1
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Yang H, Li M, Deng Y, Wen H, Luo M, Zhang W. Roles and interactions of tumor microenvironment components in medulloblastoma with implications for novel therapeutics. Genes Chromosomes Cancer 2024; 63:e23233. [PMID: 38607297 DOI: 10.1002/gcc.23233] [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: 03/08/2024] [Accepted: 03/16/2024] [Indexed: 04/13/2024] Open
Abstract
Medulloblastomas, the most common malignant pediatric brain tumors, can be classified into the wingless, sonic hedgehog (SHH), group 3, and group 4 subgroups. Among them, the SHH subgroup with the TP53 mutation and group 3 generally present with the worst patient outcomes due to their high rates of recurrence and metastasis. A novel and effective treatment for refractory medulloblastomas is urgently needed. To date, the tumor microenvironment (TME) has been shown to influence tumor growth, recurrence, and metastasis through immunosuppression, angiogenesis, and chronic inflammation. Treatments targeting TME components have emerged as promising approaches to the treatment of solid tumors. In this review, we summarize progress in research on medulloblastoma microenvironment components and their interactions. We also discuss challenges and future research directions for TME-targeting medulloblastoma therapy.
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Affiliation(s)
- Hanjie Yang
- Department of Pediatric Neurosurgery, Neurosurgery Center, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Min Li
- Department of Pediatric Neurosurgery, Neurosurgery Center, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Yuhao Deng
- Department of Pediatric Neurosurgery, Neurosurgery Center, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Huantao Wen
- Department of Pediatric Neurosurgery, Neurosurgery Center, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Minjie Luo
- Department of Pediatric Neurosurgery, Neurosurgery Center, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Wangming Zhang
- Department of Pediatric Neurosurgery, Neurosurgery Center, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Zhujiang Hospital, Southern Medical University, Guangzhou, China
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2
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Pokrajac NT, Tokarew NJA, Gurdita A, Ortin-Martinez A, Wallace VA. Meningeal macrophages inhibit chemokine signaling in pre-tumor cells to suppress mouse medulloblastoma initiation. Dev Cell 2023; 58:2015-2031.e8. [PMID: 37774709 DOI: 10.1016/j.devcel.2023.08.033] [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: 03/10/2023] [Revised: 07/10/2023] [Accepted: 08/30/2023] [Indexed: 10/01/2023]
Abstract
The microenvironment profoundly influences tumor initiation across numerous tissues but remains understudied in brain tumors. In the cerebellum, canonical Wnt signaling controlled by Norrin/Frizzled4 (Fzd4) activation in meningeal endothelial cells is a potent inhibitor of preneoplasia and tumor progression in mouse models of Sonic hedgehog medulloblastoma (Shh-MB). Single-cell transcriptome profiling and phenotyping of the meninges indicate that Norrin/Frizzled4 sustains the activation of meningeal macrophages (mMΦs), characterized by Lyve1 and CXCL4 expression, during the critical preneoplastic period. Depleting mMΦs during this period enhances preneoplasia and tumorigenesis, phenocopying the effects of Norrin loss. The anti-tumorigenic function of mMΦs is derived from the expression of CXCL4, which counters CXCL12/CXCR4 signaling in pre-tumor cells, thereby inhibiting cell-cycle progression and promoting migration away from the pre-tumor niche. These findings identify a pivotal role for mMΦs as key mediators in chemokine-regulated anti-cancer crosstalk between the stroma and pre-tumor cells in the control of MB initiation.
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Affiliation(s)
- Nenad T Pokrajac
- Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, ON M5T 2S8, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Nicholas J A Tokarew
- Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, ON M5T 2S8, Canada
| | - Akshay Gurdita
- Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, ON M5T 2S8, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Arturo Ortin-Martinez
- Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, ON M5T 2S8, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Valerie A Wallace
- Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, ON M5T 2S8, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON M5T 3A9, Canada.
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3
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Molina-Arocho W, Haldar M. How meningeal macrophages control medulloblastoma induction. Dev Cell 2023; 58:2011-2012. [PMID: 37875069 DOI: 10.1016/j.devcel.2023.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Revised: 09/19/2023] [Accepted: 09/20/2023] [Indexed: 10/26/2023]
Abstract
In this issue of Developmental Cell, Pokrajac et al. report that Wnt signaling in endothelial cells maintain CXCL4 expression in meningeal macrophages, which suppresses induction of Sonic hedgehog medulloblastoma by antagonizing the pro-tumor effects of CXCL12. This work highlights how homeostatic tissue macrophages can regulate early stages of tumor induction.
