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Tsuchiya T, Miyawaki S, Teranishi Y, Ohara K, Hirano Y, Ogawa S, Torazawa S, Sakai Y, Hongo H, Ono H, Saito N. Current molecular understanding of central nervous system schwannomas. Acta Neuropathol Commun 2025; 13:24. [PMID: 39910685 PMCID: PMC11796276 DOI: 10.1186/s40478-025-01937-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2024] [Accepted: 01/25/2025] [Indexed: 02/07/2025] Open
Abstract
BACKGROUND Schwannomas are tumors that originate from myelinating Schwann cells and can occur in cranial, spinal, and peripheral nerves. Although our understanding of the molecular biology underlying schwannomas remains incomplete, numerous studies have identified various molecular findings and biomarkers associated with schwannomas of the central nervous system (CNS). The development of these tumors is primarily linked to mutations in the NF2 gene. Merlin, the protein encoded by NF2, is integral to several signaling pathways, including Ras/Raf/MEK/ERK, PI3K/Akt/mTORC1, Wnt/β-catenin, and the Hippo pathway. MAIN BODY Recent research has also uncovered novel genetic alterations, such as the SH3PXD2A::HTRA1 fusion gene, VGLL-fusions in intraparenchymal CNS schwannomas, and the SOX10 mutation particularly in non-vestibular cranial nerve schwannomas. In addition to genetic alterations, research is also being conducted on gene expression and epigenetic regulation, with a focus on NF2 methylation and post-transcriptional silencing by micro RNA. Furthermore, the advent of advanced techniques like single-cell sequencing and multi-omics analysis has facilitated rapid discoveries related to the tumor microenvironment and tumor heterogeneity in schwannomas. CONCLUSION A deeper exploration of these molecular findings could clarify the mechanisms of schwannoma tumorigenesis and progression, ultimately guiding the development of new therapeutic targets. This review offers a comprehensive overview of the current molecular understanding of CNS schwannomas, emphasizing the insights gained from previous research, while addressing existing controversies and outlining future research and treatment perspectives.
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Affiliation(s)
- Takahiro Tsuchiya
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Satoru Miyawaki
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
| | - Yu Teranishi
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Kenta Ohara
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Yudai Hirano
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Shotaro Ogawa
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Seiei Torazawa
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Yu Sakai
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Hiroki Hongo
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Hideaki Ono
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Nobuhito Saito
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
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Li M, Huang W, Zhang Y, Du Y, Zhao S, Wang L, Sun Y, Sha B, Yan J, Ma Y, Tang J, Shi J, Li P, Jia L, Hu T, Chen P. Glucose deprivation triggers DCAF1-mediated inactivation of Rheb-mTORC1 and promotes cancer cell survival. Cell Death Dis 2024; 15:409. [PMID: 38862475 PMCID: PMC11166663 DOI: 10.1038/s41419-024-06808-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 05/27/2024] [Accepted: 06/04/2024] [Indexed: 06/13/2024]
Abstract
Low glucose is a common microenvironment for rapidly growing solid tumors, which has developed multiple approaches to survive under glucose deprivation. However, the specific regulatory mechanism remains largely elusive. In this study, we demonstrate that glucose deprivation, while not amino acid or serum starvation, transactivates the expression of DCAF1. This enhances the K48-linked polyubiquitination and proteasome-dependent degradation of Rheb, inhibits mTORC1 activity, induces autophagy, and facilitates cancer cell survival under glucose deprivation conditions. This study identified DCAF1 as a new cellular glucose sensor and uncovered new insights into mechanism of DCAF1-mediated inactivation of Rheb-mTORC1 pathway for promoting cancer cell survival in response to glucose deprivation.
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Affiliation(s)
- Miaomiao Li
- Academy of Medical Sciences, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Wenjing Huang
- Academy of Medical Sciences, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Yuan Zhang
- Academy of Medical Sciences, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Yue Du
- Academy of Medical Sciences, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Shan Zhao
- Academy of Medical Sciences, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Longhao Wang
- Academy of Medical Sciences, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, 450052, China
| | - Yaxin Sun
- Academy of Medical Sciences, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
- Sanquan College of Xinxiang Medical University, Xinxiang, 453003, China
| | - Beibei Sha
- Academy of Medical Sciences, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
- The Second Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, 450014, China
| | - Jie Yan
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, 450052, China
| | - Yangcheng Ma
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, 450052, China
| | - Jinlu Tang
- Academy of Medical Sciences, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Jianxiang Shi
- Precision Medicine Center, Henan Institute of Medical and Pharmaceutical Sciences & BGI College, Zhengzhou University, Zhengzhou, 450052, China
| | - Pei Li
- Academy of Medical Sciences, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Lijun Jia
- Cancer Institute, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, 200032, China
| | - Tao Hu
- Academy of Medical Sciences, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China.
| | - Ping Chen
- Academy of Medical Sciences, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China.
