Isolation and characterization of human thyrotropin-releasing hormone (TRH) from an endocrine pancreatic tumor

An extract of a pancreatic carcinoid tumor obtained at autopsy from a patient who had suffered from Cushing's syndrome was found to have the ability to release thyrotropin (but not any other pituitary hormones) from cultured rat anterior pituitary cells, and to bind to a specific thyrotropin-releasing hormone (TRH) antiserum. The tumor contained 2.2 and 3.9 nmol/g of TRH bio- and immunoreactivity, respectively. The active material was purified and its amino acid composition and chromatographic properties were found to be identical with those of synthetic ovine/porcine TRH. This represents the first isolation of human TRH and the first established case of a 'TRHoma', a TRH-producing tumor.