text: Heparanase is an endoglycosidase that degrades the heparan sulfate proteoglycan of the extracellular matrix by invading cells, notably metastatic tumor cells and migrating leukocytes. Transfection of the heparanase gene enhances the metastatic potential of rodent tumor cells, providing direct evidence for a role of heparanase in invasion. Heparanase inhibitors (mainly based on heparin and similar polysaccharides) have been shown to inhibit tumor growth or metastasis, angiogenesis and vascular damage in some cases in experimental models. Here, we propose to use recent advances in zinc finger DNA binding protein design to create novel transcription repressor proteins which are capable of repressing heparanase gene expression in vivo. Chimeric repressor proteins will be designed to bind to relevant target sites in the heparanase gene and repress heparanase transcription. We will determine the ability of the designed proteins to repress heparanase mRNA and protein expression in mammalian cells through transient transfection assays and the production of stable cell lines. Repression of heparanase transcription will be determined by measuring the level of reporter gene expression in the absence and presence of zinc finger binding protein. This innovative research will lead directly to the development of novel gene therapy approaches for metastatis cancer and potentially inflammatory diseases. PROPOSED COMMERCIAL APPLICATIONS: The success of this project will be a critical proof of principle for "designer repressor" technology. Designer DNA binding proteins and chimeric repressors comprise a new class of therapeutic drugs that potentially could be used to treat a large number of human diseases.