) Heparanases are a family of mammalian endoglycosidases that degrade long heparan sulfate (HS)glycosaminoglycans to shorter chains. We have described heparanase activity in highly metastatic cancer cells and demonstrated that molecules that inhibit its activity are also capable of suppressing tumor metastasis. Heparanase is also involved in angiogenesis primarily through release of active heparin-binding angiogenic factors from their storage in the extracellular matrix (ECM). The innovation of the proposed research resides in our recent cloning, expression and characterization of a unique full length cDNA encoding human heparanase. Overexpression of the heparanase cDNA in low or non-metastatic tumor cells conferred a high metastatic potential in experimental animals, resulting in an increased rate of mortality. Our preliminary results indicate that the heparanase enzyme is preferentially expressed by metastatic breast carcinoma cell lines and in human breast carcinoma tissue and urine of breast cancer patients. Based on these results we hypothesize that heparanase is casually involved in breast carcinoma progression. We propose to focus on the following specific aims: I) Use of cDNA probes and anti-heparanase antibodies to detect disseminated breast carcinoma cells in various tissues and to quantitate its amounts in plasma and urine of breast cancer patients at various stages of the disease and in response to treatment; ii) Involvement of heparanase in breast cancer metastasis and angiogenesis: Expression and activation of heparanase during breast cancer progression; Establishment of an inducible expression system to determine the effect of increased/suppressed heparanase expression on breast carcinoma metastasis and angiogenesis; iii) Transcriptional regulation of the heparanase promoter in breast cancer progression; and iv) Elucidate the effect of heparanase inhibitory antibodies, sulfated polysaccharides and synthetic polyanionic molecules on breast carcinoma metastasis. The proposed experiments are based on the availability of recombinant heparanase and appropriate molecular probes, anti-heparanase antibodies and inhibitory polyanionic molecules, breast carcinoma cell lines, animal models and human material, enabling, for the first time, to elucidate the involvement of heparanase in breast carcinoma progression. For this purpose, we plan to apply molecular, histological and cell biology techniques, both in vitro and in vivo, and to establish a close collaboration between basic scientists and expert physicians at the Oncology Research Institute of the Hadassah-Hebrew University Hospital.