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Affiliation(s)
- William Molina-Arocho
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Malay Haldar
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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4
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Wälchli T, Bisschop J, Carmeliet P, Zadeh G, Monnier PP, De Bock K, Radovanovic I. Shaping the brain vasculature in development and disease in the single-cell era. Nat Rev Neurosci 2023; 24:271-298. [PMID: 36941369 PMCID: PMC10026800 DOI: 10.1038/s41583-023-00684-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/06/2023] [Indexed: 03/23/2023]
Abstract
The CNS critically relies on the formation and proper function of its vasculature during development, adult homeostasis and disease. Angiogenesis - the formation of new blood vessels - is highly active during brain development, enters almost complete quiescence in the healthy adult brain and is reactivated in vascular-dependent brain pathologies such as brain vascular malformations and brain tumours. Despite major advances in the understanding of the cellular and molecular mechanisms driving angiogenesis in peripheral tissues, developmental signalling pathways orchestrating angiogenic processes in the healthy and the diseased CNS remain incompletely understood. Molecular signalling pathways of the 'neurovascular link' defining common mechanisms of nerve and vessel wiring have emerged as crucial regulators of peripheral vascular growth, but their relevance for angiogenesis in brain development and disease remains largely unexplored. Here we review the current knowledge of general and CNS-specific mechanisms of angiogenesis during brain development and in brain vascular malformations and brain tumours, including how key molecular signalling pathways are reactivated in vascular-dependent diseases. We also discuss how these topics can be studied in the single-cell multi-omics era.
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Affiliation(s)
- Thomas Wälchli
- Group of CNS Angiogenesis and Neurovascular Link, Neuroscience Center Zurich, and Division of Neurosurgery, University and University Hospital Zurich, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland.
- Division of Neurosurgery, University Hospital Zurich, Zurich, Switzerland.
- Group of Brain Vasculature and Perivascular Niche, Division of Experimental and Translational Neuroscience, Krembil Brain Institute, Krembil Research Institute, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada.
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, Toronto, ON, Canada.
| | - Jeroen Bisschop
- Group of CNS Angiogenesis and Neurovascular Link, Neuroscience Center Zurich, and Division of Neurosurgery, University and University Hospital Zurich, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
- Division of Neurosurgery, University Hospital Zurich, Zurich, Switzerland
- Group of Brain Vasculature and Perivascular Niche, Division of Experimental and Translational Neuroscience, Krembil Brain Institute, Krembil Research Institute, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, Toronto, ON, Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Peter Carmeliet
- Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB & Department of Oncology, KU Leuven, Leuven, Belgium
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, People's Republic of China
- Laboratory of Angiogenesis and Vascular Heterogeneity, Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Gelareh Zadeh
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, Toronto, ON, Canada
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada
| | - Philippe P Monnier
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Donald K. Johnson Research Institute, Krembil Research Institute, Krembil Discovery Tower, Toronto, ON, Canada
- Department of Ophthalmology and Vision Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Katrien De Bock
- Laboratory of Exercise and Health, Department of Health Science and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Ivan Radovanovic
- Group of Brain Vasculature and Perivascular Niche, Division of Experimental and Translational Neuroscience, Krembil Brain Institute, Krembil Research Institute, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON, Canada
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, Toronto, ON, Canada
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5
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Three dimensional reconstruction of the mouse cerebellum in Hedgehog-driven medulloblastoma models to identify Norrin-dependent effects on preneoplasia. Commun Biol 2022; 5:569. [PMID: 35680976 PMCID: PMC9184598 DOI: 10.1038/s42003-022-03507-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 05/19/2022] [Indexed: 11/08/2022] Open
Abstract
AbstractSpontaneous mouse models of medulloblastoma (MB) offer a tractable system to study malignant progression in the brain. Mouse Sonic Hedgehog (Shh)-MB tumours first appear at postnatal stages as preneoplastic changes on the surface of the cerebellum, the external granule layer (EGL). Here we compared traditional histology and 3DISCO tissue clearing in combination with light sheet fluorescence microscopy (LSFM) to identify and quantify preneoplastic changes induced by disrupting stromal Norrin/Frizzled 4 (Fzd4) signalling, a potent tumour inhibitory signal in two mouse models of spontaneous Shh-MB. We show that 3DISCO-LSFM is as accurate as traditional histology for detecting Norrin/Fzd4-associated changes in PNL formation in Ptch+/− mice and EGL hyperplasia in Neurod2-SmoA1+/− mice. Moreover, we show that the anti-tumour effect of Norrin/Fzd4 signalling is restricted to the posterior region of the cerebellum and is characterized by defective neural progenitor migration away from the EGL. In conclusion, 3DISCO-LSFM is a valid way to monitor tumour initiation events in mouse MB models and reveals an unanticipated regional restriction of stromal signalling in constraining tumour initiation.
