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Li Y, Wu Z, Hu J, Liu G, Hu H, Ouyang F, Yang J. Hydrogen sulfide ameliorates abdominal aorta coarctation-induced myocardial fibrosis by inhibiting pyroptosis through regulating eukaryotic translation initiation factor 2α phosphorylation and activating PI3K/AKT1 pathway. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2023; 27:345-356. [PMID: 37386832 PMCID: PMC10316187 DOI: 10.4196/kjpp.2023.27.4.345] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 10/31/2022] [Accepted: 11/01/2022] [Indexed: 07/01/2023]
Abstract
This study aimed to assess the effects of exogenous hydrogen sulfide (H2S) on abdominal aorta coarctation (AAC) induced myocardial fibrosis (MF) and autophagy in rats. Forty-four Sprague-Dawley rats were randomly divided into control group, AAC group, AAC + H2S group, and H2S control group. After a model of rats with AAC was built surgically, AAC + H2S group and H2S group were injected intraperitoneally with H2S (100 μmol/kg) daily. The rats in the control group and the AAC group were injected with the same amount of PBS. We observed that H2S can improve left ventricular function and the deposition of myocardial collagen fibers, inhibit pyroptosis, down-regulate the expression of P-eif2α in myocardial tissue, and inhibit cell autophagy by activating the phosphatidylinositol 3-kinase (PI3K)/AKT1 signaling pathway (p < 0.05). In addition, angiotensin II (1 μM) H9c2 cardiomyocytes were injured in vitro experiments, and it was also observed that pyroptosis was inhibited after H2S (400 μmol/kg) intervention, the expression of P-eif2α in cardiomyocytes was significantly down-regulated, and the PI3K/AKT1 signaling pathway was activated at the same time. Therefore, increasing the expression of P-eif2α reverses the activation of the PI3K/AKT1 signaling pathway by H2S. In conclusion, these findings suggest that exogenous H2S can ameliorate MF in rats with AAC by inhibiting pyroptosis, and the mechanism may be associated with inhibiting the phosphorylation of eif2α and activating the PI3K/AKT1 signaling pathway to inhibit excessive cell autophagy.
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Affiliation(s)
- Yaling Li
- Department of Cardiology, Zhuzhou Central Hospital, Zhuzhou 412000, China
| | - Zhixiong Wu
- Department of Cardiology, Zhuzhou Central Hospital, Zhuzhou 412000, China
| | - Jiangping Hu
- Department of Cardiology, Zhuzhou Central Hospital, Zhuzhou 412000, China
| | - Gongli Liu
- Department of Cardiology, Zhuzhou Central Hospital, Zhuzhou 412000, China
| | - Hongming Hu
- Department of Cardiology, The First Affiliated Hospital of University of South China, Hengyang 421001, China
| | - Fan Ouyang
- Department of Cardiology, Zhuzhou Central Hospital, Zhuzhou 412000, China
| | - Jun Yang
- Department of Cardiology, The First Affiliated Hospital of University of South China, Hengyang 421001, China
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Constitutive activation of the PI3K-Akt-mTORC1 pathway sustains the m.3243 A > G mtDNA mutation. Nat Commun 2021; 12:6409. [PMID: 34737295 PMCID: PMC8568893 DOI: 10.1038/s41467-021-26746-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 10/20/2021] [Indexed: 11/25/2022] Open
Abstract
Mutations of the mitochondrial genome (mtDNA) cause a range of profoundly debilitating clinical conditions for which treatment options are very limited. Most mtDNA diseases show heteroplasmy – tissues express both wild-type and mutant mtDNA. While the level of heteroplasmy broadly correlates with disease severity, the relationships between specific mtDNA mutations, heteroplasmy, disease phenotype and severity are poorly understood. We have carried out extensive bioenergetic, metabolomic and RNAseq studies on heteroplasmic patient-derived cells carrying the most prevalent disease related mtDNA mutation, the m.3243 A > G. These studies reveal that the mutation promotes changes in metabolites which are associated with the upregulation of the PI3K-Akt-mTORC1 axis in patient-derived cells and tissues. Remarkably, pharmacological inhibition of PI3K, Akt, or mTORC1 reduced mtDNA mutant load and partially rescued cellular bioenergetic function. The PI3K-Akt-mTORC1 axis thus represents a potential therapeutic target that may benefit people suffering from the consequences of the m.3243 A > G mutation. Heteroplasmic mtDNA mutations cause disease in humans. Here, Chung et al find the PI3K-Akt-mTORC1 pathway constitutively activated in cells with the heteroplasmic m.3243 A > G mutation, and inhibition of the pathway cell autonomously reduces mutant mtDNA load and rescues mitochondrial bioenergetics.
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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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Okada J, Matsumoto S, Yamada E, Saito T, Okada K, Watanabe T, Nakajima Y, Ozawa A, Yamada M, Ohshima K, Okada S. TBC1D8B, a GTPase-activating protein, is a novel apoptosis inducer. Biomed Res 2021; 42:95-102. [PMID: 34092754 DOI: 10.2220/biomedres.42.95] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Overexpressed TBC1D8B, a GTPase-activating protein, significantly reduced cultured HCT116 human colon cancer cell number. We tested N-terminal TBC1D8B, which is identical to wild type TBC1D8B from amino acid positions 1 to 427 and possesses a modified sequence from position 428 to 435 (ECGGLFLL) because of the introduction of a premature stop codon at position 436 to narrow down the minimum requirement element. The N-terminal TBC1D8B contains two GRAM domains but not the TBC domain essential for Rab-GTPase activity. The N-terminal TBC1D8B overexpression significantly reduced the cultured HCT116 cell number. When we tested C-terminal TBC1D8B, containing the portion of TBC1D8B absent in the N-terminal TBC1D8B, the cell number reduction was not observed. The N-terminal TBC1D8B overexpression significantly increased the coronin 1B expression and reduced the phosphorylation of serine 51 in eIF2α, respective markers of apoptosis and cell death/survival. Also, caspase 3 and poly ADP-ribose polymerase increased cleavage in suspended cells overexpressing the N-terminal TBC1D8B. Taken together, it is not the TBC domain for Rab-GTPase activity, but amino acids 1 to 435, including the two GRAM domains, that is enough for TBC1D8B to cause spontaneous apoptosis. TBC1D8B could be a potential anticancer therapeutic molecule.
