Glioma cells enhance endothelial progenitor cell angiogenesis via VEGFR-2, not VEGFR-1.

Although potential contribution of endothelial progenitor cells (EPCs) to angiogenesis in glioma has been proposed, the molecular mechanisms of EPCs recruitment to vasculature have not been fully elucidated. Here, we show that the supernatant from glioma cells promotes EPCs angiogenesis via VEGFR-2, not VEGFR-1. Moreover, VEGFR-2 siRNA inhibits VEGFR-2 expression in EPCs, tube formation on matrigel and cell migration. MMP-9 activity and expression and the Akt and ERK phosphorylations are decreased by VEGFR-2 siRNA. Thus, these results indicate that glioma cells enhance EPC angiogenesis via VEGFR-2, not VEGFR-1, mediated by the MMP-9, Akt and ERK signal pathways.