Estramustine binding protein in human brain-tumor tissue.

Estramustine, an estradiol-17 beta and nornitrogen mustard complex, is used in the treatment of advanced prostatic carcinoma. A specific estramustine binding protein (EMBP) is important for its cytotoxic action, and the presence of EMBP has previously been demonstrated in rat and human prostatic cancer tissue. Significant levels of EMBP were detected by radioimmunoassay in human brain-tumor tissue. The EMBP concentrations (expressed as ng/mg protein) in 16 astrocytomas (mean 2.6 ng/mg, range 0.5 to 6.2 ng/mg) and seven meningiomas (mean 5.1 ng/mg, range 0.3 to 9.3 ng/mg) were significantly higher than that found in four samples of epileptic brain (mean 0.7 ng/mg, range 0.5 to 1 ng/mg) and 18 samples of normal brain (mean 0.5 ng/mg, range 0.2 to 1.0 ng/mg). The uptake, metabolism, and antiproliferative effects of the prostatic anticancer agent estramustine have been previously demonstrated in cultured glioma cells. The presence of EMBP may suggest a selective binding and effectiveness in human brain-tumor tissue.