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3
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Zhang Y, Long J, Ren J, Huang X, Zhong P, Wang B. Potential Molecular Biomarkers of Vestibular Schwannoma Growth: Progress and Prospects. Front Oncol 2021; 11:731441. [PMID: 34646772 PMCID: PMC8503266 DOI: 10.3389/fonc.2021.731441] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Accepted: 09/06/2021] [Indexed: 12/25/2022] Open
Abstract
Vestibular schwannomas (VSs, also known as acoustic neuromas) are relatively rare benign brain tumors stem from the Schwann cells of the eighth cranial nerve. Tumor growth is the paramount factor for neurosurgeons to decide whether to choose aggressive treatment approach or careful follow-up with regular magnetic resonance imaging (MRI), as surgery and radiation can introduce significant trauma and affect neurological function, while tumor enlargement during long-term follow-up will compress the adjacent nerves and tissues, causing progressive hearing loss, tinnitus and vertigo. Recently, with the deepening research of VS biology, some proteins that regulate merlin conformation changes, inflammatory cytokines, miRNAs, tissue proteins and cerebrospinal fluid (CSF) components have been proposed to be closely related to tumor volume increase. In this review, we discuss advances in the study of biomarkers that associated with VS growth, providing a reference for exploring the growth course of VS and determining the optimal treatment strategy for each patient.
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Affiliation(s)
- Yu Zhang
- Department of Pharmacy, Huashan Hospital, Fudan University, Shanghai, China
| | - Jianfei Long
- Department of Pharmacy, Huashan Hospital, Fudan University, Shanghai, China
| | - Junwei Ren
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China
| | - Xiang Huang
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China
| | - Ping Zhong
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China
| | - Bin Wang
- Department of Pharmacy, Huashan Hospital, Fudan University, Shanghai, China
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4
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Ly PT, Tan YS, Koe CT, Zhang Y, Xie G, Endow S, Deng WM, Yu F, Wang H. CRL4Mahj E3 ubiquitin ligase promotes neural stem cell reactivation. PLoS Biol 2019; 17:e3000276. [PMID: 31170139 PMCID: PMC6553684 DOI: 10.1371/journal.pbio.3000276] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 05/02/2019] [Indexed: 12/22/2022] Open
Abstract
The ability of neural stem cells (NSCs) to transit between quiescence and proliferation is crucial for brain development and homeostasis. Drosophila Hippo pathway maintains NSC quiescence, but its regulation during brain development remains unknown. Here, we show that CRL4Mahj, an evolutionarily conserved E3 ubiquitin ligase, is essential for NSC reactivation (exit from quiescence). We demonstrate that damaged DNA-binding protein 1 (DDB1) and Cullin4, two core components of Cullin4-RING ligase (CRL4), are intrinsically required for NSC reactivation. We have identified a substrate receptor of CRL4, Mahjong (Mahj), which is necessary and sufficient for NSC reactivation. Moreover, we show that CRL4Mahj forms a protein complex with Warts (Wts/large tumor suppressor [Lats]), a kinase of the Hippo signaling pathway, and Mahj promotes the ubiquitination of Wts. Our genetic analyses further support the conclusion that CRL4Mahj triggers NSC reactivation by inhibition of Wts. Given that Cullin4B mutations cause mental retardation and cerebral malformation, similar regulatory mechanisms may be applied to the human brain. During the transition from quiescence to reactivation of neural stem cells, the E3 ubiquitin ligase CRL4Mahj promotes their reactivation by inhibiting Wts, a core kinase of Hippo signalling pathway.
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Affiliation(s)
- Phuong Thao Ly
- Neuroscience and Behavioural Disorders Programme, Duke-NUS Medical School, Singapore, Singapore
| | - Ye Sing Tan
- Neuroscience and Behavioural Disorders Programme, Duke-NUS Medical School, Singapore, Singapore
| | | | - Yingjie Zhang
- Neuroscience and Behavioural Disorders Programme, Duke-NUS Medical School, Singapore, Singapore
| | - Gengqiang Xie
- Department of Biological Science, Florida State University, Tallahassee, Florida, United States of America
| | - Sharyn Endow
- Neuroscience and Behavioural Disorders Programme, Duke-NUS Medical School, Singapore, Singapore
- Department of Cell Biology, Duke University Medical Centre, Durham, North Carolina, United States of America
| | - Wu-Min Deng
- Department of Biological Science, Florida State University, Tallahassee, Florida, United States of America
| | - Fengwei Yu
- Neuroscience and Behavioural Disorders Programme, Duke-NUS Medical School, Singapore, Singapore
- Temasek Life Sciences Laboratory, Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore
| | - Hongyan Wang
- Neuroscience and Behavioural Disorders Programme, Duke-NUS Medical School, Singapore, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- * E-mail:
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5
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Guo H, Zhang N, Shen S, Yu XF, Wei W. Determinants of lentiviral Vpx-CRL4 E3 ligase-mediated SAMHD1 degradation in the substrate adaptor protein DCAF1. Biochem Biophys Res Commun 2019; 513:933-939. [PMID: 31003777 DOI: 10.1016/j.bbrc.2019.04.085] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 04/12/2019] [Indexed: 11/27/2022]
Abstract
The lentiviral accessory protein Vpx enhances viral replication in macrophages, dendritic cells and resting CD4+ T cells by utilizing the host CRL4-DCAF1 E3 ligase to trigger the degradation of the intrinsic antiviral factor SAMHD1. Distinct from the species-specific recognition of either the N or C-terminus of SAMHD1 by Vpx proteins of different HIV-2 and SIV lineages, Vpx recruits SAMHD1 onto the same CRL4-DCAF1 complex. However, the determinants in DCAF1 that are required for Vpx-mediated SAMHD1 degradation have not been well characterized. Here, we demonstrate that the viral protein Vpx is resistant to suppression by a cellular inhibitor of the CRL4-DCAF1 E3 ligase, Merlin/NF2, through targeting a separate binding region in DCAF1. The Merlin binding-deficient DCAF1 truncation mutant (1-1417) is sufficient for Vpx-CRL4-DCAF1 E3 ligase assembly and SAMHD1 degradation. We found that the carboxyl-terminus ED-rich region (1312-1417) of DCAF1 is required for the nuclear localization of DCAF1 and for the Vpx-DCAF1 interaction. We identified the DCAF1 (1-1311) truncation mutant as a dominant negative mutant of wild-type DCAF1 that inhibits Vpx-mediated SAMHD1 degradation. These results suggest a unique strategy by which Vpx exploits DCAF1 to counteract this host restriction factor.
