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Cyran AM, Kleinegger F, Nass N, Naumann M, Haybaeck J, Arens C. Inhibition of EIF2α Dephosphorylation Decreases Cell Viability and Synergizes with Standard-of-Care Chemotherapeutics in Head and Neck Squamous Cell Carcinoma. Cancers (Basel) 2023; 15:5350. [PMID: 38001610 PMCID: PMC10670742 DOI: 10.3390/cancers15225350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 10/27/2023] [Accepted: 11/01/2023] [Indexed: 11/26/2023] Open
Abstract
Drug resistance is a common cause of therapy failure in head and neck squamous cell carcinoma (HNSCC). One approach to tackling it is by targeting fundamental cellular processes, such as translation. The eukaryotic translation initiation factor 2α (EIF2α) is a key player in canonical translation initiation and integrates diverse stress signals; when phosphorylated, it curbs global protein synthesis. This study evaluates EIF2α expression and phosphorylation in HNSCC. A small-molecule inhibitor of EIF2α dephosphorylation, salubrinal, was tested in vitro, followed by viability assays, flow cytometry, and immunoblot analyses. Patient-derived 3D tumor spheres (PD3DS) were cultured with salubrinal and their viability assessed. Lastly, salubrinal was evaluated with standard-of-care chemotherapeutics. Our analysis of RNA and proteomics data shows elevated EIF2α expression in HNSCC. Immunohistochemical staining reveals increasing EIF2α abundance from premalignant lesions to invasive and metastatic carcinoma. In immunoblots from intraoperative samples, EIF2α expression and steady-state phosphorylation are higher in HNSCC than in neighboring normal tissue. Inhibition of EIF2α dephosphorylation decreases HNSCC cell viability and clonogenic survival and impairs the G1/S transition. Salubrinal also decreases the viability of PD3DS and acts synergistically with cisplatin, 5-fluorouracil, bleomycin, and proteasome inhibitors. Our results indicate that pharmacological inhibition of EIF2α dephosphorylation is a potential therapeutic strategy for HNSCC.
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Affiliation(s)
- Anna M. Cyran
- Legorreta Cancer Center, Department of Pathology and Laboratory Medicine, Brown University, Providence, RI 02906, USA
- Department of Otorhinolaryngology, Head and Neck Surgery, Otto-von-Guericke University, 39120 Magdeburg, Germany
| | - Florian Kleinegger
- Diagnostic & Research Center for Molecular Biomedicine, Institute of Pathology, Medical University of Graz, 8010 Graz, Austria (J.H.)
| | - Norbert Nass
- Institute of Pathology, University Hospital Brandenburg, Brandenburg Medical School Theodor Fontane, 14770 Brandenburg an der Havel, Germany;
| | - Michael Naumann
- Institute of Experimental Internal Medicine, Otto von Guericke University, 39120 Magdeburg, Germany;
| | - Johannes Haybaeck
- Diagnostic & Research Center for Molecular Biomedicine, Institute of Pathology, Medical University of Graz, 8010 Graz, Austria (J.H.)
| | - Christoph Arens
- Department of Otorhinolaryngology, Head and Neck Surgery, Giessen and Marburg University Hospitals, Campus Giessen, 35392 Giessen, Germany;
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2
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James A, Akash K, Sharma A, Bhattacharyya S, Sriamornsak P, Nagraik R, Kumar D. Himalayan flora: targeting various molecular pathways in lung cancer. Med Oncol 2023; 40:314. [PMID: 37787816 DOI: 10.1007/s12032-023-02171-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 08/21/2023] [Indexed: 10/04/2023]
Abstract
The fatal amplification of lung cancer across the globe and the limitations of current treatment strategies emphasize the necessity for substitute therapeutics. The incorporation of phyto-derived components in chemo treatment holds promise in addressing those challenges. Despite the significant progressions in lung cancer therapeutics, the complexities of molecular mechanism and pathways underlying this disease remain inadequately understood, necessitating novel biomarker targeting. The Himalayas, abundant in diverse plant varieties with established chemotherapeutic potential, presents a promising avenue for investigating potential cures for lung carcinoma. The vast diversity of phytocompounds herein can be explored for targeting the disease. This review delves into the multifaceted targets of lung cancer and explores the established phytochemicals with their specific molecular targets. It emphasizes comprehending the intricate pathways that govern effective therapeutic interventions for lung cancer. Through this exploration of Himalayan flora, this review seeks to illuminate potential breakthroughs in lung cancer management using natural compounds. The amalgamation of Himalayan plant-derived compounds with cautiously designed combined therapeutic approaches such as nanocarrier-mediated drug delivery and synergistic therapy offers an opportunity to redefine the boundaries of lung cancer treatment by reducing the drug resistance and side effects and enabling an effective targeted delivery of drugs. Furthermore, additional studies are obligatory to understand the possible derivation of natural compounds used in current lung cancer treatment from plant species within the Himalayan region.
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Affiliation(s)
- Abija James
- Faculty of Applied Sciences and Biotechnology, Shoolini University, Solan, Himachal Pradesh, 173229, India
| | - K Akash
- Faculty of Applied Sciences and Biotechnology, Shoolini University, Solan, Himachal Pradesh, 173229, India
| | - Avinash Sharma
- Faculty of Applied Sciences and Biotechnology, Shoolini University, Solan, Himachal Pradesh, 173229, India
| | - Sanjib Bhattacharyya
- Department of Pharmaceutical Sciences and Chinese Traditional Medicine, Southwest University, Beibei, 400715, Chongqing, People's Republic of China
- Department of Sciences, Nirma University, Ahmedabad, Gujarat, 382481, India
| | | | - Rupak Nagraik
- Faculty of Applied Sciences and Biotechnology, Shoolini University, Solan, Himachal Pradesh, 173229, India.
| | - Deepak Kumar
- Department of Pharmaceutical Chemistry, School of Pharmaceutical Sciences, Shoolini University, Solan, Himachal Pradesh, 173229, India.
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3
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Talukdar G, Orr HT, Lei Z. The PERK pathway: beneficial or detrimental for neurodegenerative diseases and tumor growth and cancer. Hum Mol Genet 2023; 32:2545-2557. [PMID: 37384418 PMCID: PMC10407711 DOI: 10.1093/hmg/ddad103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 06/04/2023] [Accepted: 06/05/2023] [Indexed: 07/01/2023] Open
Abstract
Protein kinase R (PKR)-like endoplasmic reticulum (ER) kinase (PERK) is one of the three major sensors in the unfolded protein response (UPR). The UPR is involved in the modulation of protein synthesis as an adaptive response. Prolonged PERK activity correlates with the development of diseases and the attenuation of disease severity. Thus, the current debate focuses on the role of the PERK signaling pathway either in accelerating or preventing diseases such as neurodegenerative diseases, myelin disorders, and tumor growth and cancer. In this review, we examine the current findings on the PERK signaling pathway and whether it is beneficial or detrimental for the above-mentioned disorders.
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Affiliation(s)
- Gourango Talukdar
- Institute for Translational Neuroscience and Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
| | - Harry T Orr
- Institute for Translational Neuroscience and Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Zhixin Lei
- Institute for Translational Neuroscience and Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
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4
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Emerging Role of Plant-Based Dietary Components in Post-Translational Modifications Associated with Colorectal Cancer. Life (Basel) 2023; 13:life13020264. [PMID: 36836621 PMCID: PMC9962725 DOI: 10.3390/life13020264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/12/2023] [Accepted: 01/16/2023] [Indexed: 01/21/2023] Open
Abstract
Colorectal cancer (CRC) is one of the most common cancers worldwide. Its main modifiable risk factors are diet, alcohol consumption, and smoking. Thus, the right approach through lifestyle changes may lead to its prevention. In fact, some natural dietary components have exhibited chemopreventive activity through modulation of cellular processes involved in CRC development. Although cancer is a multi-factorial process, the study of post-translational modifications (PTMs) of proteins associated with CRC has recently gained interest, as inappropriate modification is closely related to the activation of cell signalling pathways involved in carcinogenesis. Therefore, this review aimed to collect the main PTMs associated with CRC, analyse the relationship between different proteins that are susceptible to inappropriate PTMs, and review the available scientific literature on the role of plant-based dietary compounds in modulating CRC-associated PTMs. In summary, this review suggested that some plant-based dietary components such as phenols, flavonoids, lignans, terpenoids, and alkaloids may be able to correct the inappropriate PTMs associated with CRC and promote apoptosis in tumour cells.
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5
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Huang C, Zhao Q, Zhou X, Huang R, Duan Y, Haybaeck J, Yang Z. The progress of protein synthesis factors eIFs, eEFs and eRFs in inflammatory bowel disease and colorectal cancer pathogenesis. Front Oncol 2022; 12:898966. [DOI: 10.3389/fonc.2022.898966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 10/14/2022] [Indexed: 11/13/2022] Open
Abstract
Colorectal diseases are threatening human health, especially inflammatory bowel disease (IBD) and colorectal cancer (CRC). IBD is a group of chronic, recurrent and incurable disease, which may affect the entire gastrointestinal tract, increasing the risk of CRC. Eukaryotic gene expression is a complicated process, which is mainly regulated at the level of gene transcription and mRNA translation. Protein translation in tissue is associated with a sequence of steps, including initiation, elongation, termination and recycling. Abnormal regulation of gene expression is the key to the pathogenesis of CRC. In the early stages of cancer, it is vital to identify new diagnostic and therapeutic targets and biomarkers. This review presented current knowledge on aberrant expression of eIFs, eEFs and eRFs in colorectal diseases. The current findings of protein synthesis on colorectal pathogenesis showed that eIFs, eEFs and eRFs may be potential targets for CRC treatment.
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6
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Yerlikaya A. Heme-regulated inhibitor: an overlooked eIF2α kinase in cancer investigations. Med Oncol 2022; 39:73. [PMID: 35568791 DOI: 10.1007/s12032-022-01668-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 01/24/2022] [Indexed: 10/18/2022]
Abstract
Heme-regulated inhibitor (HRI) kinase is a serine-threonine kinase, controlling the initiation of protein synthesis via phosphorylating α subunit of eIF2 on serine 51 residue, mainly in response to heme deprivation in erythroid cells. However, recent studies showed that HRI is also activated by several diverse signals, causing dysregulations in intracellular homeostatic mechanisms in non-erythroid cells. For instance, it was reported that the decrease in protein synthesis upon the 26S proteasomal inhibition by MG132 or bortezomib is mediated by increased eIF2α phosphorylation in an HRI-dependent manner in mouse embryonic fibroblast cells. The increase in eIF2α phosphorylation level through the activation of HRI upon 26S proteasomal inhibition is believed to protect cells against the buildup of misfolded and ubiquitinated proteins, having the potential to trigger the apoptotic response. In contrast, prolonged and sustained HRI-mediated eIF2α phosphorylation can induce cell death, which may involve ATF4 and CHOP expression. Altogether, these studies suggest that HRI-mediated eIF2α phosphorylation may be cytoprotective or cytotoxic depending on the cells, type, and duration of pharmacological agents used. It is thus hypothesized that both HRI activators, inducing eIF2α phosphorylation or HRI inhibitors causing disturbances in eIF2α phosphorylation, may be effective as novel strategies in cancer treatment if the balance in eIF2α phosphorylation is shifted in favor of autophagic or apoptotic response in cancer cells. It is here aimed to review the role of HRI in various biological mechanisms as well as the therapeutic potentials of recently developed HRI activators and inhibitors, targeting eIF2α phosphorylation in cancer cells.