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6
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Landry AP, Samuel N, Spears J, Zador Z. Integrated computational analyses reveal novel insights into the stromal microenvironment of SHH-subtype medulloblastoma. Sci Rep 2021; 11:20694. [PMID: 34667228 PMCID: PMC8526813 DOI: 10.1038/s41598-021-00244-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 10/07/2021] [Indexed: 12/16/2022] Open
Abstract
Medulloblastoma is the most common malignant brain tumour of childhood. While our understanding of this disease has progressed substantially in recent years, the role of tumour microenvironment remains unclear. Given the increasing role of microenvironment-targeted therapeutics in other cancers, this study was aimed at further exploring its role in medulloblastoma. Multiple computational techniques were used to analyze open-source bulk and single cell RNA seq data from primary samples derived from all subgroups of medulloblastoma. Gene expression is used to infer stromal subpopulations, and network-based approaches are used to identify potential therapeutic targets. Bulk data was obtained from 763 medulloblastoma samples and single cell data from an additional 7241 cells from 23 tumours. Independent bulk (285 tumours) and single cell (32,868 cells from 29 tumours) validation cohorts were used to verify results. The SHH subgroup was found to be enriched in stromal activity, including the epithelial-to-mesenchymal transition, while group 3 is comparatively stroma-suppressed. Several receptor and ligand candidates underlying this difference are identified which we find to correlate with metastatic potential of SHH medulloblastoma. Additionally, a biologically active gradient is detected within SHH medulloblastoma, from "stroma-active" to "stroma-suppressed" cells which may have relevance to targeted therapy. This study serves to further elucidate the role of the stromal microenvironment in SHH-subgroup medulloblastoma and identify novel treatment possibilities for this challenging disease.
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Affiliation(s)
- Alexander P Landry
- Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, ON, Canada.
| | - Nardin Samuel
- Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, ON, Canada
| | - Julian Spears
- Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, ON, Canada
| | - Zsolt Zador
- Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, ON, Canada.
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7
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Wei X, Meel MH, Breur M, Bugiani M, Hulleman E, Phoenix TN. Defining tumor-associated vascular heterogeneity in pediatric high-grade and diffuse midline gliomas. Acta Neuropathol Commun 2021; 9:142. [PMID: 34425907 PMCID: PMC8381557 DOI: 10.1186/s40478-021-01243-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 08/10/2021] [Indexed: 12/23/2022] Open
Abstract
The blood–brain barrier (BBB) plays important roles in brain tumor pathogenesis and treatment response, yet our understanding of its function and heterogeneity within or across brain tumor types remains poorly characterized. Here we analyze the neurovascular unit (NVU) of pediatric high-grade glioma (pHGG) and diffuse midline glioma (DMG) using patient derived xenografts and natively forming glioma mouse models. We show tumor-associated vascular differences between these glioma subtypes, and parallels between PDX and mouse model systems, with DMG models maintaining a more normal vascular architecture, BBB function and endothelial transcriptional program relative to pHGG models. Unlike prior work in angiogenic brain tumors, we find that expression of secreted Wnt antagonists do not alter the tumor-associated vascular phenotype in DMG tumor models. Together, these findings highlight vascular heterogeneity between pHGG and DMG and differences in their response to alterations in developmental BBB signals that may participate in driving these pathological differences.
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8
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Goodwin LR, Zapata G, Timpano S, Marenger J, Picketts DJ. Impaired SNF2L Chromatin Remodeling Prolongs Accessibility at Promoters Enriched for Fos/Jun Binding Sites and Delays Granule Neuron Differentiation. Front Mol Neurosci 2021; 14:680280. [PMID: 34295220 PMCID: PMC8290069 DOI: 10.3389/fnmol.2021.680280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 06/10/2021] [Indexed: 11/13/2022] Open
Abstract
Chromatin remodeling proteins utilize the energy from ATP hydrolysis to mobilize nucleosomes often creating accessibility for transcription factors within gene regulatory elements. Aberrant chromatin remodeling has diverse effects on neuroprogenitor homeostasis altering progenitor competence, proliferation, survival, or cell fate. Previous work has shown that inactivation of the ISWI genes, Smarca5 (encoding Snf2h) and Smarca1 (encoding Snf2l) have dramatic effects on brain development. Smarca5 conditional knockout mice have reduced progenitor expansion and severe forebrain hypoplasia, with a similar effect on the postnatal growth of the cerebellum. In contrast, Smarca1 mutants exhibited enlarged forebrains with delayed progenitor differentiation and increased neuronal output. Here, we utilized cerebellar granule neuron precursor (GNP) cultures from Smarca1 mutant mice (Ex6DEL) to explore the requirement for Snf2l on progenitor homeostasis. The Ex6DEL GNPs showed delayed differentiation upon plating that was not attributed to changes in the Sonic Hedgehog pathway but was associated with overexpression of numerous positive effectors of proliferation, including targets of Wnt activation. Transcriptome analysis identified increased expression of Fosb and Fosl2 while ATACseq experiments identified a large increase in chromatin accessibility at promoters many enriched for Fos/Jun binding sites. Nonetheless, the elevated proliferation index was transient and the Ex6DEL cultures initiated differentiation with a high concordance in gene expression changes to the wild type cultures. Genes specific to Ex6DEL differentiation were associated with an increased activation of the ERK signaling pathway. Taken together, this data provides the first indication of how Smarca1 mutations alter progenitor cell homeostasis and contribute to changes in brain size.
