1
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Translation Initiation Regulated by RNA-Binding Protein in Mammals: The Modulation of Translation Initiation Complex by Trans-Acting Factors. Cells 2021; 10:cells10071711. [PMID: 34359885 PMCID: PMC8306974 DOI: 10.3390/cells10071711] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/03/2021] [Accepted: 07/04/2021] [Indexed: 12/15/2022] Open
Abstract
Protein synthesis is tightly regulated at each step of translation. In particular, the formation of the basic cap-binding complex, eukaryotic initiation factor 4F (eIF4F) complex, on the 5' cap structure of mRNA is positioned as the rate-limiting step, and various cis-elements on mRNA contribute to fine-tune spatiotemporal protein expression. The cis-element on mRNAs is recognized and bound to the trans-acting factors, which enable the regulation of the translation rate or mRNA stability. In this review, we focus on the molecular mechanism of how the assembly of the eIF4F complex is regulated on the cap structure of mRNAs. We also summarize the fine-tuned regulation of translation initiation by various trans-acting factors through cis-elements on mRNAs.
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2
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Kardos GR, Gowda R, Dinavahi SS, Kimball S, Robertson GP. Salubrinal in Combination With 4E1RCat Synergistically Impairs Melanoma Development by Disrupting the Protein Synthetic Machinery. Front Oncol 2020; 10:834. [PMID: 32637352 PMCID: PMC7317660 DOI: 10.3389/fonc.2020.00834] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 04/28/2020] [Indexed: 12/15/2022] Open
Abstract
Increased protein synthesis is a key process in melanoma, which is regulated by the ALDH18A1 gene encoding pyrroline-5-carboxylate synthase (P5CS). P5CS is involved in proline biosynthesis and targeting ALDH18A1 has previously been shown to inhibit melanoma development by decreasing intracellular proline levels to increase the phosphorylation of eIF2α mediated by GCN2, which then impairs mRNA translation. Since there are no current inhibitors of P5CS, decreased eIF2α phosphorylation in melanoma was targeted using salubrinal (a specific inhibitor of eIF2α phosphatase enzymes). While salubrinal alone was ineffective, the combined use of salubrinal and 4E1RCat (a dual inhibitor of eIF4E:4E-BP1 and eIF4E:eIF4G interaction to prevent assembly of the eIF4F complex and inhibit cap-dependent translation) was found to be effective at decreasing protein synthesis, protein translation, and cell cycle progression to synergistically decrease melanoma cell viability and inhibited xenograft melanoma tumor development. The combination of these agents synergistically decreased melanoma cell viability while having minimal effect on normal cells. This is the first report demonstrating that it is possible to inhibit melanoma viability by targeting eIF2α signaling using salubrinal and 4E1RCat to disrupt assembly of the eIF4F complex.
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Affiliation(s)
- Gregory R Kardos
- Department of Pharmacology, The Pennsylvania State University College of Medicine, Hershey, PA, United States.,The Melanoma and Skin Cancer Center, The Pennsylvania State University College of Medicine, Hershey, PA, United States.,The Melanoma Therapeutics Program, The Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Raghavendra Gowda
- Department of Pharmacology, The Pennsylvania State University College of Medicine, Hershey, PA, United States.,The Melanoma and Skin Cancer Center, The Pennsylvania State University College of Medicine, Hershey, PA, United States.,The Melanoma Therapeutics Program, The Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Saketh Sriram Dinavahi
- Department of Pharmacology, The Pennsylvania State University College of Medicine, Hershey, PA, United States.,The Melanoma and Skin Cancer Center, The Pennsylvania State University College of Medicine, Hershey, PA, United States.,The Melanoma Therapeutics Program, The Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Scot Kimball
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Gavin P Robertson
- Department of Pharmacology, The Pennsylvania State University College of Medicine, Hershey, PA, United States.,The Melanoma and Skin Cancer Center, The Pennsylvania State University College of Medicine, Hershey, PA, United States.,The Melanoma Therapeutics Program, The Pennsylvania State University College of Medicine, Hershey, PA, United States.,Department of Surgery, The Pennsylvania State University College of Medicine, Hershey, PA, United States.,Department of Pathology, The Pennsylvania State University College of Medicine, Hershey, PA, United States.,Department of Dermatology, The Pennsylvania State University College of Medicine, Hershey, PA, United States
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3
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Kosciuczuk EM, Kar AK, Blyth GT, Fischietti M, Abedin S, Mina AA, Siliezar R, Rzymski T, Brzozka K, Eklund EA, Beauchamp EM, Eckerdt F, Saleiro D, Platanias LC. Inhibitory effects of SEL201 in acute myeloid leukemia. Oncotarget 2019; 10:7112-7121. [PMID: 31903169 PMCID: PMC6935253 DOI: 10.18632/oncotarget.27388] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 12/02/2019] [Indexed: 12/30/2022] Open
Abstract
MAPK interacting kinase (MNK), a downstream effector of mitogen-activated protein kinase (MAPK) pathways, activates eukaryotic translation initiation factor 4E (eIF4E) and plays a key role in the mRNA translation of mitogenic and antiapoptotic genes in acute myeloid leukemia (AML) cells. We examined the antileukemic properties of a novel MNK inhibitor, SEL201. Our studies provide evidence that SEL201 suppresses eIF4E phosphorylation on Ser209 in AML cell lines and in primary patient-derived AML cells. Such effects lead to growth inhibitory effects and leukemic cell apoptosis, as well as suppression of leukemic progenitor colony formation. Combination of SEL201 with 5'-azacytidine or rapamycin results in synergistic inhibition of AML cell growth. Collectively, these results suggest that SEL201 has significant antileukemic activity and further underscore the relevance of the MNK pathway in leukemogenesis.
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Affiliation(s)
- Ewa M Kosciuczuk
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois, USA.,Division of Hematology-Oncology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.,Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, USA
| | - Aroop K Kar
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois, USA.,Division of Hematology/Oncology/Stem Cell Transplantation, Department of Pediatrics, Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
| | - Gavin T Blyth
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois, USA.,Division of Hematology-Oncology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Mariafausta Fischietti
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois, USA.,Division of Hematology-Oncology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Sameem Abedin
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois, USA.,Division of Hematology-Oncology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.,Division of Hematology and Oncology Department of Medicine Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Alain A Mina
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois, USA.,Division of Hematology-Oncology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Rebekah Siliezar
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois, USA
| | | | | | - Elizabeth A Eklund
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois, USA.,Division of Hematology-Oncology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.,Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, USA
| | - Elspeth M Beauchamp
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois, USA.,Division of Hematology-Oncology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.,Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, USA
| | - Frank Eckerdt
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois, USA.,Department of Neurological Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Diana Saleiro
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois, USA.,Division of Hematology-Oncology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Leonidas C Platanias
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois, USA.,Division of Hematology-Oncology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.,Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, USA
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4
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Amorim IS, Lach G, Gkogkas CG. The Role of the Eukaryotic Translation Initiation Factor 4E (eIF4E) in Neuropsychiatric Disorders. Front Genet 2018; 9:561. [PMID: 30532767 PMCID: PMC6265315 DOI: 10.3389/fgene.2018.00561] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 11/06/2018] [Indexed: 12/24/2022] Open
Abstract
Protein synthesis in eukaryotic cells is a complex, multi-step and tightly regulated process. Translation initiation, the rate limiting step in protein synthesis, is dependent on the activity of eukaryotic translation Initiation Factor 4E (eIF4E). eIF4E is the cap-binding protein which, in synergy with proteins such as the helicase eIF4A and the scaffolding protein eIF4G, binds to mRNA, allowing the recruitment of ribosomes and translation initiation. The function of eIF4E is tightly regulated in cells under normal physiological conditions and can be controlled by post-translational modifications, such as phosphorylation, and by the binding of inhibitory proteins, including eIF4E binding proteins (4E-BPs) and CYFIP1. Recent studies have highlighted the importance of eIF4E in normal or aberrant function of the nervous system. In this mini-review, we will highlight the role of eIF4E function and regulation in the pathophysiology of neurodevelopmental and neuropsychiatric disorders.