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Affiliation(s)
- Junichi Okada
- Department of Medicine, Division of Endocrinology, Albert Einstein College of Medicine
| | - Shunichi Matsumoto
- Department of Medicine, Division of Endocrinology, Albert Einstein College of Medicine
| | - Eijiro Yamada
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine
| | - Tsugumichi Saito
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine
| | | | - Takuya Watanabe
- Department of Endocrinology and Metabolism, Saku Central Hospital Advanced Care Center
| | - Yasuyo Nakajima
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine
| | - Atsushi Ozawa
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine
| | - Masanobu Yamada
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine
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5
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Al-Attar R, Childers CL, Nguyen VC, Pamenter ME, Storey KB. Differential protein phosphorylation is responsible for hypoxia-induced regulation of the Akt/mTOR pathway in naked mole rats. Comp Biochem Physiol A Mol Integr Physiol 2020; 242:110653. [PMID: 31926299 DOI: 10.1016/j.cbpa.2020.110653] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 12/25/2019] [Accepted: 01/06/2020] [Indexed: 12/21/2022]
Abstract
Naked mole rats (NMRs, Heterocephalus glaber) are among the most hypoxia-tolerant mammals known. They can reduce their metabolic rate (>85%) under severe hypoxia, remain moderately active and recover with no obvious signs of damage. Hence, NMRs are an excellent model for studying mammalian hypoxia tolerance. The current study characterized the involvement of posttranslational modifications in regulating the Akt/mTOR pathway that regulates protein synthesis, and the responses of key ribosomal proteins in order to assess tissue-specific responses to 4 h exposure to 7% O2 (compared to controls at 21% O2). Results showed a tissue-specific regulation of the Akt/mTOR pathway via differential phosphorylation. Relative amounts of p-TSC(S939) in brain and of p-TSC(S939), p-Akt(473) and p-PTEN(S380) in liver increased under hypoxia, whereas levels of IGF1R(Y1135/1136) in liver decreased. In skeletal muscle, levels of p-Akt(S473) and p-PTEN(S380) decreased during hypoxia, whereas lungs showed an increase in p-mTOR(S2884) content but a decrease in p-RPS6(S235-236) under the same conditions. Analysis of the phosphorylation states of ribosomal proteins revealed increases in p-4E-BP1(T37/46) content in brain and lungs under hypoxia, as well as a rise in total 4E-BP1 protein level in liver. Phosphorylated eIF-4B(S422) content also increased in liver while levels of p-eIF-2α(S51), and eIF-4E(S209) decreased during hypoxia in liver. Overall, hypoxia altered the Akt/mTOR pathway, which correlated with a general decrease in activity of the ribosomal protein biosynthesis machinery in muscle, lung, and brain of NMRs. However, the increase in eIF-4B in liver suggests the potential promotion of cap-independent mRNA translation mechanism operating under hypoxic stress.
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Affiliation(s)
- Rasha Al-Attar
- Department of Biology, Carleton University, Ottawa, ON, Canada
| | | | - Vu C Nguyen
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Matthew E Pamenter
- Department of Biology, University of Ottawa, Ottawa, ON, Canada; uOttawa Brain and Mind Research Institute, Canada
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6
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Stevens AM, Xiang M, Heppler LN, Tošić I, Jiang K, Munoz JO, Gaikwad AS, Horton TM, Long X, Narayanan P, Seashore EL, Terrell MC, Rashid R, Krueger MJ, Mangubat-Medina AE, Ball ZT, Sumazin P, Walker SR, Hamada Y, Oyadomari S, Redell MS, Frank DA. Atovaquone is active against AML by upregulating the integrated stress pathway and suppressing oxidative phosphorylation. Blood Adv 2019; 3:4215-4227. [PMID: 31856268 PMCID: PMC6929386 DOI: 10.1182/bloodadvances.2019000499] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Accepted: 11/11/2019] [Indexed: 12/31/2022] Open
Abstract
Atovaquone, a US Food and Drug Administration-approved antiparasitic drug previously shown to reduce interleukin-6/STAT3 signaling in myeloma cells, is well tolerated, and plasma concentrations of 40 to 80 µM have been achieved with pediatric and adult dosing. We conducted preclinical testing of atovaquone with acute myeloid leukemia (AML) cell lines and pediatric patient samples. Atovaquone induced apoptosis with an EC50 <30 µM for most AML lines and primary pediatric AML specimens. In NSG mice xenografted with luciferase-expressing THP-1 cells and in those receiving a patient-derived xenograft, atovaquone-treated mice demonstrated decreased disease burden and prolonged survival. To gain a better understanding of the mechanism of atovaquone, we performed an integrated analysis of gene expression changes occurring in cancer cell lines after atovaquone exposure. Atovaquone promoted phosphorylation of eIF2α, a key component of the integrated stress response and master regulator of protein translation. Increased levels of phosphorylated eIF2α led to greater abundance of the transcription factor ATF4 and its target genes, including proapoptotic CHOP and CHAC1. Furthermore, atovaquone upregulated REDD1, an ATF4 target gene and negative regulator of the mechanistic target of rapamycin (mTOR), and caused REDD1-mediated inhibition of mTOR activity with similar efficacy as rapamycin. Additionally, atovaquone suppressed the oxygen consumption rate of AML cells, which has specific implications for chemotherapy-resistant AML blasts that rely on oxidative phosphorylation for survival. Our results provide insight into the complex biological effects of atovaquone, highlighting its potential as an anticancer therapy with novel and diverse mechanisms of action, and support further clinical evaluation of atovaquone for pediatric and adult AML.
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MESH Headings
- Activating Transcription Factor 4/metabolism
- Adolescent
- Animals
- Apoptosis/drug effects
- Atovaquone/pharmacology
- Cell Line, Tumor
- Cell Survival/drug effects
- Child
- Child, Preschool
- Disease Models, Animal
- Female
- Humans
- Infant
- Leukemia, Myeloid, Acute/genetics
- Leukemia, Myeloid, Acute/metabolism
- Leukemia, Myeloid, Acute/mortality
- Leukemia, Myeloid, Acute/pathology
- Male
- Mice
- Mice, Knockout
- Oxidative Phosphorylation/drug effects
- Signal Transduction/drug effects
- Xenograft Model Antitumor Assays
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Affiliation(s)
- Alexandra M Stevens
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Michael Xiang
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
| | - Lisa N Heppler
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
| | - Isidora Tošić
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
- Department of Biochemistry, Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia
| | - Kevin Jiang
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
| | - Jaime O Munoz
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Amos S Gaikwad
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Terzah M Horton
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Xin Long
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Padmini Narayanan
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Elizabeth L Seashore
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Maci C Terrell
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Raushan Rashid
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Michael J Krueger
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | | | | | - Pavel Sumazin
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Sarah R Walker
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
- Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA; and
| | - Yoshimasa Hamada
- Division of Molecular Biology, Institute for Genome Research, and
- Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
| | - Seiichi Oyadomari
- Division of Molecular Biology, Institute for Genome Research, and
- Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
| | - Michele S Redell
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - David A Frank
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
- Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA; and
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7
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Yılmazer M, Kartal B, Tarhan Ç, Özarabacı I, Akçaalan S, Özkan E, Karaer Uzuner S, Arıcan E, Palabıyık B. A Genome-Wide Screen for Wortmannin-Resistant Mutants in Schizosaccharomyces pombe: The Phosphorylation-Impaired Mutants Are Resistant to Signaling Defect. DNA Cell Biol 2019; 38:1427-1436. [PMID: 31657618 DOI: 10.1089/dna.2019.5003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Complex human diseases such as metabolic disorders, cancer, neurodegenerative diseases, and mitochondrial dysfunctions arise from the biochemical or genetic defects in various cellular processes. Therefore, it is important to understand which metabolic processes are affected by which cellular impairment. Because genome-wide screening of mutant collections (haploid/diploid deletion library) provides important clues for the understanding of conserved biological processes and for finding potential target genes, we screened the haploid mutant collection of Schizosaccharomyces pombe with wortmannin that inhibits phosphatidylinositol-3-kinase signaling. Using genome-wide screening, we determined that 52 mutants were resistant to this chemical. When 52 genes that are deleted in these mutants were grouped in 41 different biological processes, we found that 37 of them have human orthologues and 4 genes were associated with human metabolic disorders. In addition, when we examined the pathways in which these 52 genes function, we determined that 9 genes were related to phosphorylation process. These results might provide new insights for better understanding of certain human diseases.