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Affiliation(s)
- Laura R Goodwin
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.,Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
| | - Gerardo Zapata
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.,Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
| | - Sara Timpano
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Jacob Marenger
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - David J Picketts
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.,Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada.,Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
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9
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Shiraishi R, Kawauchi D. Epigenetic regulation in medulloblastoma pathogenesis revealed by genetically engineered mouse models. Cancer Sci 2021; 112:2948-2957. [PMID: 34050694 PMCID: PMC8353939 DOI: 10.1111/cas.14990] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/16/2021] [Accepted: 05/18/2021] [Indexed: 12/11/2022] Open
Abstract
Medulloblastoma is the most common malignant cerebellar tumor in children. Recent technological advances in multilayered ’omics data analysis have revealed 4 molecular subgroups of medulloblastoma (Wingless/int, Sonic hedgehog, Group3, and Group4). (Epi)genomic and transcriptomic profiling on human primary medulloblastomas has shown distinct oncogenic drivers and cellular origin(s) across the subgroups. Despite tremendous efforts to identify the molecular signals driving tumorigenesis, few of the identified targets were druggable; therefore, a further understanding of the etiology of tumors is required to establish effective molecular‐targeted therapies. Chromatin regulators are frequently mutated in medulloblastoma, prompting us to investigate epigenetic changes and the accompanying activation of oncogenic signaling during tumorigenesis. For this purpose, we have used germline and non‐germline genetically engineered mice to model human medulloblastoma and to conduct useful, molecularly targeted, preclinical studies. This review discusses the biological implications of chromatin regulator mutations during medulloblastoma pathogenesis, based on recent in vivo animal studies.
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Affiliation(s)
- Ryo Shiraishi
- Department of Biochemistry and Cellular Biology, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan.,Department of NCNP Brain Physiology and Pathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Daisuke Kawauchi
- Department of Biochemistry and Cellular Biology, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
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10
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El-Sehemy A, Selvadurai H, Ortin-Martinez A, Pokrajac N, Mamatjan Y, Tachibana N, Rowland K, Lee L, Park N, Aldape K, Dirks P, Wallace VA. Norrin mediates tumor-promoting and -suppressive effects in glioblastoma via Notch and Wnt. J Clin Invest 2021; 130:3069-3086. [PMID: 32182224 DOI: 10.1172/jci128994] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 03/05/2020] [Indexed: 12/28/2022] Open
Abstract
Glioblastoma multiforme (GBM) contains a subpopulation of cells, GBM stem cells (GSCs), that maintain the bulk tumor and represent a key therapeutic target. Norrin is a Wnt ligand that binds Frizzled class receptor 4 (FZD4) to activate canonical Wnt signaling. Although Norrin, encoded by NDP, has a well-described role in vascular development, its function in human tumorigenesis is largely unexplored. Here, we show that NDP expression is enriched in neurological cancers, including GBM, and its levels positively correlated with survival in a GBM subtype defined by low expression of ASCL1, a proneural factor. We investigated the function of Norrin and FZD4 in GSCs and found that it mediated opposing tumor-suppressive and -promoting effects on ASCL1lo and ASCL1hi GSCs. Consistent with a potential tumor-suppressive effect of Norrin suggested by the tumor outcome data, we found that Norrin signaling through FZD4 inhibited growth in ASCL1lo GSCs. In contrast, in ASCL1hi GSCs Norrin promoted Notch signaling, independently of WNT, to promote tumor progression. Forced ASCL1 expression reversed the tumor-suppressive effects of Norrin in ASCL1lo GSCs. Our results identify Norrin as a modulator of human brain cancer progression and reveal an unanticipated Notch-mediated function of Norrin in regulating cancer stem cell biology. This study identifies an unanticipated role of Norrin in human brain cancer progression. In addition, we provide preclinical evidence suggesting Norrin and canonical Wnt signaling as potential therapeutic targets for GBM subtype-restricted cancer stem cells.
