Overexpression of the human major vault protein in astrocytic brain tumor cells

Abstract

Evidence has shown that the major human vault protein (MVP), which is identical to lung resistance-related protein (LRP), may be causally involved in a special type of multidrug resistance (MDR). The purpose of this study was to investigate the expression and cellular localization of MVP in cells derived from brain tumors and other tumors of neuroectodermal origin. Using both established cell lines (n ‫؍‬ 22) and primary explants (n ‫؍‬ 30), we show that a distinct overexpression of the MVP gene at the mRNA (RT-PCR) and protein (Western blot) levels is a characteristic feature of cells derived from astrocytic brain tumors. Primary cultures obtained from meningioma specimens also expressed high MVP levels, in contrast to neuroblastoma and medulloblastoma cells, which rarely contained detectable amounts of MVP. Normal human astrocytes cultured in vitro expressed MVP, although at low amounts compared with most malignant cell types. Basal MVP expression correlated with resistance against diverse antineoplastic drugs including anthracyclins, cisplatin and etoposide. By Western blot, MVP was also detected in all tumor samples taken from 7 glioma and 3 meningioma patients. Taken together, these data suggest overexpression of MVP as one explanation for the low efficacy of chemotherapeutic treatment of astrocytic brain tumors.

Dynamics of chemosensitivity and chromosomal instability in recurrent glioblastoma

“…In our cell model, we found very low levels of mdr1 mRNA without detectable P-gp, persistent expression of MRP1, and reduction of MVP expression especially in BTL3 cells. In a previous study, we observed correlation between MVP expression of glioblastoma cells and resistance to anthracyclines (Berger et al, 2001), which suggests a contribution of MVP at least to doxorubicin hypersensitivity of BTL3 cells. Additionally, EGFR-transmitted signals are known to contribute to apoptosis resistance of glioblastoma cells (Shinojima et al, 2003) leading, for example, to CDDP insensitivity (Nagane et al, 1998).…”

“…When comparing alkylating agents with several other chemotherapeutics, an increased response in the recurrence-derived BTL cell lines was also observed in anthracyclines, whereas all cells were persistently unresponsive to VP-16, CDDP, and bleomycin. Highintrinsic chemoresistance of glioma cells has been reported by us and other groups involving overexpression of known drugresistance proteins like P-gp, MRP1, and MVP (Berger et al, 2001;Bredel, 2001;Spiegl-Kreinecker et al, 2002). In our cell model, we found very low levels of mdr1 mRNA without detectable P-gp, persistent expression of MRP1, and reduction of MVP expression especially in BTL3 cells.…”

“…Visualisation and quantification were performed using the ChemiDoc System (BioRad, Hercules, CA, USA). In previous studies, multiple glioblastoma cell lines established in our laboratory were extensively characterised for their expression of drug resistance genes (Berger et al, 2001;Bredel, 2001;Spiegl-Kreinecker et al, 2002). Respective protein extracts of the following cell lines have been used as positive controls in Western blot analysis: for MGMT GL80, for MVP GL54, for MRP1 GL52 and for P-gp YT-BO.…”

“…However, the use of adjuvant and/or concomitant chemotherapy and the standard of care at first relapse are still under debate (van den Bent et al, 2006). Chemotherapeutic treatment success in brain tumours is mainly limited by the blood -brain barrier and the expression of chemoresistance-related proteins like P-glycoprotein (P-gp), multidrug resistance protein 1 (MRP1), and major vault protein (MVP) also known as lung resistance protein (LRP) (Berger et al, 2001;Bredel, 2001;Spiegl-Kreinecker et al, 2002). Based on their ability to circumvent the blood -brain barrier, alkylating agents represent the gold standard in the treatment of malignant gliomas.…”

Whole genome amplification for CGH analysis: Linker‐adapter PCR as the method of choice for difficult and limited samples

“…Primary cell cultures were established from 48 histopathologically-confirmed human melanomas (10), three glioblastomas (11), and four soft tissue sarcomas. The SK-Mel-28, Calu-6, and HepG2 cell lines were obtained from the American Type Culture Collection (Rockville, MD), and the F2000 embryonic fibroblasts were obtained from Flow, Scotland.…”