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Affiliation(s)
- Inês S Amorim
- Centre for Discovery Brain Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Gilliard Lach
- Centre for Discovery Brain Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Christos G Gkogkas
- Centre for Discovery Brain Sciences, The University of Edinburgh, Edinburgh, United Kingdom.,The Patrick Wild Centre, The University of Edinburgh, Edinburgh, United Kingdom
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5
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De A, Jacobson BA, Peterson MS, Stelzner ME, Jay-Dixon J, Kratzke MG, Patel MR, Bitterman PB, Kratzke RA. Inhibition of oncogenic cap-dependent translation by 4EGI-1 reduces growth, enhances chemosensitivity and alters genome-wide translation in non-small cell lung cancer. Cancer Gene Ther 2018; 26:157-165. [DOI: 10.1038/s41417-018-0058-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 09/22/2018] [Accepted: 10/20/2018] [Indexed: 12/20/2022]
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6
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Ba Q, Li X, Huang C, Li J, Fu Y, Chen P, Duan J, Hao M, Zhang Y, Li J, Sun C, Ying H, Song H, Zhang R, Shen Z, Wang H. BCCIPβ modulates the ribosomal and extraribosomal function of S7 through a direct interaction. J Mol Cell Biol 2018; 9:209-219. [PMID: 28510697 PMCID: PMC5907838 DOI: 10.1093/jmcb/mjx019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Accepted: 05/14/2017] [Indexed: 11/14/2022] Open
Abstract
Extraribosomal functions of ribosomal proteins (RPs) have gained much attention for their implications in tumorigenesis and progression. However, the regulations for transition between the ribosomal and extraribosomal functions of RPs are rarely reported. Herein, we identified a ribosomal protein S7-interacting partner, BCCIPβ, which modulates the functional conversion of S7. Through the N-terminal acidic domain, BCCIPβ interacts with the central basic region in S7 and regulates the extraribosomal distribution of S7. BCCIPβ deficiency abrogates the ribosomal accumulation but enhances the ribosome-free location of S7. This translocation further impairs protein synthesis and triggers ribosomal stress. Consequently, BCCIPβ deficiency suppresses the ribosomal function and initiates the extraribosomal function of S7, resulting in restriction of cell proliferation. Moreover, clinically relevant S7 mutations were found to dampen the interaction with BCCIPβ and facilitate the functional transition of S7. In conclusion, BCCIPβ, as a S7 modulator, contributes to the regulation of ribosomal and extraribosomal functions of S7 and has implications in cell growth and tumor development.
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Affiliation(s)
- Qian Ba
- School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xiaoguang Li
- School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Chao Huang
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Junyang Li
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yijing Fu
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Peizhan Chen
- School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Juan Duan
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Miao Hao
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yinghua Zhang
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jingquan Li
- School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Chuanqi Sun
- Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Hao Ying
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Haiyun Song
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Ruiwen Zhang
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
| | - Zhiyuan Shen
- Rutgers Cancer Institute of New Jersey, Department of Radiation Oncology of Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, New Brunswick, NJ 08903, USA
| | - Hui Wang
- School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- Correspondence to: Hui Wang, E-mail:
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7
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Separation of low and high grade colon and rectum carcinoma by eukaryotic translation initiation factors 1, 5 and 6. Oncotarget 2017; 8:101224-101243. [PMID: 29254159 PMCID: PMC5731869 DOI: 10.18632/oncotarget.20642] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 07/31/2017] [Indexed: 02/06/2023] Open
Abstract
Colorectal cancer (CRC) is the third most common cause of cancer related death worldwide. Furthermore, with more than 1.2 million cases registered per year, it constitutes the third most frequent diagnosed cancer entity worldwide. Deregulation of protein synthesis has received considerable attention as a major step in cancer development and progression. Eukaryotic translation initiation factors (eIFs) are involved in the regulation of protein synthesis and are functionally linked to the phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway. The identification of factors accounting for colorectal carcinoma (CRC) development is a major gap in the field. Besides the importance of eIF3 subunits and the eIF4 complex, eIF1, eIF5 and eIF6 were found to be altered in primary and metastatic CRC. We observed significant difference in the expression profile between low and high grade CRC. eIF1, eIF5 and eIF6 are involved in translational control in CRC. Our findings also indicate a probable clinical impact when separating them into low and high grade colon and rectum carcinoma. eIF and mTOR expression were analysed on protein and mRNA level in primary low and high grade colon carcinoma (CC) and rectum carcinoma (RC) samples in comparison to non-neoplastic tissue without any disease-related pathology. To assess the therapeutic potential of targeting eIF1, eIF5 and eIF6 siRNA knockdown in HCT116 and HT29 cells was performed. We evaluated the eIF knockdown efficacy on protein and mRNA level and investigated proliferation, apoptosis, invasion, as well as colony forming and polysome associated fractions. These results indicate that eIFs, in particular eIF1, eIF5 and eIF6 play a major role in translational control in colon and rectum cancer.
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8
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Wang ZQ, Faddaoui A, Bachvarova M, Plante M, Gregoire J, Renaud MC, Sebastianelli A, Guillemette C, Gobeil S, Macdonald E, Vanderhyden B, Bachvarov D. BCAT1 expression associates with ovarian cancer progression: possible implications in altered disease metabolism. Oncotarget 2016; 6:31522-43. [PMID: 26372729 PMCID: PMC4741622 DOI: 10.18632/oncotarget.5159] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 08/28/2015] [Indexed: 12/17/2022] Open
Abstract
Previously, we have identified the branched chain amino-acid transaminase 1 (BCAT1) gene as notably hypomethylated in low-malignant potential (LMP) and high-grade (HG) serous epithelial ovarian tumors, compared to normal ovarian tissues. Here we show that BCAT1 is strongly overexpressed in both LMP and HG serous epithelial ovarian tumors, which probably correlates with its hypomethylated status. Knockdown of the BCAT1 expression in epithelial ovarian cancer (EOC) cells led to sharp decrease of cell proliferation, migration and invasion and inhibited cell cycle progression. BCAT1 silencing was associated with the suppression of numerous genes and pathways known previously to be implicated in ovarian tumorigenesis, and the induction of some tumor suppressor genes (TSGs). Moreover, BCAT1 suppression resulted in downregulation of numerous genes implicated in lipid production and protein synthesis, suggesting its important role in controlling EOC metabolism. Further metabolomic analyses were indicative for significant depletion of most amino acids and different phospho- and sphingolipids following BCAT1 knockdown. Finally, BCAT1 suppression led to significantly prolonged survival time in xenograft model of advanced peritoneal EOC. Taken together, our findings provide new insights about the functional role of BCAT1 in ovarian carcinogenesis and identify this transaminase as a novel EOC biomarker and putative EOC therapeutic target.
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Affiliation(s)
- Zhi-Qiang Wang
- Department of Molecular Medicine, Laval University, Québec PQ, Canada.,Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec PQ, Canada
| | - Adnen Faddaoui
- Department of Molecular Medicine, Laval University, Québec PQ, Canada.,Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec PQ, Canada
| | | | - Marie Plante
- Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec PQ, Canada.,Department of Obstetrics and Gynecology, Laval University, Québec PQ, Canada
| | - Jean Gregoire
- Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec PQ, Canada.,Department of Obstetrics and Gynecology, Laval University, Québec PQ, Canada
| | - Marie-Claude Renaud
- Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec PQ, Canada.,Department of Obstetrics and Gynecology, Laval University, Québec PQ, Canada
| | - Alexandra Sebastianelli
- Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec PQ, Canada.,Department of Obstetrics and Gynecology, Laval University, Québec PQ, Canada
| | - Chantal Guillemette
- Centre de recherche du CHU de Québec, CHUL, Québec PQ, Canada.,Faculty of Pharmacy, Laval University, Québec PQ, Canada
| | - Stéphane Gobeil
- Department of Molecular Medicine, Laval University, Québec PQ, Canada.,Centre de recherche du CHU de Québec, CHUL, Québec PQ, Canada
| | - Elizabeth Macdonald
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Barbara Vanderhyden
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Dimcho Bachvarov
- Department of Molecular Medicine, Laval University, Québec PQ, Canada.,Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec PQ, Canada
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9
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Fukao A, Aoyama T, Fujiwara T. The molecular mechanism of translational control via the communication between the microRNA pathway and RNA-binding proteins. RNA Biol 2016; 12:922-6. [PMID: 26274611 DOI: 10.1080/15476286.2015.1073436] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
MicroRNAs (miRNAs) are evolutionarily conserved small noncoding RNAs found in most plants and animals. The miRNA pathway regulates posttranscriptional gene expression through the deadenylation and translation repression of target mRNAs. Recent studies revealed that the early step of translation initiation is the target of "pure" translation repression by the miRNA pathway. Moreover, particularly in animals, the miRNA pathway is required for neuronal development, differentiation, and plasticity. In addition, some functions of miRNAs are regulated by RNA-binding proteins (RBPs) in neuronal cells. This review summarizes new insights about the molecular mechanisms of pure translation repression by miRNA pathway and the communication between the miRNA pathway and RBPs in neuronal local translation.