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Affiliation(s)
- Haoran Guo
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, Changchun, 130021, China; Institute of Translational Medicine, The First Hospital of Jilin University, Changchun, 130021, China
| | - Nannan Zhang
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, Changchun, 130021, China
| | - Siyu Shen
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, Changchun, 130021, China
| | - Xiao-Fang Yu
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, Changchun, 130021, China; Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD, 21205, USA
| | - Wei Wei
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, Changchun, 130021, China; Institute of Translational Medicine, The First Hospital of Jilin University, Changchun, 130021, China.
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6
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Ferner RE, Bakker A, Elgersma Y, Evans DGR, Giovannini M, Legius E, Lloyd A, Messiaen LM, Plotkin S, Reilly KM, Schindeler A, Smith MJ, Ullrich NJ, Widemann B, Sherman LS. From process to progress-2017 International Conference on Neurofibromatosis 1, Neurofibromatosis 2 and Schwannomatosis. Am J Med Genet A 2019; 179:1098-1106. [PMID: 30908866 DOI: 10.1002/ajmg.a.61112] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Accepted: 02/09/2019] [Indexed: 12/19/2022]
Abstract
The neurofibromatoses are inherited, tumor suppressor disorders that are characterized by multiple, benign peripheral nerve sheath tumors and other nervous system tumors. Each disease is associated with a distinct genetic mutation and with a different pathogenesis and clinical course. Neurofibromatosis 1 (NF1) is common and epitomized by multiple neurofibromas with widespread complications. NF2 and schwannomatosis are rare diseases that are typified by multiple schwannomas that are particularly painful in people with schwannomatosis. Since 1985, the Children's Tumor Foundation (formerly the National Neurofibromatosis Foundation) has hosted an international Neurofibromatosis Conference, bringing together international participants who are focused on NF research and clinical care. The 2017 Conference, held in Washington, DC, was among the largest gatherings of NF researchers to date and included presentations from clinicians and basic scientists, highlighting new data regarding the molecular and cellular mechanisms underlying each of these diseases as well as results from clinical studies and clinical trials. This article summarizes the findings presented at the meeting and represents the current state-of-the art for NF research.