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Affiliation(s)
- Merve Yılmazer
- Department of Molecular Biology and Genetics, Faculty of Science, Istanbul University, Istanbul, Turkey
| | - Burcu Kartal
- Department of Molecular Biology and Genetics, Institute of Graduate Studies in Sciences, Istanbul University, Istanbul, Turkey
| | - Çağatay Tarhan
- Department of Molecular Biology and Genetics, Faculty of Science, Istanbul University, Istanbul, Turkey
| | - Ilayda Özarabacı
- Department of Molecular Biology and Genetics, Institute of Graduate Studies in Sciences, Istanbul University, Istanbul, Turkey
| | - Sedef Akçaalan
- Department of Molecular Biology and Genetics, Institute of Graduate Studies in Sciences, Istanbul University, Istanbul, Turkey
| | - Egemen Özkan
- Department of Molecular Biology and Genetics, Institute of Graduate Studies in Sciences, Istanbul University, Istanbul, Turkey
| | - Semian Karaer Uzuner
- Department of Molecular Biology and Genetics, Faculty of Science, Istanbul University, Istanbul, Turkey
| | - Ercan Arıcan
- Department of Molecular Biology and Genetics, Faculty of Science, Istanbul University, Istanbul, Turkey
| | - Bedia Palabıyık
- Department of Molecular Biology and Genetics, Faculty of Science, Istanbul University, Istanbul, Turkey
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8
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Chu J, Pelletier J. Therapeutic Opportunities in Eukaryotic Translation. Cold Spring Harb Perspect Biol 2018; 10:cshperspect.a032995. [PMID: 29440069 DOI: 10.1101/cshperspect.a032995] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The ability to block biological processes with selective small molecules provides advantages distinct from most other experimental approaches. These include rapid time to onset, swift reversibility, ability to probe activities in manners that cannot be accessed by genetic means, and the potential to be further developed as therapeutic agents. Small molecule inhibitors can also be used to alter expression and activity without affecting the stoichiometry of interacting partners. These tenets have been especially evident in the field of translation. Small molecule inhibitors were instrumental in enabling investigators to capture short-lived complexes and characterize specific steps of protein synthesis. In addition, several drugs that are the mainstay of modern antimicrobial drug therapy are potent inhibitors of prokaryotic translation. Currently, there is much interest in targeting eukaryotic translation as decades of research have revealed that deregulated protein synthesis in cancer cells represents a targetable vulnerability. In addition to being potential therapeutics, small molecules that manipulate translation have also been shown to influence cognitive processes such as memory. In this review, we focus on small molecule modulators that target the eukaryotic translation initiation apparatus and provide an update on their potential application to the treatment of disease.
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Affiliation(s)
- Jennifer Chu
- Department of Biochemistry, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, Quebec H3G 1Y6, Canada.,Department of Oncology, McGill University, Montreal, Quebec H3G 1Y6, Canada.,Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, Quebec H3G 1Y6, Canada
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9
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Rajesh K, Krishnamoorthy J, Gupta J, Kazimierczak U, Papadakis AI, Deng Z, Wang S, Kuninaka S, Koromilas AE. The eIF2α serine 51 phosphorylation-ATF4 arm promotes HIPPO signaling and cell death under oxidative stress. Oncotarget 2018; 7:51044-51058. [PMID: 27409837 PMCID: PMC5239457 DOI: 10.18632/oncotarget.10480] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 06/23/2016] [Indexed: 11/25/2022] Open
Abstract
The HIPPO pathway is an evolutionary conserved regulator of organ size that controls both cell proliferation and death. This pathway has an important role in mediating cell death in response to oxidative stress through the inactivation of Yes-associated protein (YAP) and inhibition of anti-oxidant gene expression. Cells exposed to oxidative stress induce the phosphorylation of the alpha (α) subunit of the translation initiation factor eIF2 at serine 51 (eIF2αP), a modification that leads to the general inhibition of mRNA translation initiation. Under these conditions, increased eIF2αP facilitates the mRNA translation of activating transcription factor 4 (ATF4), which mediates either cell survival and adaptation or cell death under conditions of severe stress. Herein, we demonstrate a functional connection between the HIPPO and eIF2αP-ATF4 pathways under oxidative stress. We demonstrate that ATF4 promotes the stabilization of the large tumor suppressor 1 (LATS1), which inactivates YAP by phosphorylation. ATF4 inhibits the expression of NEDD4.2 and WWP1 mRNAs under pro-oxidant conditions, which encode ubiquitin ligases mediating the proteasomal degradation of LATS1. Increased LATS1 stability is required for the induction of cell death under oxidative stress. Our data reveal a previously unidentified ATF4-dependent pathway in the induction of cell death under oxidative stress via the activation of LATS1 and HIPPO pathway.
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Affiliation(s)
- Kamindla Rajesh
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada
| | - Jothilatha Krishnamoorthy
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada
| | - Jyotsana Gupta
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada
| | - Urszula Kazimierczak
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada.,Department of Cancer Immunology, Poznan University of Medical Sciences, Poznan, Poland
| | - Andreas I Papadakis
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada
| | - Zhilin Deng
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada
| | - Shuo Wang
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada
| | - Shinji Kuninaka
- Division of Gene Regulation, Institute for Advanced Medical Research, Keio University School of Medicine, Tokyo, Japan
| | - Antonis E Koromilas
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada.,Department of Oncology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
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10
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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: 30] [Impact Index Per Article: 4.3] [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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11
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López SN, Rodríguez-Valentín M, Rivera M, Rodríguez M, Babu M, Cubano LA, Xiong H, Wang G, Kucheryavykh L, Boukli NM. HIV-1 Gp120 clade B/C induces a GRP78 driven cytoprotective mechanism in astrocytoma. Oncotarget 2017; 8:68415-68438. [PMID: 28978127 PMCID: PMC5620267 DOI: 10.18632/oncotarget.19474] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 06/28/2017] [Indexed: 01/20/2023] Open
Abstract
HIV-1 clades are known to be one of the key factors implicated in modulating HIV-associated neurocognitive disorders. HIV-1 B and C clades account for the majority of HIV-1 infections, clade B being the most neuropathogenic. The mechanisms behind HIV-mediated neuropathogenesis remain the subject of active research. We hypothesized that HIV-1 gp120 clade B and C proteins may exert differential proliferation, cell survival and NeuroAIDS effects in human astrocytoma cells via the Unfolded Protein Response, an endoplasmic reticulum- based cytoprotective mechanism. The differential effect of gp120 clade B and C was evaluated using for the first time a Tandem Mass Tag isobaric labeling quantitative proteomic approach. Flow cytometry analyses were performed for cell cycle and cell death identification. Among the proteins differentiated by HIV-1 gp120 proteins figure cytoskeleton, oxidative stress, UPR markers and numerous glycolytic metabolism enzymes. Our results demonstrate that HIV-1 gp120 B induced migration, proliferative and protective responses granted by the expression of GRP78, while HIV-1 gp120 C induced the expression of key inflammatory and pro-apoptotic markers. These novel findings put forward the first evidence that GRP78 is a key player in HIV-1 clade B and C neuropathogenic discrepancies and can be used as a novel target for immunotherapies.
