Glucocorticoid Receptors in Cultured Skin Fibroblasts of Normal and Adrenocorticoid Disorders

Abstract

Glucocorticoid receptors (GR) in cultured fibroblasts obtained by forearm skin biopsy were characterized and GR in patients with hyper- and hypocortisolism were compared. Scatchard analysis of specific whole cell [³H]-dexamethasone binding showed a single class of high affinity receptors with a mean (±SD) binding capacity (R₀) of 126, 800±21, 600 sites/cell and mean (±SD) apparent dissociation constant (Kd) of 2.9±0.4 nM in 6 normal subjects. Competition study of various steroids revealed that glucocorticoids were the most potent competitors. The order of the strength of competition was dexamethasone > betamethasone > prednisolone > hydrocortisone. Sucrose density gradient analysis revealed a specific 8.6 S binding peak in cytosol and 3.6 S in nuclear extracts. Dexamethasone showed the dose-dependent suppressive effect on thymidine incorporation. An inverse linear correlation between CI₅₀ and % inhibition of thymidine incorporation by glucocorticoids was observed. There were no significant differences in parameters of whole cell GR among healthy controls, Cushing's disease (n=4, R₀=131, 225±29, 950/cell, Kd=3.1±0.6 nM) and Addison's disease (n=2, R₀=131, 600±25, 600/cell, Kd=3.2±0.2 nM). In one additional patient of hypercortisolism without clinical symptoms of Cushing's disease, R₀ (144, 000±12, 960) was the same as control, but Kd (5.0±1.2 nM) was higher than the control.