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Affiliation(s)
- Ahmed El-Sehemy
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.,Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Canada.,Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada
| | - Hayden Selvadurai
- Developmental and Stem Cell Biology Program and.,Arthur and Sonia Labatt Brain Tumour Research Centre, Hospital for Sick Children, Toronto, Canada
| | - Arturo Ortin-Martinez
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.,Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Canada.,Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada
| | - Neno Pokrajac
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.,Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Canada.,Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada
| | - Yasin Mamatjan
- MacFeeters Hamilton Centre for Neuro-Oncology Research, Princess Margaret Cancer Centre, Toronto, Canada
| | - Nobuhiko Tachibana
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.,Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Canada.,Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada
| | - Katherine Rowland
- Developmental and Stem Cell Biology Program and.,Arthur and Sonia Labatt Brain Tumour Research Centre, Hospital for Sick Children, Toronto, Canada
| | - Lilian Lee
- Developmental and Stem Cell Biology Program and.,Arthur and Sonia Labatt Brain Tumour Research Centre, Hospital for Sick Children, Toronto, Canada
| | - Nicole Park
- Developmental and Stem Cell Biology Program and.,Arthur and Sonia Labatt Brain Tumour Research Centre, Hospital for Sick Children, Toronto, Canada
| | - Kenneth Aldape
- MacFeeters Hamilton Centre for Neuro-Oncology Research, Princess Margaret Cancer Centre, Toronto, Canada.,Laboratory of Pathology, National Cancer Institute, NIH, Bethesda, Maryland, USA
| | - Peter Dirks
- Developmental and Stem Cell Biology Program and.,Arthur and Sonia Labatt Brain Tumour Research Centre, Hospital for Sick Children, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Division of Neurosurgery, Hospital for Sick Children, Toronto, Canada
| | - Valerie A Wallace
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.,Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Canada.,Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada
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11
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Jiang M, Zhang K, Lv Q, Li L, Fang F. Discovering the role of FZD4 Gene in human cutaneous squamous cell carcinoma. Indian J Dermatol 2021; 66:484-489. [PMID: 35068502 PMCID: PMC8751705 DOI: 10.4103/ijd.ijd_1147_20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Background: Aims: Methods: Results: Conclusion:
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12
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Ruan Y, Ogana H, Gang E, Kim HN, Kim YM. Wnt Signaling in the Tumor Microenvironment. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1270:107-121. [PMID: 33123996 DOI: 10.1007/978-3-030-47189-7_7] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Dysregulated Wnt signaling plays a central role in initiation, progression, and metastasis in many types of human cancers. Cancer development and resistance to conventional cancer therapies are highly associated with the tumor microenvironment (TME), which is composed of numerous stable non-cancer cells, including immune cells, extracellular matrix (ECM), fibroblasts, endothelial cells (ECs), and stromal cells. Recently, increasing evidence suggests that the relationship between Wnt signaling and the TME promotes the proliferation and maintenance of tumor cells, including leukemia. Here, we review the Wnt pathway, the role of Wnt signaling in different components of the TME, and therapeutic strategies for targeting Wnt signaling.
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Affiliation(s)
- Yongsheng Ruan
- Department of Pediatrics, Division of Hematology, Oncology, Blood and Marrow Transplantation, Children's Hospital Los Angeles, University of Southern California, Los Angeles, CA, USA.,Department of Pediatrics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Heather Ogana
- Department of Pediatrics, Division of Hematology, Oncology, Blood and Marrow Transplantation, Children's Hospital Los Angeles, University of Southern California, Los Angeles, CA, USA
| | - Eunji Gang
- Department of Pediatrics, Division of Hematology, Oncology, Blood and Marrow Transplantation, Children's Hospital Los Angeles, University of Southern California, Los Angeles, CA, USA
| | - Hye Na Kim
- Department of Pediatrics, Division of Hematology, Oncology, Blood and Marrow Transplantation, Children's Hospital Los Angeles, University of Southern California, Los Angeles, CA, USA
| | - Yong-Mi Kim
- Department of Pediatrics, Division of Hematology, Oncology, Blood and Marrow Transplantation, Children's Hospital Los Angeles, University of Southern California, Los Angeles, CA, USA.
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13
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Yu L, Kim HJ, Park MK, Byun HJ, Kim EJ, Kim B, Nguyen MT, Kim JH, Kang GJ, Lee H, Kim SY, Rho SB, Lee CH. Ethacrynic acid, a loop diuretic, suppresses epithelial-mesenchymal transition of A549 lung cancer cells via blocking of NDP-induced WNT signaling. Biochem Pharmacol 2020; 183:114339. [PMID: 33189676 DOI: 10.1016/j.bcp.2020.114339] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 11/02/2020] [Accepted: 11/10/2020] [Indexed: 12/20/2022]
Abstract
Lung cancer is one of the leading causes of death in cancer patients. Epithelial-mesenchymal transition (EMT) plays an important role in lung cancer progression. Therefore, for lung cancer treatment, it is crucial to find substances that inhibit EMT. Ethacrynic acid (ECA) is a diuretic that inhibits cellular ion flux and exerts anticancer effects. However, the effects of ECA on EMT in lung cancer remain unclear. We examined the effects of ECA on sphingosylphosphorylcholine (SPC) or TGF-β1-induced EMT process in A549 and H1299 cells via reverse transcription polymerase chain reaction and Western blotting. We found that ECA inhibited SPC-induced EMT and SPC-induced WNT signalling in EMT. We observed that SPC induces the expression of NDP [Norrie disease protein] and WNT-2, whereas ECA suppressed their expression. SPC-induced WNT activation, EMT, migration, and invasion were suppressed by NDP small-interfering RNA (siNDP), but NDP overexpression (pNDP) enhanced these events in A549 and H1299 cells. Accordingly, NDP expression may influence lung cancer prognosis. In summary, our results revealed that ECA inhibited SPC or TGF-β1-induced EMT in A549 and H1299 lung cancer cells by downregulating NDP expression and inhibiting WNT activation. Therefore, ECA might be a new drug candidate for lung cancer treatment.
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Affiliation(s)
- Lu Yu
- College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
| | - Hyun Ji Kim
- College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
| | - Mi Kyung Park
- National Cancer Center, Goyang 10408, Republic of Korea
| | - Hyun Jung Byun
- College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
| | - Eun Ji Kim
- College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
| | - Boram Kim
- College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
| | - Minh Tuan Nguyen
- College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
| | - Ji Hyun Kim
- College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea
| | - Gyeoung Jin Kang
- Lillehei Heart Institute, University of Minnesota, Minneapolis, MN, USA
| | - Ho Lee
- National Cancer Center, Goyang 10408, Republic of Korea
| | - Soo Youl Kim
- National Cancer Center, Goyang 10408, Republic of Korea
| | - Seung Bae Rho
- National Cancer Center, Goyang 10408, Republic of Korea.
| | - Chang Hoon Lee
- College of Pharmacy, Dongguk University, Seoul 100-715, Republic of Korea.
