High-throughput methods for measuring heparanase activity and screening potential antimetastatic and anti-inflammatory agents.

Heparanase plays an important role in the degradation of the extracellular matrix. It is implicated in inflammation, tumor angiogenesis and metastasis. We have developed two high-throughput methods for measuring heparanase activity and screening potential inhibitors. The first method involves coating fibroblast growth factor (FGF) on microtiter plates and capturing fluorescein isothiocyanate (FITC)-labeled heparin sulfate (HS), which is used as a substrate for heparanase digestion. Labeled HS fragments are released into the medium and quantitated by fluorescence intensity measurement. We have implemented this assay method into a Zeiss uHTS system and screened compound libraries for heparanase inhibitors. The second method involves labeling HS with biotin followed by FITC to generate a dual-labeled HS. The labeled material is bound to streptavidin-coated plates and used as a substrate for heparanase digestion. Both methods are sensitive and easily applicable to robotic systems. In addition, we have labeled both HS and biotin-HS with Eu-chelate, a fluorophore that exhibits long decay fluorescence. Assays using Eu-labeled HS and Eu-labeled biotin-HS have been developed and show higher sensitivity than those using FITC-labeled material. Furthermore, assays using Eu-chelate HS (or biotin-HS) should eliminate the interference of fluorescence compounds.