Progestin and estrogen receptors in human meningioma

Progestin receptors (PR) were detected with a dextran-coated charcoal assay and Scatchard plot analysis in 40 of 45 cytosols from human meningioma. The mean PR level in samples from female patients (297 +/- 104 fmol/mg protein; mean +/- SEM; n = 28) was not different from that in samples from male patients (190 +/- 76; n = 12). No differences were observed in the PR content of meningiomas resected from different locations. In the three cases studied, nuclear progestin binding was also detected. An estrogen-binding component was detected in the cytosol of 7 of 44 samples, but the binding capacity was relatively low (13 +/- 13 fmol/mg protein; mean +/- SD). During isoelectric focusing only part of this binding component behaved as might be expected from a true estrogen receptor. Nuclear estrogen binding was not observed in two samples with detectable cytoplasmic estrogen binding. The presence of both cytoplasmic and nuclear PR suggests that in meningioma a functionally active progestin-receptor system comparable with that in other progestin target tissues is operating. In contrast to these other tissues, however, the synthesis of PR in meningioma may not be influenced by estrogens. Further research should focus on evaluating whether the growth rate of meningiomas can be modulated by antiprogestins.