Detection and partial characterization of glucocorticoid-binding components in hepatic metastases of human bronchial and gastric carcinoid tumors.

Metastases of human carcinoid tumors of bronchial and gastric origin have been analysed for glucocorticoid receptors using the fluorinated compound [3H] dexamethasone. In both tumors high concentrations of glucocorticoid-binding components were detected which based on several physicochemical characteristics were identified as glucocorticoid receptors in nature. The apparent dissociation constant of the dexamethasone-binder complex was found to be 1.8 x 10(-8) mol/l for the bronchial and 2.8 x 10(-8) mol/l for the gastric carcinoid tumor. Sedimentation in sucrose gradients disclosed the binding components to be macromolecules, sedimenting at about 7.S. By agar gel electrophoresis the molecular species binding dexamethasone were found to exhibit the same electrophoretic mobility as glucocorticoid receptors from well-known target organs. The ligand specificity for binding to these components indicated a requirement of active glucocorticoids as well as anti-glucocorticoids. A regulatory function of glucocorticoids in serotonin biosyntheses is discussed, which may be of potential clinical significance.