The mortality in a variety of cancers is the result of regional and systemic metastases. Thus, the development of adequate diagnosis and effective therapy of metastases are important goals of cancer research. Enzymatic destruction of basement membranes, continuous extracellular matrices which separate parenchyma from underlying interstitial connective tissue, is thought to be important in the invasion and metastasis of tumors to distant organ sites. We have found an excellent correlation between the spontaneous metastatic potential of murine B16 melanoma and rat 13762NF mammary adenocarcinoma cells and their abilities to degrade basement membrane components, such as heparan sulfate and type IV collagen. In the proposed project heparanase from melanoma and type IV collagenase from mammary adenocarcinoma cells will be purified and characterized, and their substrate and inhibition specificities determined. Potent heparanase inhibitors will be produced by chemical modification of glycans. We will assess the effects of these inhibitors on tumor invasion in vitro and experimental metastasis in vivo. Polyclonal or monoclonal antibodies raised against these enzymes will be used for immunohistochemical studies and immunoassays, and microassay systsems for these enzymes will be improved and applied to serum samples. We will conduct comparative studies of heparanase and type IV collagenase in primary tumors and their metastases, as well as in sera from tumor-bearing hosts. Differences between primary sites of cancer and their metastases, and differences among sera from tumor-bearing hosts at different stages of the disease will be examined to determine if these assays could be of prognostic use. We will study effects of antibodies directed against the enzymes on tumor invasion in vitro and experimental metastasis in vivo. We have found degradative activities against heparan sulfate and type IV collagen in some normal invasive cells, such as macrophages and vascular endothelial cells, and cooperation between tumor cells and normal cells has been observed in the degradation of extracellular matrix components in vitro. Therefore, the interaction between normal and tumor cells in the production and release of heparanase and type IV collagenase will be investigated using a syngeneic cell system. The results should provide new information concerning the mechanisms of tumor cell invasion at the molecular level, and allow development of new approaches of diagnosis or prognosis of metastasis.
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