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Lécuyer E, Sauvageau M, Kothe U, Unrau PJ, Damha MJ, Perreault J, Abou Elela S, Bayfield MA, Claycomb JM, Scott MS. Canada's contributions to RNA research: past, present, and future perspectives. Biochem Cell Biol 2024. [PMID: 39320985 DOI: 10.1139/bcb-2024-0176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2024] Open
Abstract
The field of RNA research has provided profound insights into the basic mechanisms modulating the function and adaption of biological systems. RNA has also been at the center stage in the development of transformative biotechnological and medical applications, perhaps most notably was the advent of mRNA vaccines that were critical in helping humanity through the Covid-19 pandemic. Unbeknownst to many, Canada boasts a diverse community of RNA scientists, spanning multiple disciplines and locations, whose cutting-edge research has established a rich track record of contributions across various aspects of RNA science over many decades. Through this position paper, we seek to highlight key contributions made by Canadian investigators to the RNA field, via both thematic and historical viewpoints. We also discuss initiatives underway to organize and enhance the impact of the Canadian RNA research community, particularly focusing on the creation of the not-for-profit organization RNA Canada ARN. Considering the strategic importance of RNA research in biology and medicine, and its considerable potential to help address major challenges facing humanity, sustained support of this sector will be critical to help Canadian scientists play key roles in the ongoing RNA revolution and the many benefits this could bring about to Canada.
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Affiliation(s)
- Eric Lécuyer
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada
- Département de Biochimie et de Médecine Moléculaire, Université de Montréal, Montréal, QC, Canada
- Division of Experimental Medicine, McGill University, Montréal, QC, Canada
| | - Martin Sauvageau
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada
- Département de Biochimie et de Médecine Moléculaire, Université de Montréal, Montréal, QC, Canada
- Department of Biochemistry, McGill University, Montréal, QC, Canada
| | - Ute Kothe
- Department of Chemistry, University of Manitoba, Winnipeg, MB, Canada
| | - Peter J Unrau
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Masad J Damha
- Department of Chemistry, McGill University, Montréal, QC, Canada
| | - Jonathan Perreault
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Laval, QC, Canada
| | - Sherif Abou Elela
- Département de Microbiologie et Infectiologie, Université de Sherbrooke, Sherbrooke, QC, Canada
| | | | - Julie M Claycomb
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Michelle S Scott
- Département de Biochimie et de Génomique Fonctionnelle, Université de Sherbrooke, Sherbrooke, QC, Canada
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Kochavi A, Lovecchio D, Faller WJ, Agami R. Proteome diversification by mRNA translation in cancer. Mol Cell 2023; 83:469-480. [PMID: 36521491 DOI: 10.1016/j.molcel.2022.11.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 11/14/2022] [Accepted: 11/16/2022] [Indexed: 12/15/2022]
Abstract
mRNA translation is a highly conserved and tightly controlled mechanism for protein synthesis and is well known to be altered by oncogenes to promote cancer development. This distorted mRNA translation is accompanied by the vulnerability of cancer to inhibitors of key mRNA translation components. Novel studies also suggest that these alternations could be utilized for immunotherapy. Ribosome heterogeneity and alternative responses to nutrient shortages, which aid cancer growth and spread, are proposed to elicit aberrant protein production but may also result in previously unidentified therapeutic targets, such as the presentation of cancer-specific peptides at the surface of cancer cells (neoepitopes). This review will assess the driving forces in tRNA and ribosome function that underlie proteome diversification due to alterations in mRNA translation in cancer cells.
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Affiliation(s)
- Adva Kochavi
- Division of Oncogenomics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066CX Amsterdam, the Netherlands; Oncode Institute, the Netherlands
| | - Domenica Lovecchio
- Division of Oncogenomics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066CX Amsterdam, the Netherlands; Oncode Institute, the Netherlands
| | - William James Faller
- Division of Oncogenomics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066CX Amsterdam, the Netherlands
| | - Reuven Agami
- Division of Oncogenomics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066CX Amsterdam, the Netherlands; Oncode Institute, the Netherlands; Erasmus MC, Rotterdam University, Rotterdam, the Netherlands.
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3
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Smyth S, Zhang Z, Bah A, Tsangaris TE, Dawson J, Forman-Kay JD, Gradinaru CC. Multisite phosphorylation and binding alter conformational dynamics of the 4E-BP2 protein. Biophys J 2022; 121:3049-3060. [PMID: 35841142 PMCID: PMC9463650 DOI: 10.1016/j.bpj.2022.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 05/19/2022] [Accepted: 07/11/2022] [Indexed: 11/02/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) play critical roles in regulatory protein interactions, but detailed structural/dynamic characterization of their ensembles remain challenging, both in isolation and when they form dynamic "fuzzy" complexes. Such is the case for mRNA cap-dependent translation initiation, which is regulated by the interaction of the predominantly folded eukaryotic initiation factor 4E (eIF4E) with the intrinsically disordered eIF4E binding proteins (4E-BPs) in a phosphorylation-dependent manner. Single-molecule Förster resonance energy transfer showed that the conformational changes of 4E-BP2 induced by binding to eIF4E are non-uniform along the sequence; while a central region containing both motifs that bind to eIF4E expands and becomes stiffer, the C-terminal region is less affected. Fluorescence anisotropy decay revealed a non-uniform segmental flexibility around six different labeling sites along the chain. Dynamic quenching of these fluorescent probes by intrinsic aromatic residues measured via fluorescence correlation spectroscopy report on transient intra- and inter-molecular contacts on nanosecond-to-microsecond timescales. Upon hyperphosphorylation, which induces folding of ∼40 residues in 4E-BP2, the quenching rates decreased at most labeling sites. The chain dynamics around sites in the C-terminal region far away from the two binding motifs significantly increased upon binding to eIF4E, suggesting that this region is also involved in the highly dynamic 4E-BP2:eIF4E complex. Our time-resolved fluorescence data paint a sequence-level rigidity map of three states of 4E-BP2 differing in phosphorylation or binding status and distinguish regions that form contacts with eIF4E. This study adds complementary structural and dynamics information to recent studies of 4E-BP2, and it constitutes an important step toward a mechanistic understanding of this important IDP via integrative modeling.
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Affiliation(s)
- Spencer Smyth
- Department of Physics, University of Toronto, Toronto, Ontario, Canada; Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Zhenfu Zhang
- Department of Physics, University of Toronto, Toronto, Ontario, Canada; Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Alaji Bah
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Thomas E Tsangaris
- Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Jennifer Dawson
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Julie D Forman-Kay
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Claudiu C Gradinaru
- Department of Physics, University of Toronto, Toronto, Ontario, Canada; Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada.
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4
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Hsu YH, Wang PH, Chang CM. Functional Gene Clusters in Global Pathogenesis of Clear Cell Carcinoma of the Ovary Discovered by Integrated Analysis of Transcriptomes. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17113951. [PMID: 32498447 PMCID: PMC7312065 DOI: 10.3390/ijerph17113951] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/23/2020] [Accepted: 05/31/2020] [Indexed: 12/17/2022]
Abstract
Clear cell carcinoma of the ovary (ovarian clear cell carcinoma (OCCC)) is one epithelial ovarian carcinoma that is known to have a poor prognosis and a tendency for being refractory to treatment due to unclear pathogenesis. Published investigations of OCCC have mainly focused only on individual genes and lack of systematic integrated research to analyze the pathogenesis of OCCC in a genome-wide perspective. Thus, we conducted an integrated analysis using transcriptome datasets from a public domain database to determine genes that may be implicated in the pathogenesis involved in OCCC carcinogenesis. We used the data obtained from the National Center for Biotechnology Information (NCBI) Gene Expression Omnibus (GEO) DataSets. We found six interactive functional gene clusters in the pathogenesis network of OCCC, including ribosomal protein, eukaryotic translation initiation factors, lactate, prostaglandin, proteasome, and insulin-like growth factor. This finding from our integrated analysis affords us a global understanding of the interactive network of OCCC pathogenesis.
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Affiliation(s)
- Yueh-Han Hsu
- Department of Obstetrics and Gynecology, Taipei Veterans General Hospital, Taipei 112, Taiwan; (Y.-H.H.); (P.-H.W.)
- School of Medicine, National Yang-Ming University, Taipei 112, Taiwan
| | - Peng-Hui Wang
- Department of Obstetrics and Gynecology, Taipei Veterans General Hospital, Taipei 112, Taiwan; (Y.-H.H.); (P.-H.W.)
- School of Medicine, National Yang-Ming University, Taipei 112, Taiwan
- Institute of Clinical Medicine, National Yang-Ming University, Taipei 112, Taiwan
- Department of Medical Research, China Medical University Hospital, Taichung 440, Taiwan
- Female Cancer Foundation, Taipei 104, Taiwan
| | - Chia-Ming Chang
- Department of Obstetrics and Gynecology, Taipei Veterans General Hospital, Taipei 112, Taiwan; (Y.-H.H.); (P.-H.W.)
