Expression of multidrug-resistance P-glycoprotein (MDR1) in human brain tumors

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.