 10/21/2022]
Abstract
The eukaryotic translation initiation factor eIF4E is dysregulated in many cancers. eIF4E, through its mRNA export and translation functions, combinatorially modulates the expression of genes involved in Akt dependent survival signaling. For these activities, eIF4E must bind the 7-methyl guanosine (m(7)G) cap moiety on the 5'-end of mRNAs. We demonstrate that a physical mimic of the m(7)G cap, ribavirin, inhibits eIF4E dependent Akt survival signaling. Specifically, ribavirin impairs eIF4E mediated Akt activation via inhibiting the production of an upstream activator of Akt, NBS1. Consequently, ribavirin impairs eIF4E dependent apoptotic rescue. A ribavirin analog with distinct physico-chemical properties, tiazofurin, does not impair eIF4E activity indicating that only analogs that mimic the m(7)G cap will inhibit eIF4E function. Ribavirin represents a first-in-class strategy to inhibit eIF4E dependent cancers, through competition for m(7)G cap binding. Thus, ribavirin coordinately impairs eIF4E dependent pathways and thereby, potently inhibits its biological effects.
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Affiliation(s)
- Keith Tan
- Institute for Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Montréal, Que., Canada H4M 1J6
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Popowski M, Ferguson HA, Sion AM, Koller E, Knudsen E, Van Den Berg CL. Stress and IGF-I differentially control cell fate through mammalian target of rapamycin (mTOR) and retinoblastoma protein (pRB). J Biol Chem 2008; 283:28265-73. [PMID: 18697743 DOI: 10.1074/jbc.m805724200] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Significant discoveries have recently contributed to our knowledge of intracellular growth factor and nutrient signaling via mTOR (mammalian target of rapamycin). This signaling pathway is essential in cellular metabolism and cell survival by enhancing protein translation through phosphorylation of 4EBP-1 and p70S6K. Growth factors like insulin-like growth factor-I induce mTOR to prevent cell death during cellular stress. Agents targeting mTOR are of major interest as anticancer agents. We show here, using human breast cancer cells, that certain types of stress activate mTOR leading to 4E-BP1 and p70S6K phosphorylation. UV treatment increased phosphorylation of the translation inhibitor eIF2alpha, suggesting a potential mechanism for UV activation of Akt and mTOR. c-Myc, a survival protein regulated by cap-dependent protein translation, increased with IGF-I treatment, but this response was not inhibited by rapamycin. Additionally, UV treatment potently increased c-Myc degradation, which was reduced by co-treatment with the proteasomal inhibitor, MG-132. Together, these data suggest that protein translation does not strongly mediate cell survival in these models. In contrast, the phosphorylation status of retinoblastoma protein (pRB) was mediated by mTOR through its inhibitory effects on phosphatase activity. This effect was most notable during DNA damage and rapamycin treatment. Hypophosphorylated pRB was susceptible to inactivation by caspase-mediated cleavage, resulting in cell death. Reduction of pRB expression inhibited IGF-I survival effects. Our data support an important role of phosphatases and pRB in IGF-I/mTOR-mediated cell survival. These studies provide new directions in optimizing anticancer efficacy of mTOR inhibitors when used in combination with DNA-damaging agents.
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Affiliation(s)
- Melissa Popowski
- College of Pharmacy, University of Texas, Austin, Texas 78712-0125, USA
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Lin CJ, Cencic R, Mills JR, Robert F, Pelletier J. c-Myc and eIF4F are components of a feedforward loop that links transcription and translation. Cancer Res 2008; 68:5326-34. [PMID: 18593934 DOI: 10.1158/0008-5472.can-07-5876] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The Myc/Max/Mad family of transcription factors and the eukaryotic initiation factor 4F (eIF4F) complex play fundamental roles in regulating cell growth, proliferation, differentiation, and oncogenic transformation. eIF4F is involved in the recruitment of ribosomes to mRNAs and is thought to generally be the rate-limiting phase of translation. Here, we show that c-Myc directly activates transcription of the three subunits of eIF4F (eIF4E, eIF4AI, and eIF4GI). These transcriptional effects are mediated through canonical E-boxes (5'CACGTG3') present in the promoters of these genes. In addition, the c-Myc antagonist Mad1 down-regulates the expression of eIF4F subunits. We also show that MycER activation stimulates protein synthesis at the level of translation initiation. Increased eIF4F levels result in stimulation of c-Myc mRNA translation specifically, as assessed by quantitative reverse transcription-PCR. We use a murine model of lymphomagenesis to show the expression of eIF4F subunits is also up-regulated by c-Myc in vivo. Our results suggest the presence of a feedforward loop involving c-Myc and eIF4F that serves to link transcription and translation and that could contribute to the effects of c-Myc on cell proliferation and neoplastic growth.
