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Koromilas AE. The integrated stress response in the induction of mutant KRAS lung carcinogenesis: Mechanistic insights and therapeutic implications. Bioessays 2022; 44:e2200026. [PMID: 35587163 DOI: 10.1002/bies.202200026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 05/06/2022] [Accepted: 05/11/2022] [Indexed: 11/12/2022]
Abstract
The integrated stress response (ISR) is a key determinant of tumorigenesis in response to oncogenic forms of stress like genotoxic, proteotoxic and metabolic stress. ISR relies on the phosphorylation of the translation initiation factor eIF2 to promote the translational and transcriptional reprogramming of gene expression in stressed cells. While ISR promotes tumor survival under stress, its hyperactivation above a level of tolerance can also cause tumor death. The tumorigenic function of ISR has been recently demonstrated for lung adenocarcinomas (LUAD) with KRAS mutations. ISR mediates the translational repression of the dual-specificity phosphatase DUSP6 to stimulate ERK activity and LUAD growth. The significance of this finding is highlighted by the strong anti-tumor responses of ISR inhibitors in pre-clinical LUAD models. Elucidation of the mechanisms of ISR action in LUAD progression via cell-autonomous and immune regulatory mechanisms will provide a better understanding of its tumorigenic role to fully exploit its therapeutic potential in the treatment of a deadly form of cancer.
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Affiliation(s)
- Antonis E Koromilas
- Lady Davis Institute for Medical Research, Sir Mortimer B, Davis-Jewish General Hospital, Montreal, Quebec, Canada.,Gerald Bronfman Department of Oncology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
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Namer LS, Osman F, Banai Y, Masquida B, Jung R, Kaempfer R. An Ancient Pseudoknot in TNF-α Pre-mRNA Activates PKR, Inducing eIF2α Phosphorylation that Potently Enhances Splicing. Cell Rep 2018; 20:188-200. [PMID: 28683312 DOI: 10.1016/j.celrep.2017.06.035] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/15/2017] [Accepted: 06/12/2017] [Indexed: 12/22/2022] Open
Abstract
Tumor necrosis factor alpha (TNF-α) is expressed promptly during inflammatory responses. Efficient TNF-α mRNA splicing is achieved through a 3' UTR element that activates RNA-dependent eIF2α protein kinase (PKR). The TNF-α RNA activator, we show, folds into a pseudoknot conserved from teleost fish to humans, critical for PKR activation and mRNA splicing. The pseudoknot constrains the RNA into two double-helical stacks having parallel axes, permitting facile PKR dimerization and trans-autophosphorylation needed for kinase activation. Mutations show that the PKR activator potently enhances splicing without inhibiting translation. eIF2α phosphorylation represses translation and is essential for coping with cellular stress, yet PKR-enabled TNF mRNA splicing depends strictly on eIF2α phosphorylation. Indeed, eIF2α phosphorylation at Serine51 is necessary and sufficient to achieve highly efficient splicing, extending its role from negative control of translation to positive control of splicing. This mechanism, operational in human peripheral blood mononuclear cells (PBMCs), links stress signaling to protective immunity through TNF mRNA splicing rendered efficient upon eIF2α phosphorylation.
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Affiliation(s)
- Lise Sarah Namer
- Department of Biochemistry and Molecular Biology, Institute of Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 9112102, Israel
| | - Farhat Osman
- Department of Biochemistry and Molecular Biology, Institute of Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 9112102, Israel
| | - Yona Banai
- Department of Biochemistry and Molecular Biology, Institute of Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 9112102, Israel
| | - Benoît Masquida
- Génétique Moléculaire Génomique Microbiologie, CNRS-University of Strasbourg, Strasbourg 67084, France
| | - Rodrigo Jung
- Department of Biochemistry and Molecular Biology, Institute of Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 9112102, Israel
| | - Raymond Kaempfer
- Department of Biochemistry and Molecular Biology, Institute of Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 9112102, Israel.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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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] [What about the content of this article? (0)] [Affiliation(s)] [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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