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Affiliation(s)
- Sheila N López
- Biomedical Proteomics Facility, Department of Microbiology and Immunology, Universidad Central del Caribe, School of Medicine, Bayamón, PR, USA
| | - Madeline Rodríguez-Valentín
- Biomedical Proteomics Facility, Department of Microbiology and Immunology, Universidad Central del Caribe, School of Medicine, Bayamón, PR, USA
| | - Mariela Rivera
- Biomedical Proteomics Facility, Department of Microbiology and Immunology, Universidad Central del Caribe, School of Medicine, Bayamón, PR, USA
| | - Maridaliz Rodríguez
- Biomedical Proteomics Facility, Department of Microbiology and Immunology, Universidad Central del Caribe, School of Medicine, Bayamón, PR, USA
| | - Mohan Babu
- Department of Biochemistry, Research and Innovation Center, University of Regina, Saskatchewan, Canada
| | - Luis A Cubano
- Biomedical Proteomics Facility, Department of Microbiology and Immunology, Universidad Central del Caribe, School of Medicine, Bayamón, PR, USA
| | - Huangui Xiong
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, USA
| | - Guangdi Wang
- RCMI Cancer Research Center, Xavier University of Louisiana, New Orleans, LA, USA
| | - Lilia Kucheryavykh
- Department of Biochemistry, Universidad Central del Caribe, School of Medicine, Bayamón, PR, USA
| | - Nawal M Boukli
- Biomedical Proteomics Facility, Department of Microbiology and Immunology, Universidad Central del Caribe, School of Medicine, Bayamón, PR, USA
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12
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Adjibade P, Grenier St-Sauveur V, Droit A, Khandjian EW, Toren P, Mazroui R. Analysis of the translatome in solid tumors using polyribosome profiling/RNA-Seq. J Biol Methods 2016; 3:e59. [PMID: 31453221 PMCID: PMC6706116 DOI: 10.14440/jbm.2016.151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 09/22/2016] [Accepted: 10/18/2016] [Indexed: 01/25/2023] Open
Abstract
Gene expression involves multiple steps from the transcription of a mRNA in the nucleus to the production of the encoded protein in the cytoplasm. This final step occurs through a highly regulated process of mRNA translation on ribosomes that is required to maintain cell homeostasis. Alterations in the control of mRNA translation may lead to cell's transformation, a hallmark of cancer development. Indeed, recent advances indicated that increased translation of mRNAs encoding tumor-promoting proteins may be a key mechanism of tumor resistance in several cancers. Moreover, it was found that proteins whose encoding mRNAs are translated at higher efficiencies may be effective biomarkers. Evaluation of global changes in translation efficiency in human tumors has thus the potential of better understanding what can be used as biomarkers and therapeutic targets. Investigating changes in translation efficiency in human cancer cells has been made possible through the development and use of the polyribosome profiling combined with DNA microarray or deep RNA sequencing (RNA-Seq). While helpful, the use of cancer cell lines has many limitations and it is essential to define translational changes in human tumor samples in order to properly prioritize genes implicated in cancer phenotype. We present an optimized polyribosome RNA-Seq protocol suitable for quantitative analysis of mRNA translation that occurs in human tumor samples and murine xenografts. Applying this innovative approach to human tumors, which requires a complementary bioinformatics analysis, unlocks the potential to identify key mRNA which are preferentially translated in tumor tissue compared to benign tissue as well as translational changes which occur following treatment. These technical advances will be of interest to those researching all solid tumors, opening possibilities for understanding what may be therapeutic Achilles heels' or relevant biomarkers.
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Affiliation(s)
- Pauline Adjibade
- Centre de Recherche en Cancérologie. Centre de Recherche du CHU de Québec. Département de Biologie Moléculaire, Biochimie Médicale et Pathologie, Faculté de Médecine, Université Laval, Québec, PQ, Canada
| | - Valérie Grenier St-Sauveur
- Centre de Recherche en Cancérologie. Centre de Recherche du CHU de Québec. Département de Biologie Moléculaire, Biochimie Médicale et Pathologie, Faculté de Médecine, Université Laval, Québec, PQ, Canada
| | - Arnaud Droit
- Centre de Recherche du CHU de Québec. Département de Médecine Moléculaire, Faculté de Médecine, Université Laval, Québec, PQ, Canada
| | - Edouard W. Khandjian
- Centre de Recherche, Institut Universitaire en Santé Mentale de Québec. Département de Psychiatrie et de Neurosciences, Faculté de Médecine, Université Laval, Québec, PQ, Canada
| | - Paul Toren
- Centre de Recherche du CHU de Québec. Département de Chirurgie, Faculté de Médecine, Université Laval, Québec, PQ, Canada
| | - Rachid Mazroui
- Centre de Recherche en Cancérologie. Centre de Recherche du CHU de Québec. Département de Biologie Moléculaire, Biochimie Médicale et Pathologie, Faculté de Médecine, Université Laval, Québec, PQ, Canada
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13
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Chu J, Cargnello M, Topisirovic I, Pelletier J. Translation Initiation Factors: Reprogramming Protein Synthesis in Cancer. Trends Cell Biol 2016; 26:918-933. [PMID: 27426745 DOI: 10.1016/j.tcb.2016.06.005] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 06/03/2016] [Accepted: 06/13/2016] [Indexed: 12/11/2022]
Abstract
Control of mRNA translation plays a crucial role in the regulation of gene expression and is critical for cellular homeostasis. Dysregulation of translation initiation factors has been documented in several pathologies including cancer. Aberrant function of translation initiation factors leads to translation reprogramming that promotes proliferation, survival, angiogenesis, and metastasis. In such context, understanding how altered levels (and presumably activity) of initiation factors can contribute to tumor initiation and/or maintenance is of major interest for the development of novel therapeutic strategies. In this review we provide an overview of translation initiation mechanisms and focus on recent findings describing the role of individual initiation factors and their aberrant activity in cancer.