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14
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El-Sehemy A, Wallace VA. NORRIN plays a context-dependent role in glioblastoma stem cells. Mol Cell Oncol 2020; 7:1758540. [PMID: 32944619 PMCID: PMC7469435 DOI: 10.1080/23723556.2020.1758540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We recently reported a novel role of the atypical Wnt ligand, NORRIN, in mediating the proliferation and stemness of glioblastoma stem cells. Mechanistic and functional analysis revealed context-specific phenotypes in which NORRIN can induce opposite effects on the tumor outcome, depending on the underlying molecular signature of the tumor cells.
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Affiliation(s)
- Ahmed El-Sehemy
- Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Valerie A Wallace
- Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.,Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Ontario, Canada
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15
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Díaz-Coránguez M, Lin CM, Liebner S, Antonetti DA. Norrin restores blood-retinal barrier properties after vascular endothelial growth factor-induced permeability. J Biol Chem 2020; 295:4647-4660. [PMID: 32086377 DOI: 10.1074/jbc.ra119.011273] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 02/11/2020] [Indexed: 12/25/2022] Open
Abstract
Vascular endothelial growth factor (VEGF) contributes to blood-retinal barrier (BRB) dysfunction in several blinding eye diseases, including diabetic retinopathy. Signaling via the secreted protein norrin through the frizzled class receptor 4 (FZD4)/LDL receptor-related protein 5-6 (LRP5-6)/tetraspanin 12 (TSPAN12) receptor complex is required for developmental vascularization and BRB formation. Here, we tested the hypothesis that norrin restores BRB properties after VEGF-induced vascular permeability in diabetic rats or in animals intravitreally injected with cytokines. Intravitreal co-injection of norrin with VEGF completely ablated VEGF-induced BRB permeability to Evans Blue-albumin. Likewise, 5-month diabetic rats exhibited increased permeability of FITC-albumin, and a single norrin injection restored BRB properties. These results were corroborated in vitro, where co-stimulation of norrin with VEGF or stimulation of norrin after VEGF exposure restored barrier properties, indicated by electrical resistance or 70-kDa RITC-dextran permeability in primary endothelial cell culture. Interestingly, VEGF promoted norrin signaling by increasing the FZD4 co-receptor TSPAN12 at cell membranes in an MAPK/ERK kinase (MEK)/ERK-dependent manner. Norrin signaling through β-catenin was required for BRB restoration, but glycogen synthase kinase 3 α/β (GSK-3α/β) inhibition did not restore BRB properties. Moreover, levels of the tight junction protein claudin-5 were increased with norrin and VEGF or with VEGF alone, but both norrin and VEGF were required for enriched claudin-5 localization at the tight junction. These results suggest that VEGF simultaneously induces vascular permeability and promotes responsiveness to norrin. Norrin, in turn, restores tight junction complex organization and BRB properties in a β-catenin-dependent manner.
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Affiliation(s)
- Mónica Díaz-Coránguez
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan 48105
| | - Cheng-Mao Lin
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan 48105
| | - Stefan Liebner
- Institute of Neurology (Edinger Institute), University Hospital, Goethe University, 60538 Frankfurt, Germany
| | - David A Antonetti
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan 48105
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16
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Arvanitis CD, Ferraro GB, Jain RK. The blood-brain barrier and blood-tumour barrier in brain tumours and metastases. Nat Rev Cancer 2020; 20:26-41. [PMID: 31601988 PMCID: PMC8246629 DOI: 10.1038/s41568-019-0205-x] [Citation(s) in RCA: 891] [Impact Index Per Article: 222.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/29/2019] [Indexed: 02/06/2023]
Abstract
For a blood-borne cancer therapeutic agent to be effective, it must cross the blood vessel wall to reach cancer cells in adequate quantities, and it must overcome the resistance conferred by the local microenvironment around cancer cells. The brain microenvironment can thwart the effectiveness of drugs against primary brain tumours as well as brain metastases. In this Review, we highlight the cellular and molecular components of the blood-brain barrier (BBB), a specialized neurovascular unit evolved to maintain brain homeostasis. Tumours are known to compromise the integrity of the BBB, resulting in a vasculature known as the blood-tumour barrier (BTB), which is highly heterogeneous and characterized by numerous distinct features, including non-uniform permeability and active efflux of molecules. We discuss the challenges posed by the BBB and BTB for drug delivery, how multiple cell types dictate BBB function and the role of the BTB in disease progression and treatment. Finally, we highlight emerging molecular, cellular and physical strategies to improve drug delivery across the BBB and BTB and discuss their impact on improving conventional as well as emerging treatments, such as immune checkpoint inhibitors and engineered T cells. A deeper understanding of the BBB and BTB through the application of single-cell sequencing and imaging techniques, and the development of biomarkers of BBB integrity along with systems biology approaches, should enable new personalized treatment strategies for primary brain malignancies and brain metastases.