- School of Medicine, National Yang-Ming University, Taipei 112, Taiwan
- Correspondence: ; Tel.: +886-2-2875-7826; Fax: +886-2-5570-2788
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5
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Etemadmoghadam D, Azar WJ, Lei Y, Moujaber T, Garsed DW, Kennedy CJ, Fereday S, Mitchell C, Chiew YE, Hendley J, Sharma R, Harnett PR, Li J, Christie EL, Patch AM, George J, Au-Yeung G, Mir Arnau G, Holloway TP, Semple T, Pearson JV, Waddell N, Grimmond SM, Köbel M, Rizos H, Lomakin IB, Bowtell DDL, deFazio A. EIF1AX and NRAS Mutations Co-occur and Cooperate in Low-Grade Serous Ovarian Carcinomas. Cancer Res 2017. [PMID: 28646021 DOI: 10.1158/0008-5472.can-16-2224] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Low-grade serous ovarian carcinomas (LGSC) are associated with a poor response to chemotherapy and are molecularly characterized by RAS pathway activation. Using exome and whole genome sequencing, we identified recurrent mutations in the protein translational regulator EIF1AX and in NF1, USP9X, KRAS, BRAF, and NRAS RAS pathway mutations were mutually exclusive; however, we found significant co-occurrence of mutations in NRAS and EIF1AX Missense EIF1AX mutations were clustered at the N-terminus of the protein in a region associated with its role in ensuring translational initiation fidelity. Coexpression of mutant NRAS and EIF1AX proteins promoted proliferation and clonogenic survival in LGSC cells, providing the first example of co-occurring, growth-promoting mutational events in ovarian cancer. Cancer Res; 77(16); 4268-78. ©2017 AACR.
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Affiliation(s)
- Dariush Etemadmoghadam
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.,Sir Peter MacCallum Cancer Centre Department of Oncology, University of Melbourne, Melbourne, Victoria, Australia.,Department of Pathology, University of Melbourne, Melbourne, Victoria, Australia
| | - Walid J Azar
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Ying Lei
- Centre for Cancer Research, The Westmead Institute for Medical Research, Sydney, New South Wales, Australia.,Department of Gynaecological Oncology, Westmead Hospital, Sydney, New South Wales, Australia.,The University of Sydney, Sydney, New South Wales, Australia
| | - Tania Moujaber
- Centre for Cancer Research, The Westmead Institute for Medical Research, Sydney, New South Wales, Australia.,Department of Gynaecological Oncology, Westmead Hospital, Sydney, New South Wales, Australia.,The University of Sydney, Sydney, New South Wales, Australia.,Crown Princess Mary Cancer Care Centre, Westmead Hospital, Sydney, New South Wales, Australia
| | - Dale W Garsed
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.,Sir Peter MacCallum Cancer Centre Department of Oncology, University of Melbourne, Melbourne, Victoria, Australia
| | - Catherine J Kennedy
- Centre for Cancer Research, The Westmead Institute for Medical Research, Sydney, New South Wales, Australia.,Department of Gynaecological Oncology, Westmead Hospital, Sydney, New South Wales, Australia
| | - Sian Fereday
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Chris Mitchell
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Yoke-Eng Chiew
- Centre for Cancer Research, The Westmead Institute for Medical Research, Sydney, New South Wales, Australia.,Department of Gynaecological Oncology, Westmead Hospital, Sydney, New South Wales, Australia
| | - Joy Hendley
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Raghwa Sharma
- The University of Sydney, Sydney, New South Wales, Australia.,Pathology West ICPMR, Westmead, New South Wales, Australia.,The University of Western Sydney at Westmead Hospital, Westmead, New South Wales, Australia
| | - Paul R Harnett
- Centre for Cancer Research, The Westmead Institute for Medical Research, Sydney, New South Wales, Australia.,The University of Sydney, Sydney, New South Wales, Australia.,Crown Princess Mary Cancer Care Centre, Westmead Hospital, Sydney, New South Wales, Australia
| | - Jason Li
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | | | - Ann-Marie Patch
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Joshy George
- The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut
| | - George Au-Yeung
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | | | | | - Timothy Semple
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - John V Pearson
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Nicola Waddell
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Sean M Grimmond
- University of Melbourne Centre for Cancer Research, The University of Melbourne, Parkville, Victoria, Australia
| | - Martin Köbel
- Department of Pathology and Laboratory Medicine, Foothill Medical Center, University of Calgary, Calgary, Canada
| | - Helen Rizos
- Department of Biomedical Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Ivan B Lomakin
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut
| | - David D L Bowtell
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia. .,Sir Peter MacCallum Cancer Centre Department of Oncology, University of Melbourne, Melbourne, Victoria, Australia.,Department of Pathology, University of Melbourne, Melbourne, Victoria, Australia.,Department of Biochemistry and Molecular Biology, University of Melbourne, Melbourne, Victoria, Australia.,Kinghorn Cancer Centre, Garvan Institute for Medical Research, Darlinghurst, Sydney, New South Wales, Australia
| | - Anna deFazio
- Centre for Cancer Research, The Westmead Institute for Medical Research, Sydney, New South Wales, Australia. .,Department of Gynaecological Oncology, Westmead Hospital, Sydney, New South Wales, Australia.,The University of Sydney, Sydney, New South Wales, Australia
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6
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Eukaryotic initiation factor 4E-binding protein 1 (4E-BP1): a master regulator of mRNA translation involved in tumorigenesis. Oncogene 2016; 35:4675-88. [DOI: 10.1038/onc.2015.515] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 12/11/2015] [Accepted: 12/11/2015] [Indexed: 01/17/2023]
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7
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Martínez A, Sesé M, Losa JH, Robichaud N, Sonenberg N, Aasen T, Ramón y Cajal S. Phosphorylation of eIF4E Confers Resistance to Cellular Stress and DNA-Damaging Agents through an Interaction with 4E-T: A Rationale for Novel Therapeutic Approaches. PLoS One 2015; 10:e0123352. [PMID: 25923732 PMCID: PMC4414544 DOI: 10.1371/journal.pone.0123352] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 03/02/2015] [Indexed: 12/25/2022] Open
Abstract
Phosphorylation of the eukaryotic translation initiation factor eIF4E is associated with malignant progression and poor cancer prognosis. Accordingly, here we have analyzed the association between eIF4E phosphorylation and cellular resistance to oxidative stress, starvation, and DNA-damaging agents in vitro. Using immortalized and cancer cell lines, retroviral expression of a phosphomimetic (S209D) form of eIF4E, but not phospho-dead (S209A) eIF4E or GFP control, significantly increased cellular resistance to stress induced by DNA-damaging agents (cisplatin), starvation (glucose+glutamine withdrawal), and oxidative stress (arsenite). De novo accumulation of eIF4E-containing cytoplasmic bodies colocalizing with the eIF4E-binding protein 4E-T was observed after expression of phosphomimetic S209D, but not S209A or wild-type eIF4E. Increased resistance to cellular stress induced by eIF4E-S209D was lost upon knockdown of endogenous 4E-T or use of an eIF4E-W73A-S209D mutant unable to bind 4E-T. Cancer cells treated with the Mnk1/2 inhibitor CGP57380 to prevent eIF4E phosphorylation and mouse embryonic fibroblasts derived from Mnk1/2 knockout mice were also more sensitive to arsenite and cisplatin treatment. Polysome analysis revealed an 80S peak 2 hours after arsenite treatment in cells overexpressing phosphomimetic eIF4E, indicating translational stalling. Nonetheless, a selective increase was observed in the synthesis of some proteins (cyclin D1, HuR, and Mcl-1). We conclude that phosphorylation of eIF4E confers resistance to various cell stressors and that a direct interaction or regulation of 4E-T by eIF4E is required. Further delineation of this process may identify novel therapeutic avenues for cancer treatment, and these results support the use of modern Mnk1/2 inhibitors in conjunction with standard therapy.
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Affiliation(s)
- Alba Martínez
- Molecular Pathology, Hospital Universitari Vall d’Hebron, Vall d'Hebron Institut de Recerca, VHIR, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Marta Sesé
- Molecular Pathology, Hospital Universitari Vall d’Hebron, Vall d'Hebron Institut de Recerca, VHIR, Universitat Autònoma de Barcelona, Barcelona, Spain
| | | | - Nathaniel Robichaud
- McGill University, Department of Biochemistry, Goodman Cancer Research Centre, Montréal, Québec, Canada
| | - Nahum Sonenberg
- McGill University, Department of Biochemistry, Goodman Cancer Research Centre, Montréal, Québec, Canada
| | - Trond Aasen
- Molecular Pathology, Hospital Universitari Vall d’Hebron, Vall d'Hebron Institut de Recerca, VHIR, Universitat Autònoma de Barcelona, Barcelona, Spain
- * E-mail: (SRC); (TA)
| | - Santiago Ramón y Cajal
- Molecular Pathology, Hospital Universitari Vall d’Hebron, Vall d'Hebron Institut de Recerca, VHIR, Universitat Autònoma de Barcelona, Barcelona, Spain
- Department of Pathology, Vall d’Hebron University Hospital, Barcelona, Spain
- * E-mail: (SRC); (TA)
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Blackinton JG, Keene JD. Post-transcriptional RNA regulons affecting cell cycle and proliferation. Semin Cell Dev Biol 2014; 34:44-54. [PMID: 24882724 PMCID: PMC4163074 DOI: 10.1016/j.semcdb.2014.05.014] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 05/21/2014] [Indexed: 01/19/2023]
Abstract
The cellular growth cycle is initiated and maintained by punctual, yet agile, regulatory events involving modifications of cell cycle proteins as well as coordinated gene expression to support cyclic checkpoint decisions. Recent evidence indicates that post-transcriptional partitioning of messenger RNA subsets by RNA-binding proteins help physically localize, temporally coordinate, and efficiently translate cell cycle proteins. This dynamic organization of mRNAs encoding cell cycle components contributes to the overall economy of the cell cycle consistent with the post-transcriptional RNA regulon model of gene expression. This review examines several recent studies demonstrating the coordination of mRNA subsets encoding cell cycle proteins during nuclear export and subsequent coupling to protein synthesis, and discusses evidence for mRNA coordination of p53 targets and the DNA damage response pathway. We consider how these observations may connect to upstream and downstream post-transcriptional coordination and coupling of splicing, export, localization, and translation. Published examples from yeast, nematode, insect, and mammalian systems are discussed, and we consider genetic evidence supporting the conclusion that dysregulation of RNA regulons may promote pathogenic states of growth such as carcinogenesis.