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Affiliation(s)
- Jennifer Chu
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Marie Cargnello
- Lady Davis Institute, SMBD JGH, McGill University, Montreal, Quebec, Canada; Gerald Bronfman Department of Oncology, McGill University, Quebec, Canada
| | - Ivan Topisirovic
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada; Lady Davis Institute, SMBD JGH, McGill University, Montreal, Quebec, Canada; Gerald Bronfman Department of Oncology, McGill University, Quebec, Canada.
| | - Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada; Gerald Bronfman Department of Oncology, McGill University, Quebec, Canada; The Rosalind and Morris Goodman Cancer Research Centre, McGill University, Montreal, Quebec, Canada.
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14
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Zhang L, Hapon MB, Goyeneche AA, Srinivasan R, Gamarra-Luques CD, Callegari EA, Drappeau DD, Terpstra EJ, Pan B, Knapp JR, Chien J, Wang X, Eyster KM, Telleria CM. Mifepristone increases mRNA translation rate, triggers the unfolded protein response, increases autophagic flux, and kills ovarian cancer cells in combination with proteasome or lysosome inhibitors. Mol Oncol 2016; 10:1099-117. [PMID: 27233943 DOI: 10.1016/j.molonc.2016.05.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 04/25/2016] [Accepted: 05/11/2016] [Indexed: 12/12/2022] Open
Abstract
The synthetic steroid mifepristone blocks the growth of ovarian cancer cells, yet the mechanism driving such effect is not entirely understood. Unbiased genomic and proteomic screenings using ovarian cancer cell lines of different genetic backgrounds and sensitivities to platinum led to the identification of two key genes upregulated by mifepristone and involved in the unfolded protein response (UPR): the master chaperone of the endoplasmic reticulum (ER), glucose regulated protein (GRP) of 78 kDa, and the CCAAT/enhancer binding protein homologous transcription factor (CHOP). GRP78 and CHOP were upregulated by mifepristone in ovarian cancer cells regardless of p53 status and platinum sensitivity. Further studies revealed that the three UPR-associated pathways, PERK, IRE1α, and ATF6, were activated by mifepristone. Also, the synthetic steroid acutely increased mRNA translation rate, which, if prevented, abrogated the splicing of XBP1 mRNA, a non-translatable readout of IRE1α activation. Moreover, mifepristone increased LC3-II levels due to increased autophagic flux. When the autophagic-lysosomal pathway was inhibited with chloroquine, mifepristone was lethal to the cells. Lastly, doses of proteasome inhibitors that are inadequate to block the activity of the proteasomes, caused cell death when combined with mifepristone; this phenotype was accompanied by accumulation of poly-ubiquitinated proteins denoting proteasome inhibition. The stimulation by mifepristone of ER stress and autophagic flux offers a therapeutic opportunity for utilizing this compound to sensitize ovarian cancer cells to proteasome or lysosome inhibitors.
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Affiliation(s)
- Lei Zhang
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South Dakota, Vermillion, SD 57069, USA
| | - Maria B Hapon
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South Dakota, Vermillion, SD 57069, USA
| | - Alicia A Goyeneche
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South Dakota, Vermillion, SD 57069, USA; Department of Pathology, Faculty of Medicine, McGill University, Montreal, QC H3A 2B4, Canada
| | - Rekha Srinivasan
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South Dakota, Vermillion, SD 57069, USA
| | - Carlos D Gamarra-Luques
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South Dakota, Vermillion, SD 57069, USA
| | - Eduardo A Callegari
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South Dakota, Vermillion, SD 57069, USA
| | - Donis D Drappeau
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South Dakota, Vermillion, SD 57069, USA
| | - Erin J Terpstra
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South Dakota, Vermillion, SD 57069, USA
| | - Bo Pan
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South Dakota, Vermillion, SD 57069, USA
| | - Jennifer R Knapp
- Kansas Intellectual and Development Disabilities Research Center, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Jeremy Chien
- Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Xuejun Wang
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South Dakota, Vermillion, SD 57069, USA
| | - Kathleen M Eyster
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South Dakota, Vermillion, SD 57069, USA
| | - Carlos M Telleria
- Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South Dakota, Vermillion, SD 57069, USA; Department of Pathology, Faculty of Medicine, McGill University, Montreal, QC H3A 2B4, Canada.
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15
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Ishizawa J, Kojima K, Chachad D, Ruvolo P, Ruvolo V, Jacamo RO, Borthakur G, Mu H, Zeng Z, Tabe Y, Allen JE, Wang Z, Ma W, Lee HC, Orlowski R, Sarbassov DD, Lorenzi PL, Huang X, Neelapu SS, McDonnell T, Miranda RN, Wang M, Kantarjian H, Konopleva M, Davis RE, Andreeff M. ATF4 induction through an atypical integrated stress response to ONC201 triggers p53-independent apoptosis in hematological malignancies. Sci Signal 2016; 9:ra17. [PMID: 26884599 DOI: 10.1126/scisignal.aac4380] [Citation(s) in RCA: 129] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The clinical challenge posed by p53 abnormalities in hematological malignancies requires therapeutic strategies other than standard genotoxic chemotherapies. ONC201 is a first-in-class small molecule that activates p53-independent apoptosis, has a benign safety profile, and is in early clinical trials. We found that ONC201 caused p53-independent apoptosis and cell cycle arrest in cell lines and in mantle cell lymphoma (MCL) and acute myeloid leukemia (AML) samples from patients; these included samples from patients with genetic abnormalities associated with poor prognosis or cells that had developed resistance to the nongenotoxic agents ibrutinib and bortezomib. Moreover, ONC201 caused apoptosis in stem and progenitor AML cells and abrogated the engraftment of leukemic stem cells in mice while sparing normal bone marrow cells. ONC201 caused changes in gene expression similar to those caused by the unfolded protein response (UPR) and integrated stress responses (ISRs), which increase the translation of the transcription factor ATF4 through an increase in the phosphorylation of the translation initiation factor eIF2α. However, unlike the UPR and ISR, the increase in ATF4 abundance in ONC201-treated hematopoietic cells promoted apoptosis and did not depend on increased phosphorylation of eIF2α. ONC201 also inhibited mammalian target of rapamycin complex 1 (mTORC1) signaling, likely through ATF4-mediated induction of the mTORC1 inhibitor DDIT4. Overexpression of BCL-2 protected against ONC201-induced apoptosis, and the combination of ONC201 and the BCL-2 antagonist ABT-199 synergistically increased apoptosis. Thus, our results suggest that by inducing an atypical ISR and p53-independent apoptosis, ONC201 has clinical potential in hematological malignancies.