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Affiliation(s)
- Akira Fukao
- a Laboratory of Biochemistry; Department of Pharmacy; Kinki University ; Higashi-Osaka , Japan
| | - Tomohiko Aoyama
- b Graduate School of Pharmaceutical Sciences; Nagoya City University ; Mizuho-ku, Nagoya , Japan
| | - Toshinobu Fujiwara
- a Laboratory of Biochemistry; Department of Pharmacy; Kinki University ; Higashi-Osaka , Japan
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10
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Hanash S, Taguchi A, Wang H, Ostrin EJ. Deciphering the complexity of the cancer proteome for diagnostic applications. Expert Rev Mol Diagn 2016; 16:399-405. [PMID: 26694525 DOI: 10.1586/14737159.2016.1135738] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The proteome is the most functional component encoded in the genome, yet most features of the proteome that are deregulated in cancer cannot be predicted from genomic analysis alone. These include post-translational modifications (PTMs), sub-cellular localization, networks and circuitry, formation of complexes, and functional activity, all of which could play a role or be affected as part of tumorigenesis. Thus, there is a substantial opportunity to elucidate protein alterations in cancer and to translate knowledge into diagnostics and therapeutics. The progress made in mining the cancer proteome for diagnostic applications and the path forward are herein reviewed.
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Affiliation(s)
- Samir Hanash
- a Department of Clinical Cancer Prevention , University of Texas MD Anderson Cancer Center , Houston , Texas , US
| | - Ayumu Taguchi
- b Department of Translational Molecular Pathology , University of Texas MD Anderson Cancer Center , Houston , Texas , US
| | - Hong Wang
- a Department of Clinical Cancer Prevention , University of Texas MD Anderson Cancer Center , Houston , Texas , US
| | - Edwin J Ostrin
- c Department of Pulmonary Medicine , University of Texas MD Anderson Cancer Center , Houston , Texas , US
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11
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Kardos GR, Robertson GP. Therapeutic interventions to disrupt the protein synthetic machinery in melanoma. Pigment Cell Melanoma Res 2015; 28:501-19. [PMID: 26139519 PMCID: PMC4716672 DOI: 10.1111/pcmr.12391] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 06/30/2015] [Indexed: 01/23/2023]
Abstract
Control of the protein synthetic machinery is deregulated in many cancers, including melanoma, to increase the protein production. Tumor suppressors and oncogenes play key roles in protein synthesis from the transcription of rRNA and ribosome biogenesis to mRNA translation initiation and protein synthesis. Major signaling pathways are altered in melanoma to modulate the protein synthetic machinery, thereby promoting tumor development. However, despite the importance of this process in melanoma development, involvement of the protein synthetic machinery in this cancer type is an underdeveloped area of study. Here, we review the coupling of melanoma development to deregulation of the protein synthetic machinery. We examine existing knowledge regarding RNA polymerase I inhibition and mRNA translation focusing on their inhibition for therapeutic applications in melanoma. Furthermore, the contribution of amino acid biosynthesis and involvement of ribosomal proteins are also reviewed as future therapeutic strategies to target deregulated protein production in melanoma.
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Affiliation(s)
- Gregory R. Kardos
- Department of Pharmacology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
- The Melanoma and Skin Cancer Center, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
- The Melanoma Therapeutics Program, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
| | - Gavin P. Robertson
- Department of Pharmacology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
- Department of Pathology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
- Department of Dermatology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
- Department of Surgery, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
- The Melanoma and Skin Cancer Center, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
- The Melanoma Therapeutics Program, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
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12
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Chicher J, Simonetti A, Kuhn L, Schaeffer L, Hammann P, Eriani G, Martin F. Purification of mRNA-programmed translation initiation complexes suitable for mass spectrometry analysis. Proteomics 2015; 15:2417-25. [PMID: 25914180 DOI: 10.1002/pmic.201400628] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2014] [Revised: 02/27/2015] [Accepted: 04/21/2015] [Indexed: 12/21/2022]
Abstract
Liquid Chromatography coupled to tandem mass spectrometry (nanoLC-MS/MS) is a powerful analytical technique for the identification and mass analysis of complex protein mixtures. Here, we present a combination of methods developed for the extensive/deep proteomic analysis of purified ribosome/mRNA particles assembled in rabbit reticulocyte lysate (RRL). Ribosomes are assembled on chimeric biotinylated mRNA-DNA molecules immobilized on streptavidin-coated beads and incubated with RRL to form initiation complexes. After washing steps, the complexes are trypsin-digested directly on the beads in semi-native condition or after their elution from the beads in denaturing Laemmli buffer. The nanoLC-MS/MS analysis performed on complexes assembled on β-globin, viral HCV, and histone H4 mRNAs revealed significant differences in initiation factors composition in agreement with models of translation initiation used by these different types of mRNAs. Using Laemmli-denaturing condition induces release of deeply buried peptides from the ribosome and eukaryotic initiation factor 3 (eIF3) allowing the identification of the nearly complete set of ribosomal proteins.
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Affiliation(s)
- Johana Chicher
- Institut de Biologie Moléculaire et Cellulaire, Plateforme Protéomique Strasbourg - Esplanade, Université De Strasbourg, Strasbourg, France
| | - Angelita Simonetti
- Institut de Biologie Moléculaire et Cellulaire, "Architecture et Réactivité de l'ARN", Université De Strasbourg, Strasbourg, France
| | - Lauriane Kuhn
- Institut de Biologie Moléculaire et Cellulaire, Plateforme Protéomique Strasbourg - Esplanade, Université De Strasbourg, Strasbourg, France
| | - Laure Schaeffer
- Institut de Biologie Moléculaire et Cellulaire, "Architecture et Réactivité de l'ARN", Université De Strasbourg, Strasbourg, France
| | - Philippe Hammann
- Institut de Biologie Moléculaire et Cellulaire, Plateforme Protéomique Strasbourg - Esplanade, Université De Strasbourg, Strasbourg, France
| | - Gilbert Eriani
- Institut de Biologie Moléculaire et Cellulaire, "Architecture et Réactivité de l'ARN", Université De Strasbourg, Strasbourg, France
| | - Franck Martin
- Institut de Biologie Moléculaire et Cellulaire, "Architecture et Réactivité de l'ARN", Université De Strasbourg, Strasbourg, France
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13
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Eukaryotic Translation Initiation Factor 4E Is a Feed-Forward Translational Coactivator of Transforming Growth Factor β Early Protransforming Events in Breast Epithelial Cells. Mol Cell Biol 2015; 35:2597-609. [PMID: 25986608 DOI: 10.1128/mcb.00324-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 05/12/2015] [Indexed: 12/18/2022] Open
Abstract
Eukaryotic translation initiation factor 4E (eIF4E) is overexpressed early in breast cancers in association with disease progression and reduced survival. Much remains to be understood regarding the role of eIF4E in human cancer. We determined, using immortalized human breast epithelial cells, that elevated expression of eIF4E translationally activates the transforming growth factor β (TGF-β) pathway, promoting cell invasion, a loss of cell polarity, increased cell survival, and other hallmarks of early neoplasia. Overexpression of eIF4E is shown to facilitate the selective translation of integrin β1 mRNA, which drives the translationally controlled assembly of a TGF-β receptor signaling complex containing α3β1 integrins, β-catenin, TGF-β receptor I, E-cadherin, and phosphorylated Smad2/3. This receptor complex acutely sensitizes nonmalignant breast epithelial cells to activation by typically substimulatory levels of activated TGF-β. TGF-β can promote cellular differentiation or invasion and transformation. As a translational coactivator of TGF-β, eIF4E confers selective mRNA translation, reprogramming nonmalignant cells to an invasive phenotype by reducing the set point for stimulation by activated TGF-β. Overexpression of eIF4E may be a proinvasive facilitator of TGF-β activity.
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14
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Abstract
Dysregulation of mRNA translation is a frequent feature of neoplasia. Many oncogenes and tumour suppressors affect the translation machinery, making aberrant translation a widespread characteristic of tumour cells, independent of the genetic make-up of the cancer. Therefore, therapeutic agents that target components of the protein synthesis apparatus hold promise as novel anticancer drugs that can overcome intra-tumour heterogeneity. In this Review, we discuss the role of translation in cancer, with a particular focus on the eIF4F (eukaryotic translation initiation factor 4F) complex, and provide an overview of recent efforts aiming to 'translate' these results to the clinic.
