IMMUNOHISTOCHEMICAL EXPRESSION OF THE ESTROGEN RECEPTOR-RELATED ANTIGEN (ER-D5) IN HUMAN INTRACRANIAL TUMORS

Background. Expression of the estrogen receptor-related antigen (ER-D5 ) has been reported in some normal and neoplastic tissues. The authors evaluated the expression of ER-D5 in 143 intracranial tumors of diffe rent histologic types. Methods. Formalin fixed, paraffin embedded tumo r sections were stained with the monoclonal D5 antibody by avidin-biot in complex immunohistochemistry. Results. Eighty-eight (62%) of the 14 3 brain tumors showed positive ER-D5 immunoreactivity. ER-D5 expressio n was observed in 9/30 low grade astrocytomas, in 6/13 anaplastic astr ocytomas, in 16/27 glioblastomas, in 2/5 ependymomas, in 5/8 medullobl astomas, in 10/15 meningiomas, in 20/23 schwannomas, in 11/11 hemangio blastomas, in 9/9 germ cell tumors, in 0/2 oligodendrogliomas, and in 17/28 pediatric and childhood brain tumors. The mean percentage of ER- D5-positive cells varied in different tumor types, was lowest in the m eningotheliomatous meningiomas, and was highest in the hemangioblastom as. ER-D5 immunoreactivity was also observed in the microvascular endo thelial proliferations and in tumor blood vessels. ER-D5 expression in tumors was not related to the overall tumor grades, but a statistical ly significant higher percentage of ER-D5-positive cells was noted in the glioblastomas compared with the low grade astrocytomas (P < 0.05) and in the combined high grade tumors compared with the low grade tumo rs (P < 0.005) if vascular-origin tumor hemangioblastomas are consider ed a separate entity from other brain tumors. Conclusion. The current study suggests that the ER-D5 antigen may participate in the growth of the intracranial tumors and tumor angiogenesis. ER-D5 in embryonal an d germ cell brain tumors suggests that ER-D5 may be a developmentally regulated protein.