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Affiliation(s)
- Azmi Yerlikaya
- Department of Medical Biology, Faculty of Medicine, Kutahya Health Sciences University, Kutahya, Turkey.
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7
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Kachaev ZM, Ivashchenko SD, Kozlov EN, Lebedeva LA, Shidlovskii YV. Localization and Functional Roles of Components of the Translation Apparatus in the Eukaryotic Cell Nucleus. Cells 2021; 10:3239. [PMID: 34831461 PMCID: PMC8623629 DOI: 10.3390/cells10113239] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 11/11/2021] [Accepted: 11/16/2021] [Indexed: 12/15/2022] Open
Abstract
Components of the translation apparatus, including ribosomal proteins, have been found in cell nuclei in various organisms. Components of the translation apparatus are involved in various nuclear processes, particularly those associated with genome integrity control and the nuclear stages of gene expression, such as transcription, mRNA processing, and mRNA export. Components of the translation apparatus control intranuclear trafficking; the nuclear import and export of RNA and proteins; and regulate the activity, stability, and functional recruitment of nuclear proteins. The nuclear translocation of these components is often involved in the cell response to stimulation and stress, in addition to playing critical roles in oncogenesis and viral infection. Many components of the translation apparatus are moonlighting proteins, involved in integral cell stress response and coupling of gene expression subprocesses. Thus, this phenomenon represents a significant interest for both basic and applied molecular biology. Here, we provide an overview of the current data regarding the molecular functions of translation factors and ribosomal proteins in the cell nucleus.
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Affiliation(s)
- Zaur M. Kachaev
- Department of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia; (Z.M.K.); (S.D.I.); (E.N.K.); (L.A.L.)
- Center for Genetics and Life Science, Sirius University of Science and Technology, 354340 Sochi, Russia
| | - Sergey D. Ivashchenko
- Department of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia; (Z.M.K.); (S.D.I.); (E.N.K.); (L.A.L.)
| | - Eugene N. Kozlov
- Department of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia; (Z.M.K.); (S.D.I.); (E.N.K.); (L.A.L.)
| | - Lyubov A. Lebedeva
- Department of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia; (Z.M.K.); (S.D.I.); (E.N.K.); (L.A.L.)
| | - Yulii V. Shidlovskii
- Department of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia; (Z.M.K.); (S.D.I.); (E.N.K.); (L.A.L.)
- Center for Genetics and Life Science, Sirius University of Science and Technology, 354340 Sochi, Russia
- Department of Biology and General Genetics, Sechenov First Moscow State Medical University (Sechenov University), 119992 Moscow, Russia
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8
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Role of RONS and eIFs in Cancer Progression. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:5522054. [PMID: 34285764 PMCID: PMC8275427 DOI: 10.1155/2021/5522054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 04/19/2021] [Accepted: 05/14/2021] [Indexed: 12/05/2022]
Abstract
Various research works have piled up conflicting evidence questioning the effect of oxidative stress in cancer. Reactive oxygen and nitrogen species (RONS) are the reactive radicals and nonradical derivatives of oxygen and nitrogen. RONS can act as a double-edged weapon. On the one hand, RONS can promote cancer initiation through activating certain signal transduction pathways that direct proliferation, survival, and stress resistance. On the other hand, they can mitigate cancer progression via their resultant oxidative stress that causes many cancer cells to die, as some recent studies have proposed that high RONS levels can limit the survival of cancer cells during certain phases of cancer development. Similarly, eukaryotic translation initiation factors are key players in the process of cellular transformation and tumorigenesis. Dysregulation of such translation initiation factors in the form of overexpression, downregulation, or phosphorylation is associated with cancer cell's altering capability of survival, metastasis, and angiogenesis. Nonetheless, eIFs can affect tumor age-related features. Data shows that alternating the eukaryotic translation initiation apparatus can impact many downstream cellular signaling pathways that directly affect cancer development. Hence, researchers have been conducting various experiments towards a new trajectory to find novel therapeutic molecular targets to improve the efficacy of anticancer drugs as well as reduce their side effects, with a special focus on oxidative stress and initiation of translation to harness their effect in cancer development. An increasing body of scientific evidence recently links oxidative stress and translation initiation factors to cancer-related signaling pathways. Therefore, in this review, we present and summarize the recent findings in this field linking certain signaling pathways related to tumorigeneses such as MAPK and PI3K, with either RONS or eIFs.
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9
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Nogueira G, Fernandes R, García-Moreno JF, Romão L. Nonsense-mediated RNA decay and its bipolar function in cancer. Mol Cancer 2021; 20:72. [PMID: 33926465 PMCID: PMC8082775 DOI: 10.1186/s12943-021-01364-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 04/19/2021] [Indexed: 12/17/2022] Open
Abstract
Nonsense-mediated decay (NMD) was first described as a quality-control mechanism that targets and rapidly degrades aberrant mRNAs carrying premature termination codons (PTCs). However, it was found that NMD also degrades a significant number of normal transcripts, thus arising as a mechanism of gene expression regulation. Based on these important functions, NMD regulates several biological processes and is involved in the pathophysiology of a plethora of human genetic diseases, including cancer. The present review aims to discuss the paradoxical, pro- and anti-tumorigenic roles of NMD, and how cancer cells have exploited both functions to potentiate the disease. Considering recent genetic and bioinformatic studies, we also provide a comprehensive overview of the present knowledge of the advantages and disadvantages of different NMD modulation-based approaches in cancer therapy, reflecting on the challenges imposed by the complexity of this disease. Furthermore, we discuss significant advances in the recent years providing new perspectives on the implications of aberrant NMD-escaping frameshifted transcripts in personalized immunotherapy design and predictive biomarker optimization. A better understanding of how NMD differentially impacts tumor cells according to their own genetic identity will certainly allow for the application of novel and more effective personalized treatments in the near future.
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Affiliation(s)
- Gonçalo Nogueira
- Departamento de Genética Humana, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016, Lisbon, Portugal.,BioISI - Instituto de Biossistemas e Ciências Integrativas, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisbon, Portugal
| | - Rafael Fernandes
- Departamento de Genética Humana, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016, Lisbon, Portugal.,BioISI - Instituto de Biossistemas e Ciências Integrativas, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisbon, Portugal
| | - Juan F García-Moreno
- Departamento de Genética Humana, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016, Lisbon, Portugal.,BioISI - Instituto de Biossistemas e Ciências Integrativas, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisbon, Portugal
| | - Luísa Romão
- Departamento de Genética Humana, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016, Lisbon, Portugal. .,BioISI - Instituto de Biossistemas e Ciências Integrativas, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisbon, Portugal.
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10
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Amodio G, Pagliara V, Moltedo O, Remondelli P. Structural and Functional Significance of the Endoplasmic Reticulum Unfolded Protein Response Transducers and Chaperones at the Mitochondria-ER Contacts: A Cancer Perspective. Front Cell Dev Biol 2021; 9:641194. [PMID: 33842465 PMCID: PMC8033034 DOI: 10.3389/fcell.2021.641194] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 02/22/2021] [Indexed: 01/15/2023] Open
Abstract
In the last decades, the endoplasmic reticulum (ER) has emerged as a key coordinator of cellular homeostasis, thanks to its physical interconnection to almost all intracellular organelles. In particular, an intense and mutual crosstalk between the ER and mitochondria occurs at the mitochondria–ER contacts (MERCs). MERCs ensure a fine-tuned regulation of fundamental cellular processes, involving cell fate decision, mitochondria dynamics, metabolism, and proteostasis, which plays a pivotal role in the tumorigenesis and therapeutic response of cancer cells. Intriguingly, recent studies have shown that different components of the unfolded protein response (UPR) machinery, including PERK, IRE1α, and ER chaperones, localize at MERCs. These proteins appear to exhibit multifaceted roles that expand beyond protein folding and UPR transduction and are often related to the control of calcium fluxes to the mitochondria, thus acquiring relevance to cell survival and death. In this review, we highlight the novel functions played by PERK, IRE1α, and ER chaperones at MERCs focusing on their impact on tumor development.
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Affiliation(s)
- Giuseppina Amodio
- Department of Medicine, Surgery and Dentistry "Scuola Medica Salernitana," University of Salerno, Baronissi, Italy
| | - Valentina Pagliara
- Department of Medicine, Surgery and Dentistry "Scuola Medica Salernitana," University of Salerno, Baronissi, Italy
| | - Ornella Moltedo
- Department of Pharmacy, University of Salerno, Fisciano, Italy
| | - Paolo Remondelli
- Department of Medicine, Surgery and Dentistry "Scuola Medica Salernitana," University of Salerno, Baronissi, Italy
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11
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Smith RCL, Kanellos G, Vlahov N, Alexandrou C, Willis AE, Knight JRP, Sansom OJ. Translation initiation in cancer at a glance. J Cell Sci 2021; 134:jcs248476. [PMID: 33441326 DOI: 10.1242/jcs.248476] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cell division, differentiation and function are largely dependent on accurate proteome composition and regulated gene expression. To control this, protein synthesis is an intricate process governed by upstream signalling pathways. Eukaryotic translation is a multistep process and can be separated into four distinct phases: initiation, elongation, termination and recycling of ribosomal subunits. Translation initiation, the focus of this article, is highly regulated to control the activity and/or function of eukaryotic initiation factors (eIFs) and permit recruitment of mRNAs to the ribosomes. In this Cell Science at a Glance and accompanying poster, we outline the mechanisms by which tumour cells alter the process of translation initiation and discuss how this benefits tumour formation, proliferation and metastasis.