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15
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Kim TH, Leslie P, Zhang Y. Ribosomal proteins as unrevealed caretakers for cellular stress and genomic instability. Oncotarget 2015; 5:860-71. [PMID: 24658219 PMCID: PMC4011588 DOI: 10.18632/oncotarget.1784] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Ribosomal proteins (RPs) have gained much attention for their extraribosomal functions particularly with respect to p53 regulation. To date, about fourteen RPs have shown to bind to MDM2 and regulate p53. Upon binding to MDM2, the RPs suppress MDM2 E3 ubiquitin ligase activity resulting in the stabilization and activation of p53. Of the RPs that bind to MDM2, RPL5 and RPL11 are the most studied and RPL11 appears to have the most significant role in p53 regulation. Considering that more than 17% of RP species have been shown to interact with MDM2, one of the questions remains unresolved is why so many RPs bind MDM2 and modulate p53. Genes encoding RPs are widely dispersed on different chromosomes in both mice and humans. As components of ribosome, RP expression is tightly regulated to meet the appropriate stoichiometric ratio between RPs and rRNAs. Once genomic instability (e.g. aneuploidy) occurs, transcriptional and translational changes due to change of DNA copy number can result in an imbalance in the expression of RPs including those that bind to MDM2. Such an imbalance in RP expression could lead to failure to assemble functional ribosomes resulting in ribosomal stress. We propose that RPs have evolved ability to regulate MDM2 in response to genomic instability as an additional layer of p53 regulation. Full understanding of the biological roles of RPs could potentially establish RPs as a novel class of therapeutic targets in human diseases such as cancer.
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Affiliation(s)
- Tae-Hyung Kim
- Department of Radiation Oncology, University of North Carolina, Chapel Hill, NC, USA
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16
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Nandagopal N, Roux PP. Regulation of global and specific mRNA translation by the mTOR signaling pathway. ACTA ACUST UNITED AC 2015; 3:e983402. [PMID: 26779414 DOI: 10.4161/21690731.2014.983402] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 08/22/2014] [Accepted: 10/29/2014] [Indexed: 11/19/2022]
Abstract
The translation of mRNA into polypeptides is a key step in eukaryotic gene expression. Translation is mostly controlled at the level of initiation, which is partly regulated by the mammalian/mechanistic target of rapamycin (mTOR) signaling pathway. Whereas mTOR controls global protein synthesis through specific effector proteins, its role in the translation of select groups of mRNAs, such as those harboring a terminal oligopyrimidine (TOP) tract at their 5' end, remains more enigmatic. In this article, we describe the current knowledge on the role of mTOR in global mRNA translation, but also focus on the potential molecular mechanisms underlying the regulation of specific translational programs.
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Affiliation(s)
- Neethi Nandagopal
- Institute for Research in Immunology and Cancer (IRIC); Université de Montréal ; Montréal, Québec, Canada
| | - Philippe P Roux
- Institute for Research in Immunology and Cancer (IRIC); Université de Montréal; Montréal, Québec, Canada; Department of Pathology and Cell Biology; Faculty of Medicine; Université de Montréal; Montréal, Québec, Canada
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17
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Shrotriya S, Deep G, Lopert P, Patel M, Agarwal R, Agarwal C. Grape seed extract targets mitochondrial electron transport chain complex III and induces oxidative and metabolic stress leading to cytoprotective autophagy and apoptotic death in human head and neck cancer cells. Mol Carcinog 2014; 54:1734-47. [PMID: 25557495 DOI: 10.1002/mc.22246] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 10/02/2014] [Accepted: 10/07/2014] [Indexed: 12/19/2022]
Abstract
Head and neck squamous cell carcinoma (HNSCC) is a major killer worldwide and innovative measures are urgently warranted to lower the morbidity and mortality caused by this malignancy. Aberrant redox and metabolic status in HNSCC cells offer a unique opportunity to specifically target cancer cells. Therefore, we investigated the efficacy of grape seed extract (GSE) to target the redox and bioenergetic alterations in HNSCC cells. GSE treatment decreased the mitochondrial electron transport chain complex III activity, increased the mitochondrial superoxide levels and depleted the levels of cellular antioxidant (glutathione), thus resulting in the loss of mitochondrial membrane potential in human HNSCC Detroit 562 and FaDu cells. Polyethylene glycol-SOD addition reversed the GSE-mediated apoptosis without restoring complex III activity. Along with redox changes, GSE inhibited the extracellular acidification rate (representing glycolysis) and oxygen consumption rate (indicating oxidative phosphorylation) leading to metabolic stress in HNSCC cells. Molecular studies revealed that GSE activated AMP-activated protein kinase (AMPK), and suppressed Akt/mTOR/4E-BP1/S6K signaling in both Detroit 562 and FaDu cells. Interestingly, GSE increased the autophagic load specifically in FaDu cells, and autophagy inhibition significantly augmented the apoptosis in these cells. Consistent with in vitro results, in vivo analyses also showed that GSE feeding in nude mice activated AMPK and induced-autophagy in FaDu xenograft tumor tissues. Overall, these findings are innovative as we for the first time showed that GSE targets ETC complex III and induces oxidative and metabolic stress, thereby, causing autophagy and apoptotic death in HNSCC cells.
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Affiliation(s)
- Sangeeta Shrotriya
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, Aurora, Colorado
| | - Gagan Deep
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, Aurora, Colorado.,University of Colorado Cancer Center, Aurora, Colorado
| | - Pamela Lopert
- Neuroscience Training Program, University of Colorado Denver, Aurora, Colorado
| | - Manisha Patel
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, Aurora, Colorado
| | - Rajesh Agarwal
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, Aurora, Colorado.,University of Colorado Cancer Center, Aurora, Colorado
| | - Chapla Agarwal
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, Aurora, Colorado.,University of Colorado Cancer Center, Aurora, Colorado
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18
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Fukao A, Mishima Y, Takizawa N, Oka S, Imataka H, Pelletier J, Sonenberg N, Thoma C, Fujiwara T. MicroRNAs trigger dissociation of eIF4AI and eIF4AII from target mRNAs in humans. Mol Cell 2014; 56:79-89. [PMID: 25280105 DOI: 10.1016/j.molcel.2014.09.005] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 07/18/2014] [Accepted: 08/28/2014] [Indexed: 12/13/2022]
Abstract
In animals, key functions of microRNA-induced silencing complex (miRISC) are translational repression and deadenylation followed by mRNA decay. While miRISC represses translation initiation, it is poorly understood how miRISC exerts this function. Here we assessed the effect of miRISC on synergistic recruitment of translation initiation factors to target mRNAs by using direct biochemical assays. We show that miRISC promotes eIF4AI and eIF4AII release from target mRNAs prior to dissociation of eIF4E and eIF4G in a deadenylation-independent manner. Strikingly, miRISC-induced release of eIF4AI and eIF4AII from target mRNAs and miRISC-induced inhibition of cap-dependent translation can both be counteracted by the RNA-binding protein HuD via a direct interaction of HuD with eIF4A. Furthermore, the pharmacological eIF4A inhibitor silvestrol, which locks eIF4A on mRNAs, conferred resistance to miRNA-mediated translational repression. In summary, we propose that both eIF4AI and eIF4AII are functionally important targets in miRISC-mediated translation control.
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Affiliation(s)
- Akira Fukao
- Laboratory of Hygienic Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan
| | - Yuichiro Mishima
- Institute of Molecular and Cellular Biosciences, Department of Medical Genome Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Naoki Takizawa
- Institute of Microbial Chemistry, Laboratory of Basic Biology, 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan
| | - Shigenori Oka
- Pharma Medical Division, Life & Healthcare Products Department, Nagase & Co., Ltd., 2-2-3 Murotani, Nishi-ku, Kobe, Hyogo 651-2241, Japan
| | - Hiroaki Imataka
- Department of Materials Science and Chemistry, Graduate School of Engineering, University of Hyogo, Himeji 671-2280, Japan
| | - Jerry Pelletier
- Department of Biochemistry, Department of Oncology, and The Rosalind and Morris Goodman Cancer Research Center and McGill Cancer Centre, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Nahum Sonenberg
- Department of Biochemistry, Department of Oncology, and The Rosalind and Morris Goodman Cancer Research Center and McGill Cancer Centre, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Christian Thoma
- Department of Medicine II, University Hospital of Freiburg, Hugstetterstr. 55, 79106 Freiburg, Germany
| | - Toshinobu Fujiwara
- Laboratory of Hygienic Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan.
