Intermediate-sized Filaments and Specific Markers in a Human Salivary Gland Adenocarcinoma Cell Line and Its Nude Mouse Tumors1

The adenocarcinoma cell line HSG from human salivary gland, which proliferates in vitro or in nude mice, was examined by the immunoperoxidase method for the expression of three different types of intermediate-sized filaments (IPs) and of specific anti gens such as carcinoembryonic antigen, S-100 protein, secretory component, lactoferrin, myosin, tropomyosin, and actin. The cultured HSG cells were found to express three different types of IPs defined by antibodies to keratin, vimentin, and desmin. In HSG cells proliferating in vitro at 34°C and 37°C but not at 39°C, the expression of tropomyosin and carcinoembryonic antigen was observed, although myosin and S-100 protein were not detected. The expressions of actin, lactoferrin, and secretory component were restricted to cultured HSG cells at 39°Cand 37°C,respectively. Transplantation of HSG cells into nude mice resulted in the establishment of a nude mouse system with malignant characteristics such as invasion and metastasis. The expression of IPs in the primary tumors was restricted to keratin and desmin IPs, whereas coexpression of keratin, vimentin, and desmin IPs was observed in some neoplastic cells present in the metastatic tumors in regional lymph nodes and lung. In addition, expression of actin, myosin, tropomyosin, and S-100 protein was found in the metastatic tumors, whereas myosin and S-100 protein were not detected in the primary tumors. Moreover, the metastatic tumors were almost occupied by the neoplastic cells with oncocytic changes, although oncocytic change was not found in the cultured HSG cells and their primary tumors.