Brain Advance Access published online on August 9, 2008
Brain, doi:10.1093/brain/awn182
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VEGF-dependent induction of CD62E on endothelial cells mediates glioma tropism of adult haematopoietic progenitor cells
1Department of General Neurology, Laboratory of Molecular Neurooncology, Hertie Institute for Clinical Brain Research, 2Institute of Brain Research, University of T übingen, T übingen, Germany, 3Institute of Neuropathology, University of Zurich, Switzerland, 4Department of Neurosurgery, Klinikum Großhadern, Ludwig-Maximilians University of Munich, Munich, 5Department of Internal Medicine II (Hematology), University of T übingen, T übingen, Germany, 6Department of Neurology, University of Zurich, Switzerland and 7Clinical Cooperation Unit Neurooncology, German Cancer Research Center, Heidelberg, Germany
Correspondence to:
Ghazaleh Tabatabai, MD, Department of General Neurology, Laboratory of Molecular Neurooncology, Hertie Institute for Clinical Brain Research, University of T übingen, Hoppe-Seyler-Strasse 3, 72076 T übingen, Germany E-mail: ghazaleh.tabatabai{at}uni-tuebingen.de
Haematopoietic progenitor cells (HPC) are attracted by experimental gliomas in vivo. This attraction is further enhanced by irradiation or hypoxic preconditioning of the glioma cells. Adhesive interactions might be critical to the preferential accumulation of HPC within the glioma tissue. Here, we studied the interactions of HPC with endothelial cells. Exposure of human cerebral endothelial cells (SV-HCEC), human microvascular endothelial cells (HMEC) and brain tumour endothelial cells derived from human glioblastomas (BTEC) to supernatants of glioma cells and primary glioma cells (SN-G) induced the expression of E-selectin (CD62E). CD62E expression was further enhanced when the glioma cells had been exposed to irradiation or hypoxia prior to the collection of supernatants, as well as by irradiation or exposure to hypoxia of the endothelial cells. Vascular cell adhesion molecule 1 (VCAM-1) was constitutively expressed on SV-HCEC, HMEC and BTEC, but was not modulated by SN-G, irradiation or hypoxia. Transendothelial HPC migration was enhanced after CD62E induction in vitro. Neutralizing antibodies to CD62E strongly reduced the homing of lin–Sca-1+c-kit+ cells to orthotopic SMA-560 gliomas in vivo. Tissue microarray sampling normal brain tissue and astrocytomas of WHO grades II–IV revealed a selective expression of CD62E on endothelial cells of tumour vessels. SN-G-induced CD62E expression on endothelial cells in vitro required transforming growth factor (TGF)-β signalling in glioma cells and vascular endothelial growth factor (VEGF)/VEGF receptor 2 (VEGF-R2) signalling in endothelial cells. Further, we observed a nuclear factor kappa B-dependent activation of the CD62E promoter peaking at 12 h after VEGF-R2 activation by glioma-derived VEGF. Taken together, we identify glioma cell-induced CD62E expression on endothelial cells as one mediator of the glioma tropism of HPC.
Key Words: brain tumour; haematopoietic progenitor cells; hypoxia; irradiation; vascular endothelial growth factor, CD62E
Abbreviations:
BTEC, brain tumour endothelial cells isolated from human glioblastoma tissue; CD, cluster of differentiation; CD62E, E-selectin; CD62P, platelet selectin; CXCL12, CXC chemokine ligand 12; DAPI, 4',6-diamidino-2-phenylindole; ELISA, Enzyme-linked immunosorbent assay; FCS, foetal calf serum; G-CSF, granulocyte colony stimulating factor; HIF, hypoxia-inducible factor; HMEC, human microvascular endothelial cells; HPC, haematopoietic progenitor and stem cells; IL, interleukin; LSK, lin–Sca-1+c-kit+; NF
B, nuclear factor kappa B; NT, no treatment; pVEGF-R2, phosphorylated VEGF-R2; sKitL, soluble Kit ligand; sCD62E, soluble E-selectin; SCF, stem cell factor; SDF, stromal cell-derived factor; SN-G, supernatant of glioma cell lines LNT-229, LN-308 and primary glioma cultures T113, T132, T159; SN-Gp, supernatant of LNT-229 puro cells; SN-GpSD-208, supernatant of SD-208-treated LNT-229 puro cells; SN-G-siTGF-β, supernatant of LNT-229 siTGF-β1,2 cells stably expressing shRNAs targeting TGF-β1 and TGF-β2; SN-FHAS, supernatant of SV-FHAS cells; SN-GRT, supernatant of irradiated glioma cells; SN-GHO, supernatant of hypoxic glioma cells; SFM, serum-free medium; SFI, specific fluorescence index; SV-HCEC, human cerebral endothelial cells; SV-FHAS, human astrocytic cell line; TGF-β, transforming growth factor-β; TNF-
, tumour necrosis factor-; VCAM, vascular cell adhesion molecule; VEGF, vascular endothelial growth factor; VEGF-R, VEGF receptor
Received December 18, 2007. Revised July 11, 2008. Accepted July 17, 2008.