High incidence and characterization of glucocorticoid receptors in human malignant melanoma.

The glucocorticoid receptor was characterized in biopsy samples from patients with recurrent malignant melanoma. Glucocorticoid receptors were measured by the charcoal-adsorption technique. Tumor cytosol from approximately 86% (25/29) of the patients contained large quantities of receptors (20-324 fmol/mg protein). The dissociation constant of this cytoplasmic receptor was determined to be 2-22 nM. This binding component sedimented at 7.1S on sucrose gradients of low ionic strength and dissociated into lower molecular weight components that sedimented at 4.4S on sucrose gradients of high ionic strength. Receptor binding was specific for glucocorticoids. Although progestins competed well for the binding that is typical for glycocorticoid receptor as reported in the literature, other steroids, e.g., 17 beta-estradiol and 5 alpha-dihydrotestosterone, were only weak competitors. These results demonstrated that this neoplasm contains large quantities of glucocorticoid receptors that are similar in their physicochemical characteristics to those found in normal tissues. This finding in human melanoma biopsy specimens may be of therapeutic value in the management of patients with malignant melanoma.