IN-VITRO TUMOR ANGIOGENESIS ASSAYS - PLASMINOGEN LYSINE-BINDING-SITE-1 INHIBITS IN-VITRO TUMOR-INDUCED ANGIOGENESIS

It is generally accepted that tumors are angiogenesis-dependent. For r esearch and clinical purposes it would be very attractive to have a si mple in vitro model that allows a rapid screening of the angiogenic po tential of tumors and to study the effect of angiogenic inhibitors. In vitro angiogenesis models were developed, based on endothelial sprout ing/tube formation on a collagen gel, using both tumor cell lines and tumor biopsies. Best results were obtained using conditioned medium of tumor cell lines. In this model it was found that the plasminogen fra gment lysine binding site 1 (LBS-1) inhibited in vitro endothelial cel l sprouting. This is the first demonstration that LBS-1, which include s angiostatin, is inhibitory for new vessel formation in an in vitro a ngiogenesis model. We conclude that the assay system allows for rapid and reliable screening of angiogenesis inhibitors.