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Affiliation(s)
- Jo Ishizawa
- Section of Molecular Hematology and Therapy, Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Kensuke Kojima
- Section of Molecular Hematology and Therapy, Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. Division of Hematology, Respiratory Medicine and Oncology, Department of Medicine, Saga University, Saga 840-8502, Japan
| | - Dhruv Chachad
- Section of Molecular Hematology and Therapy, Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Peter Ruvolo
- Section of Molecular Hematology and Therapy, Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Vivian Ruvolo
- Section of Molecular Hematology and Therapy, Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Rodrigo O Jacamo
- Section of Molecular Hematology and Therapy, Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Gautam Borthakur
- Section of Molecular Hematology and Therapy, Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Hong Mu
- Section of Molecular Hematology and Therapy, Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Zhihong Zeng
- Section of Molecular Hematology and Therapy, Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yoko Tabe
- Section of Molecular Hematology and Therapy, Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. Department of Clinical Laboratory Medicine, Juntendo University School of Medicine, Tokyo 113-8431, Japan
| | | | - Zhiqiang Wang
- Department of Lymphoma/Myeloma, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Wencai Ma
- Department of Lymphoma/Myeloma, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Hans C Lee
- Department of Lymphoma/Myeloma, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Robert Orlowski
- Department of Lymphoma/Myeloma, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Dos D Sarbassov
- Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Philip L Lorenzi
- Department of Bioinformatics and Computational Biology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Xuelin Huang
- Department of Biostatistics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Sattva S Neelapu
- Department of Lymphoma/Myeloma, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Timothy McDonnell
- Department of Hematopathology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Roberto N Miranda
- Department of Hematopathology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Michael Wang
- Department of Lymphoma/Myeloma, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Hagop Kantarjian
- Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Marina Konopleva
- Section of Molecular Hematology and Therapy, Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - R Eric Davis
- Department of Lymphoma/Myeloma, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
| | - Michael Andreeff
- Section of Molecular Hematology and Therapy, Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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16
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Caruso M, Zhang X, Ma D, Yang Z, Qi Y, Yi Z. Novel Endogenous, Insulin-Stimulated Akt2 Protein Interaction Partners in L6 Myoblasts. PLoS One 2015; 10:e0140255. [PMID: 26465754 PMCID: PMC4605787 DOI: 10.1371/journal.pone.0140255] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 09/23/2015] [Indexed: 12/28/2022] Open
Abstract
Insulin resistance and Type 2 diabetes are marked by an aberrant response in the insulin signaling network. The phosphoinositide-dependent serine/threonine kinase, Akt2, plays a key role in insulin signaling and glucose uptake, most notably within skeletal muscle. Protein-protein interaction regulates the functional consequence of Akt2 and in turn, Akt2's role in glucose uptake. However, only few insulin-responsive Akt2 interaction partners have been identified in skeletal muscle cells. In the present work, rat L6 myoblasts, a widely used insulin sensitive skeletal muscle cell line, were used to examine endogenous, insulin-stimulated Akt2 protein interaction partners. Akt2 co-immunoprecipitation was coupled with 1D-SDS-PAGE and fractions were analyzed by HPLC-ESI-MS/MS to reveal Akt2 protein-protein interactions. The pull-down assay displayed specificity for the Akt2 isoform; Akt1 and Akt3 unique peptides were not detected. A total of 49 were detected with a significantly increased (47) or decreased (2) association with Akt2 following insulin administration (n = 4; p<0.05). Multiple pathways were identified for the novel Akt2 interaction partners, such as the EIF2 and ubiquitination pathways. These data suggest that multiple new endogenous proteins may associate with Akt2 under basal as well as insulin-stimulated conditions, providing further insight into the insulin signaling network. Data are available via ProteomeXchange with identifier PXD002557.
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Affiliation(s)
- Michael Caruso
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI, United States of America
| | - Xiangmin Zhang
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI, United States of America
| | - Danjun Ma
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI, United States of America
| | - Zhao Yang
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI, United States of America
| | - Yue Qi
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI, United States of America
| | - Zhengping Yi
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI, United States of America
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17
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Shin S, Buel GR, Wolgamott L, Plas DR, Asara JM, Blenis J, Yoon SO. ERK2 Mediates Metabolic Stress Response to Regulate Cell Fate. Mol Cell 2015; 59:382-98. [PMID: 26190261 DOI: 10.1016/j.molcel.2015.06.020] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 05/13/2015] [Accepted: 06/11/2015] [Indexed: 12/12/2022]
Abstract
Insufficient nutrients disrupt physiological homeostasis, resulting in diseases and even death. Considering the physiological and pathological consequences of this metabolic stress, the adaptive responses that cells utilize under this condition are of great interest. We show that under low-glucose conditions, cells initiate adaptation followed by apoptosis responses using PERK/Akt and MEK1/ERK2 signaling, respectively. For adaptation, cells engage the ER stress-induced unfolded protein response, which results in PERK/Akt activation and cell survival. Sustained and extreme energetic stress promotes a switch to isoform-specific MEK1/ERK2 signaling, induction of GCN2/eIF2α phosphorylation, and ATF4 expression, which overrides PERK/Akt-mediated adaptation and induces apoptosis through ATF4-dependent expression of pro-apoptotic factors including Bid and Trb3. ERK2 activation during metabolic stress contributes to changes in TCA cycle and amino acid metabolism, and cell death, which is suppressed by glutamate and α-ketoglutarate supplementation. Taken together, our results reveal promising targets to protect cells or tissues from metabolic stress.
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Affiliation(s)
- Sejeong Shin
- Department of Pharmacology, Meyer Cancer Center, Weill Cornell Medical College, New York, NY 10065, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Gwen R Buel
- Department of Pharmacology, Meyer Cancer Center, Weill Cornell Medical College, New York, NY 10065, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Laura Wolgamott
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - David R Plas
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - John M Asara
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02115, USA
| | - John Blenis
- Department of Pharmacology, Meyer Cancer Center, Weill Cornell Medical College, New York, NY 10065, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
| | - Sang-Oh Yoon
- Department of Pharmacology, Meyer Cancer Center, Weill Cornell Medical College, New York, NY 10065, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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18
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Tenkerian C, Krishnamoorthy J, Mounir Z, Kazimierczak U, Khoutorsky A, Staschke KA, Kristof AS, Wang S, Hatzoglou M, Koromilas AE. mTORC2 Balances AKT Activation and eIF2α Serine 51 Phosphorylation to Promote Survival under Stress. Mol Cancer Res 2015; 13:1377-88. [PMID: 26130148 DOI: 10.1158/1541-7786.mcr-15-0184-t] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 06/19/2015] [Indexed: 11/16/2022]
Abstract
UNLABELLED The mTOR nucleates two complexes, namely mTOR complex 1 and 2 (mTORC1 and mTORC2), which are implicated in cell growth, survival, metabolism, and cancer. Phosphorylation of the α-subunit of translation initiation factor eIF2 at serine 51 (eIF2αS51P) is a key event of mRNA translation initiation and a master regulator of cell fate during cellular stress. Recent studies have implicated mTOR signaling in the stress response, but its connection to eIF2αS51P has remained unclear. Herein, we report that genetic as well as catalytic inhibition of mTORC2 induces eIF2αS51P. On the other hand, the allosteric inhibitor rapamycin induces eIF2αS51P through pathways that are independent of mTORC1 inactivation. Increased eIF2αS51P by impaired mTORC2 depends on the inactivation of AKT, which primes the activation of the endoplasmic reticulum (ER)-resident kinase PERK/PEK. The biologic function of eIF2αS51P was characterized in tuberous sclerosis complex (TSC)-mutant cells, which are defective in mTORC2 and AKT activity. TSC-mutant cells exhibit increased PERK activity, which is downregulated by the reconstitution of the cells with an activated form of AKT1. Also, TSC-mutant cells are increasingly susceptible to ER stress, which is reversed by AKT1 reconstitution. The susceptibility of TSC-mutant cells to ER stress is further enhanced by the pharmacologic inhibition of PERK or genetic inactivation of eIF2αS51P. Thus, the PERK/eIF2αS51P arm is an important compensatory prosurvival mechanism, which substitutes for the loss of AKT under ER stress. IMPLICATIONS A novel mechanistic link between mTOR function and protein synthesis is identified in TSC-null tumor cells under stress and reveals potential for the development of antitumor treatments with stress-inducing chemotherapeutics.
