Growth in vitro and ultrastructure of cells from a medullary carcinoma of the human thyroid gland: transformation by simian virus 40 and evidenc of thyrocalcitonin and prostaglandins.

Continuous single layer tissue cultures were established with explants from a metastatic nodule of medullary carcinoma primary in the thyroid gland. Some cultures were infected with simian virus 40 and the cells acquired morphologic and growth characteristics associated with viral transformation. Thyrocalcitonin activity was detected by radioimmunoassay of culture fluids as late as 7 months after initiation of the single layers. Substances with the chemical and biological properties of (PG) prostaglandins E2 and F2alpha were extracted from culture fluids after 4 months. The original carcinoma cells contained abundant cyctoplasmic secretory granules, which were demonstrated by electron microscopy. These granules disappeared during subculture of the monolayers, and electron-dense secretory substance accumulated within dilated cisternae of the ribosome-bound endoplasmic reticulum. Ultrastructural differences in surface organization of the virus transformed and uninfected culture cells were noted. Amyloid was present in the original tumor stroma and tissue culture explants, but could not be identified in those serial subcultures derived from the monolayer outgrowths.