Distribution of estramustine-binding protein during postnatal development of rat brain

Estramustine-binding protein (EMBP) is expressed in several types of brain tumors, such as astrocytoma, ependymoma, and meningioma. It binds the cytot oxic drug estramustine with high affinity and is suggested to cause accumul ation of the drug in EMBP-expressing tumor cells. In this study, the spatia l distribution of EMBP in normal rat brain was studied with immunohistochem istry. Brains from male and female rats of different ages were used. EMBP w as found in the cytoplasm of ependymal cells, in the leptomeninges, mainly the arachnoid, and in scattered neurons. Moreover, staining was seen in nuc lei of choroid plexus cells, in the granular cell layer in the cerebellum, and in a few scattered endothelial cells. The nuclear staining was more fre quent in younger animals. No obvious difference in EMBP expression between male and female rats was observed. The expression of EMBP in rat brain was confirmed with nested RT-PCR. Future studies are justified to elucidate the role of EMBP-like proteins in CNS and in brain tumors.