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Affiliation(s)
- Clara Tenkerian
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada. Division of Experimental Medicine, Department of Medicine, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
| | - Jothilatha Krishnamoorthy
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada
| | | | - Urszula Kazimierczak
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada. Department of Cancer Immunology, Chair of Medical Biotechnology, Poznan University of Medical Sciences, Poland
| | - Arkady Khoutorsky
- Department of Biochemistry, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
| | - Kirk A Staschke
- Oncology Research Division, Lilly Research Laboratories, Indianapolis, Indiana
| | - Arnold S Kristof
- Department of Critical Care, McGill University Health Centre and Meakins-Christie Laboratories, Montreal, Quebec, Canada. Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Shuo Wang
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada
| | - Maria Hatzoglou
- Department of Nutrition, School of Medicine, Case Western University, Cleveland, Ohio
| | - Antonis E Koromilas
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada. Department of Oncology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.
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19
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Abstract
Dysregulation of mRNA translation is a frequent feature of neoplasia. Many oncogenes and tumour suppressors affect the translation machinery, making aberrant translation a widespread characteristic of tumour cells, independent of the genetic make-up of the cancer. Therefore, therapeutic agents that target components of the protein synthesis apparatus hold promise as novel anticancer drugs that can overcome intra-tumour heterogeneity. In this Review, we discuss the role of translation in cancer, with a particular focus on the eIF4F (eukaryotic translation initiation factor 4F) complex, and provide an overview of recent efforts aiming to 'translate' these results to the clinic.
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20
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Phosphorylation of the translation initiation factor eIF2α at serine 51 determines the cell fate decisions of Akt in response to oxidative stress. Cell Death Dis 2015; 6:e1591. [PMID: 25590801 PMCID: PMC4669752 DOI: 10.1038/cddis.2014.554] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 10/29/2014] [Accepted: 11/26/2014] [Indexed: 12/15/2022]
Abstract
Phosphorylation of the α subunit of the translation initiation factor eIF2 at serine 51 (eIF2αP) is a master regulator of cell adaptation to various forms of stress with implications in antitumor treatments with chemotherapeutic drugs. Herein, we demonstrate that genetic loss of the eIF2α kinases PERK and GCN2 or impaired eIF2αP by genetic means renders immortalized mouse fibroblasts as well as human tumor cells increasingly susceptible to death by oxidative stress. We also show that eIF2αP facilitates Akt activation in cells subjected to oxidative insults. However, whereas Akt activation has a pro-survival role in eIF2αP-proficient cells, the lesser amount of activated Akt in eIF2αP-deficient cells promotes death. At the molecular level, we demonstrate that eIF2αP acts through an ATF4-independent mechanism to control Akt activity via the regulation of mTORC1. Specifically, eIF2αP downregulates mTORC1 activity, which in turn relieves the feedback inhibition of PI3K resulting in the upregulation of the mTORC2-Akt arm. Inhibition of mTORC1 by rapamycin restores Akt activity in eIF2αP-deficient cells but renders them highly susceptible to Akt-mediated death by oxidative stress. Our data demonstrate that eIF2αP acts as a molecular switch that dictates either cell survival or death by activated Akt in response to oxidative stress. Hence, we propose that inactivation of eIF2αP may be a suitable approach to unleash the killing power of Akt in tumor cells treated with pro-oxidant drugs.
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Koromilas AE. Roles of the translation initiation factor eIF2α serine 51 phosphorylation in cancer formation and treatment. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:871-80. [PMID: 25497381 DOI: 10.1016/j.bbagrm.2014.12.007] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 12/03/2014] [Accepted: 12/07/2014] [Indexed: 01/12/2023]
Abstract
Cells respond to various forms of stress by activating anti-proliferative pathways, which allow them to correct the damage caused by stress before re-entering proliferation. If the damage, however, is beyond repair, stressed cells are eliminated from the host by undergoing death. The balance between cell survival and death is essential for cancer formation and is determined by several key pathways that impact on different stages of gene expression. In recent years, it has become evident that phosphorylation of the alpha (α) subunit of the translation initiation factor eIF2 at serine 51 (eIF2αS51P) is an important determinant of cell fate in response to stress. Induction of eIF2αS51P is mediated by a family of four kinases namely, HRI, PKR, PERK and GCN2, each of which responds to distinct forms of stress. Increased eIF2αS51P results in a global inhibition of protein synthesis but at the same time enhances the translation of select mRNAs encoding for proteins that control cell adaptation to stress. Short-term induction of eIF2αS51P has been associated with cell survival whereas long-term induction with cell death. Studies in mouse and human models of cancer have provided compelling evidence that eIF2αS51P plays an essential role in stress-induced tumorigenesis. Increased eIF2αS51P exhibits cell autonomous as well as immune regulatory effects, which can influence tumor growth and the efficacy of anti-tumor therapies. The findings suggest that eIF2αS51P may be of prognostic value and a suitable target for the design and implementation of effective anti-tumor therapies. This article is part of a Special Issue entitled: Translation and Cancer.
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Affiliation(s)
- Antonis E Koromilas
- Lady Davis Institute for Medical Research-McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada; Department of Oncology, Faculty of Medicine, McGill University, Montreal, Quebec H2W 1S6, Canada.
