Article
Nogo-A and S1PR2 as novel regulators of developmental and tumor angiogenesis in the CNS
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Authors
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Thomas Wälchli
- Group of CNS Angiogenesis and Neurovascular Link, and Physician-Scientist Program, Swiss Center for Regenerative Medicine and Division of Surgical Research, and Neuroscience Center Zurich and Division of Neurosurgery, University and University Hospital Zurich, and Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland; Division of Neurosurgery, University Hospital Zurich, Zurich, Switzerland; Brain Research Institute, University of Zurich and Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
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Martin E. Schwab
- Brain Research Institute, University of Zurich and Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
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Michael Weller
- Division of Neurology and Laboratory of Molecular Neurooncology, University Hospital Zurich, Zurich, Switzerland
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Oliver Bozinov
- Division of Neurosurgery, University Hospital Zurich, Zurich, Switzerland
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Luca Regli
- Division of Neurosurgery, University Hospital Zurich, Zurich, Switzerland
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Simon P. Hoerstrup
- Group of CNS Angiogenesis and Neurovascular Link, and Physician-Scientist Program, Swiss Center for Regenerative Medicine and Division of Surgical Research, and Neuroscience Center Zurich and Division of Neurosurgery, University and University Hospital Zurich, and Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| Published: | June 8, 2016 |
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Outline
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Objective: One hallmark of glioblastoma (GBM) growth is angiogenesis, the growth of blood vessels. Classical approaches to target glioblastoma angiogenesis – for instance using the anti-VEGF-A antibody bevacizumab/Avastin® – have not led to the desired improvement of patient survival. The membrane protein Nogo-A is mainly expressed in the central nervous system (CNS) and has well-known functions as a potent, myelin-derived neurite outgrowth inhibitor and as a regulator of axonal growth in the CNS. Recently, we have identified a new, unexpected function for Nogo-A as a negative regulator of angiogenesis in the developing CNS and the Nogo-A specific receptor in neurons has recently been identified as the Sphingosine 1-Phosphate-Receptor 2 (S1PR2). Therefore, we hypothesize that Nogo-A and S1PR2 may constitute a novel ligand-receptor pair regulating angiogenesis during developmental and tumor angiogenesis in the CNS.
Method: Immunofluorescent stainings and confocal microscopy: 40µm coronal tissue sections of WT-, Nogo-A KO- and S1PR2 KO animals at the age of postnatal day 8 (P8), of glioma (GL261)-bearing adult WT mice as well as of human glioblastoma samples were stained for the endothelial markers Isolectin B4 (IB4), CD31, Endomucin, for the perivascular cell markers PDGFRβ, GFAP, Iba1, and for Nogo-A and S1PR2. Western blot and qRT-PCR: mRNA expression levels of endothelial markers as well as of Nogo-A and S1PR2 were analyzed. Nanopillar arrays and migration assays: Endothelial cells isolated from P8 WT and S1PR2 KO mice as well as from human glioblastoma samples were analyzed for filopodia and lamellipodia retraction and for cell migration.
Results: Nogo-A was expressed in vicinitv of growing blood vessels and endothelial tip cells expressing S1PR2 during mouse and human brain development in vivo. During mouse and human glioblastoma angiogenesis, Nogo-A showed a perivascular expression pattern whereas S1PR2 was expressed on the glioblastoma vasculature. In a mouse glioma model (GL-261), S1PR2 was upregulated within the tumor as compared to the surrounding brain tissue and in vicinity of brain tumor endothelial tip cells. Moreover, Nogo-A inhibited the adhesion, spreading, migration and filopodia- and lamellipodia of human glioblastoma-derived MVECs in vitro. Interestingly, these effects were partially mediated by S1PR2.
Conclusions: In summary, our data support a negative regulatory role for Nogo-A-S1PR2 in mouse and human developmental brain- and glioblastoma angiogenesis.