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19
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Gao B, Roux PP. Translational control by oncogenic signaling pathways. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:753-65. [PMID: 25477072 DOI: 10.1016/j.bbagrm.2014.11.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Revised: 11/17/2014] [Accepted: 11/19/2014] [Indexed: 01/04/2023]
Abstract
Messenger RNA (mRNA) translation is highly regulated in cells and plays an integral role in the overall process of gene expression. The initiation phase of translation is considered to be the most rate-limiting and is often targeted by oncogenic signaling pathways to promote global protein synthesis and the selective translation of tumor-promoting mRNAs. Translational control is a crucial component of cancer development as it allows cancer cells to adapt to the altered metabolism that is generally associated with the tumor state. The phosphoinositide 3-kinase (PI3K)/Akt and Ras/mitogen-activated protein kinase (MAPK) pathways are strongly implicated in cancer etiology, and they exert their biological effects by modulating both global and specific mRNA translation. In addition to having respective translational targets, these pathways also impinge on the mechanistic/mammalian target of rapamycin (mTOR), which acts as a critical signaling node linking nutrient sensing to the coordinated regulation of cellular metabolism. mTOR is best known as a central regulator of protein synthesis and has been implicated in an increasing number of pathological conditions, including cancer. In this article, we describe the current knowledge on the roles and regulation of mRNA translation by various oncogenic signaling pathways, as well as the relevance of these molecular mechanisms to human malignancies. This article is part of a Special Issue entitled: Translation and cancer.
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Affiliation(s)
- Beichen Gao
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montréal, Québec, Canada
| | - Philippe P Roux
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montréal, Québec, Canada; Department of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada.
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20
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Bitterman PB, Polunovsky VA. eIF4E-mediated translational control of cancer incidence. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:774-80. [PMID: 25263391 DOI: 10.1016/j.bbagrm.2014.09.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Revised: 09/03/2014] [Accepted: 09/10/2014] [Indexed: 11/16/2022]
Abstract
Mitogen activated translation initiation factor eIF4E mediates normal cell proliferation, yet induces tumorigenesis when deregulated and overexpressed. It remains unknown, how activated eIF4E directs such distinct biological outputs. Our experimental data provide evidence that distinct threshold levels of eIF4E govern its biological output in lactating mammary glands and that eIF4E overexpression in the context of cell population expansion can initiate malignant transformation by enabling cells to evade DNA damage checkpoints caused by hyperproliferative oncogenic stimuli. These findings point at the cellular level of eIF4E as an important sensor for normal or pro-neoplastic propagation of cells. Here, we describe a model that links the pro-neoplastic function of eIF4F to its ability to disable oncogene-activated tumor surveillance programs; and propose a novel therapeutic strategy for cancer prevention based upon targeting aberrant eIF4E with safe doses of small-molecule antagonists to ensure the maintenance of eIF4E levels below the pro-neoplastic threshold. This article is part of a Special Issue entitled: Translation and Cancer.
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Affiliation(s)
- Peter B Bitterman
- Department of Medicine, University of Minnesota, 420 Delaware Street S.E., MMC 276, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, 420 Delaware Street S.E., MMC 276, Minneapolis, MN 55455, USA.
| | - Vitaly A Polunovsky
- Department of Medicine, University of Minnesota, 420 Delaware Street S.E., MMC 276, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, 420 Delaware Street S.E., MMC 276, Minneapolis, MN 55455, USA.
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21
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Kardos GR, Dai MS, Robertson GP. Growth inhibitory effects of large subunit ribosomal proteins in melanoma. Pigment Cell Melanoma Res 2014; 27:801-12. [PMID: 24807543 DOI: 10.1111/pcmr.12259] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 04/29/2014] [Indexed: 12/26/2022]
Abstract
Ribosome biogenesis can modulate protein synthesis, a process heavily relied upon for cancer cell proliferation. In this study, involvement of large subunit ribosomal proteins (RPLs) in melanoma has been dissected and RPLs categorized based on modulation of cell proliferation and therapeutic targeting potential. Based on these results, two categories of RPLs were identified: the first causing negligible effects on cell viability, p53 expression, and protein translation, while the second category decreased cell viability and inhibited protein synthesis mediated with or without p53 protein stabilization. RPL13 represents the second category, where siRNA-mediated targeting inhibited tumor development through decreased cellular proliferation. Mechanistically, decreased RPL13 levels increased p53 stability mediated by RPL5 and RPL11 binding to and preventing MDM2 from targeting p53 for degradation. The consequence was p53-dependent cell cycle arrest and decreased protein translation. Thus, targeting certain category 2 RPL proteins can inhibit melanoma tumor development mediated through the MDM2-p53 pathway.
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Affiliation(s)
- Gregory R Kardos
- Department of Pharmacology, The Pennsylvania State University College of Medicine, Hershey, PA, USA; The Melanoma Center, The Pennsylvania State University College of Medicine, Hershey, PA, USA; The Melanoma Therapeutics Program, The Pennsylvania State University College of Medicine, Hershey, PA, USA
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22
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Akcakanat A, Hong DS, Meric-Bernstam F. Targeting translation initiation in breast cancer. ACTA ACUST UNITED AC 2014; 2:e28968. [PMID: 26779407 PMCID: PMC4705830 DOI: 10.4161/trla.28968] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 04/09/2014] [Accepted: 04/22/2014] [Indexed: 12/23/2022]
Abstract
Over the past 20 years, a better understanding of cancer biology, screening for early detection, improved adjuvant treatment, and targeted therapies have decreased the rate of breast cancer deaths. However, resistance to treatment is common, and new approaches are needed. Deregulation of translation initiation is associated with the commencement and progression of cancer. Often, translation initiation factors are overexpressed and the related signaling pathways activated in human tumors. Recently, a significant number of inhibitors that target translation factors and pathways have become available. These inhibitors are being tested alone or in combination with chemotherapeutic agents in clinical trials. The results are varied, and it is not yet clear which drug treatments most effectively inhibit tumor growth. This review highlights the pathways and downstream effects of the activation of translation and discusses targeting the control of translation initiation as a therapeutic approach in cancer, focusing on breast cancer clinical trials.
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Affiliation(s)
- Argun Akcakanat
- Department of Investigational Cancer Therapeutics; Houston, TX USA
| | - David S Hong
- Department of Investigational Cancer Therapeutics; Houston, TX USA
| | - Funda Meric-Bernstam
- Department of Investigational Cancer Therapeutics; Houston, TX USA; Department of Surgical Oncology; The University of Texas MD Anderson Cancer Center; Houston, TX USA
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23
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Flavaglines target primitive leukemia cells and enhance anti-leukemia drug activity. Leukemia 2014; 28:1960-8. [PMID: 24577530 DOI: 10.1038/leu.2014.93] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 02/19/2014] [Accepted: 02/21/2014] [Indexed: 01/28/2023]
Abstract
Identification of agents that target human leukemia stem cells is an important consideration for the development of new therapies. The present study demonstrates that rocaglamide and silvestrol, closely related natural products from the flavagline class of compounds, are able to preferentially kill functionally defined leukemia stem cells, while sparing normal stem and progenitor cells. In addition to efficacy as single agents, flavaglines sensitize leukemia cells to several anticancer compounds, including front-line chemotherapeutic drugs used to treat leukemia patients. Mechanistic studies indicate that flavaglines strongly inhibit protein synthesis, leading to the reduction of short-lived antiapoptotic proteins. Notably though, treatment with flavaglines, alone or in combination with other drugs, yields a much stronger cytotoxic activity toward leukemia cells than the translational inhibitor temsirolimus. These results indicate that the underlying cell death mechanism of flavaglines is more complex than simply inhibiting general protein translation. Global gene expression profiling and cell biological assays identified Myc inhibition and the disruption of mitochondrial integrity to be features of flavaglines, which we propose contribute to their efficacy in targeting leukemia cells. Taken together, these findings indicate that rocaglamide and silvestrol are distinct from clinically available translational inhibitors and represent promising candidates for the treatment of leukemia.