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Affiliation(s)
- Rosalie E Ferner
- Department of Neurology, Neurofibromatosis Centre, Guy's and St. Thomas' NHS Foundation Trust, and King's College London, London, UK
| | | | - Ype Elgersma
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands
| | - D Gareth R Evans
- Centre for Genomic Medicine, St. Mary's Hospital, Manchester, UK.,Manchester Academic Health Sciences Centre (MAHSC), Division of Evolution and Genomic Science, University of Manchester, Manchester, UK
| | - Marco Giovannini
- Department of Head and Neck Surgery, University of California, Los Angeles
| | - Eric Legius
- Department of Human Genetics, University Hospital Leuven, Leuven, Herestraat, Belgium
| | - Alison Lloyd
- Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Ludwine M Messiaen
- Medical Genomics Laboratory, Department of Genetics, University of Alabama, Birmingham, Alabama
| | - Scott Plotkin
- Department of Neurology and Cancer Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Karlyne M Reilly
- Rare Tumors Initiative, Center for Cancer Research, National Institutes of Health, Bethesda, Maryland
| | - Aaron Schindeler
- Orthopaedic Research & Biotechnology, The Children's Hospital at Westmead, Westmead, New South Wales, Australia
| | - Miriam J Smith
- Centre for Genomic Medicine, St. Mary's Hospital, Manchester, UK.,Manchester Academic Health Sciences Centre (MAHSC), Division of Evolution and Genomic Science, University of Manchester, Manchester, UK
| | - Nicole J Ullrich
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Brigitte Widemann
- Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Larry S Sherman
- Division of Neuroscience, Oregon National Primate Research Center, and Department of Cell, Developmental and Cancer Biology, Oregon Health & Science University, Portland, Oregon
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7
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Cellular prion protein (PrP C) in the development of Merlin-deficient tumours. Oncogene 2017; 36:6132-6142. [PMID: 28692055 DOI: 10.1038/onc.2017.200] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 04/14/2017] [Accepted: 05/17/2017] [Indexed: 12/17/2022]
Abstract
Loss of function mutations in the neurofibromatosis Type 2 (NF2) gene, coding for a tumour suppressor, Merlin, cause multiple tumours of the nervous system such as schwannomas, meningiomas and ependymomas. These tumours may occur sporadically or as part of the hereditary condition neurofibromatosis Type 2 (NF2). Current treatment is confined to (radio) surgery and no targeted drug therapies exist. NF2 mutations and/or Merlin inactivation are also seen in other cancers including some mesothelioma, breast cancer, colorectal carcinoma, melanoma and glioblastoma. To study the relationship between Merlin deficiency and tumourigenesis, we have developed an in vitro model comprising human primary schwannoma cells, the most common Merlin-deficient tumour and the hallmark for NF2. Using this model, we show increased expression of cellular prion protein (PrPC) in schwannoma cells and tissues. In addition, a strong overexpression of PrPC is observed in human Merlin-deficient mesothelioma cell line TRA and in human Merlin-deficient meningiomas. PrPC contributes to increased proliferation, cell-matrix adhesion and survival in schwannoma cells acting via 37/67 kDa non-integrin laminin receptor (LR/37/67 kDa) and downstream ERK1/2, PI3K/AKT and FAK signalling pathways. PrPC protein is also strongly released from schwannoma cells via exosomes and as a free peptide suggesting that it may act in an autocrine and/or paracrine manner. We suggest that PrPC and its interactor, LR/37/67 kDa, could be potential therapeutic targets for schwannomas and other Merlin-deficient tumours.
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8
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Blakeley JO, Bakker A, Barker A, Clapp W, Ferner R, Fisher MJ, Giovannini M, Gutmann DH, Karajannis MA, Kissil JL, Legius E, Lloyd AC, Packer RJ, Ramesh V, Riccardi VM, Stevenson DA, Ullrich NJ, Upadhyaya M, Stemmer-Rachamimov A. The path forward: 2015 International Children's Tumor Foundation conference on neurofibromatosis type 1, type 2, and schwannomatosis. Am J Med Genet A 2017; 173:1714-1721. [PMID: 28436162 DOI: 10.1002/ajmg.a.38239] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 02/22/2017] [Indexed: 01/16/2023]
Abstract
The Annual Children's Tumor Foundation International Neurofibromatosis Meeting is the premier venue for connecting discovery, translational and clinical scientists who are focused on neurofibromatosis types 1 and 2 (NF1 and NF2) and schwannomatosis (SWN). The meeting also features rare tumors such as glioma, meningioma, sarcoma, and neuroblastoma that occur both within these syndromes and spontaneously; associated with somatic mutations in NF1, NF2, and SWN. The meeting addresses both state of the field for current clinical care as well as emerging preclinical models fueling discovery of new therapeutic targets and discovery science initiatives investigating mechanisms of tumorigenesis. Importantly, this conference is a forum for presenting work in progress and bringing together all stakeholders in the scientific community. A highlight of the conference was the involvement of scientists from the pharmaceutical industry who presented growing efforts for rare disease therapeutic development in general and specifically, in pediatric patients with rare tumor syndromes. Another highlight was the focus on new investigators who presented new data about biomarker discovery, tumor pathogenesis, and diagnostic tools for NF1, NF2, and SWN. This report summarizes the themes of the meeting and a synthesis of the scientific discoveries presented at the conference in order to make the larger research community aware of progress in the neurofibromatoses.