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Affiliation(s)
- Jeff G Blackinton
- Department of Molecular Genetics & Microbiology, Duke University Medical Center, Box 3020, Durham, NC 27710, USA
| | - Jack D Keene
- Department of Molecular Genetics & Microbiology, Duke University Medical Center, Box 3020, Durham, NC 27710, USA.
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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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10
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Eukaryotic translation initiation factors in cancer development and progression. Cancer Lett 2013; 340:9-21. [PMID: 23830805 DOI: 10.1016/j.canlet.2013.06.019] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 06/11/2013] [Accepted: 06/14/2013] [Indexed: 01/03/2023]
Abstract
Eukaryotic gene expression is a complicated process primarily regulated at the levels of gene transcription and mRNA translation. The latter involves four main steps: initiation, elongation, termination and recycling. Translation regulation is primarily achieved during initiation which is orchestrated by 12 currently known eukaryotic initiation factors (eIFs). Here, we review the current state of eIF research and present a concise summary of the various eIF subunits. As eIFs turned out to be critically implicated in different oncogenic processes the various eIF members and their contribution to onset and progression of cancer are featured.
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11
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Dobson T, Chen J, Krushel LA. Dysregulating IRES-dependent translation contributes to overexpression of oncogenic Aurora A Kinase. Mol Cancer Res 2013; 11:887-900. [PMID: 23661421 DOI: 10.1158/1541-7786.mcr-12-0707] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
UNLABELLED Overexpression of the oncoprotein Aurora A kinase occurs in multiple types of cancer, often early during cell transformation. To identify the mechanism(s) contributing to enhanced Aurora A protein expression, a comparison between normal human lung fibroblast and breast epithelial cells to nontumorigenic breast (MCF10A and MCF12A) and tumorigenic breast (MCF-7) and cervical cell lines (HeLa S3) was performed. A subset of these immortalized lines (MCF10A, MCF12A, and HeLa S3) exhibited increased levels of Aurora A protein, independent of tumorigenicity. The increase in Aurora A protein in these immortalized cells was not due to increased transcription/RNA stability, protein half-life, or cap-dependent translation. Assays utilizing monocistronic and dicistronic RNA constructs revealed that the 5'-leader sequence of Aurora A contains an internal ribosomal entry site (IRES), which is regulated in a cell cycle-dependent manner, peaking in G2/M phase. Moreover, IRES activity was increased in the immortalized cell lines in which Aurora A protein expression was also enhanced. Additional studies indicated that the increased internal initiation is specific to the IRES of Aurora A and may be an early event during cancer progression. These results identify a novel mechanism contributing to Aurora A kinase overexpression. IMPLICATIONS The current study indicates that Aurora A kinase contributes to immortalization and tumorigenesis.
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Affiliation(s)
- Tara Dobson
- Department of Biochemistry and Molecular Biology, University of Texas MD Anderson Cancer Center, 6767 Bertner Ave, Houston, TX 77030, USA
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12
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Willimott S, Beck D, Ahearne MJ, Adams VC, Wagner SD. Cap-translation inhibitor, 4EGI-1, restores sensitivity to ABT-737 apoptosis through cap-dependent and -independent mechanisms in chronic lymphocytic leukemia. Clin Cancer Res 2013; 19:3212-23. [PMID: 23633452 DOI: 10.1158/1078-0432.ccr-12-2185] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE The lymph node microenvironment promotes resistance to chemotherapy in chronic lymphocytic leukemia (CLL), partly through induction of BCL2 family prosurvival proteins. Currently available inhibitors do not target all BCL2 family prosurvival proteins and their effectiveness is also modified by proapoptotic BCL2 homology domain 3 (BH3) only protein expression. The goal of this study was to evaluate synergy between the eIF4E/eIF4G interaction inhibitor, 4EGI-1, and the BH3 mimetic, ABT-737. EXPERIMENTAL DESIGN CLL cells were cultured in conditions to mimic the lymph node microenvironment. Protein synthesis and cap-complex formation were determined. Polysome association of mRNAs from BCL2 family survival genes was analyzed by translational profiling. The effects of 4EGI-1 and the BCL2/BCL2L1 antagonist, ABT-737, on CLL cell apoptosis were determined. RESULTS Protein synthesis was increased approximately 6-fold by stromal cell/CD154 culture in a phosphoinositide 3-kinase α (PI3Kα)-specific manner and was reduced by 4EGI-1. PI3K inhibitors and 4EGI-1 also reduced cap-complex formation but only 4EGI-1 consistently reduced BCL2L1 and BCL2A1 protein levels. 4EGI-1, but not PI3K inhibitors or rapamycin, induced an endoplasmic reticulum stress response including proapoptotic NOXA and the translation inhibitor phosphorylated eIF2α. 4EGI-1 and ABT-737 synergized to cause apoptosis, independent of levels of prosurvival protein expression in individual patients. CONCLUSIONS Overall protein synthesis and cap-complex formation are induced by microenvironment stimuli in CLL. Inhibition of the cap-complex was not sufficient to repress BCL2 family prosurvival expression, but 4EGI-1 inhibited BCL2A1 and BCL2L1 while inducing NOXA through cap-dependent and -independent mechanisms. 4EGI-1 and ABT-737 synergized to produce apoptosis, and these agents may be the basis for a therapeutically useful combination.
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Affiliation(s)
- Shaun Willimott
- Department of Cancer Studies and Molecular Medicine and MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
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13
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D'Ambrogio A, Nagaoka K, Richter JD. Translational control of cell growth and malignancy by the CPEBs. Nat Rev Cancer 2013; 13:283-90. [PMID: 23446545 DOI: 10.1038/nrc3485] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The cytoplasmic polyadenylation element binding proteins (CPEBs) associate with specific sequences in mRNA 3' untranslated regions to promote translation. They do so by inducing cytoplasmic polyadenylation, which requires specialized poly(A) polymerases. Aberrant expression of these proteins correlates with certain types of cancer, indicating that cytoplasmic RNA 3' end processing is important in the control of growth. Several CPEB-regulated mRNAs govern cell cycle progression, regulate senescence, establish cell polarity, and promote tumorigenesis and metastasis. In this Opinion article, we discuss the emerging evidence that indicates a key role for the CPEBs in cancer biology.
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Affiliation(s)
- Andrea D'Ambrogio
- The Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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Abstract
Colorectal cancers (CRC) are one of the most common causes of morbidity and mortality in high-income countries. Targeted screening programs have resulted in early treatment and a substantial decrease in mortality. However, treatment strategies for CRC still require improvement. Understanding the etiology and pathogenesis of CRC would provide tools for improving treatment of patients with this disease. It is only recently that deregulation of the protein synthesis apparatus has begun to gain attention as a major player in cancer development and progression. Among the numerous steps of protein synthesis, deregulation of the process of translation initiation appears to play a key role in cancer growth and proliferation. This manuscript discusses a fascinating and rapidly growing field exploring translation initiation as a fundamental component in CRC development and progression and summarizing CRC treatment perspectives based on agents targeting translation initiation.
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Affiliation(s)
- Armen Parsyan
- Department of Surgery, McGill University, Montreal, Canada.
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15
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Martineau Y, Azar R, Bousquet C, Pyronnet S. Anti-oncogenic potential of the eIF4E-binding proteins. Oncogene 2012; 32:671-7. [DOI: 10.1038/onc.2012.116] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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16
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Suppression of cellular transformation by poly (A) binding protein interacting protein 2 (Paip2). PLoS One 2011; 6:e25116. [PMID: 21957478 PMCID: PMC3177865 DOI: 10.1371/journal.pone.0025116] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 08/24/2011] [Indexed: 12/28/2022] Open
Abstract
Controlling translation is crucial for the homeostasis of a cell. Its deregulation can facilitate the development and progression of many diseases including cancer. Poly (A) binding protein interacting protein 2 (Paip2) inhibits efficient initiation of translation by impairing formation of the necessary closed loop of mRNA. The over production of Paip2 in the presence of a constitutively active form of hRasV12 can reduce colony formation in a semi-solid matrix and focus formation on a cell monolayer. The ability of Paip2 to bind to Pabp is required to suppress the transformed phenotype mediated by hRasV12. These observations indicate that Paip2 is able to function as a tumor suppressor.
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17
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Fowler CL, Zimmer CC, Zimmer SG. Spontaneous Progression of a Stage IV-S Human Neuroblastoma Cell Line Involves the Increased Expression of the Protooncogenes RAS and Eukaryotic Initiation Factor 4E. ACTA ACUST UNITED AC 2010. [DOI: 10.1080/15513810009168650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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18
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Abstract
Remarkable progress has been made in defining a new understanding of the role of mRNA translation and protein synthesis in human cancer. Translational control is a crucial component of cancer development and progression, directing both global control of protein synthesis and selective translation of specific mRNAs that promote tumour cell survival, angiogenesis, transformation, invasion and metastasis. Translational control of cancer is multifaceted, involving alterations in translation factor levels and activities unique to different types of cancers, disease stages and the tumour microenvironment. Several clinical efforts are underway to target specific components of the translation apparatus or unique mRNA translation elements for cancer therapeutics.