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24
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Resistance to mTOR kinase inhibitors in lymphoma cells lacking 4EBP1. PLoS One 2014; 9:e88865. [PMID: 24586420 PMCID: PMC3931643 DOI: 10.1371/journal.pone.0088865] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 01/13/2014] [Indexed: 11/19/2022] Open
Abstract
Inhibitors of the mechanistic target of rapamycin (mTOR) hold promise for treatment of hematological malignancies. Analogs of the allosteric mTOR inhibitor rapamycin are approved for mantle cell lymphoma but have limited efficacy in other blood cancers. ATP-competitive "active-site" mTOR inhibitors produce more complete mTOR inhibition and are more effective than rapamycin in preclinical models of leukemia, lymphoma and multiple myeloma. In parallel to clinical trials of active-site mTOR inhibitors, it will be important to identify resistance mechanisms that might limit drug efficacy in certain patients. From a panel of diffuse large B-cell lymphoma cell lines, we found that the VAL cell line is particularly resistant to apoptosis in the presence of active-site mTOR inhibitors. Mechanistic investigation showed that VAL does not express eukaryotic initiation factor 4E-binding protein-1 (4EBP1), a key negative regulator of translation controlled by mTOR. Although VAL cells express the related protein 4EBP2, mTOR inhibitor treatment fails to displace eukaryotic initiation factor 4G from the mRNA cap-binding complex. Knockdown of eukaryotic initiation factor 4E, or re-expression of 4EBP1, sensitizes cells to apoptosis when treated with active-site mTOR inhibitors. These findings provide a naturally occurring example of 4EBP deficiency driving lymphoma cell resistance to active-site mTOR inhibitors.
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25
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Abstract
Ribosome-inactivating proteins (RIPs) were first isolated over a century ago and have been shown to be catalytic toxins that irreversibly inactivate protein synthesis. Elucidation of atomic structures and molecular mechanism has revealed these proteins to be a diverse group subdivided into two classes. RIPs have been shown to exhibit RNA N-glycosidase activity and depurinate the 28S rRNA of the eukaryotic 60S ribosomal subunit. In this review, we compare archetypal RIP family members with other potent toxins that abolish protein synthesis: the fungal ribotoxins which directly cleave the 28S rRNA and the newly discovered Burkholderia lethal factor 1 (BLF1). BLF1 presents additional challenges to the current classification system since, like the ribotoxins, it does not possess RNA N-glycosidase activity but does irreversibly inactivate ribosomes. We further discuss whether the RIP classification should be broadened to include toxins achieving irreversible ribosome inactivation with similar turnovers to RIPs, but through different enzymatic mechanisms.
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Affiliation(s)
- Matthew J Walsh
- RNA Biology Laboratory; Sheffield Institute for Translational Neuroscience (SITraN); Department of Neuroscience; University of Sheffield; Sheffield, UK
| | - Jennifer E Dodd
- RNA Biology Laboratory; Sheffield Institute for Translational Neuroscience (SITraN); Department of Neuroscience; University of Sheffield; Sheffield, UK
| | - Guillaume M Hautbergue
- RNA Biology Laboratory; Sheffield Institute for Translational Neuroscience (SITraN); Department of Neuroscience; University of Sheffield; Sheffield, UK
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26
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Eukaryotic translation initiation factor 4E (eIF4E) expression is associated with breast cancer tumor phenotype and predicts survival after anthracycline chemotherapy treatment. Breast Cancer Res Treat 2013; 141:79-88. [PMID: 23974830 DOI: 10.1007/s10549-013-2671-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 08/14/2013] [Indexed: 10/26/2022]
Abstract
Abnormal translation of mRNAs frequently occurring during carcinogenesis is among the mechanisms that can affect the expression of proteins involved in tumor development and progression. Eukaryotic initiation factor eIF4E is a key regulator of translation of many cancer-related transcripts and its expression is altered in various cancers and has been associated with worse survival. We determined the eIF4E protein levels using immunohistochemistry (IHC) in 1,233 breast tumors on tissue microarrays. We analyzed the effects of the IHC expression level on tumor characteristics and patient survival, also with stratification by adjuvant chemotherapy treatment. In 1,085 successfully stained tumors, high level of eIF4E protein expression was associated with features of aggressive tumor phenotype, namely grade, estrogen and progesterone receptor negativity, HER2 receptor positivity, and high expression of p53 and Ki67, and with triple negative subtype (p < 0.001). High eIF4E expression was associated with worse breast cancer-specific survival with a hazard ratio (HR) of 1.99 (95 % CI 1.32-3.00, p = 0.0008) and was in a multivariate analysis an independent prognostic factor. High eIF4E expression was associated with worse outcome also after detection of distant metastasis (HR = 1.88, 95 % CI 1.20-2.94, p = 0.0060). In the subgroup analysis the survival effect was strongest among patients treated with anthracycline chemotherapy (HR = 3.34, 95 % CI 1.72-6.48, p = 0.0002), whereas no such effect was seen among patients who had not received anthracycline with significant difference in heterogeneity between the two groups (p = 0.0358). High expression of eIF4E is associated with adverse tumor characteristics and predicts poor breast cancer-specific survival. This effect is emphasized in patients treated with anthracycline chemotherapy. eIF4E as a treatment predictive factor warrants further studies.
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27
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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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28
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Nho RS, Polunovsky V. Translational control of the fibroblast-extracellular matrix association: An application to pulmonary fibrosis. TRANSLATION (AUSTIN, TEX.) 2013; 1:e23934. [PMID: 26824013 PMCID: PMC4718055 DOI: 10.4161/trla.23934] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 02/05/2013] [Accepted: 02/08/2013] [Indexed: 12/28/2022]
Abstract
Pulmonary fibrosis is a severe lung disease characterized by sustained propagation of lung fibroblasts and relentless accumulation of extracellular matrix (ECM). Idiopathic pulmonary fibrosis (IPF) is the most severe chronic form of pulmonary fibrosis and results both in the gradual exchange of normal lung parenchyma with fibrotic tissue and in the irreversible impairment of gas exchange in the lung. Despite the urgency for novel therapies in IPF treatment, there is no effective and proven medical therapy available. Molecular mechanisms underlying IPF pathogenesis include aberrant ECM signaling through the canonical integrin/PI3K/Akt/mTORC1 signal transduction pathway. One important and well-characterized downstream effector of this pathway is the cellular protein synthesis machinery. Here we will review the recent advances in our understanding of the function of ECM and integrin receptor signaling in development of IPF and will present evidence indicating that the dysregulation of the eIF4F-mediated translational apparatus is an important factor in the development and progression of IPF and other fibrotic disorders. We further discuss the perspectives and challenges to curbing this deadly disease by targeting aberrant translation.
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Affiliation(s)
| | - Vitaly Polunovsky
- Department of Medicine, University of Minnesota, Minneapolis, MN USA
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29
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Inhibition of Mnk kinase activity by cercosporamide and suppressive effects on acute myeloid leukemia precursors. Blood 2013; 121:3675-81. [PMID: 23509154 DOI: 10.1182/blood-2013-01-477216] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mnk kinases regulate the phosphorylation and activation of the eukaryotic initiation factor 4E (eIF4E), a protein that plays key roles in the initiation of messenger RNA translation and whose activity is critical for various cellular functions. eIF4E is deregulated in acute myeloid leukemia (AML), and its aberrant activity contributes to leukemogenesis. We determined whether cercosporamide, an antifungal agent that was recently shown to act as a unique Mnk inhibitor, exhibits antileukemic properties. Treatment of AML cells with cercosporamide resulted in a dose-dependent suppression of eIF4E phosphorylation. Such suppression of Mnk kinase activity and eIF4E phosphorylation by cercosporamide resulted in dose-dependent suppressive effects on primitive leukemic progenitors (CFU-L) from AML patients and enhanced the antileukemic properties of cytarabine (Ara-C) or mammalian target of rapamycin (mTOR) complex 1 inhibition. Similarly, the combination of cercosporamide with cytarabine resulted in enhanced antileukemic responses in a xenograft mouse model in vivo. Altogether, this work demonstrates that the unique Mnk inhibitor cercosporamide suppresses phosphorylation of eIF4E and exhibits antileukemic effects, in support of future clinical-translational efforts involving combinations of Mnk inhibitors with cytarabine and/or mTOR inhibitors for the treatment of AML.