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Affiliation(s)
- Rachael C L Smith
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, G61 1QH, UK
| | - Georgios Kanellos
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
| | - Nikola Vlahov
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
| | | | - Anne E Willis
- MRC Toxicology Unit, University of Cambridge, Cambridge CB2 1QW, UK
| | - John R P Knight
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
| | - Owen J Sansom
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, G61 1QH, UK
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12
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Minnee E, Faller WJ. Translation initiation and its relevance in colorectal cancer. FEBS J 2021; 288:6635-6651. [PMID: 33382175 PMCID: PMC9291299 DOI: 10.1111/febs.15690] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 12/22/2020] [Accepted: 12/29/2020] [Indexed: 01/08/2023]
Abstract
Protein synthesis is one of the most essential processes in every kingdom of life, and its dysregulation is a known driving force in cancer development. Multiple signaling pathways converge on the translation initiation machinery, and this plays a crucial role in regulating differential gene expression. In colorectal cancer, dysregulation of initiation results in translational reprogramming, which promotes the selective translation of mRNAs required for many oncogenic processes. The majority of upstream mutations found in colorectal cancer, including alterations in the WNT, MAPK, and PI3K\AKT pathways, have been demonstrated to play a significant role in translational reprogramming. Many translation initiation factors are also known to be dysregulated, resulting in translational reprogramming during tumor initiation and/or maintenance. In this review, we outline the role of translational reprogramming that occurs during colorectal cancer development and progression and highlight some of the most critical factors affecting the etiology of this disease.
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Affiliation(s)
- Emma Minnee
- Division of Oncogenomics, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - William James Faller
- Division of Oncogenomics, Netherlands Cancer Institute, Amsterdam, The Netherlands
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13
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Rahem SM, Epsi NJ, Coffman FD, Mitrofanova A. Genome-wide analysis of therapeutic response uncovers molecular pathways governing tamoxifen resistance in ER+ breast cancer. EBioMedicine 2020; 61:103047. [PMID: 33099086 PMCID: PMC7585053 DOI: 10.1016/j.ebiom.2020.103047] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 09/02/2020] [Accepted: 09/18/2020] [Indexed: 01/10/2023] Open
Abstract
Background Prioritization of breast cancer patients based on the risk of resistance to tamoxifen plays a significant role in personalized therapeutic planning and improving disease course and outcomes. Methods In this work, we demonstrate that a genome-wide pathway-centric computational framework elucidates molecular pathways as markers of tamoxifen resistance in ER+ breast cancer patients. In particular, we associated activity levels of molecular pathways with a wide spectrum of response to tamoxifen, which defined markers of tamoxifen resistance in patients with ER+ breast cancer. Findings We identified five biological pathways as markers of tamoxifen failure and demonstrated their ability to predict the risk of tamoxifen resistance in two independent patient cohorts (Test cohort1: log-rank p-value = 0.02, adjusted HR = 3.11; Test cohort2: log-rank p-value = 0.01, adjusted HR = 4.24). We have shown that these pathways are not markers of aggressiveness and outperform known markers of tamoxifen response. Furthermore, for adoption into clinic, we derived a list of pathway read-out genes and their associated scoring system, which assigns a risk of tamoxifen resistance for new incoming patients. Interpretation We propose that the identified pathways and their read-out genes can be utilized to prioritize patients who would benefit from tamoxifen treatment and patients at risk of tamoxifen resistance that should be offered alternative regimens. Funding This work was supported by the Rutgers SHP Dean's research grant, Rutgers start-up funds, Libyan Ministry of Higher Education and Scientific Research, and Katrina Kehlet Graduate Award from The NJ Chapter of the Healthcare Information Management Systems Society.
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Affiliation(s)
- Sarra M Rahem
- Department of Biomedical and Health Informatics, Rutgers School of Health Professions, Rutgers Biomedical and Health Sciences, USA
| | - Nusrat J Epsi
- Department of Biomedical and Health Informatics, Rutgers School of Health Professions, Rutgers Biomedical and Health Sciences, USA
| | - Frederick D Coffman
- Department of Biomedical and Health Informatics, Rutgers School of Health Professions, Rutgers Biomedical and Health Sciences, USA; Department of Physician Assistant Studies and Practice, USA; Department of Pathology & Laboratory Medicine, New Jersey Medical School, Newark, New Jersey 07107, USA
| | - Antonina Mitrofanova
- Department of Biomedical and Health Informatics, Rutgers School of Health Professions, Rutgers Biomedical and Health Sciences, USA; Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, USA.
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14
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Schmidt S, Denk S, Wiegering A. Targeting Protein Synthesis in Colorectal Cancer. Cancers (Basel) 2020; 12:cancers12051298. [PMID: 32455578 PMCID: PMC7281195 DOI: 10.3390/cancers12051298] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 05/15/2020] [Accepted: 05/19/2020] [Indexed: 12/19/2022] Open
Abstract
Under physiological conditions, protein synthesis controls cell growth and survival and is strictly regulated. Deregulation of protein synthesis is a frequent event in cancer. The majority of mutations found in colorectal cancer (CRC), including alterations in the WNT pathway as well as activation of RAS/MAPK and PI3K/AKT and, subsequently, mTOR signaling, lead to deregulation of the translational machinery. Besides mutations in upstream signaling pathways, deregulation of global protein synthesis occurs through additional mechanisms including altered expression or activity of initiation and elongation factors (e.g., eIF4F, eIF2α/eIF2B, eEF2) as well as upregulation of components involved in ribosome biogenesis and factors that control the adaptation of translation in response to stress (e.g., GCN2). Therefore, influencing mechanisms that control mRNA translation may open a therapeutic window for CRC. Over the last decade, several potential therapeutic strategies targeting these alterations have been investigated and have shown promising results in cell lines, intestinal organoids, and mouse models. Despite these encouraging in vitro results, patients have not clinically benefited from those advances so far. In this review, we outline the mechanisms that lead to deregulated mRNA translation in CRC and highlight recent progress that has been made in developing therapeutic strategies that target these mechanisms for tumor therapy.
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Affiliation(s)
- Stefanie Schmidt
- Department of Biochemistry and Molecular Biology, Theodor Boveri Institute, Biocenter, University of Würzburg, 97074 Würzburg, Germany; (S.S.); (S.D.)
- Department of General, Visceral, Transplant, Vascular and Pediatric Surgery, University Hospital Würzburg, 97074 Würzburg, Germany
| | - Sarah Denk
- Department of Biochemistry and Molecular Biology, Theodor Boveri Institute, Biocenter, University of Würzburg, 97074 Würzburg, Germany; (S.S.); (S.D.)
- Department of General, Visceral, Transplant, Vascular and Pediatric Surgery, University Hospital Würzburg, 97074 Würzburg, Germany
| | - Armin Wiegering
- Department of Biochemistry and Molecular Biology, Theodor Boveri Institute, Biocenter, University of Würzburg, 97074 Würzburg, Germany; (S.S.); (S.D.)
- Department of General, Visceral, Transplant, Vascular and Pediatric Surgery, University Hospital Würzburg, 97074 Würzburg, Germany
- Department of Biochemistry and Molecular Biology, Comprehensive Cancer Center Mainfranken, University of Würzburg, 97074 Würzburg, Germany
- Correspondence: ; Tel.: +49-931-20138714
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Wan Mohd Tajuddin WNB, Lajis NH, Abas F, Othman I, Naidu R. Mechanistic Understanding of Curcumin's Therapeutic Effects in Lung Cancer. Nutrients 2019; 11:E2989. [PMID: 31817718 PMCID: PMC6950067 DOI: 10.3390/nu11122989] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 11/22/2019] [Accepted: 11/30/2019] [Indexed: 12/24/2022] Open
Abstract
Lung cancer is among the most common cancers with a high mortality rate worldwide. Despite the significant advances in diagnostic and therapeutic approaches, lung cancer prognoses and survival rates remain poor due to late diagnosis, drug resistance, and adverse effects. Therefore, new intervention therapies, such as the use of natural compounds with decreased toxicities, have been considered in lung cancer therapy. Curcumin, a natural occurring polyphenol derived from turmeric (Curcuma longa) has been studied extensively in recent years for its therapeutic effects. It has been shown that curcumin demonstrates anti-cancer effects in lung cancer through various mechanisms, including inhibition of cell proliferation, invasion, and metastasis, induction of apoptosis, epigenetic alterations, and regulation of microRNA expression. Several in vitro and in vivo studies have shown that these mechanisms are modulated by multiple molecular targets such as STAT3, EGFR, FOXO3a, TGF-β, eIF2α, COX-2, Bcl-2, PI3KAkt/mTOR, ROS, Fas/FasL, Cdc42, E-cadherin, MMPs, and adiponectin. In addition, limitations, strategies to overcome curcumin bioavailability, and potential side effects as well as clinical trials were also reviewed.
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Affiliation(s)
- Wan Nur Baitty Wan Mohd Tajuddin
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, Selangor Darul Ehsan 47500, Malaysia; (W.N.B.W.M.T.); (I.O.)
| | - Nordin H. Lajis
- Laboratory of Natural Products, Faculty of Science, Universiti Putra Malaysia, UPM, Serdang 43400, Malaysia; (N.H.L.); (F.A.)
| | - Faridah Abas
- Laboratory of Natural Products, Faculty of Science, Universiti Putra Malaysia, UPM, Serdang 43400, Malaysia; (N.H.L.); (F.A.)
- Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, UPM, Serdang 43400, Malaysia
| | - Iekhsan Othman
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, Selangor Darul Ehsan 47500, Malaysia; (W.N.B.W.M.T.); (I.O.)
| | - Rakesh Naidu
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, Selangor Darul Ehsan 47500, Malaysia; (W.N.B.W.M.T.); (I.O.)
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Anti-proliferative bioactivity against HT-29 colon cancer cells of a withanolides-rich extract from golden berry (Physalis peruviana L.) calyx investigated by Foodomics. J Funct Foods 2019. [DOI: 10.1016/j.jff.2019.103567] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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Schmidt S, Gay D, Uthe FW, Denk S, Paauwe M, Matthes N, Diefenbacher ME, Bryson S, Warrander FC, Erhard F, Ade CP, Baluapuri A, Walz S, Jackstadt R, Ford C, Vlachogiannis G, Valeri N, Otto C, Schülein-Völk C, Maurus K, Schmitz W, Knight JRP, Wolf E, Strathdee D, Schulze A, Germer CT, Rosenwald A, Sansom OJ, Eilers M, Wiegering A. A MYC-GCN2-eIF2α negative feedback loop limits protein synthesis to prevent MYC-dependent apoptosis in colorectal cancer. Nat Cell Biol 2019; 21:1413-1424. [PMID: 31685988 PMCID: PMC6927814 DOI: 10.1038/s41556-019-0408-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 09/20/2019] [Indexed: 12/12/2022]
Abstract
Tumours depend on altered rates of protein synthesis for growth and survival, which suggests that mechanisms controlling mRNA translation may be exploitable for therapy. Here, we show that loss of APC, which occurs almost universally in colorectal tumours, strongly enhances the dependence on the translation initiation factor eIF2B5. Depletion of eIF2B5 induces an integrated stress response and enhances translation of MYC via an internal ribosomal entry site. This perturbs cellular amino acid and nucleotide pools, strains energy resources and causes MYC-dependent apoptosis. eIF2B5 limits MYC expression and prevents apoptosis in APC-deficient murine and patient-derived organoids and in APC-deficient murine intestinal epithelia in vivo. Conversely, the high MYC levels present in APC-deficient cells induce phosphorylation of eIF2α via the kinases GCN2 and PKR. Pharmacological inhibition of GCN2 phenocopies eIF2B5 depletion and has therapeutic efficacy in tumour organoids, which demonstrates that a negative MYC-eIF2α feedback loop constitutes a targetable vulnerability of colorectal tumours.