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19
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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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20
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Ly TK, Wang J, Pereira R, Rojas KS, Peng X, Feng Q, Cerione RA, Wilson KF. Activation of the Ran GTPase is subject to growth factor regulation and can give rise to cellular transformation. J Biol Chem 2009; 285:5815-26. [PMID: 20028979 DOI: 10.1074/jbc.m109.071886] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although the small GTPase Ran is best known for its roles in nucleocytoplasmic transport, mitotic spindle assembly, and nuclear envelope formation, recent studies have demonstrated the overexpression of Ran in multiple tumor types and that its expression is correlated with a poor patient prognosis, providing evidence for the importance of this GTPase in cell growth regulation. Here we show that Ran is subject to growth factor regulation by demonstrating that it is activated in a serum-dependent manner in human breast cancer cells and, in particular, in response to heregulin, a growth factor that activates the Neu/ErbB2 tyrosine kinase. The heregulin-dependent activation of Ran requires mTOR (mammalian target of rapamycin) and stimulates the capped RNA binding capability of the cap-binding complex in the nucleus, thus influencing gene expression at the level of mRNA processing. We further demonstrate that the excessive activation of Ran has important consequences for cell growth by showing that a novel, activated Ran mutant is sufficient to transform NIH-3T3 cells in an mTOR- and epidermal growth factor receptor-dependent manner and that Ran-transformed cells form tumors in mice.
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Affiliation(s)
- Thi K Ly
- Department of Molecular Medicine, Cornell University, Ithaca, New York 14853, USA
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21
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Cuesta R, Gupta M, Schneider RJ. The regulation of protein synthesis in cancer. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 90:255-92. [PMID: 20374744 DOI: 10.1016/s1877-1173(09)90007-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Translational control of cancer is a multifaceted process, involving alterations in translation factor levels and activities that are unique to the different types of cancers and the different stages of disease. Translational alterations in cancer include adaptations of the tumor itself, of the tumor microenvironment, an integral component in disease, and adaptations that occur as cancer progresses from development to local disease and ultimately to metastatic disease. Adaptations include the overexpression and increased activity of specific translation factors, the physical or functional loss of translation regulatory components, increased production of ribosomes, selective mRNA translation, and alteration of signal transduction pathways to permit unfettered activation of protein synthesis. There is intense clinical interest to capitalize on the emerging new understanding of translational control in cancer by targeting specific components of the translation apparatus that are altered in disease for the development of specific cancer therapeutics. Clinical trial data are nascent but encouraging, suggesting that translational control constitutes an important new area for drug development in human cancer.
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Affiliation(s)
- Rafael Cuesta
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
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22
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Fraser CS. The molecular basis of translational control. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 90:1-51. [PMID: 20374738 DOI: 10.1016/s1877-1173(09)90001-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Our current understanding of eukaryotic protein synthesis has emerged from many years of biochemical, genetic and biophysical approaches. Significant insight into the molecular details of the mechanism has been obtained, although there are clearly many aspects of the process that remain to be resolved. Importantly, our understanding of the mechanism has identified a number of key stages in the pathway that contribute to the regulation of general and gene-specific translation. Not surprisingly, translational control is now widely accepted to play a role in aspects of cell stress, growth, development, synaptic function, aging, and disease. This chapter reviews the mechanism of eukaryotic protein synthesis and its relevance to translational control.
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Affiliation(s)
- Christopher S Fraser
- Department of Molecular and Cellular Biology, University of California at Davis, Davis, California 95616, USA
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23
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Jin H, Xu CX, Lim HT, Park SJ, Shin JY, Chung YS, Park SC, Chang SH, Youn HJ, Lee KH, Lee YS, Ha YC, Chae CH, Beck GR, Cho MH. High dietary inorganic phosphate increases lung tumorigenesis and alters Akt signaling. Am J Respir Crit Care Med 2009; 179:59-68. [PMID: 18849498 PMCID: PMC2615662 DOI: 10.1164/rccm.200802-306oc] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Accepted: 10/09/2008] [Indexed: 02/07/2023] Open
Abstract
RATIONALE Phosphate (Pi) is an essential nutrient to living organisms. Recent surveys indicate that the intake of Pi has increased steadily. Our previous studies have indicated that elevated Pi activates the Akt signaling pathway. An increased knowledge of the response of lung cancer tissue to high dietary Pi may provide an important link between diet and lung tumorigenesis. OBJECTIVES The current study was performed to elucidate the potential effects of high dietary Pi on lung cancer development. METHODS Experiments were performed on 5-week-old male K-ras(LA1) lung cancer model mice and 6-week-old male urethane-induced lung cancer model mice. Mice were fed a diet containing 0.5% Pi (normal Pi) and 1.0% Pi (high Pi) for 4 weeks. At the end of the experiment, all mice were killed. Lung cancer development was evaluated by diverse methods. MEASUREMENT AND MAIN RESULTS A diet high in Pi increased lung tumor progression and growth compared with normal diet. High dietary Pi increased the sodium-dependent inorganic phosphate transporter-2b protein levels in the lungs. High dietary consumption of Pi stimulated pulmonary Akt activity while suppressing the protein levels of tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 as well as Akt binding partner carboxyl-terminal modulator protein, resulting in facilitated cap-dependent protein translation. In addition, high dietary Pi significantly stimulated cell proliferation in the lungs of K-ras(LA1) mice. CONCLUSIONS Our results showed that high dietary Pi promoted tumorigenesis and altered Akt signaling, thus suggesting that careful regulation of dietary Pi may be critical for lung cancer prevention as well as treatment.
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Affiliation(s)
- Hua Jin
- Laboratory of Toxicology, College of Veterinary Medicine, Seoul National University, Seoul, Korea
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24
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Gallagher JW, Kubica N, Kimball SR, Jefferson LS. Reduced eukaryotic initiation factor 2Bepsilon-subunit expression suppresses the transformed phenotype of cells overexpressing the protein. Cancer Res 2008; 68:8752-60. [PMID: 18974117 DOI: 10.1158/0008-5472.can-08-1042] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Eukaryotic initiation factor 2B (eIF2B), a five-subunit guanine nucleotide exchange factor, plays a key role in the regulation of mRNA translation. Expression of its epsilon-subunit is specifically up-regulated in certain conditions associated with increased cell growth. Therefore, the purpose of the present study was to examine the effect of repressing eIF2Bepsilon expression on growth rate, protein synthesis, and other characteristics of two tumorigenic cell lines that display up-regulated expression of the epsilon-subunit. Experiments were designed to compare spontaneously transformed fibroblasts to transformed mouse embryonic fibroblasts infected with a lentivirus containing a short hairpin RNA directed against eIF2Bepsilon. Cells expressing the short hairpin RNA displayed a reduction in eIF2Bepsilon abundance to 30% of the value observed in uninfected transformed mouse embryonic fibroblasts, with no change in the expression of any of the other four subunits. The repression of eIF2Bepsilon expression was accompanied by reductions in guanine nucleotide exchange factor activity and global rates of protein synthesis. Moreover, repressed eIF2Bepsilon expression led to marked reductions in cell growth rate in culture, colony formation in soft agar, and tumor progression in nude mice. Similar results were obtained in MCF-7 human breast cancer cells in which eIF2Bepsilon expression was repressed through transient transfection with a small interfering RNA directed against the epsilon-subunit. Overall, the results support a role for eIF2Bepsilon in the regulation of cell growth and suggest that it might represent a therapeutic target for the treatment of human cancer.
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Affiliation(s)
- James W Gallagher
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA
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25
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Liu Y, Wang E. Transcriptional analysis of normal human fibroblast responses to microgravity stress. GENOMICS PROTEOMICS & BIOINFORMATICS 2008; 6:29-41. [PMID: 18558383 PMCID: PMC5054092 DOI: 10.1016/s1672-0229(08)60018-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
To understand the molecular mechanism(s) of how spaceflight affects cellular signaling pathways, quiescent normal human WI-38 fibroblasts were flown on the STS-93 space shuttle mission. Subsequently, RNA samples from the space-flown and ground-control cells were used to construct two cDNA libraries, which were then processed for suppression subtractive hybridization (SSH) to identify spaceflight-specific gene expression. The SSH data show that key genes related to oxidative stress, DNA repair, and fatty acid oxidation are activated by spaceflight, suggesting the induction of cellular oxidative stress. This is further substantiated by the up-regulation of neuregulin 1 and the calcium-binding protein calmodulin 2. Another obvious stress sign is that spaceflight evokes the Ras/mitogen-activated protein kinase and phosphatidylinositol-3 kinase signaling pathways, along with up-regulating several G1-phase cell cycle traverse genes. Other genes showing up-regulation of expression are involved in protein synthesis and pro-apoptosis, as well as pro-survival. Interactome analysis of functionally related genes shows that c-Myc is the “hub” for those genes showing significant changes. Hence, our results suggest that microgravity travel may impact changes in gene expression mostly associated with cellular stress signaling, directing cells to either apoptotic death or premature senescence.
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Affiliation(s)
- Yongqing Liu
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, KY 40202, USA
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26
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Chung J, Kim TH. Integrin-dependent translational control: Implication in cancer progression. Microsc Res Tech 2008; 71:380-6. [PMID: 18300291 DOI: 10.1002/jemt.20566] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The importance of translational control in cancer progression has been underscored by a number of recent studies. However, little is known how cancer cells maintain their high efficiency of translation. Here, we summarize studies that support the role of integrins in translational control, especially at the initiation step, and discuss the various mechanisms by which integrins regulate the recruitment of translational machinery. This review also examines the hypothesis that integrins contribute to various aspects of cancer progression such as proliferation, survival, angiogenesis, and invasion through translational control.
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Affiliation(s)
- Jun Chung
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130, USA.
