Multidrug resistance (MDR) is associated with the expression of P-glycoprot
ein (P-gp), an ATP-dependent transporter which expels anti-cancer drugs fro
m cells. In the present study, MDRI P-gp was immunodetected by Western blot
analysis in 60 human brain tumors, including meningiomas, schwannomas, low
-grade gliomas (astrocytomas, pilocytic astrocytomas) and high-grade glioma
s (anaplastic astrocytomas, glioblastomas and anaplastic oligodendrogliomas
), Most samples from primary tumors expressed P-gp at the same levels as no
rmal brain tissue except for schwannomas, in which levels were reduced by 6
5%, and meningiomas, in which levels were more than 10-fold higher in 7 of
10 samples. P-gp levels were 70% and 95% lower in brain metastases from mel
anomas and lung adenocarcinomas, respectively, than in normal brain tissue,
These results indicate that the majority of primary brain tumors express M
DRI P-gp and that its high expression levels in meningiomas may be a marker
for this type of brain tumor. (C) 2001 Wiley-Liss, Inc.