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Affiliation(s)
- Stefanie Schmidt
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
- Department of General, Visceral, Vascular and Pediatric Surgery, University Hospital Würzburg, Würzburg, Germany
| | | | - Friedrich Wilhelm Uthe
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
- Department of General, Visceral, Vascular and Pediatric Surgery, University Hospital Würzburg, Würzburg, Germany
| | - Sarah Denk
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
- Department of General, Visceral, Vascular and Pediatric Surgery, University Hospital Würzburg, Würzburg, Germany
| | | | - Niels Matthes
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
- Department of General, Visceral, Vascular and Pediatric Surgery, University Hospital Würzburg, Würzburg, Germany
| | | | | | | | - Florian Erhard
- Institute for Virology and Immunobiology, University of Würzburg, Würzburg, Germany
| | - Carsten Patrick Ade
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Apoorva Baluapuri
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Susanne Walz
- Comprehensive Cancer Center Mainfranken, Core Unit Bioinformatics, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | | | | | | | - Nicola Valeri
- Division of Molecular Pathology, The Institute of Cancer Research, London, UK
- Department of Medicine, The Royal Marsden NHS Trust, London, UK
| | - Christoph Otto
- Department of General, Visceral, Vascular and Pediatric Surgery, University Hospital Würzburg, Würzburg, Germany
| | | | - Katja Maurus
- Comprehensive Cancer Center Mainfranken, University of Würzburg, Würzburg, Germany
| | - Werner Schmitz
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | | | - Elmar Wolf
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | | | - Almut Schulze
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
- Comprehensive Cancer Center Mainfranken, University of Würzburg, Würzburg, Germany
| | - Christoph-Thomas Germer
- Department of General, Visceral, Vascular and Pediatric Surgery, University Hospital Würzburg, Würzburg, Germany
- Comprehensive Cancer Center Mainfranken, University of Würzburg, Würzburg, Germany
| | - Andreas Rosenwald
- Comprehensive Cancer Center Mainfranken, University of Würzburg, Würzburg, Germany
| | - Owen James Sansom
- CRUK Beatson Institute, Glasgow, UK
- Institute of Cancer Sciences, University of Glasgow, Glasgow, UK
| | - Martin Eilers
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany.
- Comprehensive Cancer Center Mainfranken, University of Würzburg, Würzburg, Germany.
| | - Armin Wiegering
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany.
- Department of General, Visceral, Vascular and Pediatric Surgery, University Hospital Würzburg, Würzburg, Germany.
- Comprehensive Cancer Center Mainfranken, University of Würzburg, Würzburg, Germany.
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Kim HJ. Cell Fate Control by Translation: mRNA Translation Initiation as a Therapeutic Target for Cancer Development and Stem Cell Fate Control. Biomolecules 2019; 9:biom9110665. [PMID: 31671902 PMCID: PMC6921038 DOI: 10.3390/biom9110665] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 10/28/2019] [Accepted: 10/28/2019] [Indexed: 12/11/2022] Open
Abstract
Translation of mRNA is an important process that controls cell behavior and gene regulation because proteins are the functional molecules that determine cell types and function. Cancer develops as a result of genetic mutations, which lead to the production of abnormal proteins and the dysregulation of translation, which in turn, leads to aberrant protein synthesis. In addition, the machinery that is involved in protein synthesis plays critical roles in stem cell fate determination. In the current review, recent advances in the understanding of translational control, especially translational initiation in cancer development and stem cell fate control, are described. Therapeutic targets of mRNA translation such as eIF4E, 4EBP, and eIF2, for cancer treatment or stem cell fate regulation are reviewed. Upstream signaling pathways that regulate and affect translation initiation were introduced. It is important to regulate the expression of protein for normal cell behavior and development. mRNA translation initiation is a key step to regulate protein synthesis, therefore, identifying and targeting molecules that are critical for protein synthesis is necessary and beneficial to develop cancer therapeutics and stem cells fate regulation.
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Affiliation(s)
- Hyun-Jung Kim
- Laboratory of Molecular Stem Cell Pharmacology, College of Pharmacy, Chung-Ang University, Seoul 156-756, Korea.
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Dual role of Endoplasmic Reticulum Stress-Mediated Unfolded Protein Response Signaling Pathway in Carcinogenesis. Int J Mol Sci 2019; 20:ijms20184354. [PMID: 31491919 PMCID: PMC6770252 DOI: 10.3390/ijms20184354] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 08/30/2019] [Accepted: 09/03/2019] [Indexed: 12/24/2022] Open
Abstract
Cancer constitutes a grave problem nowadays in view of the fact that it has become one of the main causes of death worldwide. Poor clinical prognosis is presumably due to cancer cells metabolism as tumor microenvironment is affected by oxidative stress. This event triggers adequate cellular response and thereby creates appropriate conditions for further cancer progression. Endoplasmic reticulum (ER) stress occurs when the balance between an ability of the ER to fold and transfer proteins and the degradation of the misfolded ones become distorted. Since ER is an organelle relatively sensitive to oxidative damage, aforementioned conditions swiftly cause the activation of the unfolded protein response (UPR) signaling pathway. The output of the UPR, depending on numerous factors, may vary and switch between the pro-survival and the pro-apoptotic branch, and hence it displays opposing effects in deciding the fate of the cancer cell. The role of UPR-related proteins in tumorigenesis, such as binding the immunoglobulin protein (BiP) and inositol-requiring enzyme-1α (IRE1α), activating transcription factor 6 (ATF6) or the protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK), has already been specifically described so far. Nevertheless, due to the paradoxical outcomes of the UPR activation as well as gaps in current knowledge, it still needs to be further investigated. Herein we would like to elicit the actual link between neoplastic diseases and the UPR signaling pathway, considering its major branches and discussing its potential use in the development of a novel, anti-cancer, targeted therapy.
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Baldelli G, De Santi M, Fraternale D, Brandi G, Fanelli M, Schiavano GF. Chemopreventive Potential of Apple Pulp Callus Against Colorectal Cancer Cell Proliferation and Tumorigenesis. J Med Food 2019; 22:614-622. [PMID: 31058564 DOI: 10.1089/jmf.2018.0188] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
This study focused on the evaluation of the chemopreventive potential of tissue in vitro culture of the "Mela Rosa Marchigiana" apple (MRM callus) that allows the amplification of secondary metabolites. The MRM pulp and MRM callus chemopreventive potential was evaluated in terms of antiproliferative activity, inhibition of tumorigenesis in soft agar cultures, cell cycle and western blotting analyses in CaCo2 and LoVo colon cancer cell lines and in JB6 promotion-sensitive (JB6 P+) cells. MRM callus induced a strong concentration-dependent inhibition of colon cancer cell proliferation and suppressed 12-o-tetra-decanoyl-phorbol-13-acetate-induced tumorigenesis of JB6 P+ cells in soft agar cultures. MRM callus inhibited the phosphorylation of JNK, p38, and eIF2alpha. Our data indicate that the MRM callus exerts a good antiproliferative and antitumorigenic potential through the MAP kinase inhibition and could provide natural compounds with chemopreventive properties.
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Affiliation(s)
- Giulia Baldelli
- 1 Department of Biomolecular Sciences, Hygiene Unit, University of Urbino Carlo Bo, Urbino, Italy
| | - Mauro De Santi
- 1 Department of Biomolecular Sciences, Hygiene Unit, University of Urbino Carlo Bo, Urbino, Italy
| | - Daniele Fraternale
- 2 Department of Biomolecular Sciences, Plant Biology Unit, University of Urbino Carlo Bo, Urbino, Italy
| | - Giorgio Brandi
- 1 Department of Biomolecular Sciences, Hygiene Unit, University of Urbino Carlo Bo, Urbino, Italy
| | - Mirco Fanelli
- 3 Department of Biomolecular Sciences, Biotechnology Unit, University of Urbino Carlo Bo, Fano, Italy
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Maida I, Zanna P, Guida S, Ferretta A, Cocco T, Palese LL, Londei P, Benelli D, Azzariti A, Tommasi S, Guida M, Pellacani G, Guida G. Translational control mechanisms in cutaneous malignant melanoma: the role of eIF2α. J Transl Med 2019; 17:20. [PMID: 30634982 PMCID: PMC6329103 DOI: 10.1186/s12967-019-1772-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 01/02/2019] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Melanoma cells develop adaptive responses in order to cope with particular conditions of tumor microenvironment, characterized by stress conditions and deregulated proliferation. Recently, the interplay between the stress response and the gene expression programs leading to metastatic spread has been reported. METHODS We evaluated levels and localization of eIF2α/peIF2α in V600BRAF and wtBRAF metastatic melanoma cell lines by means of western blot and confocal microscopy analyses. Furthermore, we performed a sequence analyses and structure and dynamics studies of eIF2α protein to reveal the role of eIF2α and its correlations in different pathways involved in the invasive phase of melanoma. RESULTS We found peIF2α both in cytoplasm and nucleus. Nuclear localization was more represented in V600BRAF melanoma cell lines. Our studies on eIF2α protein sequence indicated the presence of a predicted bipartite NLS as well as a nuclear export signal NES and an S1 domain, typical of RNA interacting proteins. Furthermore, we found high levels of transcription factor EB (TFEB), a component of the MiT/TFE family, and low β-catenin levels in V600BRAF cells. CONCLUSIONS Based on our results, we suggest that peIF2α nuclear localization can be crucial in ER stress response and in driving the metastatic spread of melanoma, through lysosomal signaling and Wnt/β-catenin pathway. In conclusion, this is the first evidence of nuclear localization of peIF2α, representing a possible target for future therapeutic approaches for metastatic melanoma.