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27
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Graff JR, Konicek BW, Carter JH, Marcusson EG. Targeting the eukaryotic translation initiation factor 4E for cancer therapy. Cancer Res 2008; 68:631-4. [PMID: 18245460 DOI: 10.1158/0008-5472.can-07-5635] [Citation(s) in RCA: 258] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The eukaryotic translation initiation factor 4E (eIF4E) is frequently overexpressed in human cancers in relation to disease progression and drives cellular transformation, tumorigenesis, and metastatic progression in experimental models. Enhanced eIF4E function results from eIF4E overexpression and/or activation of the ras and phosphatidylinositol 3-kinase/AKT pathways and selectively increases the translation of key mRNAs involved in tumor growth, angiogenesis, and cell survival. Consequently, by simultaneously and selectively reducing the expression of numerous potent growth and survival factors critical for malignancy, targeting eIF4E for inhibition may provide an attractive therapy for many different tumor types. Recent work has now shown the plausibility of therapeutically targeting eIF4E and has resulted in the advance of the first eIF4E-specific therapy to clinical trials. These studies illustrate the increased susceptibility of tumor tissues to eIF4E inhibition and support the notion that the enhanced eIF4E function common to many tumor types may represent an Achilles' heel for cancer.
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Affiliation(s)
- Jeremy R Graff
- Cancer Growth and Translational Genetics, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285, USA.
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28
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Graff JR, Konicek BW, Vincent TM, Lynch RL, Monteith D, Weir SN, Schwier P, Capen A, Goode RL, Dowless MS, Chen Y, Zhang H, Sissons S, Cox K, McNulty AM, Parsons SH, Wang T, Sams L, Geeganage S, Douglass LE, Neubauer BL, Dean NM, Blanchard K, Shou J, Stancato LF, Carter JH, Marcusson EG. Therapeutic suppression of translation initiation factor eIF4E expression reduces tumor growth without toxicity. J Clin Invest 2007; 117:2638-48. [PMID: 17786246 PMCID: PMC1957541 DOI: 10.1172/jci32044] [Citation(s) in RCA: 294] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Accepted: 06/27/2007] [Indexed: 12/14/2022] Open
Abstract
Expression of eukaryotic translation initiation factor 4E (eIF4E) is commonly elevated in human and experimental cancers, promoting angiogenesis and tumor growth. Elevated eIF4E levels selectively increase translation of growth factors important in malignancy (e.g., VEGF, cyclin D1) and is thereby an attractive anticancer therapeutic target. Yet to date, no eIF4E-specific therapy has been developed. Herein we report development of eIF4E-specific antisense oligonucleotides (ASOs) designed to have the necessary tissue stability and nuclease resistance required for systemic anticancer therapy. In mammalian cultured cells, these ASOs specifically targeted the eIF4E mRNA for destruction, repressing expression of eIF4E-regulated proteins (e.g., VEGF, cyclin D1, survivin, c-myc, Bcl-2), inducing apoptosis, and preventing endothelial cells from forming vessel-like structures. Most importantly, intravenous ASO administration selectively and significantly reduced eIF4E expression in human tumor xenografts, significantly suppressing tumor growth. Because these ASOs also target murine eIF4E, we assessed the impact of eIF4E reduction in normal tissues. Despite reducing eIF4E levels by 80% in mouse liver, eIF4E-specific ASO administration did not affect body weight, organ weight, or liver transaminase levels, thereby providing the first in vivo evidence that cancers may be more susceptible to eIF4E inhibition than normal tissues. These data have prompted eIF4E-specific ASO clinical trials for the treatment of human cancers.
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Affiliation(s)
- Jeremy R Graff
- Lilly Research Labs, Eli Lilly and Company, Indianapolis, Indiana 46285, USA.
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29
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Jastrzebski K, Hannan KM, Tchoubrieva EB, Hannan RD, Pearson RB. Coordinate regulation of ribosome biogenesis and function by the ribosomal protein S6 kinase, a key mediator of mTOR function. Growth Factors 2007; 25:209-26. [PMID: 18092230 DOI: 10.1080/08977190701779101] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Current understanding of the mechanisms by which cell growth is regulated lags significantly behind our knowledge of the complex processes controlling cell cycle progression. Recent studies suggest that the mammalian target of rapamycin (mTOR) pathway is a key regulator of cell growth via the regulation of protein synthesis. The key mTOR effectors of cell growth are eukaryotic initiation factor 4E-binding protein 1 (4EBP-1) and the ribosomal protein S6 kinase (S6K). Here we will review the current models for mTOR dependent regulation of ribosome function and biogenesis as well as its role in coordinating growth factor and nutrient signaling to facilitate homeostasis of cell growth and proliferation. We will place particular emphasis on the role of S6K1 signaling and will highlight the points of cross talk with other key growth control pathways. Finally, we will discuss the impact of S6K signaling and the consequent feedback regulation of the PI3K/Akt pathway on disease processes including cancer.
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Affiliation(s)
- Katarzyna Jastrzebski
- Growth Control and Differentiation Program, Trescowthick Research Laboratories, Peter MacCallum Cancer Centre, Melbourne, Australia
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30
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Shantz LM, Levin VA. Regulation of ornithine decarboxylase during oncogenic transformation: mechanisms and therapeutic potential. Amino Acids 2007; 33:213-23. [PMID: 17443268 DOI: 10.1007/s00726-007-0531-2] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2006] [Accepted: 02/01/2007] [Indexed: 01/10/2023]
Abstract
The activity of ornithine decarboxylase (ODC(1)), the first enzyme in polyamine biosynthesis, is induced during carcinogenesis by a variety of oncogenic stimuli. Intracellular levels of ODC and the polyamines are tightly controlled during normal cell growth, and regulation occurs at the levels of transcription, translation and protein degradation. Several known proto-oncogenic pathways appear to control ODC transcription and translation, and dysregulation of pathways downstream of ras and myc result in the constitutive elevation of ODC activity that occurs with oncogenesis. Inhibition of ODC activity reverts the transformation of cells in vitro and reduces tumor growth in several animal models, suggesting high levels of ODC are necessary for the maintenance of the transformed phenotype. The ODC irreversible inactivator DFMO has proven to be not only a valuable tool in the study of ODC in cancer, but also shows promise as a chemopreventive and chemotherapeutic agent in certain types of malignancies.
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Affiliation(s)
- L M Shantz
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
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31
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Goldson TM, Vielhauer G, Staub E, Miller S, Shim H, Hagedorn CH. Eukaryotic initiation factor 4E variants alter the morphology, proliferation, and colony-formation properties of MDA-MB-435 cancer cells. Mol Carcinog 2007; 46:71-84. [PMID: 17091471 DOI: 10.1002/mc.20276] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Eukaryotic initiation factor 4E (eIF4E) binds to the 5' m(7)G cap of mRNAs and is a focal point of regulation of initiation of mRNA translation. High levels of expression of eIF4E in many epithelial cancers, including breast, head and neck, colon, and bladder, correlate with increased tissue invasion and metastasis. To further examine the role of eIF4E in the biology of cancer cells, variants of eIF4E with impaired 5' cap binding function were expressed in MDA-MB-435 carcinoma cells. Cell lines overexpressing variants of eIF4E had impaired growth properties and exhibited a different morphology compared to cells expressing similar amounts of exogenous wild-type eIF4E or control cells. Cells expressing variant eIF4E did not form foci in culture and produced smaller colonies in soft agar compared to cells expressing wild-type eIF4E. In addition, analysis of polyribosomes for vascular endothelial growth factor (VEGF) mRNA demonstrated a shift from translationally active to inactive fractions in variant eIF4E cells, while GAPDH mRNA did not. The long G-C rich 5' untranslated region of VEGF mRNA is a feature of other mRNAs encoding growth regulating proteins that are predicted to have their translation enhanced by increases in eIF4E; whereas mRNA with shorter and less structured 5' UTRs, like that of GAPDH, are predicted to be largely unaffected. These data suggest that targeting the 5' cap-binding domain of eIF4E may be a viable option to slow cancer cell growth and alter the malignant phenotype.
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Affiliation(s)
- Tovë M Goldson
- Program in Biochemistry, Cell and Developmental Biology, Emory University School of Medicine, Atlanta, Georgia, USA
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32
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Spence J, Duggan BM, Eckhardt C, McClelland M, Mercola D. Messenger RNAs under differential translational control in Ki-ras-transformed cells. Mol Cancer Res 2006; 4:47-60. [PMID: 16446406 DOI: 10.1158/1541-7786.mcr-04-0187] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Microarrays have been used extensively to identify differential gene expression at the level of transcriptional control in oncogenesis. However, increasing evidence indicates that changes in translational control are critical to oncogenic transformation. This study identifies mRNA transcripts that are differentially regulated, primarily at the level of translation, in the immortalized human embryonic prostate epithelial cell line 267B1 and the v-Ki-ras-transformed counterpart by comparing total mRNA to polysome-bound mRNA by using Affymetrix oligonucleotide microarrays. Among the transcripts that were identified were those encoding proteins involved in DNA replication, cell cycle control, cell-to-cell interactions, electron transport, G protein signaling, and translation. Many of these proteins are known to contribute to oncogenesis or have the potential to contribute to oncogenesis. Differential expression of RNA-binding proteins and the presence of highly conserved motifs in the 5' and 3' untranslated regions of the mRNAs are consistent with multiple pathways and mechanisms governing the changes in translational control. Although Alu sequences were found to be associated with increased translation in transformed cells, an evolutionarily conserved motif was identified in the 3' untranslated regions of ephrinB1, calreticulin, integrin alpha3, and mucin3B that was associated with decreased polysome association in 267B1/Ki-ras.
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Affiliation(s)
- Jean Spence
- Sidney Kimmel Cancer Center, San Diego, CA, USA.
