Glioma-conditioned Medium Blocks Endothelial Cells' Apoptosis Induced by Hypoxia and Promotes Its Angiogenesis via Up-regulation of u-PA/u-PAR

Objective： To investigate the role of urokinase-type plasminogen activator/urokinase-type plasminogen receptor（u-PA/u-PAR） system in glioma angiogenesis under hypoxic conditions, we studied the effect of glioma-conditioned medium on the hypoxia induced changes in human endothelial-like ECV304 cells proliferation, apoptosis, cord formation in vitro and u-PA/u-PAR expression. Methods： MTT assay was used to examine the changes in cell proliferation. Cell apoptosis was analyzed by Hoechst 33258 staining. Matrigel cord-like formation assay was used to evaluate the angiogenesis ability of ECV304 cells in vitro. Expressions of u-PA/u-PAR mRNA were detected by quantitative real-time RT-PCR. Results： Hypoxia inhibited ECV304 cells proliferation and induced cell apoptosis. Hypoxic conditioned medium（H-CM） while not normoxic conditioned medium（N-CM） of U251 glioma ceils partially blocked the effect of hypoxia on ECV304 cells proliferation and apoptosis. H-CM of U251 glioma ceils also promoted the cord formation of ECV304 cells seeded on matrigel. When u-PA or u-PAR monoclonal antibodies were added into ECV304 cells culturing medium, cord formation ability was partially inhibited. H-CM of U251 glioma cells induced uPA and uPAR expression in ECV304 cells. Conclusion： These suggest that u-PA/u-PAR system is involved in glioma angiogenesis trigged by hypoxic microenviroment.