Membranous expression of glucose transporter-1 protein (GLUT-1) in embryonal neoplasms of the central nervous system

The human erythrocyte GLUT-1 is a transmembrane protein which facilitates t ransport of glucose in the cell in an energy-independent fashion. Neuroecto dermal stem cells show strong membrane immunoreactivitry with this marker a t early developmental stages in rodents. Membranous expression by undiffere ntiated neuroectodermal cells gradually decreases while GLUT-1 becomes conf ined to the endothelial cells, when these acquire blood-brain barrier funct ion. We thus sought to determine whether GLUT-1 expression was limited to e mbryonal neoplasms of the central nervous system (CNS) which are presumably derived from developmentally arrested neuroectodermal stem cells. Archival material of 40 primary CNS neoplasms were examined for immunoreactivity wi th anti-GLUT-1. This included both non-embryonal neoplasms (18 astrocytic t umours, one ependymoma and three oligodendroglioma) and embryonal neoplasms (12 cerebellar medulloblastomas, four supratentorial PNETs and two atypica l teratoid/rhabdoid tumours (AT/RhT)). In addition, cell lines and nude mic e xenografts derived from both undifferentiated and differentiated tumours were assessed for GLUT-1 immunoreactivity by both immunohistochemistry and Western blotting. All embryonal tumours, MBs and PNET xenografts consistent ly showed GLUT-1 membrane staining. Non-embryonal neoplasms were negative e xcept for vascular staining. Membrane protein fraction of embryonal tumours cell lines immunoreacted by immunoblot with GLUT-1, whereas the glioblasto ma cell line was negative. Expression of GLUT-1 supports the stem cell natu re of the cells of origin of MBs, supratentorial PNET and AT/RhTs. As a res ult, GLUT-1 is a useful marker to define the embryonal nature of CNS neopla sms.