Expression of the human TSH receptor in a human thyroid carcinoma cell line that lacks an endogenous TSH receptor: growth inhibition by cAMP.

The role of TSH and its receptor in controlling growth of thyroid carcinomas is far from well understood. In order to study this subject further we established a new human thyroid carcinoma cell line. We transfected human thyroid carcinoma cells lacking an endogenous TSH receptor with the human TSH receptor cDNA. Transfected cells, designated HTC-TSHr, expressed the TSH receptor mRNA and synthesized a functional TSH receptor with a TSH binding affinity in the order of magnitude of normal thyroid cells. In response to TSH stimulation HTC-TSHr cells accumulated cAMP, indicating a functional TSH receptor-adenylate cyclase system. However, HTC-TSHr cells did not concentrate iodide and lacked thyroglobulin immunoreactivity, although they did express low amounts of thyroglobulin mRNA. Proliferation of HTC-TSHr cells was inhibited by dibutyryl-cAMP and forskolin and also by TSH via the re-expressed TSH receptor.