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Chen L, Aktas BH, Wang Y, He X, Sahoo R, Zhang N, Denoyelle S, Kabha E, Yang H, Freedman RY, Supko JG, Chorev M, Wagner G, Halperin JA. Tumor suppression by small molecule inhibitors of translation initiation. Oncotarget 2013; 3:869-81. [PMID: 22935625 PMCID: PMC3478463 DOI: 10.18632/oncotarget.598] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Translation initiation factors are over-expressed and/or activated in many human cancers and may contribute to their genesis and/or progression. Removal of physiologic restraints on translation initiation causes malignant transformation. Conversely, restoration of physiological restrains on translation initiation reverts malignant phenotypes. Here, we extensively characterize the anti-cancer activity of two small molecule inhibitors of translation initiation: #1181, which targets the eIF2-GTP-Met-tRNAi ternary complex, and 4EGI-1, which targets the eIF4F complex. In vitro, both molecules inhibit translation initiation, abrogate preferentially translation of mRNAs coding for oncogenic proteins, and inhibit proliferation of human cancer cells. In vivo, both #1181 and 4EGI-1 strongly inhibit growth of human breast and melanoma cancer xenografts without any apparent macroscopic- or microscopic-toxicity. Mechanistically, #1181 phosphorylates eIF2α while 4EGI-1 disrupts eIF4G/eIF4E interaction in the tumors excised from mice treated with these agents. These data indicate that inhibition of translation initiation is a new paradigm in cancer therapy.
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31
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Cencic R, Pelletier J. Throwing a monkey wrench in the motor: targeting DExH/D box proteins with small molecule inhibitors. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:894-903. [PMID: 23385390 DOI: 10.1016/j.bbagrm.2013.01.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 01/21/2013] [Accepted: 01/24/2013] [Indexed: 01/04/2023]
Abstract
DExH/D box proteins are molecular motors that utilize the energy derived from NTP hydrolysis to perform work - from helicases that remodel RNA to RNPases that alter RNA-protein complexes. Members of this class of proteins are uniquely placed along the RNA information highway to regulate the flow of genetic information. They have been implicated in a number of nodal points encompassing nuclear, cytoplasmic, and organellar RNA-based processes. The identification and characterization of three unique natural products that selectively inhibit the activity of eukaryotic initiation factor (eIF)4A (DDX2) has provided proof-of-principle that the activity of DExH/D box family members can be selectively targeted. Extending these achievements to other DExH/D box proteins is an important future challenge for drugging this family of proteins. This article is part of a Special Issue entitled: The Biology of RNA helicases - Modulation for life.
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Affiliation(s)
- Regina Cencic
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
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32
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BLF1, the first Burkholderia pseudomallei toxin, connects inhibition of host protein synthesis with melioidosis. Biochem Soc Trans 2012; 40:842-5. [PMID: 22817745 DOI: 10.1042/bst20120057] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Melioidosis is a disease caused by infection with Burkholderia pseudomallei. The molecular basis for the pathogenicity of B. pseudomallei is poorly understood. However, recent work has identified the first toxin from this bacterium and shown that it inhibits host protein synthesis. Here, we review the illness that is potentially associated with biological warfare, the pathogen and its deadly molecular mechanism of action, as well as therapeutic developments that may follow.
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33
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Martelli AM, Chiarini F, Evangelisti C, Cappellini A, Buontempo F, Bressanin D, Fini M, McCubrey JA. Two hits are better than one: targeting both phosphatidylinositol 3-kinase and mammalian target of rapamycin as a therapeutic strategy for acute leukemia treatment. Oncotarget 2012; 3:371-94. [PMID: 22564882 PMCID: PMC3380573 DOI: 10.18632/oncotarget.477] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Phosphatidylinositol 3-kinase (PI3K) and mammalian target of rapamycin (mTOR) are two key components of the PI3K/Akt/mTOR signaling pathway. This signal transduction cascade regulates a wide range of physiological cell processes, that include differentiation, proliferation, apoptosis, autophagy, metabolism, motility, and exocytosis. However, constitutively active PI3K/Akt/mTOR signaling characterizes many types of tumors where it negatively influences response to therapeutic treatments. Hence, targeting PI3K/Akt/mTOR signaling with small molecule inhibitors may improve cancer patient outcome. The PI3K/Akt/mTOR signaling cascade is overactive in acute leukemias, where it correlates with enhanced drug-resistance and poor prognosis. The catalytic sites of PI3K and mTOR share a high degree of sequence homology. This feature has allowed the synthesis of ATP-competitive compounds targeting the catalytic site of both kinases. In preclinical models, dual PI3K/mTOR inhibitors displayed a much stronger cytotoxicity against acute leukemia cells than either PI3K inhibitors or allosteric mTOR inhibitors, such as rapamycin. At variance with rapamycin, dual PI3K/mTOR inhibitors targeted both mTOR complex 1 and mTOR complex 2, and inhibited the rapamycin-resistant phosphorylation of eukaryotic initiation factor 4E-binding protein 1, resulting in a marked inhibition of oncogenic protein translation. Therefore, they strongly reduced cell proliferation and induced an important apoptotic response. Here, we reviewed the evidence documenting that dual PI3K/mTOR inhibitors may represent a promising option for future targeted therapies of acute leukemia patients.
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Affiliation(s)
- Alberto M Martelli
- Department of Human Anatomy, University of Bologna, Cellular Signalling Laboratory, Bologna, Italy.
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34
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Automated high-throughput RNAi screening in human cells combined with reporter mRNA transfection to identify novel regulators of translation. PLoS One 2012; 7:e45943. [PMID: 23029333 PMCID: PMC3459937 DOI: 10.1371/journal.pone.0045943] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 08/23/2012] [Indexed: 12/21/2022] Open
Abstract
Proteins that promote angiogenesis, such as vascular endothelial growth factor (VEGF), are major targets for cancer therapy. Accordingly, proteins that specifically activate expression of factors like VEGF are potential alternative therapeutic targets and may help to combat evasive resistance to angiogenesis inhibitors. VEGF mRNA contains two internal ribosome entry sites (IRESs) that enable selective activation of VEGF protein synthesis under hypoxic conditions that trigger angiogenesis. To identify novel regulators of VEGF IRES-driven translation in human cells, we have developed a high-throughput screening approach that combines siRNA treatment with transfection of a VEGF-IRES reporter mRNA. We identified the kinase MAPK3 as a novel positive regulator of VEGF IRES-driven translation and have validated its regulatory effect on endogenous VEGF. Our automated method is scalable and readily adapted for use with other mRNA regulatory elements. Consequently, it should be a generally useful approach for high-throughput identification of novel regulators of mRNA translation.
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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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36
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Galicia-Vázquez G, Cencic R, Robert F, Agenor AQ, Pelletier J. A cellular response linking eIF4AI activity to eIF4AII transcription. RNA (NEW YORK, N.Y.) 2012; 18:1373-84. [PMID: 22589333 PMCID: PMC3383968 DOI: 10.1261/rna.033209.112] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2012] [Accepted: 04/05/2012] [Indexed: 05/18/2023]
Abstract
The recruitment of ribosomes to eukaryotic cellular mRNAs requires the activity of two prototypic RNA helicases, eukaryotic initiation factor (eIF) 4AI and eIF4AII. The eIF4A isoforms are highly conserved, are thought to be functionally interchangeable, and are directed to the 5' m(7)GpppN cap structure of mRNAs during translation initiation by virtue of their assembly into eIF4F, a heterotrimeric complex that also harbors the eIF4E cap binding protein and eIF4G scaffolding unit. During the course of RNA interference experiments aimed at investigating the respective roles of eIF4AI and eIF4AII in translation, we uncovered a cellular response pathway whereby suppression of eIF4AI increases transcription of the eIF4AII gene, leading to elevated eIF4AII mRNA and protein levels. Inhibition of eIF4AI suppresses protein synthesis, and although eIF4AII protein levels increase above and beyond what should be sufficient to compensate for the decrease in eIF4AI levels, there is no corresponding rescue of translation or of the block on cellular proliferation that occurs upon eIF4AI suppression. These results were phenocopied using the small molecule eIF4A inhibitor hippuristanol. Taken together, our results indicate that eIF4AI and eIF4AII expression appear linked and that the two protein isoforms exhibit functional differences.
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Affiliation(s)
| | | | | | | | - Jerry Pelletier
- Department of Biochemistry and
- The Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, Quebec, Canada, H3G 1Y6
- Corresponding authorE-mail
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Versatility of RNA-Binding Proteins in Cancer. Comp Funct Genomics 2012; 2012:178525. [PMID: 22666083 PMCID: PMC3359819 DOI: 10.1155/2012/178525] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 02/28/2012] [Indexed: 01/22/2023] Open
Abstract
Posttranscriptional gene regulation is a rapid and efficient process to adjust the proteome of a cell to a changing environment. RNA-binding proteins (RBPs) are the master regulators of mRNA processing and translation and are often aberrantly expressed in cancer. In addition to well-studied transcription factors, RBPs are emerging as fundamental players in tumor development. RBPs and their mRNA targets form a complex network that plays a crucial role in tumorigenesis. This paper describes mechanisms by which RBPs influence the expression of well-known oncogenes, focusing on precise examples that illustrate the versatility of RBPs in posttranscriptional control of cancer development. RBPs appeared very early in evolution, and new RNA-binding domains and combinations of them were generated in more complex organisms. The identification of RBPs, their mRNA targets, and their mechanism of action have provided novel potential targets for cancer therapy.