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Affiliation(s)
| | | | | | - Wade Clapp
- Indiana University, Indianapolis, Indiana
| | - Rosalie Ferner
- Guy's Hospital and St. Thomas' Hospital, London, United Kingdom
| | | | | | - David H Gutmann
- Washington University School of Medicine, St. Louis, Missouri
| | | | | | - Eric Legius
- Center for Human Genetics-University Hospital, Leuven, Belgium
| | - Alison C Lloyd
- MRC Laboratory for Molecular Cell Biology, University College, London, United Kingdom
| | - Roger J Packer
- Children's National Medical Center, Washington, District of Columbia
| | | | | | | | - Nicole J Ullrich
- Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Meena Upadhyaya
- Institute of Cancer Genetics, Cardiff University, Wales, United Kingdom
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9
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Bassiri K, Ferluga S, Sharma V, Syed N, Adams CL, Lasonder E, Hanemann CO. Global Proteome and Phospho-proteome Analysis of Merlin-deficient Meningioma and Schwannoma Identifies PDLIM2 as a Novel Therapeutic Target. EBioMedicine 2017; 16:76-86. [PMID: 28126595 PMCID: PMC5474504 DOI: 10.1016/j.ebiom.2017.01.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 01/13/2017] [Accepted: 01/13/2017] [Indexed: 12/20/2022] Open
Abstract
Loss or mutation of the tumour suppressor Merlin predisposes individuals to develop multiple nervous system tumours, including schwannomas and meningiomas, sporadically or as part of the autosomal dominant inherited condition Neurofibromatosis 2 (NF2). These tumours display largely low grade features but their presence can lead to significant morbidity. Surgery and radiotherapy remain the only treatment options despite years of research, therefore an effective therapeutic is required. Unbiased omics studies have become pivotal in the identification of differentially expressed genes and proteins that may act as drug targets or biomarkers. Here we analysed the proteome and phospho-proteome of these genetically defined tumours using primary human tumour cells to identify upregulated/activated proteins and/or pathways. We identified over 2000 proteins in comparative experiments between Merlin-deficient schwannoma and meningioma compared to human Schwann and meningeal cells respectively. Using functional enrichment analysis we highlighted several dysregulated pathways and Gene Ontology terms. We identified several proteins and phospho-proteins that are more highly expressed in tumours compared to controls. Among proteins jointly dysregulated in both tumours we focused in particular on PDZ and LIM domain protein 2 (PDLIM2) and validated its overexpression in several tumour samples, while not detecting it in normal cells. We showed that shRNA mediated knockdown of PDLIM2 in both primary meningioma and schwannoma leads to significant reductions in cellular proliferation. To our knowledge, this is the first comprehensive assessment of the NF2-related meningioma and schwannoma proteome and phospho-proteome. Taken together, our data highlight several commonly deregulated factors, and indicate that PDLIM2 may represent a novel, common target for meningioma and schwannoma. Proteome and phosphoproteome of Merlin-deficient schwannomas and meningiomas were analysed. Comparative studies highlighted several pathways relevant for therapeutic intervention. PDLIM2 was identified as a novel, commonly upregulated protein in both tumours. PDLIM2 knockdown led to a significant reduction in proliferation in both cell types.
Loss or mutation of the protein Merlin causes a genetic condition known as Neurofibromatosis 2 (NF2) characterised by the growth of schwannomas and meningiomas. We analysed several of these tumour samples and identified over 2000 proteins in comparative experiments between Merlin-deficient schwannoma and meningioma compared to normal controls. We identified PDZ and LIM domain protein 2 (PDLIM2) as overexpressed in both tumour types and further showed that knockdown of PDLIM2 leads to significant reductions in cellular proliferation. Taken together, our data highlight several deregulated signalling pathways, and indicate that PDLIM2 may represent a novel, common target for meningioma and schwannoma.
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Affiliation(s)
- Kayleigh Bassiri
- Institute of Translational and Stratified Medicine, Plymouth University Peninsula Schools of Medicine and Dentistry, John Bull Building, Plymouth Science Park, Research Way, Derriford, Plymouth PL6 8BU, UK
| | - Sara Ferluga
- Institute of Translational and Stratified Medicine, Plymouth University Peninsula Schools of Medicine and Dentistry, John Bull Building, Plymouth Science Park, Research Way, Derriford, Plymouth PL6 8BU, UK
| | - Vikram Sharma
- School of Biomedical and Healthcare Sciences, Plymouth University, Drakes Circus, Plymouth PL4 8AA, UK
| | - Nelofer Syed
- John Fulcher Neuro-oncology Laboratory, Division of Brain Sciences, Faculty of Medicine, Imperial College London, London W6 8RP, UK
| | - Claire L Adams
- Institute of Translational and Stratified Medicine, Plymouth University Peninsula Schools of Medicine and Dentistry, John Bull Building, Plymouth Science Park, Research Way, Derriford, Plymouth PL6 8BU, UK
| | - Edwin Lasonder
- School of Biomedical and Healthcare Sciences, Plymouth University, Drakes Circus, Plymouth PL4 8AA, UK
| | - C Oliver Hanemann
- Institute of Translational and Stratified Medicine, Plymouth University Peninsula Schools of Medicine and Dentistry, John Bull Building, Plymouth Science Park, Research Way, Derriford, Plymouth PL6 8BU, UK.