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Affiliation(s)
- Immacolata Maida
- Department of Basic Medical Sciences Neurosciences and Sense Organs, University of Bari, Bari, Italy
| | - Paola Zanna
- Department of Basic Medical Sciences Neurosciences and Sense Organs, University of Bari, Bari, Italy
| | - Stefania Guida
- Dermatology Unit, Department of Surgical, Medical, Dental and Morphological Science with Interest Transplant, Oncological and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy
| | - Anna Ferretta
- Department of Basic Medical Sciences Neurosciences and Sense Organs, University of Bari, Bari, Italy
| | - Tiziana Cocco
- Department of Basic Medical Sciences Neurosciences and Sense Organs, University of Bari, Bari, Italy
| | - Luigi Leonardo Palese
- Department of Basic Medical Sciences Neurosciences and Sense Organs, University of Bari, Bari, Italy
| | - Paola Londei
- Department of Cellular Biotechnology and Hematology BCE, Sapienza University of Rome, Rome, Italy
| | - Dario Benelli
- Department of Cellular Biotechnology and Hematology BCE, Sapienza University of Rome, Rome, Italy
| | - Amalia Azzariti
- National Cancer Research Centre “Giovanni Paolo II”, Bari, Italy
| | - Stefania Tommasi
- National Cancer Research Centre “Giovanni Paolo II”, Bari, Italy
| | - Michele Guida
- National Cancer Research Centre “Giovanni Paolo II”, Bari, Italy
| | - Giovanni Pellacani
- Dermatology Unit, Department of Surgical, Medical, Dental and Morphological Science with Interest Transplant, Oncological and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy
| | - Gabriella Guida
- Department of Basic Medical Sciences Neurosciences and Sense Organs, University of Bari, Bari, Italy
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Burwick N, Aktas BH. The eIF2-alpha kinase HRI: a potential target beyond the red blood cell. Expert Opin Ther Targets 2017; 21:1171-1177. [PMID: 29063813 DOI: 10.1080/14728222.2017.1397133] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
INTRODUCTION The eIF2α kinase heme-regulated inhibitor (HRI) is one of four well-described kinases that phosphorylate eIF2α in response to various cell stressors, resulting in reduced ternary complex formation and attenuation of mRNA translation. Although HRI is well known for its role as a heme sensor in erythroid progenitors, pharmacologic activation of HRI has been demonstrated to have anti-cancer activity across a wide range of tumor sub-types. Here, the potential of HRI activators as novel cancer therapeutics is explored. Areas covered: We provide an introduction to eIF2 signaling pathways in general, and specifically review data on the eIF2α kinase HRI in erythroid and non-erythroid cells. We review aspects of targeting eIF2 signaling in cancer and highlight promising data using HRI activators against tumor cells. Expert opinion: Pharmacologic activation of HRI inhibits tumor growth as a single agent without appreciable toxicity in vivo. The ability of HRI activators to provide direct and sustained eIF2α phosphorylation without inducing oxidative stress or broad eIF2α kinase activation may be especially advantageous for tolerability. Combination therapy with established therapeutics may further augment anti-cancer activity to overcome disease resistance.
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Affiliation(s)
- Nicholas Burwick
- a Division of hematology , VA Puget Sound Health Care System , Seattle , WA , USA.,b Division of Hematology , University of Washington School of Medicine , Seattle WA , USA
| | - Bertal H Aktas
- c Department of Medicine , Brigham and Women's Hospital and Harvard Medical School , Boston , MA , USA
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Ali MU, Ur Rahman MS, Jia Z, Jiang C. Eukaryotic translation initiation factors and cancer. Tumour Biol 2017; 39:1010428317709805. [PMID: 28653885 DOI: 10.1177/1010428317709805] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Recent technological advancements have shown tremendous mechanistic accomplishments in our understanding of the mechanism of messenger RNA translation in eukaryotic cells. Eukaryotic messenger RNA translation is very complex process that includes four phases (initiation, elongation, termination, and ribosome recycling) and diverse mechanisms involving protein and non-protein molecules. Translation regulation is principally achieved during initiation step of translation, which is organized by multiple eukaryotic translation initiation factors. Eukaryotic translation initiation factor proteins help in stabilizing the formation of the functional ribosome around the start codon and provide regulatory mechanisms in translation initiation. Dysregulated messenger RNA translation is a common feature of tumorigenesis. Various oncogenic and tumor suppressive genes affect/are affected by the translation machinery, making the components of the translation apparatus promising therapeutic targets for the novel anticancer drug. This review provides details on the role of eukaryotic translation initiation factors in messenger RNA translation initiation, their contribution to onset and progression of tumor, and how dysregulated eukaryotic translation initiation factors can be used as a target to treat carcinogenesis.
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Affiliation(s)
- Muhammad Umar Ali
- 1 Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Muhammad Saif Ur Rahman
- 1 Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhenyu Jia
- 2 Institute of Occupational Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, China
| | - Cao Jiang
- 1 Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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Salton GD, Laurino CCFC, Mega NO, Delgado-Cañedo A, Setterblad N, Carmagnat M, Xavier RM, Cirne-Lima E, Lenz G, Henriques JAP, Laurino JP. Deletion of eIF2β lysine stretches creates a dominant negative that affects the translation and proliferation in human cell line: A tool for arresting the cell growth. Cancer Biol Ther 2017; 18:560-570. [PMID: 28692326 DOI: 10.1080/15384047.2017.1345383] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Eukaryote initiation factor 2 subunit β (eIF2β) plays a crucial role in regulation protein synthesis, which mediates the interaction of eIF2 with mRNA. eIF2β contains evolutionarily conserved polylysine stretches in amino-terminal region and a zinc finger motif in the carboxy-terminus. METHODS The gene eIF2β was cloned under tetracycline transcription control and the polylysine stretches were deleted by site-directed mutagenesis (eIF2βΔ3K). The plasmid was transfected into HEK 293 TetR cells. These cells were analyzed for their proliferative and translation capacities as well as cell death rate. Experiments were performed using gene reporter assays, western blotting, flow cytometry, cell sorting, cell proliferation assays and confocal immunofluorescence. RESULTS eIF2βΔ3K affected negatively the protein synthesis, cell proliferation and cell survival causing G2 cell cycle arrest and increased cell death, acting in a negative dominant manner against the native protein. Polylysine stretches are also essential for eIF2β translocated from the cytoplasm to the nucleus, accumulating in the nucleolus and eIF2βΔ3K did not make this translocation. DISCUSSION eIF2β is involved in the protein synthesis process and should act in nuclear processes as well. eIF2βΔ3K reduces cell proliferation and causes cell death. Since translation control is essential for normal cell function and survival, the development of drugs or molecules that inhibit translation has become of great interest in the scenario of proliferative disorders. In conclusion, our results suggest the dominant negative eIF2βΔ3K as a therapeutic strategy for the treatment of proliferative disorders and that eIF2β polylysine stretch domains are promising targets for this.
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Affiliation(s)
- Gabrielle Dias Salton
- a Post-Graduation Program in Cellular and Molecular Biology, Molecular Radiobiology Laboratory, Biotechnology Center , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) , Brazil , Cryobiology Unit and Umbilical Cord Blood Bank, Hemotherapy Service , Hospital de Clínicas de Porto Alegre , Porto Alegre (RS) , Brazil
| | - Claudia Cilene Fernandes Correia Laurino
- b Molecular Biology for Auto-immune and Infectious Diseases Laboratory, Experimental Research Center, Hospital de Clínicas de Porto Alegre , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) , Brazil . Embriology and Cellular Differentiation Laboratory, Experimental Research Center, Hospital de Clínicas de Porto Alegre; Faculdade de Veterinária , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) , Brazil . Faculdade Nossa Senhora de Fátima , Caxias do Sul (RS) , Brazil . Instituto Brasileiro de Saúde , Porto Alegre (RS) , Brazil
| | - Nicolás Oliveira Mega
- c Animal Biology Post-Graduation Program , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) , Brazil
| | - Andrés Delgado-Cañedo
- d Biotechnology Research Center for Interdisciplinary Research , Universidade Federal do Pampa , São Gabriel (RS) , Brazil
| | - Niclas Setterblad
- e Imaging, Cell Selection and Genomics Platform , Institut Universitaire d'Hématologie, Hôpital Saint-Louis , Paris , France
| | - Maryvonnick Carmagnat
- f Immunology and Histocompatibility Laboratory AP-HP , INSERM UMRS 940, Institut Universitaire d'Hématologie , Paris , France
| | - Ricardo Machado Xavier
- g Molecular Biology for Auto-immune and Infectious Diseases Laboratory, Experimental Research Center, Hospital de Clínicas de Porto Alegre , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) , Brazil
| | - Elizabeth Cirne-Lima
- h Embriology and Cellular Differentiation Laboratory, Experimental Research Center, Hospital de Clínicas de Porto Alegre; Faculdade de Veterinária , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) , Brazil
| | - Guido Lenz
- i Cell Signaling Laboratory, Biophysics Department, Biotechnology Center and Post-Graduation Program in Cellular and Molecular Biology , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) , Brazil
| | - João Antonio Pêgas Henriques
- j Molecular Radiobiology Laboratory, Biotechnology Center and Post-Graduation Program in Cellular and Molecular Biology , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) ; Biotechnology Institute , Universidade de Caxias do Sul , Caxias do Sul (RS) , Brazil
| | - Jomar Pereira Laurino
- k Biotechnology Institute , Universidade de Caxias do Sul, Caxias do Sul (RS) and Instituto Brasileiro de Saúde , Porto Alegre (RS) , Brazil
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25
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Guo L, Chi Y, Xue J, Ma L, Shao Z, Wu J. Phosphorylated eIF2α predicts disease-free survival in triple-negative breast cancer patients. Sci Rep 2017; 7:44674. [PMID: 28294178 PMCID: PMC5353635 DOI: 10.1038/srep44674] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 02/13/2017] [Indexed: 12/13/2022] Open
Abstract
Phosphorylated eukaryotic translation initiation factor 2α (p-eIF2α), which functions as a marker of endoplasmic reticulum stress, has been reported to be associated with patient prognosis in various cancers. However, little is known about the prognostic value of p-eIF2α in breast cancer, particularly in different breast cancer subtypes. An immunohistochemistry screen for p-eIF2α was performed using a tissue microarray containing 233 tumors and paired peritumoral tissues from female patients diagnosed with breast cancer. The staining results were scored semiquantitatively, and the p-eIF2α expression level in breast cancer and its potential prognostic value were investigated. In this retrospective cohort study, we found that p-eIF2α levels were significantly upregulated in breast cancer (P < 0.001). p-eIF2α level was negatively correlated with lymph node status (P = 0.039). Survival analysis by Kaplan–Meier estimation and Cox regression showed that p-eIF2α level was correlated with better disease free survival (P = 0.026) and served as an independent prognostic factor (P = 0.046) in patients with triple-negative breast cancer. Our study revealed that p-eIF2α was upregulated in breast cancer and represented a novel predictor of prognosis in patients with triple-negative subtype.