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33
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Vega F, Medeiros LJ, Leventaki V, Atwell C, Cho-Vega JH, Tian L, Claret FX, Rassidakis GZ. Activation of mammalian target of rapamycin signaling pathway contributes to tumor cell survival in anaplastic lymphoma kinase-positive anaplastic large cell lymphoma. Cancer Res 2006; 66:6589-97. [PMID: 16818631 PMCID: PMC4839264 DOI: 10.1158/0008-5472.can-05-3018] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALCL) frequently carries the t(2;5)(p23;q35) resulting in aberrant expression of chimeric nucleophosmin-ALK. Previously, nucleophosmin-ALK has been shown to activate phosphatidylinositol 3-kinase (PI3K) and its downstream effector, the serine/threonine kinase AKT. In this study, we hypothesized that the mammalian target of rapamycin (mTOR) pathway, which functions downstream of AKT, mediates the oncogenic effects of activated PI3K/AKT in ALK+ ALCL. Here, we provide evidence that mTOR signaling phosphoproteins, including mTOR, eukaryotic initiation factor 4E-binding protein-1, p70S6K, and ribosomal protein S6, are highly phosphorylated in ALK+ ALCL cell lines and tumors. We also show that AKT activation contributes to mTOR phosphorylation, at least in part, as forced expression of constitutively active AKT by myristoylated AKT adenovirus results in increased phosphorylation of mTOR and its downstream effectors. Conversely, inhibition of AKT expression or activity results in decreased mTOR phosphorylation. In addition, pharmacologic inhibition of PI3K/AKT down-regulates the activation of the mTOR signaling pathway. We also show that inhibition of mTOR with rapamycin, as well as silencing mTOR gene product expression using mTOR-specific small interfering RNA, decreased phosphorylation of mTOR signaling proteins and induced cell cycle arrest and apoptosis in ALK+ ALCL cells. Cell cycle arrest was associated with modulation of G(1)-S-phase regulators, including the cyclin-dependent kinase inhibitors p21(waf1) and p27(kip1). Apoptosis following inhibition of mTOR expression or function was associated with down-regulation of antiapoptotic proteins, including c-FLIP, MCL-1, and BCL-2. These findings suggest that the mTOR pathway contributes to nucleophosmin-ALK/PI3K/AKT-mediated tumorigenesis and that inhibition of mTOR represents a potential therapeutic strategy in ALK+ ALCL.
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MESH Headings
- Anaplastic Lymphoma Kinase
- Apoptosis/drug effects
- Apoptosis/physiology
- Cell Cycle/physiology
- Cell Line, Tumor
- Cell Survival/physiology
- Chromones/pharmacology
- Down-Regulation
- Enzyme Activation
- Humans
- Lymphoma, Large B-Cell, Diffuse/enzymology
- Lymphoma, Large B-Cell, Diffuse/genetics
- Lymphoma, Large B-Cell, Diffuse/metabolism
- Lymphoma, Large B-Cell, Diffuse/pathology
- Morpholines/pharmacology
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphoinositide-3 Kinase Inhibitors
- Phosphorylation
- Protein Kinases/genetics
- Protein Kinases/metabolism
- Protein-Tyrosine Kinases/biosynthesis
- Protein-Tyrosine Kinases/metabolism
- Proto-Oncogene Proteins c-akt/antagonists & inhibitors
- Proto-Oncogene Proteins c-akt/metabolism
- RNA, Small Interfering/genetics
- Receptor Protein-Tyrosine Kinases
- Signal Transduction
- Sirolimus/pharmacology
- TOR Serine-Threonine Kinases
- Transfection
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Affiliation(s)
- Francisco Vega
- Department of Hematopathology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - L. Jeffrey Medeiros
- Department of Hematopathology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Vasiliki Leventaki
- Department of Hematopathology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Coralyn Atwell
- Department of Hematopathology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Jeong Hee Cho-Vega
- Department of Molecular Pathology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Ling Tian
- Department of Molecular Therapeutics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Francois-Xavier Claret
- Department of Molecular Therapeutics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - George Z. Rassidakis
- Department of Hematopathology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas
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O'Kelly J, Uskokovic M, Lemp N, Vadgama J, Koeffler HP. Novel Gemini-vitamin D3 analog inhibits tumor cell growth and modulates the Akt/mTOR signaling pathway. J Steroid Biochem Mol Biol 2006; 100:107-16. [PMID: 16777406 DOI: 10.1016/j.jsbmb.2006.04.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Accepted: 04/24/2006] [Indexed: 10/24/2022]
Abstract
We have shown previously that 1alpha, 25-dihydroxy-21-(3-hydroxy-3-methylbutyl)vitamin D3 (Gemini) compounds, which have two side chains attached to carbon-20, had increased anti-tumor activities against breast, prostate and leukemia cell lines in comparison to 1,25(OH)2 vitamin D3. This prompted us to synthesize additional Gemini compounds with further modifications and evaluate their anticancer effects. Most effective in this series was 1,25-dihydroxy-20S-21(3-hydroxy-3-methyl-butyl)-23-yne-26,27-hexafluoro-vitamin D3 [Gemini-23-yne-26,27-hexafluoro-D3]. This analog was approximately 10-fold more potent than previously characterized Gemini compounds in inhibiting the clonal growth of HL-60, MCF-7 and LNCaP cell lines. Also in MCF-7 cells, Gemini-23-yne-26,27-hexafluoro-D3 caused dephosphorylation of the oncogenic kinase, Akt, resulting in dephosphorylation of the Akt target proteins, Forkhead transcription factor and mammalian target of rapamycin (mTOR). Downstream effectors of mTOR were also inhibited by the analog as demonstrated by decreased phosphorylation of both S6 kinase, and the translation inhibitor, 4E-BP1. The mTOR pathway regulates mRNA translation; exposure of MCF-7 cells to Gemini-23-yne-26,27-hexafluoro-D3 decreased their rate of protein synthesis and increased the association of 4EBP-1 with the translation initiation factor, eIF4E. Inhibition of the Akt-mTOR pathway represents a novel mechanism by which vitamin D3 analogs may modulate the expression and activity of proteins involved in cancer cell proliferation.
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Affiliation(s)
- James O'Kelly
- Division of Hematology/Oncology, Cedars Sinai Medical Center, UCLA School of Medicine, Los Angeles, CA, USA.
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35
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Affiliation(s)
- R Schäfer
- Department of Pathology, University of Zurich, Switzerland
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36
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Abstract
The oncogene AKT (also called protein kinase B (PKB)) signals to the translational machinery, and activation of protein synthesis by Akt is associated with cancer formation. Akt directly stimulates the activity of translation initiation factors and upregulates ribosome biogenesis. Activation of protein synthesis by Akt is phylogenetically conserved from Drosophila to humans, and is important for regulating cell growth, proliferation and cell survival. Consequently, translation defects due to aberrant Akt activation may be a crucial mechanism leading to tumorigenesis. However, few in vivo studies have established a causative role for aberrant protein synthesis control in cancer. A major challenge in the future will be to identify the specific mRNAs regulated at the level of translation control directly relevant for cellular transformation. In this review, we highlight and discuss the emerging molecular and genetic evidence that support a model by which deregulation of specific or global protein synthesis contributes to cancer.
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Affiliation(s)
- Davide Ruggero
- Human Genetics Program, Fox Chase Cancer Center, PA 19111, USA.
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37
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Ding H, Zhang C, Wu X, Yang C, Zhang X, Ding J, Xie Y. Novel indole α-methylene-γ-lactones as potent inhibitors for AKT-mTOR signaling pathway kinases. Bioorg Med Chem Lett 2005; 15:4799-802. [PMID: 16143526 DOI: 10.1016/j.bmcl.2005.07.050] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2005] [Revised: 07/04/2005] [Accepted: 07/18/2005] [Indexed: 10/25/2022]
Abstract
In an effort to generate novel anticancer agents, a series of hybrids of alpha-methylene-gamma-lactones and 2-phenyl indoles has been synthesized and evaluated for inhibition activities on the phosphorylation of AKT, mTOR, p70S6 kinase, and 4E-BP1. The results indicate that substitutes on the gamma-position of lactones have a rather significant influence on inhibition activities.
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Affiliation(s)
- Huasheng Ding
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the CAS, 555 Zuchongzhi Road, Shanghai 201203, PR China
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38
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Jansen AP, Camalier CE, Colburn NH. Epidermal expression of the translation inhibitor programmed cell death 4 suppresses tumorigenesis. Cancer Res 2005; 65:6034-41. [PMID: 16024603 DOI: 10.1158/0008-5472.can-04-2119] [Citation(s) in RCA: 180] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Programmed cell death 4 (Pdcd4) is a novel repressor of in vitro transformation. Pdcd4 directly inhibits the helicase activity of eukaryotic translation initiation factor 4A, a component of the translation initiation complex. To ascertain whether Pdcd4 suppresses tumor development in vivo, we have generated transgenic mice that overexpress Pdcd4 in the epidermis (K14-Pdcd4). K14-regulated Pdcd4 expression caused a neonatal short-hair phenotype due to early catagen entry compared with matched wild-type siblings. In response to the 7,12-dimethylbenz(a)anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA) mouse skin carcinogenesis protocol, K14-Pdcd4 mice showed significant reductions in papilloma formation, carcinoma incidence, and papilloma-to-carcinoma conversion frequency compared with wild-type mice. The translational efficiency of an mRNA engineered to form a structured 5' untranslated region (UTR) was attenuated in primary keratinocytes when Pdcd4 was overexpressed. Pdcd4 inhibited by 46% TPA-induced activator protein-1 (AP-1)-dependent transcription, an event required for tumorigenesis. CDK4 and ornithine decarboxylase (ODC) are candidates for Pdcd4-regulated translation as their mRNAs contain 5'structured UTRs. In K14-Pdcd4 primary keratinocytes expressing activated Ha-Ras to mimic DMBA-initiated epidermis, ODC and CDK4 protein levels were decreased by 40% and 46%, respectively. Expression of a protein encoded by 5' unstructured mRNA showed no change. These results extend to an in vivo model the observations that Pdcd4 inhibits both translation initiation and AP-1 activation while decreasing benign tumor development and malignant progression. The K14-Pdcd4 mice seem to validate translation initiation as a novel target for cancer prevention.
