CALCITONIN RECEPTOR MESSENGER-RNA IS EXPRESSED IN HUMAN MEDULLARY-THYROID CARCINOMA

We recently reported the presence of a truncated form (h-CTR2) of the human calcitonin receptor (CTR) in TT cells, a cell line derived from medullary thyroid carcinoma (MTC). This form (h-CTR2), characterized b y the absence of 16 amino acids in the first intracellular domain, was also detected in two cases of MTC. In the present study we determined the expression of CTR mRNA in a larger sample, representative of the different clinical forms of MTC, and in normal thyroid. h-CTR2 was exp ressed in all MTC specimens (both sporadic and familial) and in the no rmal thyroid samples. The expression of the receptor mRNA was higher i n MTC compared with normal thyroid. Moreover, CT and CTR mRNA levels w ere modified significantly during proliferation. This result suggests that CT may be involved in proliferation of MTC via autocrine/paracrin e regulation. Calcitonin secretion by MTC may play a role in the devel opment and spread of these tumors.