Estrogen receptor immunoreactivity in meningiomas

Abstract

✓ Estrogen receptor (ER) analysis was performed in 70 meningioma samples by means of two assays: an enzyme immunoassay that used monoclonal antibodies against human ER protein (estrophilin), and a sensitive radioligand binding assay that used iodine-125-labeled estradiol as the radioligand. Low levels of ER immunoreactivity were found in tumors from 51% of patients, whereas ER binding activity was demonstrated in 40% of the meningiomas examined. In eight (11%) of the tissue samples, multiple binding sites for estradiol were observed. The immunoreactive binding sites corresponded to those of the classic high-affinity ER. In ligand binding studies, however, measurement of classic ER was considerably influenced by a second low-affinity high-capacity estrogen binding component, even at low ligand concentrations. Binding activity of the progesterone receptor (PR) and androgen receptor (AR) was determined concurrently using 17α-methyl-3H-promegestone (3H-R 5020) and 17α-methyl-3H-trienolone (3H-R 1881), a synthetic gestagen and androgen, respectively. High concentrations of PR were detected in 53 (76%) of the tumors, whereas a moderate number of AR binding sites were demonstraetd in 33 (47%) of the tumors. A positive correlation between ER immunoreactivity and AR binding activity is suggestive of estrogen regulation of AR via the ER system. The presence of gonadal steroid receptors in a large proportion of meningiomas and the tendency toward a dependence of receptor concentrations on the histological subtype of the meningioma could have implications for tumor therapy.