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Affiliation(s)
- Liang Guo
- Department of Breast Surgery, Key Laboratory of Breast Cancer in Shanghai, Fudan University Shanghai Cancer Center, Shanghai 200032, PR China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, PR China
| | - Yayun Chi
- Department of Breast Surgery, Key Laboratory of Breast Cancer in Shanghai, Fudan University Shanghai Cancer Center, Shanghai 200032, PR China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, PR China
| | - Jingyan Xue
- Department of Breast Surgery, Key Laboratory of Breast Cancer in Shanghai, Fudan University Shanghai Cancer Center, Shanghai 200032, PR China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, PR China
| | - Linxiaoxi Ma
- Department of Breast Surgery, Key Laboratory of Breast Cancer in Shanghai, Fudan University Shanghai Cancer Center, Shanghai 200032, PR China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, PR China
| | - Zhiming Shao
- Department of Breast Surgery, Key Laboratory of Breast Cancer in Shanghai, Fudan University Shanghai Cancer Center, Shanghai 200032, PR China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, PR China
| | - Jiong Wu
- Department of Breast Surgery, Key Laboratory of Breast Cancer in Shanghai, Fudan University Shanghai Cancer Center, Shanghai 200032, PR China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, PR China.,Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
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26
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Proteomic Analysis of Liver Proteins in a Rat Model of Chronic Restraint Stress-Induced Depression. BIOMED RESEARCH INTERNATIONAL 2017; 2017:7508316. [PMID: 28293639 PMCID: PMC5331273 DOI: 10.1155/2017/7508316] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 11/28/2016] [Accepted: 12/22/2016] [Indexed: 01/16/2023]
Abstract
Depression is a global mental disorder disease and greatly threatened human health and stress is considered to be one of the important factors that lead to depression. In this study, we used newly developed iTRAQ labeling and high performance liquid chromatography (HPLC) and mass spectrum united analysis technology obtained the 2176 accurate proteins. Successively, we used the GO analysis and IPA software to analyze the 98 differentially expressed proteins of liver in depression rats due to chronic restraint stress, showing a map of proteomics analysis of liver proteins from the aspects of related functions, disease and function analysis, canonical pathway analysis, and associated network. This study provide important information for comprehensively understanding the mechanisms of dysfunction or injury in the liver in depression.
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27
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Role of Eukaryotic Initiation Factors during Cellular Stress and Cancer Progression. J Nucleic Acids 2016; 2016:8235121. [PMID: 28083147 PMCID: PMC5204094 DOI: 10.1155/2016/8235121] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Accepted: 11/14/2016] [Indexed: 12/12/2022] Open
Abstract
Protein synthesis can be segmented into distinct phases comprising mRNA translation initiation, elongation, and termination. Translation initiation is a highly regulated and rate-limiting step of protein synthesis that requires more than 12 eukaryotic initiation factors (eIFs). Extensive evidence shows that the transcriptome and corresponding proteome do not invariably correlate with each other in a variety of contexts. In particular, translation of mRNAs specific to angiogenesis, tumor development, and apoptosis is altered during physiological and pathophysiological stress conditions. In cancer cells, the expression and functions of eIFs are hampered, resulting in the inhibition of global translation and enhancement of translation of subsets of mRNAs by alternative mechanisms. A precise understanding of mechanisms involving eukaryotic initiation factors leading to differential protein expression can help us to design better strategies to diagnose and treat cancer. The high spatial and temporal resolution of translation control can have an immediate effect on the microenvironment of the cell in comparison with changes in transcription. The dysregulation of mRNA translation mechanisms is increasingly being exploited as a target to treat cancer. In this review, we will focus on this context by describing both canonical and noncanonical roles of eIFs, which alter mRNA translation.
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28
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Gawron D, Gevaert K, Van Damme P. The proteome under translational control. Proteomics 2014; 14:2647-62. [PMID: 25263132 DOI: 10.1002/pmic.201400165] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 08/21/2014] [Accepted: 09/23/2014] [Indexed: 02/02/2023]
Abstract
A single eukaryotic gene can give rise to a variety of protein forms (proteoforms) as a result of genetic variation and multilevel regulation of gene expression. In addition to alternative splicing, an increasing line of evidence shows that alternative translation contributes to the overall complexity of proteomes. Identifying the repertoire of proteins and micropeptides expressed by alternative selection of (near-)cognate translation initiation sites and different reading frames however remains challenging with contemporary proteomics. MS-enabled identification of proteoforms is expected to benefit from transcriptome and translatome data by the creation of customized and sample-specific protein sequence databases. Here, we focus on contemporary integrative omics approaches that complement proteomics with DNA- and/or RNA-oriented technologies to elucidate the mechanisms of translational control. Together, these technologies enable to map the translation (initiation) landscape and more comprehensively define the inventory of proteoforms raised upon alternative translation, thus assisting in the (re-)annotation of genomes.
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Affiliation(s)
- Daria Gawron
- Department of Medical Protein Research, VIB, Ghent, Belgium; Department of Biochemistry, Ghent University, Ghent, Belgium
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29
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Translational regulator eIF2α in tumor. Tumour Biol 2014; 35:6255-64. [DOI: 10.1007/s13277-014-1789-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 02/21/2014] [Indexed: 11/29/2022] Open
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30
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Marchal JA, Lopez GJ, Peran M, Comino A, Delgado JR, García-García JA, Conde V, Aranda FM, Rivas C, Esteban M, Garcia MA. The impact of PKR activation: from neurodegeneration to cancer. FASEB J 2014; 28:1965-74. [PMID: 24522206 DOI: 10.1096/fj.13-248294] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
An inverse association between cancer and neurodegeneration is plausible because these biological processes share several genes and signaling pathways. Whereas uncontrolled cell proliferation and decreased apoptotic cell death governs cancer, excessive apoptosis contributes to neurodegeneration. Protein kinase R (PKR), an interferon-inducible double-stranded RNA protein kinase, is involved in both diseases. PKR activation blocks global protein synthesis through eIF2α phosphorylation, leading to cell death in response to a variety of cellular stresses. However, PKR also has the dual role of activating the nuclear factor κ-B pathway, promoting cell proliferation. Whereas PKR is recognized for its negative effects on neurodegenerative diseases, in part, inducing high level of apoptosis, the role of PKR activation in cancer remains controversial. In general, PKR is considered to have a tumor suppressor function, and some clinical data show a correlation between suppressed or inactivated PKR and a poor prognosis for several cancers. However, other studies show high PKR expression and activation levels in various cancers, suggesting that PKR might contribute to neoplastic progression. Understanding the cellular factors and signals involved in the regulation of PKR in these age-related diseases is relevant and may have important clinical implications. The present review highlights the current knowledge on the role of PKR in neurodegeneration and cancer, with special emphasis on its regulation and clinical implications.
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Affiliation(s)
- Juan A Marchal
- 1University Hospital Virgen de las Nieves, Azpitarte sn., Granada E-18012, Spain.
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Kunkeaw N, Jeon SH, Lee K, Johnson BH, Tanasanvimon S, Javle M, Pairojkul C, Chamgramol Y, Wongfieng W, Gong B, Leelayuwat C, Lee YS. Cell death/proliferation roles for nc886, a non-coding RNA, in the protein kinase R pathway in cholangiocarcinoma. Oncogene 2013; 32:3722-31. [PMID: 22926522 PMCID: PMC3869796 DOI: 10.1038/onc.2012.382] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 07/09/2012] [Accepted: 07/23/2012] [Indexed: 12/25/2022]
Abstract
We have recently identified nc886 (pre-miR-886 or vtRNA2-1) as a novel type of non-coding RNA that inhibits activation of protein kinase R (PKR). PKR's pro-apoptotic role through eukaryotic initiation factor 2 α (eIF2α) phosphorylation is well established in the host defense against viral infection. Paradoxically, some cancer patients have elevated PKR activity; however, its cause and consequence are not understood. Initially, we evaluated the expression of nc886, PKR and eIF2α in non-malignant cholangiocyte and cholangiocarcinoma (CCA) cells. nc886 is repressed in CCA cells and this repression is the cause of PKR's activation therein. nc886 alone is necessary and sufficient for suppression of PKR via direct physical interaction. Consistently, artificial suppression of nc886 in cholangiocyte cells activates the canonical PKR/eIF2α cell death pathway, suggesting a potential significance of the nc886 suppression and the consequent PKR activation in eliminating pre-malignant cells during tumorigenesis. In comparison, active PKR in CCA cells does not induce phospho-eIF2α nor apoptosis, but promotes the pro-survival nuclear factor-κB pathway. Thus, PKR has a dual life or death role during tumorigenesis. Similarly to the CCA cell lines, nc886 tends to be decreased but PKR tends to be activated in our clinical samples from CCA patients. Collectively from our data, we propose a tumor surveillance model for nc886's role in the PKR pathway during tumorigenesis.
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Affiliation(s)
- Nawapol Kunkeaw
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX77555-1072, USA
- The Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
| | - Sung Ho Jeon
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX77555-1072, USA
- Department of Life Science, Hallym University, Chuncheon 200-702, Korea
| | - Kwanbok Lee
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX77555-1072, USA
| | - Betty H. Johnson
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX77555-1072, USA
| | - Suebpong Tanasanvimon
- Department of Medicine, King Chulalongkorn Memorial Hospital, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- Department of Gastroenterology, Hepatology, and Nutrition, MD Anderson Cancer Center, Houston, TX
| | - Milind Javle
- Gastrointestinal Medical Oncology, MD Anderson Cancer Center, Houston, TX
| | - Chawalit Pairojkul
- Liver Fluke and Cholangiocarcinoma Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Yaovalux Chamgramol
- Liver Fluke and Cholangiocarcinoma Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Wipaporn Wongfieng
- The Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
| | - Bin Gong
- Department of Pathology, The University of Texas Medical Branch, Galveston, TX
| | - Chanvit Leelayuwat
- The Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
- Liver Fluke and Cholangiocarcinoma Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Yong Sun Lee
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX77555-1072, USA
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32
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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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33
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Translational control gone awry: a new mechanism of tumorigenesis and novel targets of cancer treatments. Biosci Rep 2011; 31:1-15. [PMID: 20964625 DOI: 10.1042/bsr20100077] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Translational control is one of primary regulation mechanisms of gene expression. Eukaryotic translational control mainly occurs at the initiation step, the speed-limiting step, which involves more than ten translation initiation factors [eIFs (eukaryotic initiation factors)]. Changing the level or function of these eIFs results in abnormal translation of specific mRNAs and consequently abnormal growth of cells that leads to human diseases, including cancer. Accumulating evidence from recent studies showed that the expression of many eIFs was associated with malignant transformation, cancer prognosis, as well as gene expression regulation. In the present paper, we perform a critical review of recent advances in understanding the role and mechanism of eIF action in translational control and cancer as well as the possibility of targeting eIFs for therapeutic development.
