Demonstration of glucocorticoid receptors in human mammary carcinomas

Tumor regression is sometimes observed during glucocorticoid treatment of patients with breast cancer. The possibility of a direct tumor-growth-suppressing effect, mediated by steroid-hormone receptors, cannot be excluded. A 3H-dexamethasone-binding component in the cytoplasmatic fraction of human breast cancers was studied by agar-gel electrophoresis. Of 90 samples, 51% contained a significant amount of an apparent glucocorticoid receptor. In two specimens from metastases, in which a preexisting lymph node structure was almost completely replaced by tumor tissue, the glucocorticoid receptor character of the binding component was studied extensively. The component satisfied the steroid-hormone receptor criteria in being a high affinity (Kd approximately 4--9 X 10(9) M), low capacity binder. Competition studies with excess unlabelled steroids of different classes confirmed the specific glucocorticoid receptor character of the component. Both tumors contained also estrogen and androgen receptors and one contained an apparent progestin receptor.