Glycoconjugates, primarily glycoproteins, are implicated in oncogenesis, maintenance of the neoplastic state and metastasis. "Shedding" of tumor glycoproteins into the circulation has been suggested as playing an important role in tumor growth and/or metastasis. We propose to examine two aspects of glycoprotein shedding: first, correlation of serum glycoprotein:N-acetylneuraminic acid transferase activity with tumor burden and second, identification, characterization and kinetics of release (shedding) of tumor glycoproteins. Two rat mammary tumors will be used, the transplantable hormone-responsive R3230AC and the DMBA-induced hormone-dependent adenocarcinomas arising in situ. To correlate NANA transferase activity and tumor burden, serum activity will be measured at frequent times during a variety of selected regimens that alter tumor growth (hormone therapy, endocrine organ ablation), as well as during carcinogenic transformation of normal cells. Elevations in enzyme activity prior to appearance of carcinoma would suggest this assay as a prognostic test. Glycoprotein "shedding" will be studied using tumors radiolabeled with fucose and/or glucosamine in vitro, transplantation of cells to animals and following the release of labeled glycoconjugates into the host's circulation. The influence of tumor burden and hormonal status on release of labeled glycoconjugates and characterization of the labeled components will be examined. Other enzymes involved in glycoprotein metabolism and proteolytic enzymes will be explored as potential markers for tumor growth and spread. Changes in serum NANA transferase activities and glycoconjugates druing normal physiological alteration of the host will also be studied.