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Affiliation(s)
- Aaron P Jansen
- Gene Regulation Section, Laboratory of Cancer Prevention, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, USA.
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39
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Othumpangat S, Kashon M, Joseph P. Eukaryotic Translation Initiation Factor 4E Is a Cellular Target for Toxicity and Death Due to Exposure to Cadmium Chloride. J Biol Chem 2005; 280:25162-9. [PMID: 15878868 DOI: 10.1074/jbc.m414303200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Whether translation initiation factor 4E (eIF4E), the mRNA cap binding and rate-limiting factor required for translation, is a target for cytotoxicity and cell death induced by cadmium, a human carcinogen, was investigated. Exposure of human cell lines, HCT15, PLC/PR/5, HeLa, and Chang, to cadmium chloride resulted in cytotoxicity and cell death, and this was associated with a significant decrease in eIF4E protein levels. Similarly, specific silencing of the expression of the eIF4E gene, caused by a small interfering RNA, resulted in significant cytotoxicity and cell death. On the other hand, overexpression of the eIF4E gene was protective against the cadmium-induced cytotoxicity and cell death. Further studies revealed the absence of alterations in the eIF4E mRNA level in the cadmium-treated cells despite their decreased eIF4E protein level. In addition, exposure of cells to cadmium resulted in enhanced ubiquitination of eIF4E protein while inhibitors of proteasome activity reversed the cadmium-induced decrease of eIF4E protein. Exposure of cells to cadmium, as well as the specific silencing of eIF4E gene, also resulted in decreased cellular levels of cyclin D1, a critical cell cycle and growth regulating gene, suggesting that the observed inhibition of cyclin D1 gene expression in the cadmium-treated cells is most likely due to decreased cellular level of eIF4E. Taken together, our results demonstrate that the exposure of cells to cadmium chloride resulted in cytotoxicity and cell death due to enhanced ubiquitination and consequent proteolysis of eIF4E protein, which in turn diminished cellular levels of critical genes such as cyclin D1.
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Affiliation(s)
- Sreekumar Othumpangat
- Molecular Carcinogenesis Laboratory, Toxicology and Molecular Biology Branch, Biostatistics and Epidemiology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, West Virginia 26505, USA
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40
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Topisirovic I, Kentsis A, Perez JM, Guzman ML, Jordan CT, Borden KLB. Eukaryotic translation initiation factor 4E activity is modulated by HOXA9 at multiple levels. Mol Cell Biol 2005; 25:1100-12. [PMID: 15657436 PMCID: PMC544005 DOI: 10.1128/mcb.25.3.1100-1112.2005] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The eukaryotic translation initiation factor 4E (eIF4E) alters gene expression on multiple levels. In the cytoplasm, eIF4E acts in the rate-limiting step of translation initiation. In the nucleus, eIF4E facilitates nuclear export of a subset of mRNAs. Both of these functions contribute to eIF4E's ability to oncogenically transform cells. We report here that the homeodomain protein, HOXA9, is a positive regulator of eIF4E. HOXA9 stimulates eIF4E-dependent export of cyclin D1 and ornithine decarboxylase (ODC) mRNAs in the nucleus, as well as increases the translation efficiency of ODC mRNA in the cytoplasm. These activities depend on direct interactions of HOXA9 with eIF4E and are independent of the role of HOXA9 in transcription. At the biochemical level, HOXA9 mediates these effects by competing with factors that repress eIF4E function, in particular the proline-rich homeodomain PRH/Hex. This competitive mechanism of eIF4E regulation is disrupted in a subset of leukemias, where HOXA9 displaces PRH from eIF4E, thereby contributing to eIF4E's dysregulation. In regard to these results and our previous finding that approximately 200 homeodomain proteins contain eIF4E binding sites, we propose that homeodomain modulation of eIF4E activity is a novel means through which this family of proteins implements their effects on growth and development.
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MESH Headings
- Active Transport, Cell Nucleus/genetics
- Acute Disease
- Amino Acid Sequence
- Bone Marrow Cells/metabolism
- Cell Nucleus/genetics
- Cell Nucleus/metabolism
- Cyclin D1/genetics
- Cyclin D1/metabolism
- Cytoplasm/genetics
- Cytoplasm/metabolism
- Eukaryotic Initiation Factor-4E/genetics
- Eukaryotic Initiation Factor-4E/metabolism
- Homeodomain Proteins/genetics
- Homeodomain Proteins/metabolism
- Humans
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism
- Leukemia, Myeloid/genetics
- Leukemia, Myeloid/metabolism
- Molecular Sequence Data
- Ornithine Decarboxylase/genetics
- Ornithine Decarboxylase/metabolism
- Sequence Homology, Amino Acid
- Transcription Factors
- Transcription, Genetic
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Affiliation(s)
- Ivan Topisirovic
- Institute for Research in Immunovirology and Cancer, University of Montreal, Montreal, Quebec H3T 1J4, Canada
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41
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Worch J, Tickenbrock L, Schwäble J, Steffen B, Cauvet T, Mlody B, Buerger H, Koeffler HP, Berdel WE, Serve H, Müller-Tidow C. The serine-threonine kinase MNK1 is post-translationally stabilized by PML-RARalpha and regulates differentiation of hematopoietic cells. Oncogene 2005; 23:9162-72. [PMID: 15516979 DOI: 10.1038/sj.onc.1208164] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Microarray analyses were performed to identify target genes that are shared by the acute myeloid leukemia (AML) translocation products PML-RARalpha, PLZF-RARalpha and AML1-ETO in inducibly transfected U937 cell lines. The cytoplasmic serine and threonine kinase MNK1 was identified as one of the target genes. At the protein level, MNK1 was significantly induced by each of the three fusion proteins. Protein half-life analyses showed that PML-RARalpha enhanced MNK1 protein stability in U937 cells and ATRA exposure decreased MNK1 half-life in NB4 cells. EIF4E, the main MNK1 substrate, plays a role in the pathogenesis of a variety of cancers. Upon MNK1 overexpression, eIF4E phosphorylation increased as a sign of functional activation. Interestingly, MNK1 protein expression decreased during myeloid differentiation. Inhibition of MNK1 activity by a specific inhibitor (CGP57380) enhanced differentiation of HL60 and 32D cells, further suggesting a role for MNK1 in the myeloid differentiation. In addition, kinase dead mutants of MNK1 significantly impaired proliferation of 32D cells. Immunohistochemistry of primary AML bone marrow biopsies showed strong cytoplasmic MNK1 expression in 25 of 99 AML specimens (25%). MNK1 expression was associated with high levels of c-myc expression. Taken together, we identified MNK1 as a target gene of several leukemogenic fusion proteins in AML. MNK1 plays a role in myeloid differentiation. These data suggest a role for MNK1 in the AML fusion protein-associated differentiation block.
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Affiliation(s)
- Jennifer Worch
- Department of Medicine, Hematology and Oncology, University of Münster, Domagkstr. 3, 48129 Münster, Germany
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42
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Duncan RF, Peterson H, Sevanian A. Signal transduction pathways leading to increased eIF4E phosphorylation caused by oxidative stress. Free Radic Biol Med 2005; 38:631-43. [PMID: 15683719 DOI: 10.1016/j.freeradbiomed.2004.09.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2004] [Accepted: 09/29/2004] [Indexed: 11/17/2022]
Abstract
Phosphorylation of eIF4E is associated with increased activity of the translational machinery. Oxidative stress of resident vascular cells and macrophages potently enhances eIF4E phosphorylation. Oxidative stress activates numerous intracellular signaling pathways, including MAP-family kinase pathways and pathways leading to S6 kinase activation. The activation of MAP-family kinase pathways leads to the activation of Mnk and hence eIF4E phosphorylation, whereas the S6 kinase pathway is not involved, based on insensitivity to its inhibitors rapamycin and wortmannin. Ca-dependent pathways have been implicated in eIF4E phosphorylation, but the oxidative stress response pathway targeting eIF4E does not appear to require their participation. The results suggest that the potent activation of ERK and p38 protein kinases is sufficient to account for the enhanced eIF4E phosphorylation. Either is independently sufficient to effect the change, as neither PD098059 (Erk pathway inhibitor) nor SB202190 (p38 pathway inhibitor) alone can block the response, but when combined the response is almost completely abrogated. Mnk activation by oxidative stress leading to enhanced eIF4E phosphorylation may play a role in promoting stress-induced hyperproliferative diseases, such as smooth muscle cell proliferation and hypertrophy in cardiovascular disease, as the synthesis of several key regulators of cell growth has been shown to be held in check by moderation of eIF4E activity.
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Affiliation(s)
- Roger F Duncan
- Department of Molecular Pharmacology and Toxicology, School of Pharmacy, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90033, USA.
