EphrinB2 drives perivascular invasion and proliferation of glioblastoma stem-like cells

Glioblastomas (GBM) are aggressive and therapy-resistant brain tumours, which contain a subpopulation of tumour-propagating glioblastoma stem-like cells (GSC) thought to drive progression and recurrence. Diffuse invasion of the brain parenchyma, including along preexisting blood vessels, is a leading cause of therapeutic resistance, but the mechanisms remain unclear. Here, we show that ephrin-B2 mediates GSC perivascular invasion. Intravital imaging, coupled with mechanistic studies in murine GBM models and patient-derived GSC, revealed that endothelial ephrin-B2 compartmentalises non-tumourigenic cells. In contrast, upregulation of the same ephrin-B2 ligand in GSC enabled perivascular migration through homotypic forward signalling. Surprisingly, ephrin-B2 reverse signalling also promoted tumourigenesis cell-autonomously, by mediating anchorage-independent cytokinesis via RhoA. In human GSC-derived orthotopic xenografts, EFNB2 knock-down blocked tumour initiation and treatment of established tumours with ephrin-B2-blocking antibodies suppressed progression. Thus, our results indicate that targeting ephrin-B2 may be an effective strategy for the simultaneous inhibition of invasion and proliferation in GBM.this work was funded by the Medical Research Council, UK (CO, BK, MPC, KG, SK, AA, TD and SP), the Royal Society (SP) and the Regional Government of Madrid/European Social Fund (JLM-T) We thank A Uren and C Jorgensen for critical reading of the manuscript, A Lloyd, A Ridley, E Batlle, H Augustin and M Herlyn for constructs and A. Lloyd for NF1fl/fl brain tissue. We are also grateful to the Imperial College Healthcare Tissue Bank for supplying the human glioblastoma samples and to the patients who donated their tissue for research.S