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Affiliation(s)
- Chen-Ju Lin
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
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Borden KLB. Pondering the puzzle of PML (promyelocytic leukemia) nuclear bodies: can we fit the pieces together using an RNA regulon? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:2145-54. [PMID: 18616965 DOI: 10.1016/j.bbamcr.2008.06.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 06/03/2008] [Accepted: 06/10/2008] [Indexed: 12/26/2022]
Abstract
The promyelocytic leukemia protein PML and its associated nuclear bodies are hot topics of investigation. This interest arises for multiple reasons including the tight link between the integrity of PML nuclear bodies and several disease states and the impact of the PML protein and PML nuclear bodies on proliferation, apoptosis and viral infection. Unfortunately, an understanding of the molecular underpinnings of PML nuclear body function remains elusive. Here, a general overview of the PML field is provided and is extended to discuss whether some of the basic tenets of "PML-ology" are still valid. For instance, recent findings suggest that some components of PML nuclear bodies form bodies in the absence of the PML protein. Also, a new model for PML nuclear body function is proposed which provides a unifying framework for its effects on diverse biochemical pathways such as Akt signaling and the p53-Mdm2 axis. In this model, the PML protein acts as an inhibitor of gene expression post-transcriptionally via inhibiting a network node in the eIF4E RNA regulon. An example is given for how the PML RNA regulon model provided the basis for the development of a new anti-cancer strategy being tested in the clinic.
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Affiliation(s)
- Katherine L B Borden
- Institute for Research in Immunology and Cancer and Department of Pathology and Cell Biology, Université de Montréal, Montréal, Québec, Canada H4M 1J6.
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Culjkovic B, Tan K, Orolicki S, Amri A, Meloche S, Borden KLB. The eIF4E RNA regulon promotes the Akt signaling pathway. ACTA ACUST UNITED AC 2008; 181:51-63. [PMID: 18391071 PMCID: PMC2287285 DOI: 10.1083/jcb.200707018] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Eukaryotic initiation factor 4E (eIF4E) promotes cellular proliferation and can rescue cells from apoptotic stimuli such as serum starvation. However, the mechanisms underlying apoptotic rescue are not well understood. In this study, we demonstrate that eIF4E overexpression leads to enhanced survival signaling through Akt and that eIF4E requires Akt1 to rescue serum-deprived fibroblasts. Furthermore, a mutant form of eIF4E (W73A), which is messenger RNA (mRNA) export competent but does not promote translation, rescues cells as readily as wild-type eIF4E. We show that eIF4E mediates Akt activation via up-regulation of Nijmegen breakage syndrome 1 (NBS1), a phosphoinositide-3 kinase–Akt pathway upstream activator. Additionally, eIF4E coordinately up-regulates the expression of downstream effectors of the Akt pathway, thereby amplifying Akt signaling effects. A negative regulator of eIF4E, the promyelocytic leukemia protein (PML), suppresses Akt activation and apoptotic rescue. These PML activities likely arise, at least in part, through its inhibition of eIF4E-mediated NBS1 mRNA export. In summary, eIF4E coordinately regulates gene expression to potentiate Akt activation, an activity required for apoptotic rescue.
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Affiliation(s)
- Biljana Culjkovic
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Québec H4M 1J6, Canada
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Rosenwald IB, Koifman L, Savas L, Chen JJ, Woda BA, Kadin ME. Expression of the translation initiation factors eIF-4E and eIF-2* is frequently increased in neoplastic cells of Hodgkin lymphoma. Hum Pathol 2008; 39:910-6. [PMID: 18234281 DOI: 10.1016/j.humpath.2007.10.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2007] [Revised: 10/05/2007] [Accepted: 10/25/2007] [Indexed: 02/02/2023]
Abstract
The rate of protein synthesis is regulated in part by 2 key translation initiation factors, eIF-4E and eIF-2*. The expression and activity of both factors are increased transiently when normal resting cells are stimulated to proliferate, but they are constitutively elevated in oncogene-transformed cultured cells. Overexpression of either initiation factor induces a tumorigenic phenotype in rodent cells. We have shown earlier that expression of both eIF-4E and eIF-2* is increased in non-Hodgkin lymphomas (non-HLs). In this study, we performed an immunohistochemical survey of these translation initiation factors in neoplastic cells of HL. We also used Western blot to addressed the possibility that eIF-4E increases expression of NFkappaB. Our results indicate that both eIF-4E and eIF-2* are strongly expressed in neoplastic cells of HL in most cases examined as compared with weak or undetectable expression in most surrounding lymphocytes. An increase in eIF-4E expression may lead to constitutively high expression of NFkappaB, a transcription factor implicated in resistance to apoptosis and induction of cytokine gene expression in various cells, including neoplastic cells of HL.
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Affiliation(s)
- Igor B Rosenwald
- Department of Pathology, New England Medical Center, Boston, MA 02111, USA.
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Davies JE, Sarkar S, Rubinsztein DC. Wild-type PABPN1 is anti-apoptotic and reduces toxicity of the oculopharyngeal muscular dystrophy mutation. Hum Mol Genet 2008; 17:1097-108. [DOI: 10.1093/hmg/ddm382] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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