Mortality in a variety of cancers is the result of regional and systemic metastases. Thus, the development of adequate means of diagnosis and effective therapy for metastases are important goals of cancer research. The ability of tumor cells to metastasize to distant organ sites is thought to depend, in part, on tumor cell secreted enzymes capable of degrading stromal tissues and basement membranes. We have been studying the tumor basement membrane degradative enzymes such as heparan sufate degrading endoglucuronidase (lieparanase) and type TV collagenolytic metalloproteinases using animal models. We have successfully purified and partially sequenced a murine melanoma heparanase, and have found similar characteristics between murine and human melanoma heparanases. Heparanases are also expressed in elevated levels by highly metastatic human tumor cells. Increased levels of heparanase in serum have been found to be associated with some types of metastatic tumors. Synthetic and natural heparanase inhibitors were shown to have antimetastatic effects in animal experiments. These findings suggest that heparanase plays an important role in tumor metastasis. Heparanase activity is not unique to tumor cells and has been known to exist in normal tissues and cells. There are four different types of heparan sulfate and heparin degrading endoglucuronidases reported, based on their substrate specificities. However, none of the normal cell heparanases have been well characterized yet because of the difficulties of purification. Therefore, we will study the structures and biochemical characteristics of heparanases produced by human melanoma and normal cells. We will purify. characterize. and compare melanoma and normal cell heparanases. Peptide sequences will be analyzed and melanoma heparanase CDNA wig be cloned and sequenced. Using nucleotide probes and immunological probes specific to a human melanoma heparanase, heparanase expression at various stages of melanoma progression and in various tumor and normal tissues and cells will be investigated. We will further investigate the relationship between the heparanase levels in cancer patients' sera and the stages of disease using immunoassay techniques. The results from these studies 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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