Expression of thyroid hormone receptors in human pituitary tumor cells

To understand the expression of thyroid hormone receptors (TRs) in various types of pituitary tumor cells, we performed the reverse transcription coupled to polymerase chain reaction (RT-PCR). Specimens of pituitary adenomas were obtained by transsphenoidal adenomectomies from 2 patients with acromegaly, 6 patients with prolactinoma, 3 patients with Cushing's disease, 2 patients with gonadotropin-secreting tumors, one patient with a TSH-secreting tumor, and 3 patients with non-functioning adenoma with no clinical evidence of pituitary hormone overproduction. Human thyroid hormone receptors β1 and α1, α2 (h-TRβ1, α1, α2) are expressed in nonfuctioning adenomas; h-TRα1 and β1 are specific for prolactinomas; h-TRβ1 is involved in acromegalies and FSH-secreting tumors, while h-TRα1, α2, and β1 are not expressed in TSH-secreting and ACTH-secreting tumors. The results suggest that human thyroid hormone receptors are differentially expressed in human pituitary tumor cells, and our studies have shed new light on the understanding of the role of TRs in pituitary tumors.