Endothelial endostatin release is induced by general cell stress and modulated by the nitric oxide/cGMP pathway.

Endostatin is a 20 kDa carboxyl-terminal fragment of collagen XVIII that, when added exogenously, inhibits endothelial proliferation and migration in vitro and angiogenesis and tumor growth in vivo. Previous results showed endostatin/collagen XVIII labeling in few endothelial cells in human glioblastoma multiforme. We have now observed constitutive release of endostatin from one of four endothelial cell lines.