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 different histologic types. Methods. Formalin fixed, paraffin embedded tumor sections were stained with the monoclonal D5 antibody by avidin-biotin complex immunohistochemistry. Results. Eighty-eight (62%) of the 143 brain tumors showed positive ER-D5 immunoreactivity. ER-D5 expression was observed in 9/30 low grade astrocytomas, in 6/13 anaplastic astrocytomas, in 16/27 glioblastomas, in 2/5 ependymomas, in 5/8 medulloblastomas, in 10/15 meningiomas, in 20/23 schwannomas, in 11/11 hemangioblastomas, 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 meningotheliomatous meningiomas, and was highest in the hemangioblastomas. ER-D5 immunoreactivity was also observed in the microvascular endothelial proliferations and in tumor blood vessels. ER-D5 expression in tumors was not related to the overall tumor grades, but a statistically 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 tumors (P < 0.005) if vascular-origin tumor hemangioblastomas are considered 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 and germ cell brain tumors suggests that ER-D5 may be a developmentally regulated protein.