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10
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Castelnovo LF, Bonalume V, Melfi S, Ballabio M, Colleoni D, Magnaghi V. Schwann cell development, maturation and regeneration: a focus on classic and emerging intracellular signaling pathways. Neural Regen Res 2017; 12:1013-1023. [PMID: 28852375 PMCID: PMC5558472 DOI: 10.4103/1673-5374.211172] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The development, maturation and regeneration of Schwann cells (SCs), the main glial cells of the peripheral nervous system, require the coordinate and complementary interaction among several factors, signals and intracellular pathways. These regulatory molecules consist of integrins, neuregulins, growth factors, hormones, neurotransmitters, as well as entire intracellular pathways including protein-kinase A, C, Akt, Erk/MAPK, Hippo, mTOR, etc. For instance, Hippo pathway is overall involved in proliferation, apoptosis, regeneration and organ size control, being crucial in cancer proliferation process. In SCs, Hippo is linked to merlin and YAP/TAZ signaling and it seems to respond to mechanic/physical challenges. Recently, among factors regulating SCs, also the signaling intermediates Src tyrosine kinase and focal adhesion kinase (FAK) proved relevant for SC fate, participating in the regulation of adhesion, motility, migration and in vitro myelination. In SCs, the factors Src and FAK are regulated by the neuroactive steroid allopregnanolone, thus corroborating the importance of this steroid in the control of SC maturation. In this review, we illustrate some old and novel signaling pathways modulating SC biology and functions during the different developmental, mature and regenerative states.
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Affiliation(s)
- Luca Franco Castelnovo
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Veronica Bonalume
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Simona Melfi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Marinella Ballabio
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Deborah Colleoni
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Valerio Magnaghi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
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11
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Sang Y, Yan F, Ren X. The role and mechanism of CRL4 E3 ubiquitin ligase in cancer and its potential therapy implications. Oncotarget 2016; 6:42590-602. [PMID: 26460955 PMCID: PMC4767455 DOI: 10.18632/oncotarget.6052] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 09/23/2015] [Indexed: 12/21/2022] Open
Abstract
CRLs (Cullin-RING E3 ubiquitin ligases) are the largest E3 ligase family in eukaryotes, which ubiquitinate a wide range of substrates involved in cell cycle regulation, signal transduction, transcriptional regulation, DNA damage response, genomic integrity, tumor suppression and embryonic development. CRL4 E3 ubiquitin ligase, as one member of CRLs family, consists of a RING finger domain protein, cullin4 (CUL4) scaffold protein and DDB1–CUL4 associated substrate receptors. The CUL4 subfamily includes two members, CUL4A and CUL4B, which share extensively sequence identity and functional redundancy. Aberrant expression of CUL4 has been found in a majority of tumors. Given the significance of CUL4 in cancer, understanding its detailed aspects of pathogenesis of human malignancy would have significant value for the treatment of cancer. Here, the work provides an overview to address the role of CRL4 E3 ubiquitin ligase in cancer development and progression, and discuss the possible mechanisms of CRL4 ligase involving in many cellular processes associated with tumor. Finally, we discuss its potential value in cancer therapy.
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Affiliation(s)
- Youzhou Sang
- Department of Immunology, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China.,National Clinical Research Center of Cancer, Tianjin, China.,Key Laboratory of Cancer Immunology and Biotherapy, Tianjin, China
| | - Fan Yan
- Department of Immunology, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China.,National Clinical Research Center of Cancer, Tianjin, China.,Key Laboratory of Cancer Immunology and Biotherapy, Tianjin, China
| | - Xiubao Ren
- Department of Biotherapy, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China.,National Clinical Research Center of Cancer, Tianjin, China.,Key Laboratory of Cancer Immunology and Biotherapy, Tianjin, China
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12
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Tumor Biology of Vestibular Schwannoma: A Review of Experimental Data on the Determinants of Tumor Genesis and Growth Characteristics. Otol Neurotol 2016; 36:1128-36. [PMID: 26049313 DOI: 10.1097/mao.0000000000000788] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
OBJECTIVE Provide an overview of the literature on vestibular schwannoma biology with special attention to tumor behavior and targeted therapy. BACKGROUND Vestibular schwannomas are benign tumors originating from the eighth cranial nerve and arise due to inactivation of the NF2 gene and its product merlin. Unraveling the biology of these tumors helps to clarify their growth pattern and is essential in identifying therapeutic targets. METHODS PubMed search for English-language articles on vestibular schwannoma biology from 1994 to 2014. RESULTS Activation of merlin and its role in cell signaling seem as key aspects of vestibular schwannoma biology. Merlin is regulated by proteins such as CD44, Rac, and myosin phosphatase-targeting subunit 1. The tumor-suppressive functions of merlin are related to receptor tyrosine kinases, such as the platelet-derived growth factor receptor and vascular endothelial growth factor receptor. Merlin mediates the Hippo pathway and acts within the nucleus by binding E3 ubiquiting ligase CRL4. Angiogenesis is an important mechanism responsible for the progression of these tumors and is affected by processes such as hypoxia and inflammation. Inhibiting angiogenesis by targeting vascular endothelial growth factor receptor seems to be the most successful pharmacologic strategy, but additional therapeutic options are emerging. CONCLUSION Over the years, the knowledge on vestibular schwannoma biology has significantly increased. Future research should focus on identifying new therapeutic targets by investigating vestibular schwannoma (epi)genetics, merlin function, and tumor behavior. Besides identifying novel targets, testing new combinations of existing treatment strategies can further improve vestibular schwannoma therapy.
