Secretion of calcitonin and carcinoembryonic antigen in long-term organ culture of human medullary thyroid carcinoma: biochemical and immunocytochemical studies.

Tissue cultures of four C-cell carcinomas (medullary thyroid carcinoma, MTC) were prepared to study the basal and stimulated calcitonin (CT) and carcinoembryonic antigen (CEA) release. Immunohistological staining of the explants for CT and CEA have been performed after various periods of culture. These MTC explants were able continuously to release CT and CEA for periods up to 157 days. The spontaneous CT and CEA release decreased sharply during the 1st week of culture, then remained nearly constant over the observation period. THE CEA/CT secretion ratio slightly declined during long-term culture; CEA release seems to drop earlier than CT production. CT and CEA could be detected in the same cells by immunocytochemical technique. The septal tissue consisting of dense connective tissue and amyloid produced by tumor cells seemed to increase during long-term culture. CT, but not CEA, was stimulated by pentagastrin (10(-5) M), glucagon (6 x 10 (-6) M), and dose related by calcium (2.5-20 mM) in vitro. The MTC explant organ long-term culture proved to be a useful model for studies of human CT and CEA secretion.