INHIBITION OF GROWTH OF THE HUMAN-MALIGNANT GLIOMA CELL-LINE (U87MG) BY THE STEROID-HORMONE ANTAGONIST RU486

Treatment of nude mice bearing xenografts of the human malignant gliom a U87MG cell line with the steroid hormone antagonist RU486 for 4 week s resulted in a significant and dose-dependent suppression of tumor vo lume and weight. Receptor analyses of tumor cytosol preparations demon strated a single class of high affinity binding sites for dexamethason e, but the absence of receptors for progesterone. RU486 also nullified the stimulatory effect of dexamethasone on proliferation of U87MG cel ls in vitro. These results indicate that the growth of U87MG human mal ignant glioma is dependent on corticoids. The antiproliferative effect of RU486 appears to be due to the inhibition of binding of glucocorti coid hormones to their receptor proteins. Our results suggest a new th erapy for some brain tumors, such as malignant gliomas based on the st eroid hormone antagonist RU486.