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38
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Overexpression of eIF3a in Squamous Cell Carcinoma of the Oral Cavity and Its Putative Relation to Chemotherapy Response. JOURNAL OF ONCOLOGY 2012; 2012:901956. [PMID: 22619676 PMCID: PMC3347757 DOI: 10.1155/2012/901956] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 02/10/2012] [Indexed: 01/23/2023]
Abstract
The eukaryotic translation initiation factor eIF3a is one of the core subunits of the translation initiation complex eIF3, responsible for ribosomal subunit joining and mRNA recruitment to the ribosome. It is known to play an important role in general translation initiation as well as in the specific translational regulation of various gene products, among which many influence tumour development, progression, and the therapeutically important pathways of DNA damage repair. Therefore, beyond its role in protein synthesis, eIF3a is emerging as regulator in tumour pathogenesis and therapy response and, therefore, a potential tumor marker. By means of a tissue microarray (TMA) for histopathological and statistical assessment, we here show eIF3a expression in 103 cases of squamous cell carcinoma of the oral cavity (OSCC), representing tissues from 103 independent patients. A subset of the study cohort was treated with platinum based therapy. Our results show that the 170 kDa protein is upregulated in OSCC and correlates with good overall survival. Overexpressing tumors respond better to platinum-based chemotherapy, suggesting eIF3a as a putative predictive as well as prognostic tumor marker in OSCC.
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39
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Hautbergue G. [Characterisation of Burkholderia pseudomallei Lethal Factor 1 (BLF1). A breakthrough against melioidosis]. Med Sci (Paris) 2012; 28:262-4. [PMID: 22480647 DOI: 10.1051/medsci/2012283011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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40
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Sun Y, Atas E, Lindqvist L, Sonenberg N, Pelletier J, Meller A. The eukaryotic initiation factor eIF4H facilitates loop-binding, repetitive RNA unwinding by the eIF4A DEAD-box helicase. Nucleic Acids Res 2012; 40:6199-207. [PMID: 22457067 PMCID: PMC3401463 DOI: 10.1093/nar/gks278] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Eukaryotic translation initiation is a highly regulated process in protein synthesis. The principal translation initiation factor eIF4AI displays helicase activity, unwinding secondary structures in the mRNAs 5'-UTR. Single molecule fluorescence resonance energy transfer (sm-FRET) is applied here to directly observe and quantify the helicase activity of eIF4AI in the presence of the ancillary RNA-binding factor eIF4H. Results show that eIF4H can significantly enhance the helicase activity of eIF4AI by strongly binding both to loop structures within the RNA transcript as well as to eIF4AI. In the presence of ATP, the eIF4AI/eIF4H complex exhibits persistent rapid and repetitive cycles of unwinding and re-annealing. ATP titration assays suggest that this process consumes a single ATP molecule per cycle. In contrast, helicase unwinding activity does not occur in the presence of the non-hydrolysable analog ATP-γS. Based on our sm-FRET results, we propose an unwinding mechanism where eIF4AI/eIF4H can bind directly to loop structures to destabilize duplexes. Since eIF4AI is the prototypical example of a DEA(D/H)-box RNA helicase, it is highly likely that this unwinding mechanism is applicable to a myriad of DEAD-box helicases employed in RNA metabolism.
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Affiliation(s)
- Yingjie Sun
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
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41
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Bitterman PB, Polunovsky VA. Translational control of cell fate: from integration of environmental signals to breaching anticancer defense. Cell Cycle 2012; 11:1097-107. [PMID: 22356766 DOI: 10.4161/cc.11.6.19610] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Despite their genetic diversity, different cancers manifest common features at the protein pathway level. They share a core group of perturbed pathways that converge upon a few regulatory hubs linking the cellular signaling network with the basic metabolic machinery. Available evidence indicates that one such hub is the eIF4F-mediated cap-dependent mRNA translation initiation apparatus, whose integrity is required for physiological control of growth, proliferation and viability. However, when hyperactivated by upstream oncogenic signaling, eIF4F selectively stimulates the translation of a group of mRNAs required for cancer genesis and progression. Here, we describe a model that links the pro-neoplastic function of eIF4F to its ability to disable oncogene-activated tumor surveillance programs and propose a novel therapeutic strategy for cancer based upon targeting aberrant eIF4F with small-molecule antagonists.
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Affiliation(s)
- Peter B Bitterman
- Department of Medicine and Masonic Cancer Center, University of Minnesota; Minneapolis, MN, USA
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42
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Hanash S, Schliekelman M, Zhang Q, Taguchi A. Integration of proteomics into systems biology of cancer. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2012; 4:327-37. [PMID: 22407608 DOI: 10.1002/wsbm.1169] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Deciphering the complexity and heterogeneity of cancer, benefits from integration of proteomic level data into systems biology efforts. The opportunities available as a result of advances in proteomic technologies, the successes to date, and the challenges involved in integrating diverse datasets are addressed in this review.
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Affiliation(s)
- S Hanash
- Molecular Diagnostics Program, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
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43
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Bugaut A, Balasubramanian S. 5'-UTR RNA G-quadruplexes: translation regulation and targeting. Nucleic Acids Res 2012; 40:4727-41. [PMID: 22351747 PMCID: PMC3367173 DOI: 10.1093/nar/gks068] [Citation(s) in RCA: 469] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
RNA structures in the untranslated regions (UTRs) of mRNAs influence post-transcriptional regulation of gene expression. Much of the knowledge in this area depends on canonical double-stranded RNA elements. There has been considerable recent advancement of our understanding of guanine(G)-rich nucleic acids sequences that form four-stranded structures, called G-quadruplexes. While much of the research has been focused on DNA G-quadruplexes, there has recently been a rapid emergence of interest in RNA G-quadruplexes, particularly in the 5′-UTRs of mRNAs. Collectively, these studies suggest that RNA G-quadruplexes exist in the 5′-UTRs of many genes, including genes of clinical interest, and that such structural elements can influence translation. This review features the progresses in the study of 5′-UTR RNA G-quadruplex-mediated translational control. It covers computational analysis, cell-free, cell-based and chemical biology studies that have sought to elucidate the roles of RNA G-quadruplexes in both cap-dependent and -independent regulation of mRNA translation. We also discuss protein trans-acting factors that have been implicated and the evidence that such RNA motifs have potential as small molecule target. Finally, we close the review with a perspective on the future challenges in the field of 5′-UTR RNA G-quadruplex-mediated translation regulation.
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Affiliation(s)
- Anthony Bugaut
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
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44
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Cencic R, Galicia-Vázquez G, Pelletier J. Inhibitors of translation targeting eukaryotic translation initiation factor 4A. Methods Enzymol 2012; 511:437-61. [PMID: 22713332 DOI: 10.1016/b978-0-12-396546-2.00020-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The RNA helicases eIF4AI and eIF4AII play key roles in recruiting ribosomes to mRNA templates during eukaryotic translation initiation. Small molecule inhibitors of eIF4AI and eIF4AII have been useful for chemically dissecting their role in translation in vitro and in vivo. Here, we describe a screen performed on a small focused library of kinase inhibitors to identify a novel helicase inhibitor. We describe assays that have been critical for characterizing novel RNA helicase inhibitors.
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Affiliation(s)
- Regina Cencic
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
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45
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Rodrigo CM, Cencic R, Roche SP, Pelletier J, Porco JA. Synthesis of rocaglamide hydroxamates and related compounds as eukaryotic translation inhibitors: synthetic and biological studies. J Med Chem 2011; 55:558-62. [PMID: 22128783 DOI: 10.1021/jm201263k] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The rocaglates/rocaglamides are a class of natural products known to display potent anticancer activity. One such derivative, silvestrol, has shown activity comparable to taxol in certain settings. Here, we report the synthesis of various rocaglamide analogues and identification of a hydroxamate derivative (-)-9 having activity similar to silvestrol in vitro and ex vivo for inhibition of protein synthesis. We also show that (-)-9 synergizes with doxorubicin in vivo to reduce Eμ-Myc driven lymphomas.
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Affiliation(s)
- Christina M Rodrigo
- Department of Chemistry, Center for Chemical Methodology and Library Development (CMLD-BU), Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
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