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Affiliation(s)
- Costas D Arvanitis
- School of Mechanical Engineering, Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
| | - Gino B Ferraro
- Edwin L. Steele Laboratories, Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Rakesh K Jain
- Edwin L. Steele Laboratories, Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
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17
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Tamayo-Orrego L, Charron F. Recent advances in SHH medulloblastoma progression: tumor suppressor mechanisms and the tumor microenvironment. F1000Res 2019; 8. [PMID: 31700613 PMCID: PMC6820827 DOI: 10.12688/f1000research.20013.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/23/2019] [Indexed: 12/13/2022] Open
Abstract
Medulloblastoma, the most common of the malignant pediatric brain tumors, is a group of four molecularly and clinically distinct cancers with different cells of origin. One of these medulloblastoma groups displays activation of Sonic hedgehog (SHH) signaling and originates from granule cell precursors of the developing cerebellum. Ongoing basic and clinical research efforts are tailored to discover targeted and safer therapies, which rely on the identification of the basic mechanisms regulating tumor initiation, progression, and metastasis. In SHH medulloblastoma, the mechanisms regulating neural progenitor transformation and progression to advanced tumors have been studied in some detail. The present review discusses recent advances on medulloblastoma progression derived from studies using mouse models of SHH medulloblastoma. We focus on mechanisms that regulate progression from precancerous lesions to medulloblastoma, describing novel roles played by tumor suppressor mechanisms and the tumor microenvironment.
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Affiliation(s)
- Lukas Tamayo-Orrego
- Montreal Clinical Research Institute (IRCM), Montreal, Quebec, Canada.,Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada.,Grupo Neuroaprendizaje, Autonomous University of Manizales, Manizales, Colombia
| | - Frédéric Charron
- Montreal Clinical Research Institute (IRCM), Montreal, Quebec, Canada.,Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada.,Department of Anatomy and Cell Biology, Division of Experimental Medicine, McGill University, Quebec, Canada.,Department of Medicine, University of Montreal, Montreal, Quebec, Canada
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18
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Li D, Tian Y, Hu Y, Qi Y, Tian N, Li S, Hu P, Wu F, Wei Q, Wei Z, Wang S, Yin B, Jiang T, Yuan J, Qiang B, Han W, Peng X. Glioma-associated human endothelial cell-derived extracellular vesicles specifically promote the tumourigenicity of glioma stem cells via CD9. Oncogene 2019; 38:6898-6912. [DOI: 10.1038/s41388-019-0903-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Revised: 10/07/2018] [Accepted: 05/01/2019] [Indexed: 11/09/2022]
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19
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Zhang C, Lai MB, Pedler MG, Johnson V, Adams RH, Petrash JM, Chen Z, Junge HJ. Endothelial Cell-Specific Inactivation of TSPAN12 (Tetraspanin 12) Reveals Pathological Consequences of Barrier Defects in an Otherwise Intact Vasculature. Arterioscler Thromb Vasc Biol 2019; 38:2691-2705. [PMID: 30354230 PMCID: PMC6221394 DOI: 10.1161/atvbaha.118.311689] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Supplemental Digital Content is available in the text. Objective— Blood-CNS (central nervous system) barrier defects are implicated in retinopathies, neurodegenerative diseases, stroke, and epilepsy, yet, the pathological mechanisms downstream of barrier defects remain incompletely understood. Blood-retina barrier (BRB) formation and retinal angiogenesis require β-catenin signaling induced by the ligand norrin (NDP [Norrie disease protein]), the receptor FZD4 (frizzled 4), coreceptor LRP5 (low-density lipoprotein receptor-like protein 5), and the tetraspanin TSPAN12 (tetraspanin 12). Impaired NDP/FZD4 signaling causes familial exudative vitreoretinopathy, which may lead to blindness. This study seeked to define cell type-specific functions of TSPAN12 in the retina. Approach and Results— A loxP-flanked Tspan12 allele was generated and recombined in endothelial cells using a tamoxifen-inducible Cdh5-CreERT2 driver. Resulting phenotypes were documented using confocal microscopy. RNA-Seq, histopathologic analysis, and electroretinogram were performed on retinas of aged mice. We show that TSPAN12 functions in endothelial cells to promote vascular morphogenesis and BRB formation in developing mice and BRB maintenance in adult mice. Early loss of TSPAN12 in endothelial cells causes lack of intraretinal capillaries and increased VE-cadherin (CDH5 [cadherin5 aka VE-cadherin]) expression, consistent with premature vascular quiescence. Late loss of TSPAN12 strongly impairs BRB maintenance without affecting vascular morphogenesis, pericyte coverage, or perfusion. Long-term BRB defects are associated with immunoglobulin extravasation, complement deposition, cystoid edema, and impaired b-wave in electroretinograms. RNA-sequencing reveals transcriptional responses to the perturbation of the BRB, including genes involved in vascular basement membrane alterations in diabetic retinopathy. Conclusions— This study establishes mice with late endothelial cell–specific loss of Tspan12 as a model to study pathological consequences of BRB impairment in an otherwise intact vasculature.