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Guan BJ, Krokowski D, Majumder M, Schmotzer CL, Kimball SR, Merrick WC, Koromilas AE, Hatzoglou M. Translational control during endoplasmic reticulum stress beyond phosphorylation of the translation initiation factor eIF2α. J Biol Chem 2014; 289:12593-611. [PMID: 24648524 DOI: 10.1074/jbc.m113.543215] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The accumulation of unfolded/misfolded proteins in the endoplasmic reticulum (ER) causes stress to which an unfolded protein response is activated to render cell survival or apoptosis (chronic stress). Transcriptional and translational reprogramming is tightly regulated during the unfolded protein response to ensure specific gene expression. The master regulator of this response is the PERK/eIF2α/ATF4 signaling where eIF2α is phosphorylated (eIF2α-P) by the kinase PERK. This signal leads to global translational shutdown, but it also enables translation of the transcription factor ATF4 mRNA. We showed recently that ATF4 induces an anabolic program through the up-regulation of selected amino acid transporters and aminoacyl-tRNA synthetases. Paradoxically, this anabolic program led cells to apoptosis during chronic ER stress in a manner that involved recovery from stress-induced protein synthesis inhibition. By using eIF2α-P-deficient cells as an experimental system, we identified a communicating network of signaling pathways that contribute to the inhibition of protein synthesis during chronic ER stress. This eIF2α-P-independent network includes (i) inhibition of mammalian target of rapamycin kinase protein complex 1 (mTORC1)-targeted protein phosphorylation, (ii) inhibited translation of a selective group of 5'-terminal oligopyrimidine mRNAs (encoding proteins involved in the translation machinery and translationally controlled by mTORC1 signaling), and (iii) inhibited translation of non-5'-terminal oligopyrimidine ribosomal protein mRNAs and ribosomal RNA biogenesis. We propose that the PERK/eIF2α-P/ATF4 signaling acts as a brake in the decline of protein synthesis during chronic ER stress by positively regulating signaling downstream of the mTORC1 activity. These studies advance our knowledge on the complexity of the communicating signaling pathways in controlling protein synthesis rates during chronic stress.
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Krishnamoorthy J, Rajesh K, Mirzajani F, Kesoglidou P, Papadakis AI, Koromilas AE. Evidence for eIF2α phosphorylation-independent effects of GSK2656157, a novel catalytic inhibitor of PERK with clinical implications. Cell Cycle 2014; 13:801-6. [PMID: 24401334 PMCID: PMC3979916 DOI: 10.4161/cc.27726] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The endoplasmic reticulum (ER)-resident protein kinase PERK is a major component of the unfolded protein response (UPR), which promotes the adaptation of cells to various forms of stress. PERK phosphorylates the α subunit of the translation initiation factor eIF2 at serine 51, a modification that plays a key role in the regulation of mRNA translation in stressed cells. Several studies have demonstrated that the PERK-eIF2α phosphorylation pathway maintains insulin biosynthesis and glucose homeostasis, facilitates tumor formation and decreases the efficacy of tumor treatment with chemotherapeutic drugs. Recently, a selective catalytic PERK inhibitor termed GSK2656157 has been developed with anti-tumor properties in mice. Herein, we provide evidence that inhibition of PERK activity by GSK2656157 does not always correlate with inhibition of eIF2α phosphorylation. Also, GSK2656157 does not always mimic the biological effects of the genetic inactivation of PERK. Furthermore, cells treated with GSK2656157 increase eIF2α phosphorylation as a means to compensate for the loss of PERK. Using human tumor cells impaired in eIF2α phosphorylation, we demonstrate that GSK2656157 induces ER stress-mediated death suggesting that the drug acts independent of the inhibition of eIF2α phosphorylation. We conclude that GSK2656157 might be a useful compound to dissect pathways that compensate for the loss of PERK and/or identify PERK pathways that are independent of eIF2α phosphorylation.
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Affiliation(s)
- Jothilatha Krishnamoorthy
- Lady Davis Institute for Medical Research; McGill University; Sir Mortimer B. Davis-Jewish General Hospital; Montreal, Quebec, Canada
| | - Kamindla Rajesh
- Lady Davis Institute for Medical Research; McGill University; Sir Mortimer B. Davis-Jewish General Hospital; Montreal, Quebec, Canada
| | - Farzaneh Mirzajani
- Lady Davis Institute for Medical Research; McGill University; Sir Mortimer B. Davis-Jewish General Hospital; Montreal, Quebec, Canada
| | - Polixenia Kesoglidou
- Lady Davis Institute for Medical Research; McGill University; Sir Mortimer B. Davis-Jewish General Hospital; Montreal, Quebec, Canada
| | - Andreas I Papadakis
- Lady Davis Institute for Medical Research; McGill University; Sir Mortimer B. Davis-Jewish General Hospital; Montreal, Quebec, Canada
| | - Antonis E Koromilas
- Lady Davis Institute for Medical Research; McGill University; Sir Mortimer B. Davis-Jewish General Hospital; Montreal, Quebec, Canada; Department of Oncology; Faculty of Medicine; McGill University; Montreal, Quebec, Canada
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Rajesh K, Papadakis AI, Kazimierczak U, Peidis P, Wang S, Ferbeyre G, Kaufman RJ, Koromilas AE. eIF2α phosphorylation bypasses premature senescence caused by oxidative stress and pro-oxidant antitumor therapies. Aging (Albany NY) 2013; 5:884-901. [PMID: 24334569 PMCID: PMC3883705 DOI: 10.18632/aging.100620] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
Eukaryotic cells respond to various forms of stress by blocking mRNA translation initiation via the phosphorylation of the alpha (α) subunit of eIF2 at serine 51 (S51) (eIFαP). An important role of eIF2αP is the regulation of redox homeostasis and adaptation of cells to oxidative stress. Herein, we demonstrate that eIF2αP guards cells from intracellular reactive oxygen species (ROS) via the inhibition of senescence. Specifically, genetic inactivation of either eIF2αP or eIF2α kinase PERK in primary mouse or human fibroblasts leads to proliferative defects associated with increased DNA damage, G2/M accumulation and induction of premature senescence. Impaired proliferation of either PERK or eIF2αP-deficient primary cells is caused by increased ROS and restored by anti-oxidant treatment. Contrary to primary cells, impaired eIF2αP in immortalized mouse fibroblasts or human tumor cells provides tolerance to elevated intracellular ROS levels. However, eIF2αP-deficient human tumor cells are highly susceptible to extrinsic ROS generated by the pro-oxidant drug doxorubicin by undergoing premature senescence. Our work demonstrates that eIF2αP determines cell destiny through its capacity to control senescence in response to oxidative stress. Also, inhibition of eIF2αP may be a suitable means to increase the anti-tumor effects of pro-oxidant drugs through the induction of senescence.
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Affiliation(s)
- Kamindla Rajesh
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
| | - Andreas I. Papadakis
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
| | - Urszula Kazimierczak
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
- Department of Cancer Immunology, Chair of Medical Biotechnology, Poznan University of Medical Sciences, Poland
| | - Philippos Peidis
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
| | - Shuo Wang
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
| | - Gerardo Ferbeyre
- Département de Biochimie, Université de Montréal; Montréal, Québec H3C 3J7, Canada
| | - Randal J. Kaufman
- Center for Neuroscience, Aging and Stem Cell Research, Sanford Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Antonis E. Koromilas
- Lady Davis Institute for Medical Research, McGill University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
- Department of Oncology, Faculty of Medicine, McGill University, Montreal, Quebec H2W 1S6, Canada
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