Location-dependent role of the human glioma cell peripheral-type benzodiazepine receptor in proliferation and steroid biosynthesis

We examined the localization and function of the peripheral-type benzodiaze pine receptor (PBR), a protein highly expressed in steroidogenic tissues an d aggressive tumor cells, in cell lines derived from glioblastoma multiform e tumors. In MGM-1 cells, PER is located in the nucleus, and cells prolifer ate in response to PER ligands but do not synthesize steroids de novo. In M GM-3 cells, PER is located in mitochondria and the cells synthesize steroid s, but do not proliferate in response to PER ligands. In glioblastoma biops ies, PER is expressed in the nuclei of cells, while it is found in the cyto sol of astrocytomas, and is absent from meningioma and medulloblastoma tumo r biopsies. These data suggest that the subcellular localization of PER def ines its function. (C) 2000 Elsevier Science Ireland Ltd. All rights reserv ed.