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43
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Joseph P, Lei YX, Ong TM. Up-regulation of expression of translation factors--a novel molecular mechanism for cadmium carcinogenesis. Mol Cell Biochem 2004; 255:93-101. [PMID: 14971650 DOI: 10.1023/b:mcbi.0000007265.38475.f7] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The molecular mechanisms potentially responsible for cadmium carcinogenesis were investigated by differential gene expression analysis of Balb/c-3T3 cells morphologically transformed with cadmium chloride. Differential display analysis of gene expression revealed overexpression of mouse Translation Initiation Factor 3 (TIF3; GenBank Accession Number AF 271072) and Translation Elongation Factor-1delta (TEF-1delta; GenBank Accession Number AF 304351) in the transformed cells compared with the control cells. The full length cDNAs for TIF3 and TEF-1delta were cloned and sequenced. Transfection of mammalian cells with an expression vector containing either TIF3 or TEF-1delta cDNA resulted in overexpression of the encoded protein. Overexpression of the cDNA-encoded TIF3 and TEF-1delta proteins in NIH3T3 cells was oncogenic as evidenced by the appearance of transformed foci capable of anchorage-independent growth on soft agar and tumorigenesis in nude mouse. Blocking the translation of TIF3 and TEF-1delta proteins using the corresponding antisense mRNA resulted in a significant reversal of the oncogenic potential of cadmium transformed Balb/c-3T3 cells as evidenced from the suppression of anchorage-independent growth on soft agar and diminished tumorigenesis in nude mouse. These findings demonstrate that the up-regulation of expression of TIF3 and TEF-1delta is a novel molecular mechanism responsible, at least in part, for cadmium carcinogenesis.
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Affiliation(s)
- Pius Joseph
- Molecular Epidemiology Laboratory, Toxicology and Molecular Biology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA.
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44
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Joseph P, O'Kernick CM, Othumpangat S, Lei YX, Yuan BZ, Ong TM. Expression profile of eukaryotic translation factors in human cancer tissues and cell lines. Mol Carcinog 2004; 40:171-9. [PMID: 15224349 DOI: 10.1002/mc.20033] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Several studies have demonstrated the overexpression of certain eukaryotic translation factors in human cancer cell lines and in malignant tissues. In this study, with human cancer cell lines derived from lungs, breast, prostate, and skin, we have examined the expression profile of 36 translation factors consisting of 27 initiation factors, 8 elongation factors, and 1 termination factor. Translation initiation factors 2C2 and 4E1 and translation elongation factors 1A2 and 1delta were found overexpressed (2- to 2000-fold) in many of the cancer cell lines compared to their corresponding normal cell lines. Among the translation factors analyzed, translation elongation factor 1A2 exhibited the most significant alteration in expression: 10- to 2000-fold overexpression was noticed in nine out of ten cancer cell lines analyzed. Whether the overexpression of translation elongation factor 1A2 can be used as a potential tumor marker was tested with the cancer profiling array (BD Biosciences, Palo Alto, CA) consisting of 241 paired cDNA samples generated from 13 different cancer/noncancer tissue types. Overexpression of translation elongation factor 1A2 was noticed in several tumor tissue samples, most notably in the human colon cancer samples which exhibited at least a twofold overexpression among 35% of the samples analyzed. Besides colon, tumor samples derived from lungs, kidney, rectum, and ovary also exhibited more than a twofold overexpression of translation elongation factor 1A2 in at least 20% of the samples analyzed. These results indicate that human carcinogenesis is often associated with alterations in the expression of various translation factors especially the overexpression of eukaryotic translation elongation factor 1A2.
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Affiliation(s)
- Pius Joseph
- Molecular Carcinogenesis Laboratory, Toxicology and Molecular Biology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, West Virginia 26505, USA
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45
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Abstract
Activation of the phosphatidylinositol 3' kinase-Akt pathway has long been associated with malignant transformation and antiapoptotic signaling. Mutations downstream of Akt that activate the TOR kinase are found in tumor-prone syndromes, while overexpression of translation initiation complex components, such as eIF4E, occurs frequently in human cancer. However, direct roles for TOR signaling or eIF4E overexpression, in the genesis of cancer, have been lacking. Recent papers, including one by in this issue of Cancer Cell, clearly establish that dysregulation of cap-dependent translation confers malignant characteristics and induces cancer by suppressing apoptosis, underscoring the potential of therapeutics that selectively target the Akt-TOR-eIF4E pathway.
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Affiliation(s)
- Mary-Ann Bjornsti
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, 332 N. Lauderdale St., Memphis, TN 38105, USA
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46
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Abstract
The contribution of the mRNA cap-binding protein, eIF-4E, to malignant transformation and progression has been illuminated over the past decade. eIF-4E overexpression has been demonstrated in human tumors of the breast, head and neck, colon, prostate, bladder, cervix and lung, and has been related to disease progression. Overexpression of eIF-4E in experimental models dramatically alters cellular morphology, enhances proliferation and induces cellular transformation, tumorigenesis and metastasis. Conversely, blocking eIF-4E function by expression of antisense RNA, or overexpression of the inhibitory eIF-4E binding proteins (4E-BPs), suppresses cellular transformation, tumor growth, tumor invasiveness and metastasis. Although eIF-4E regulates the recruitment of mRNA to ribosomes, and thereby globally regulates cap-dependent protein synthesis, eIF-4E contributes to malignancy by selectively enabling the translation of a limited pool of mRNAs--those that generally encode key proteins involved in cellular growth, angiogenesis, survival and malignancy (e.g. cyclin D1, c-myc, vascular endothelial growth factor, matrix metalloprotease 9). A deeper understanding of the role of eIF-4E in regulating the translation of the diverse gene products involved in all aspects of malignancy will improve the capacity to exploit eIF-4E as a therapeutic target and as a marker for human cancer progression.
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Affiliation(s)
- Arrigo De Benedetti
- Department of Biochemistry and Molecular Biology, Louisiana State University Medical Center, Shreveport, 1501 Kings Highway, PO Box 33932, Shreveport, LA 71130, USA.
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47
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Holland EC, Sonenberg N, Pandolfi PP, Thomas G. Signaling control of mRNA translation in cancer pathogenesis. Oncogene 2004; 23:3138-44. [PMID: 15094763 DOI: 10.1038/sj.onc.1207590] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The regulation of translation and the control of ribosome biogenesis are essential cellular processes whose impact on cell growth and proliferation is manifested at a number of specific levels. Disruption in one or more of the steps that control protein biosynthesis has been associated with alterations in the regulation of cell growth and cell cycle progression. Consistent with this, tumor suppressors and proto-oncogenes have been found to act on these functions and may therefore regulate malignant progression by affecting the protein synthetic machinery. Although many studies have correlated deregulation of protein biosynthesis with cancer, it remains to be established whether this process is necessary and/or sufficient for neoplastic transformation and metastasis.
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Affiliation(s)
- Eric C Holland
- Department of Surgery, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA.
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48
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Mamane Y, Petroulakis E, Rong L, Yoshida K, Ler LW, Sonenberg N. eIF4E--from translation to transformation. Oncogene 2004; 23:3172-9. [PMID: 15094766 DOI: 10.1038/sj.onc.1207549] [Citation(s) in RCA: 352] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Over the years, studies have focused on the transcriptional regulation of oncogenesis. More recently, a growing emphasis has been placed on translational control. The Ras and Akt signal transduction pathways play a critical role in regulating mRNA translation and cellular transformation. The question arises: How might the Ras and Akt signaling pathways affect translation and mediate transformation? These pathways converge on a crucial effector of translation, the initiation factor eIF4E, which binds the 5'cap of mRNAs. This review focuses on the role of eIF4E in oncogenesis. eIF4E controls the translation of various malignancy-associated mRNAs which are involved in polyamine synthesis, cell cycle progression, activation of proto-oncogenes, angiogenesis, autocrine growth stimulation, cell survival, invasion and communication with the extracellular environment. eIF4E-mediated translational modulation of these mRNAs plays a pivotal role in both tumor formation and metastasis. Interestingly, eIF4E activity is implicated in mitosis, embryogenesis and in apoptosis. Finally, the finding that eIF4E is overexpressed in several human cancers makes it a prime target for anticancer therapies.
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Affiliation(s)
- Yaël Mamane
- Department of Biochemistry, McGill Cancer Centre, McGill University, 3655 Promenade Sir-William-Osler, Montreal, Quebec, Canada, H3G 1Y6
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49
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Affiliation(s)
- Mary-Ann Bjornsti
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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50
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Perkins DJ, Barber GN. Defects in translational regulation mediated by the alpha subunit of eukaryotic initiation factor 2 inhibit antiviral activity and facilitate the malignant transformation of human fibroblasts. Mol Cell Biol 2004; 24:2025-40. [PMID: 14966282 PMCID: PMC350553 DOI: 10.1128/mcb.24.5.2025-2040.2004] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Suppression of protein synthesis through phosphorylation of the translation initiation factor alpha subunit of eukaryotic initiation factor 2 (eIF2alpha) is known to occur in response to many forms of cellular stress. To further study this, we have developed novel cell lines that inducibly express FLAG-tagged versions of either the phosphomimetic eIF2alpha variant, eIF2alpha-S51D, or the phosphorylation-insensitive eIF2alpha-S51A. These variants showed authentic subcellular localization, were incorporated into endogenous ternary complexes, and were able to modulate overall rates of protein synthesis as well as influence cell division. However, phosphorylation of eIF2alpha failed to induce cell death or sensitize cells to killing by proapoptotic stimuli, though it was able to inhibit viral replication, confirming the role of eIF2alpha in host defense. Further, although the eIF2alpha-S51A variant has been shown to transform NIH 3T3 cells, it was unable to transform the murine fibroblast 3T3 L1 cell line. To therefore clarify this issue, we explored the role of eIF2alpha in growth control and demonstrated that the eIF2alpha-S51A variant is capable of collaborating with hTERT and the simian virus 40 large T antigen in the transformation of primary human kidney cells. Thus, dysregulation of translation initiation is indeed sufficient to cooperate with defined oncogenic elements and participate in the tumorigenesis of human tissue.
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Affiliation(s)
- Darren J Perkins
- Department of Microbiology and Immunology and Sylvester Comprehensive Cancer Center, University of Miami School of Medicine, Miami, Florida 33136, USA
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