Steroid receptors in human uterine carcinoma. Their biological importance and therapeutic implications

Surgical material of primary uterine carcinoma from postmenopausal patients was analyzed with regard to cytosol content of estradiol (ER) and progesterone (PR) receptors, as well as their binding sites in nuclear compartment. A dextrancoated charcoal technique was used and binding data were calculated from Scatchard plots. In all examined specimens intracellular high-affinity, low-capacity estrogen - and progesterone-binding proteins (which have the characteristics of steroid receptors), with equilibrium dissociation constants (Kd's) of 10(-10)M and 10(-9)M respectively, have been observed in detectable levels. DNA binding ability of steroid-receptor complexes was examined and clearly demonstrated even at 4 degrees C by using DNA-cellulose slurry. Preheating of complexes at 25 degrees cause increased DNA binding ability in some specimens, but significant loss of this ability in other tumors. The relationship between the nuclear retention of steroid-receptor complexes and their interaction with nuclear components (giving a response) is discussed on the basis of steroid-responsive and unresponsive systems. Present investigation indicate that described steroid analysis may become an important tool in predicting the value of endocrine therapy in human uterine carcinoma.