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35
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Dupasquier S, Quittau-Prévostel C. A disrupted expression in cancers: multiple potential causes. C R Biol 2009; 332:1-14. [PMID: 19200921 DOI: 10.1016/j.crvi.2008.10.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Accepted: 10/03/2008] [Indexed: 10/21/2022]
Abstract
Tumor cells exhibit significant variations in the rate of pro- or anti-tumoral proteins that provide them a selective advantage of growth over normal cells. The control of these rates occurs at the three DNA, RNA and protein levels, and is determined by the structure of each of these three actors for the implementation of the molecular mechanisms involved in the control of the synthesis, maturation and stability of the mRNA and the protein itself. We give here an overview of the main events that can lead to a disruption of these mechanisms.
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Affiliation(s)
- Sébastien Dupasquier
- CNRS, UMR 5203, Institut de génomique fonctionnelle, 141 rue de la Cardonille, 34094 Montpellier cedex, France
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36
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Tejada S, Lobo MVT, García-Villanueva M, Sacristán S, Pérez-Morgado MI, Salinas M, Martín ME. Eukaryotic initiation factors (eIF) 2alpha and 4E expression, localization, and phosphorylation in brain tumors. J Histochem Cytochem 2009; 57:503-12. [PMID: 19188486 DOI: 10.1369/jhc.2009.952929] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Increased protein synthesis is regulated, in part, by two eukaryotic translation initiation factors (eIFs): eIF4E and eIF2alpha. One or both of these factors are often overexpressed in several types of cancer cells; however, no data are available at present regarding eIF4E and eIF2alpha levels in brain tumors. In this study, we analyzed the expression, subcellular localization and phosphorylation states of eIF4E and eIF2alpha in 64 brain tumors (26 meningiomas, 16 oligodendroglial tumors, and 22 astrocytomas) and investigated the correlation with the expression of MIB-1, p53, and cyclin D1 proteins as well. There are significant differences in the phosphorylated eIF4E levels between the tumors studied, being the highest in meningiomas and the lowest in the oligodendroglial tumors. Relative to subcellular localization, eIF4E is frequently found in the nucleus of the oligodendroglial tumors and rarely in the same compartment of the meningiomas, whereas eIF2alpha showed an inverse pattern. Finally, cyclin D1 levels directly correlate with the phosphorylation status of both factors. The different expression, phosphorylation, or/and subcellular distribution of eIF2alpha and eIF4E within the brain types of tumors studied could indicate that different pathways are activated for promoting cell cycle proliferation, for instance, leading to increased cyclin D1 expression.
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Affiliation(s)
- Sonia Tejada
- Servicio de Neurocirugía, Hospital Ramón y Cajal, Ctra. Colmenar Km. 9, 28034 Madrid, Spain
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37
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Edgerton ME, Fisher DH, Tang L, Frey LJ, Chen Z. Data Mining for Gene Networks Relevant to Poor Prognosis in Lung Cancer via Backward-Chaining Rule Induction. Cancer Inform 2007. [DOI: 10.1177/117693510700300016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We use Backward Chaining Rule Induction (BCRI), a novel data mining method for hypothesizing causative mechanisms, to mine lung cancer gene expression array data for mechanisms that could impact survival. Initially, a supervised learning system is used to generate a prediction model in the form of “IF <conditions> THEN <outcome>” style rules. Next, each antecedent (i.e. an IF condition) of a previously discovered rule becomes the outcome class for subsequent application of supervised rule induction. This step is repeated until a termination condition is satisfied. “Chains” of rules are created by working backward from an initial condition (e.g. survival status). Through this iterative process of “backward chaining,” BCRI searches for rules that describe plausible gene interactions for subsequent validation. Thus, BCRI is a semi-supervised approach that constrains the search through the vast space of plausible causal mechanisms by using a top-level outcome to kick-start the process. We demonstrate the general BCRI task sequence, how to implement it, the validation process, and how BCRI-rules discovered from lung cancer microarray data can be combined with prior knowledge to generate hypotheses about functional genomics.
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Affiliation(s)
- Mary E. Edgerton
- Department of Pathology and Department of Biomedical Informatics, Vanderbilt University, currently Department of Anatomic Pathology, University of Texas, M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030
| | - Douglas H. Fisher
- Department of Electrical Engineering and Computer Science, Vanderbilt University, Salt Lake City, UT 84112
| | - Lianhong Tang
- Vanderbilt-Ingram Cancer Center, currently Department of Biomedical Informatics, Vanderbilt University, Salt Lake City, UT 84112
| | - Lewis J. Frey
- Department of Biomedical Informatics, Vanderbilt University, currently Department of Biomedical Informatics, University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Zhihua Chen
- Department of Electrical Engineering and Computer Science, Vanderbilt University, currently Department of Interdisciplinary Oncology, H. Lee Moffitt Cancer Center and Research Institute, SRB3,12902 Magnolia Drive, Tampa, FL 33612
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38
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Langland JO, Jacobs BL. Inhibition of PKR by vaccinia virus: role of the N- and C-terminal domains of E3L. Virology 2004; 324:419-29. [PMID: 15207627 DOI: 10.1016/j.virol.2004.03.012] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2003] [Revised: 01/12/2004] [Accepted: 03/17/2004] [Indexed: 01/27/2023]
Abstract
The process of eukaryotic translation initiation can be regulated by a highly conserved mechanism involving the phosphorylation of the translation initiation factor eIF2 on the alpha subunit. This mechanism is recognized as an efficient step in the host antiviral response. Vaccinia virus (VV), like many other viruses, encodes proteins to overcome this inhibitory process. The C-terminus of the vaccinia virus E3L is known to bind to double-stranded RNA (dsRNA) thereby sequestering the activator of this antiviral response. In this report, the N-terminus of E3L was found to be required for the additional regulation of eIF2alpha phosphorylation. This phosphorylation event did not lead to a global shutdown in protein synthesis. Because the N-terminus of E3L is required for full viral pathogenesis in mice, these results suggest an alternative role of eIF2alpha phosphorylation in regulating viral replication.
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Affiliation(s)
- Jeffrey O Langland
- Graduate Program in Microbiology, School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
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39
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Clemens MJ. Targets and mechanisms for the regulation of translation in malignant transformation. Oncogene 2004; 23:3180-8. [PMID: 15094767 DOI: 10.1038/sj.onc.1207544] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
There is increasing evidence that deregulation of gene expression at the level of mRNA translation can contribute to cell transformation and the malignant phenotype. Two steps in the pathway of polypeptide chain initiation, viz. the assembly of the 43S initiation complex catalysed by polypeptide chain initiation factor eIF2 and the binding of eIF4E to eIF4G during the recruitment of mRNA to the ribosome, have been shown to be likely targets for changes associated with tumorigenesis. The activity of eIF2 is controlled by changes in phosphorylation of the alpha subunit of this factor. The availability of eIF4E for binding to eIF4G is regulated by the phosphorylation of a small family of eIF4E-binding proteins (the 4E-BPs). The activities of the protein kinases and/or phosphatases responsible for the (de)phosphorylation of these substrates may in turn be controlled by cellular and viral oncogenes and tumour-suppressor genes. This review will describe recent aspects of the mechanisms involved, with particular emphasis on the regulation of the eIF2 alpha kinase PKR and the control of 4E-BP phosphorylation by viral gene products, growth-inhibitory cytokines and the tumour-suppressor protein p53.
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Affiliation(s)
- Michael J Clemens
- Translational Control Group, Biochemistry and Immunology, Department of Basic Medical Sciences, St George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK.
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40
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Rosenwald IB. The role of translation in neoplastic transformation from a pathologist's point of view. Oncogene 2004; 23:3230-47. [PMID: 15094773 DOI: 10.1038/sj.onc.1207552] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Increased cell proliferation, which is a hallmark of aggressive malignant neoplasms, requires a general increase in protein synthesis and a specific increase in the synthesis of replication-promoting proteins. Transient increase in the general protein synthesis rate, as well as preferential translation of specific mRNAs coding for growth promoting proteins (e.g. cyclin D1), takes place during normal mitogenic response. A number of extensively studied growth signal transduction pathways (Ras, PI3K, MAPK, mTOR-dependent pathways) activate the function and expression of various components of the translational machinery. In abnormal situations, constitutive activation of signal transduction pathways (e.g. oncogenic activation of Ras or Myc) leads to continuous upregulation of key elements of translational machinery. On the other hand, tumor suppressor genes (p53, pRb) downregulate ribosomal and tRNA synthesis, and their inactivation results in uncontrolled production of these translational components. During recent years, a significant effort has been dedicated to determining whether expression of translation factors is increased in human tumors using clinical biopsy specimens. The results of these studies indicate that expression of particular translation initiation factors is not always increased in human neoplasms. The pattern of expression is characteristic for a particular tumor type. For example, eIF-4E is usually increased in bronchioloalveolar carcinomas but not in squamous cell carcinomas of the lung. Interestingly, in certain highly proliferative and aggressive neoplasms (e.g. squamous cell carcinoma of the lung, melanoma), the expression of eIF-4E is barely detectable. These findings suggest that mechanisms for increasing general protein synthesis in various neoplasms differ significantly. Finally, the possibility of qualitative alterations in the translational machinery, rather than a simple increase in the activity of its components, is discussed along with the possibility of targeting those qualitative differences for tumor therapy.
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Affiliation(s)
- Igor B Rosenwald
- Department of Pathology, Division of Hematopathology, University of New Mexico, BRF Building, Room 323 B, MSC08 4640, 1 University of New Mexico, Albuquerque, NM 87131, USA.
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41
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Rajasekhar VK, Holland EC. Postgenomic global analysis of translational control induced by oncogenic signaling. Oncogene 2004; 23:3248-64. [PMID: 15094774 DOI: 10.1038/sj.onc.1207546] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
It is commonly assumed that developmental and oncogenic signaling achieve their phenotypic effects primarily by directly regulating the transcriptional profile of cells. However, there is growing evidence that the direct effect on transcription may be overshadowed by differential effects on the translational efficiency of specific existing mRNA species. Global analysis of this effect using microarrays indicates that this mechanism of controlling protein production provides a highly specific, robust, and rapid response to oncogenic and developmental stimuli. The mRNAs so affected encode proteins involved in cell-cell interaction, signal transduction, and growth control. Furthermore, a large number of transcription factors capable of secondarily rearranging the transcriptional profile of the cell are controlled at this level as well. To what degree this translational control is either necessary or sufficient for tumor formation or maintenance remains to be determined.
