Estramustine-binding protein in meningioma

The presence of estramustine-binding protein has been suggested to positive ly correlate with the effect of the cytotoxic drug estramustine, a combinat ion of estradiol and nornitrogen mustard used in the treatment of prostatic carcinoma. This study demonstrates expression of estramustine-binding prot ein in a series of meningioma using different ligand-based and immunologica l techniques. Scatchard plot analysis showed specific binding sites for [H- 3]estramustine in meningioma tissue with a dissociation constant of 22-26 n M. Immunohistochemistry revealed an immunoreactivity in meningioma comparab le to that demonstrated in prostatic carcinoma. The mean concentration (it = 6) of estramustine-binding protein in meningioma, as determined by radioi mmunoassay was 159 ng/g tissue (range 18-274 ng/g). Moreover, partial chara cterization using size exclusion chromatography of [H-3]estramustine-labele d tumor extracts and Western blot analysis of immunoprecipitated samples in dicated that the structure of the estramustine-binding protein in meningiom a is similar to that in rat prostate, with three polypeptide components of 10, 14, and 16 kDa, as compared to 8, 10-11, and 12 kDa in rat prostate. In conclusion, the novel observation of estramustine-binding protein and spec ific binding of estramustine in meningioma justify further evaluation regar ding the role of estramustine-binding protein in the growth behavior of men ingioma and the potential for estramustine and similar hormone-related drug s in the treatment of relapsing meningioma.