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Toren A, Reichardt JK, Andalibi A, Hsu NYH, Doherty J, Slattery W, Mehrian-Shai R. Novel age-dependent targets in vestibular schwannomas. Hum Genomics 2014; 8:10. [PMID: 24980480 PMCID: PMC4097955 DOI: 10.1186/1479-7364-8-10] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 06/15/2014] [Indexed: 11/10/2022] Open
Abstract
Background Schwannomas are the most common neurofibromatosis type 2 (NF2)-associated tumors with significant phenotypic heterogeneity in patients. The most severe subtype has an early and rapid progression and the mild type has a later onset and a less aggressive course. The aim of this study was to elucidate the underlying molecular differences between these groups. We compared the gene expression pattern between patients with early to late age of onset. Results A gene signature of 21 genes was constructed to differentiate between early-onset and late-onset patients. We confirmed these results by real-time PCR for SNF1LK2, NGFRAP1L1 (BEX 5), GMNN, and EPHA2. Conclusion Genes identified here may be additional aberrations in merlin-depleted cells that govern the disease onset. A significant number of these genes have been suggested as having a role in carcinogenesis and are used as biomarkers for prognosis in several other cancers. The role of these genes in NF2 carcinogenesis and their potential as biomarkers or drug target are worthwhile exploring.
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Affiliation(s)
| | | | | | | | | | | | - Ruty Mehrian-Shai
- Institute for Genetic Medicine, University of Southern California, Keck School of Medicine, Los Angeles, CA 90089, USA.
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Wang ZQ, Keita M, Bachvarova M, Gobeil S, Morin C, Plante M, Gregoire J, Renaud MC, Sebastianelli A, Trinh XB, Bachvarov D. Inhibition of RUNX2 transcriptional activity blocks the proliferation, migration and invasion of epithelial ovarian carcinoma cells. PLoS One 2013; 8:e74384. [PMID: 24124450 PMCID: PMC3790792 DOI: 10.1371/journal.pone.0074384] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 07/31/2013] [Indexed: 01/19/2023] Open
Abstract
Previously, we have identified the RUNX2 gene as hypomethylated and overexpressed in post-chemotherapy (CT) primary cultures derived from serous epithelial ovarian cancer (EOC) patients, when compared to primary cultures derived from matched primary (prior to CT) tumors. However, we found no differences in the RUNX2 methylation in primary EOC tumors and EOC omental metastases, suggesting that DNA methylation-based epigenetic mechanisms have no impact on RUNX2 expression in advanced (metastatic) stage of the disease. Moreover, RUNX2 displayed significantly higher expression not only in metastatic tissue, but also in high-grade primary tumors and even in low malignant potential tumors. Knockdown of the RUNX2 expression in EOC cells led to a sharp decrease of cell proliferation and significantly inhibited EOC cell migration and invasion. Gene expression profiling and consecutive network and pathway analyses confirmed these findings, as various genes and pathways known previously to be implicated in ovarian tumorigenesis, including EOC tumor invasion and metastasis, were found to be downregulated upon RUNX2 suppression, while a number of pro-apoptotic genes and some EOC tumor suppressor genes were induced. Taken together, our data are indicative for a strong oncogenic potential of the RUNX2 gene in serous EOC progression and suggest that RUNX2 might be a novel EOC therapeutic target. Further studies are needed to more completely elucidate the functional implications of RUNX2 and other members of the RUNX gene family in ovarian tumorigenesis.
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Affiliation(s)
- Zhi-Qiang Wang
- Department of Molecular Medicine, Laval University, Québec (Québec), Canada
- Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec (Québec), Canada
| | - Mamadou Keita
- Department of Molecular Medicine, Laval University, Québec (Québec), Canada
- Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec (Québec), Canada
| | - Magdalena Bachvarova
- Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec (Québec), Canada
| | - Stephane Gobeil
- Department of Molecular Medicine, Laval University, Québec (Québec), Canada
- Centre de recherche du CHU de Québec, CHUL, Québec (Québec), Canada
| | - Chantale Morin
- Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec (Québec), Canada
| | - Marie Plante
- Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec (Québec), Canada
- Department of Obstetrics and Gynecology, Laval University, Québec (Québec), Canada
| | - Jean Gregoire
- Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec (Québec), Canada
- Department of Obstetrics and Gynecology, Laval University, Québec (Québec), Canada
| | - Marie-Claude Renaud
- Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec (Québec), Canada
- Department of Obstetrics and Gynecology, Laval University, Québec (Québec), Canada
| | - Alexandra Sebastianelli
- Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec (Québec), Canada
- Department of Obstetrics and Gynecology, Laval University, Québec (Québec), Canada
| | - Xuan Bich Trinh
- Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec (Québec), Canada
- Department of Gynecological Oncology, Antwerp University Hospital, Antwerp, Belgium
| | - Dimcho Bachvarov
- Department of Molecular Medicine, Laval University, Québec (Québec), Canada
- Centre de recherche du CHU de Québec, L'Hôtel-Dieu de Québec, Québec (Québec), Canada
- * E-mail:
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Morrow KA, Shevde LA. Merlin: the wizard requires protein stability to function as a tumor suppressor. Biochim Biophys Acta Rev Cancer 2012; 1826:400-6. [PMID: 22750751 DOI: 10.1016/j.bbcan.2012.06.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 06/18/2012] [Accepted: 06/20/2012] [Indexed: 11/27/2022]
Abstract
Neurofibromatosis type 2 (NF2), characterized by tumors of the nervous system, is a result of functional loss of the NF2 gene. The NF2 gene encodes Merlin (moesin-ezrin-radixin-like protein), an ERM (Ezrin, Radixin, Moesin) protein family member. Merlin functions as a tumor suppressor through impacting mechanisms related to proliferation, apoptosis, survival, motility, adhesion, and invasion. Several studies have summarized the tumor intrinsic mutations in Merlin. Given the fact that tumor cells are not in isolation, but rather in an intricate, mutually sustaining synergy with their surrounding stroma, the dialog between the tumor cells and the stroma can potentially impact the molecular homeostasis and promote evolution of the malignant phenotype. This review summarizes the epigenetic modifications, transcript stability, and post-translational modifications that impact Merlin. We have reviewed the role of extrinsic factors originating from the tumor milieu that influence the availability of Merlin inside the cell. Information regarding Merlin regulation could lead to novel therapeutics by stabilizing Merlin protein in tumors that have reduced Merlin protein expression without displaying any NF2 genetic alterations.
