Steven R. Hull

Biosynthesis of the Cell Surface Sialomucin from Ascites 13762 Rat Mammary Adenocarcinoma Cells: Intracellular Maturation

Considerable attention has been directed in recent years toward tumor cell surface sialomucins (Carraway and Spielman, 1986). The presence of these O-glycosylated glycoproteins has been correlated with metastasis in the 13762NF rat mammary adenocarcinoma (Steck and Nicolson, 1983), and they are proposed to protect carcinomas from immune destruction by “masking” cell surface antigens, including histocompatibility antigens (Codington, 1981). Monoclonal antibodies prepared against whole tumor cells (Lan et al., 1985), tumor cell membranes (Kufe et al., 1984) or human milk fat globule membranes (Taylor-Papadimitriou, 1981) in many cases react specifically with carcinoma cell sialomucins and are being investigated for their potential in diagnosis and therapy (Schlom, 1986). Why should these mucin-like molecules, which are also products of normal tissues (Ceriani et al., 1983), be recognized as “carcinoma-associated antigens”? One possibility is that changes in the glycosylation of these glycoproteins in carcinomas yields epitopes which are absent or uncommon in normal tissues or other tumors (Hull and Carraway, 1988).