EXPRESSION OF ESTRAMUSTINE-BINDING PROTEIN IN EPENDYMOMAS AND IN HUMAN AND DEVELOPING RAT EPENDYMAL CELLS

The mainstays of primary treatment of ependymoma are aggressive surger y followed by radiotherapy. Although spreading occasionally occurs in the cerebrospinal pathways, chemotherapy is still not established and no ultimate drug has so far been found. Estramustine-phosphate (EMP), with a demonstrated effect on astrocytoma in vitro, has been shown to penetrate the blood-tumor barrier and to accumulate in human brain tum or tissue including ependymoma. It has been proposed that the cytotoxi c effect of EMP depends on the presence of a binding protein, estramus tine-binding protein (EMBP). In the present paper we have, for the fir st time, immunohistochemically demonstrated an EMBP-like protein in a series of ependymomas. Immunoreactivity was found within the cytoplasm of the tumor cells with a tendency to increase with increasing malign ancy of the tumor. In addition, the occurence of EMBP-like protein was demonstrated in human ependymal cells. In the rat brain, a weak immun oreactivity was detected in early fetal neuroepithelial cells while th e staining intensity was increased in mature ependymal cells in late f etal, neonatal, and adult rat. Thus, immunoreactivity for an EMBP-like protein was demonstrated in ependymoma tissue, normal human ependyma and in the developing rat ependymal cells.