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Affiliation(s)
- K Adam Morrow
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
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Zhou L, Hanemann CO. Merlin, a multi-suppressor from cell membrane to the nucleus. FEBS Lett 2012; 586:1403-8. [PMID: 22595235 DOI: 10.1016/j.febslet.2012.03.016] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 03/12/2012] [Accepted: 03/13/2012] [Indexed: 01/07/2023]
Abstract
Recent evidence suggests that the neurofibromatosis type 2 (NF2) gene encoded protein merlin suppresses mitogenic signalling not only at the cell membrane but also in the nucleus. At the membrane, merlin inhibits signalling by integrins and tyrosine receptor kinases (RTKs) and the activation of downstream pathways, including the Ras/Raf/MEK/ERK, FAK/Src, PI3K/AKT, Rac/PAK/JNK, mTORC1, and Wnt/β-catenin pathways. In the nucleus, merlin suppresses the E3 ubiquitin ligase CRL4(DCAF1) to inhibit proliferation. Gene expression analysis suggested that CRL4(DCAF1) could also regulate the expression of integrins and RTKs. In this review, we explore the links between merlin function at the membrane and in the nucleus, and discuss the potential of targeting the master regulator CRL4 (DCAF1) to treat NF2 and other merlin-deficient tumours.
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Affiliation(s)
- Lu Zhou
- Clinical Neurobiology, Peninsula College of Medicine and Dentistry, University of Plymouth, Plymouth, UK
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James MF, Stivison E, Beauchamp R, Han S, Li H, Wallace MR, Gusella JF, Stemmer-Rachamimov AO, Ramesh V. Regulation of mTOR complex 2 signaling in neurofibromatosis 2-deficient target cell types. Mol Cancer Res 2012; 10:649-59. [PMID: 22426462 DOI: 10.1158/1541-7786.mcr-11-0425-t] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Inactivating mutations in the neurofibromatosis 2 (NF2) tumor suppressor gene results in the development of schwannomas and meningiomas. Using NF2-deficient meningioma cells and tumors, together with the normal cellular counterparts that meningiomas derive, arachnoid cells, we identified merlin as a novel negative regulator of mTOR complex 1 (mTORC1). We now show that merlin positively regulates the kinase activity of mTORC2, a second functionally distinct mTOR complex, and that downstream phosphorylation of mTORC2 substrates, including Akt, is reduced upon acute merlin deficiency in cells. In response to general growth factor stimulation, Akt signaling is attenuated in merlin RNA interference-suppressed human arachnoid and Schwann cells by mechanisms mediated by hyperactive mTORC1 and impaired mTORC2. Moreover, Akt signaling is impaired differentially in a cell type-dependent manner in response to distinct growth factor stimuli. However, contrary to activation of mTORC1, the attenuated mTORC2 signaling profiles exhibited by normal arachnoid and Schwann cells in response to acute merlin loss were not consistently reflected in NF2-deficient meningiomas and schwannomas, suggesting additional genetic events may have been acquired in tumors after initial merlin loss. This finding contrasts with another benign tumor disorder, tuberous sclerosis complex, which exhibits attenuated mTORC2 signaling profiles in both cells and tumors. Finally, we examined rapamycin, as well as the mTOR kinase inhibitor, Torin1, targeting both mTOR complexes to identify the most efficacious class of compounds for blocking mTOR-mediated signaling and proliferation in merlin-deficient meningioma cells. These studies may ultimately aid in the development of suitable therapeutics for NF2-associated tumors.
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Affiliation(s)
- Marianne F James
- Center for Human Genetic Research, Massachusetts General Hospital, Richard B. Simches Research Building, 185 Cambridge Street, Boston, MA 02114, USA
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