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Affiliation(s)
- Chi Zhang
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder (C.Z., M.B.L., V.J., Z.C., H.J.J.)
| | - Maria B Lai
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder (C.Z., M.B.L., V.J., Z.C., H.J.J.)
| | - Michelle G Pedler
- Department of Ophthalmology, University of Colorado School of Medicine, Aurora (M.G.P., J.M.P.)
| | - Verity Johnson
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder (C.Z., M.B.L., V.J., Z.C., H.J.J.)
| | - Ralf H Adams
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, Faculty of Medicine, University of Münster, Germany (R.H.A.)
| | - J Mark Petrash
- Department of Ophthalmology, University of Colorado School of Medicine, Aurora (M.G.P., J.M.P.)
| | - Zhe Chen
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder (C.Z., M.B.L., V.J., Z.C., H.J.J.)
| | - Harald J Junge
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder (C.Z., M.B.L., V.J., Z.C., H.J.J.)
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20
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Norrin maintains malignancy of gastric cancer cells in part through activating AKT signaling. Biochem Biophys Res Commun 2019; 512:405-411. [DOI: 10.1016/j.bbrc.2019.03.044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 03/07/2019] [Indexed: 01/09/2023]
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21
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Bay SN, Long AB, Caspary T. Disruption of the ciliary GTPase Arl13b suppresses Sonic hedgehog overactivation and inhibits medulloblastoma formation. Proc Natl Acad Sci U S A 2018; 115:1570-1575. [PMID: 29378965 PMCID: PMC5816136 DOI: 10.1073/pnas.1706977115] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Medulloblastoma (MB) is the most common malignant pediatric brain tumor, and overactivation of the Sonic Hedgehog (Shh) signaling pathway, which requires the primary cilium, causes 30% of MBs. Current treatments have known negative side effects or resistance mechanisms, so new treatments are necessary. Shh signaling mutations, like those that remove Patched1 (Ptch1) or activate Smoothened (Smo), cause tumors dependent on the presence of cilia. Genetic ablation of cilia prevents these tumors by removing Gli activator, but cilia are a poor therapeutic target since they support many biological processes. A more appropriate strategy would be to identify a protein that functionally disentangles Gli activation and ciliogenesis. Our mechanistic understanding of the ciliary GTPase Arl13b predicts that it could be such a target. Arl13b mutants retain short cilia, and loss of Arl13b results in ligand-independent, constitutive, low-level pathway activation but prevents maximal signaling without disrupting Gli repressor. Here, we show that deletion of Arl13b reduced Shh signaling levels in the presence of oncogenic SmoA1, suggesting Arl13b acts downstream of known tumor resistance mechanisms. Knockdown of ARL13B in human MB cell lines and in primary mouse MB cell culture decreased proliferation. Importantly, loss of Arl13b in a Ptch1-deleted mouse model of MB inhibited tumor formation. Postnatal depletion of Arl13b does not lead to any overt phenotypes in the epidermis, liver, or cerebellum. Thus, our in vivo and in vitro studies demonstrate that disruption of Arl13b inhibits cilia-dependent oncogenic Shh overactivation.
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Affiliation(s)
- Sarah N Bay
- Department of Human Genetics, Emory University, Atlanta, GA 30322
- Genetics and Molecular Biology Program, Emory University, Atlanta, GA 30322
| | - Alyssa B Long
- Department of Human Genetics, Emory University, Atlanta, GA 30322
| | - Tamara Caspary
- Department of Human Genetics, Emory University, Atlanta, GA 30322;
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22
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Abstract
Many stem cell niches contain support cells that increase contact with stem cells by enwrapping them in cellular processes. One example is the germ stem cell niche in C. elegans, which is composed of a single niche cell termed the distal tip cell (DTC) that extends cellular processes, constructing an elaborate plexus that enwraps germ stem cells. To identify genes required for plexus formation and to explore the function of this specialized enwrapping behavior, a series of targeted and tissue-specific RNAi screens were performed. Here we identify genes that promote stem cell enwrapment by the DTC plexus, including a set that specifically functions within the DTC, such as the chromatin modifier lin-40/MTA1, and others that act within the germline, such as the 14-3-3 signaling protein par-5. Analysis of genes that function within the germline to mediate plexus development reveal that they are required for expansion of the germ progenitor zone, supporting the emerging idea that germ stem cells signal to the niche to stimulate enwrapping behavior. Examination of wild-type animals with asymmetric plexus formation and animals with reduced DTC plexus elaboration via loss of two candidates including lin-40 indicate that cellular enwrapment promotes GLP-1/Notch signaling and germ stem cell fate. Together, our work identifies novel regulators of cellular enwrapment and suggests that reciprocal signaling between the DTC niche and the germ stem cells promotes enwrapment behavior and stem cell fate.
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