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Affiliation(s)
- Vinagolu K Rajasekhar
- Department of Surgery (Neurosurgery), Neurology, Cancer Biology and Genetics, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10021, USA.
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42
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Rosenwald IB, Wang S, Savas L, Woda B, Pullman J. Expression of translation initiation factor eIF-2alpha is increased in benign and malignant melanocytic and colonic epithelial neoplasms. Cancer 2003; 98:1080-8. [PMID: 12942578 DOI: 10.1002/cncr.11619] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Stimulation of resting cells by growth factors leads to an increase in the rate of protein synthesis, which is necessary for cell growth and division. Translation initiation factor eIF-2alpha is one of the key translation factors mediating the effects of growth factors on protein synthesis. In normal cells, expression of eIF-2alpha is increased transiently, but its levels are elevated constitutively in oncogene-transformed cells. Overexpression of constitutively active eIF-2alpha in rodent cells makes them tumorigenic. In this article, the authors report their findings on the increased expression of eIF-2alpha in human benign and malignant neoplasms originating from melanocytes and colonic epithelium. METHODS Immunohistochemistry was used to analyze the expression of eIF-2alpha, eIF-4E, and cyclin D1 in melanocytic nevi and melanomas and the expression of eIF-2alpha in colonic adenomas and carcinomas. RESULTS The authors found that the expression of eIF-2alpha was increased markedly in both benign and malignant neoplasms of melanocytes and colonic epithelium. CONCLUSIONS Increased expression of eIF-2alpha took place in both benign and malignant neoplasms of melanocytes and colonic epithelium. These findings suggest that elevated expression of this translation initiation factor may contribute to tumor initiation and progression but that it is not sufficient for establishing a malignant phenotype in the tumors analyzed in this study.
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Affiliation(s)
- Igor B Rosenwald
- Department of Pathology, Montefiore Medical Center, Bronx, New York, USA.
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Martín de la Vega C, Burda J, Toledo Lobo MV, Salinas M. Cerebral postischemic reperfusion-induced demethylation of the protein phosphatase 2A catalytic subunit. J Neurosci Res 2002; 69:540-9. [PMID: 12210847 DOI: 10.1002/jnr.10306] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Brain reperfusion after a period of global ischemia induces changes in the phosphorylation state of a great number of proteins. Neuronal responses to ischemia and reperfusion are quite different depending on the brain region, and phosphorylation changes may be implicated in this tissue-specific response. For this reason, we have used both biochemical and immunohistochemical methods to investigate the potential role of PP2A, the most abundant Ser/Thr phosphatase in the brain, in ischemic injury. PP2A activity as measured with phosphorylase a as substrate was slightly inhibited after 30 min ischemia followed by 30 min reperfusion, and this inhibition correlated with an increased S6K1 and ERK1/2 phosphorylation. Using a monoclonal antibody unable to recognize the methylated form of PP2Ac, we demonstrated that the catalytic subunit of PP2A (PP2Ac) was highly methylated in the brain. In addition, the postischemic reperfusion-induced changes in PP2Ac methylation were studied in sections from cerebral cortex, hippocampus and striatum. Regional differences in PP2Ac methylation were observed within control brains, and the postischemic reperfusion caused a generalized demethylation of PP2Ac. Those regions in the control brains containing highest levels of methylated PP2Ac were the most intensively demethylated after reperfusion and corresponded to the regions most vulnerable to ischemic damage.
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Watkins SJ, Norbury CJ. Translation initiation and its deregulation during tumorigenesis. Br J Cancer 2002; 86:1023-7. [PMID: 11953842 PMCID: PMC2364173 DOI: 10.1038/sj.bjc.6600222] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2002] [Accepted: 02/08/2002] [Indexed: 12/16/2022] Open
Abstract
Regulation of protein synthesis at the level of translation initiation is fundamentally important for the control of cell proliferation under normal physiological conditions. Conversely, misregulation of protein synthesis is emerging as a major contributory factor in cancer development. Most bulk protein synthesis is initiated via recognition of the mRNA 5' cap and subsequent recognition of the initiator AUG codon by a directional scanning mechanism. However, several key regulators of tumour development are translated by a cap-independent pathway. Here we review eukaryotic translation initiation, its regulation and the ways in which this regulation can break down during tumorigenesis.
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Affiliation(s)
- S J Watkins
- Cancer Research UK Molecular Oncology Laboratory, University of Oxford, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DS, UK
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Abstract
The emerging field of nuclear eIF research has yielded many surprises and led to the dissolution of some dogmatic/ideological viewpoints of the place of translation in the regulation of gene expression. Eukaryotic initiation factors (eIFs) are classically defined by their cytoplasmic location and ability to regulate the initiation phase of protein synthesis. For instance, in the cytoplasm, the m7G cap-binding protein eIF4E plays a distinct role in cap-dependent translation initiation. Disruption of eIF4E's regulatory function drastically effects cell growth and may lead to oncogenic transformation. A growing number of studies indicate that many eIFs, including a substantial fraction of eIF4E, are found in the nucleus. Indeed, nuclear eIF4E participates in a variety of important RNA-processing events including the nucleocytoplasmic transport of specific, growth regulatory mRNAs. Although unexpected, it is possible that some eIFs regulate protein synthesis within the nucleus. This review will focus on the novel, nuclear functions of eIF4E and how they contribute to eIF4E's growth-activating and oncogenic properties. Both the cytoplasmic and nuclear functions of eIF4E appear to be dependent on its intrinsic ability to bind to the 5' m7G cap of mRNA. For example, Promyelocytic Leukemia Protein (PML) potentially acts as a negative regulator of nuclear eIF4E function by decreasing eIF4E's affinity for the m7G cap. Therefore, eIF4E protein is flexible enough to utilize a common biochemical activity, such as m7G cap binding, to participate in divergent processes in different cellular compartments.
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Affiliation(s)
- Stephen Strudwick
- Structural Biology Program, Department of Physiology & Biophysics, Mount Sinai School of Medicine, New York University, One Gustave Levy Place, New York, NY 10029, USA
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DeGracia DJ, Kumar R, Owen CR, Krause GS, White BC. Molecular pathways of protein synthesis inhibition during brain reperfusion: implications for neuronal survival or death. J Cereb Blood Flow Metab 2002; 22:127-41. [PMID: 11823711 DOI: 10.1097/00004647-200202000-00001] [Citation(s) in RCA: 184] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protein synthesis inhibition occurs in neurons immediately on reperfusion after ischemia and involves at least alterations in eukaryotic initiation factors 2 (eIF2) and 4 (eIF4). Phosphorylation of the alpha subunit of eIF2 [eIF2(alphaP)] by the endoplasmic reticulum transmembrane eIF2alpha kinase PERK occurs immediately on reperfusion and inhibits translation initiation. PERK activation, along with depletion of endoplasmic reticulum Ca2+ and inhibition of the endoplasmic reticulum Ca2+ -ATPase, SERCA2b, indicate that an endoplasmic reticulum unfolded protein response occurs as a consequence of brain ischemia and reperfusion. In mammals, the upstream unfolded protein response components PERK, IRE1, and ATF6 activate prosurvivial mechanisms (e.g., transcription of GRP78, PDI, SERCA2b ) and proapoptotic mechanisms (i.e., activation of Jun N-terminal kinases, caspase-12, and CHOP transcription). Sustained eIF2(alphaP) is proapoptotic by inducing the synthesis of ATF4, the CHOP transcription factor, through "bypass scanning" of 5' upstream open-reading frames in ATF4 messenger RNA; these upstream open-reading frames normally inhibit access to the ATF4 coding sequence. Brain ischemia and reperfusion also induce mu-calpain-mediated or caspase-3-mediated proteolysis of eIF4G, which shifts message selection to m 7 G-cap-independent translation initiation of messenger RNAs containing internal ribosome entry sites. This internal ribosome entry site-mediated translation initiation (i.e., for apoptosis-activating factor-1 and death-associated protein-5) can also promote apoptosis. Thus, alterations in eIF2 and eIF4 have major implications for which messenger RNAs are translated by residual protein synthesis in neurons during brain reperfusion, in turn constraining protein expression of changes in gene transcription induced by ischemia and reperfusion. Therefore, our current understanding shifts the focus from protein synthesis inhibition to the molecular pathways that underlie this inhibition, and the role that these pathways play in prosurvival and proapoptotic processes that may be differentially expressed in vulnerable and resistant regions of the reperfused brain.
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Affiliation(s)
- Donald J DeGracia
- Department of Emergency Medicine, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
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Lobo MVT, Alonso FJM, Arenas MI, Caso E, Fraile B, del Río RM. Ultrastructural staining with sodium metaperiodate and sodium borohydride. J Histochem Cytochem 2002; 50:11-9. [PMID: 11748290 DOI: 10.1177/002215540205000102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
This article describes new ultrastructural staining methods for osmicated tissues based on the incubation of sections with sodium metaperiodate and sodium borohydride solutions before uranyl/lead staining. Sections incubated with sodium metaperiodate and sodium borohydride, treated with Triton X-100, and stained with ethanolic uranyl acetate/lead citrate showed a good contrast for the nucleolus and the interchromatin region, whereas the chromatin masses were bleached. Chromatin bleaching depended on the incubation with these oxidizing (metaperiodate) and reducing (borohydride) agents. Other factors that influenced the staining of the chromatin masses were the en bloc staining with uranyl acetate, the incubation of sections with Triton X-100, and the staining with aqueous or ethanolic uranyl acetate. The combination of these factors on sections treated with metaperiodate/borohydride provided a different appearance to the chromatin, from bleached to highly contrasted. Most cytoplasmic organelles showed a similar appearance with these procedures than with conventional uranyl/lead staining. However, when sections were incubated with metaperiodate/borohydride and Triton X-100 before uranyl/lead staining, the collagen fibers, and the glycocalix and zymogen granules of pancreatic acinar cells, appeared bleached. The possible combination of these methods with the immunolocalization of the amino acid taurine was also analyzed. (J Histochem Cytochem 50:11-19, 2002)
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Affiliation(s)
- Maria V T Lobo
- Servicio de Neurobiología, Departamento de Investigación, Hospital Ramón y Cajal, Universidad de Alcala, Alcala de Henares, Madrid, Spain
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