The Peripheral-Type Benzodiazepine Receptor and Tumorigenicity: Isoquinoline Binding Protein (IBP) Antisense Knockdown in the C6 Glioma Cell Line
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- 作者：Evgeny Levin ; Arumugam Premkumar ; Leo Veenman ; Wilfried Kugler ; Svetlana Leschiner ; Ilana Spanier ; Gary Weisinger ; Max Lakomek ; Abraham Weizman ; O ; Solomon H. Snyder ; Gavril W. Pasternak ; an
- 刊名：Biochemistry
- 出版年：2005
- 出版时间：July 26, 2005
- 年：2005
- 卷：44
- 期：29
- 页码：9924 - 9935
- 全文大小：296K
- 年卷期：v.44,no.29(July 26, 2005)
- ISSN：1520-4995
文摘
Peripheral-type benzodiazepine receptors (PBR) are constituted by three protein components,the isoquinoline binding protein (IBP), the voltage-dependent anion channel (VDAC), and the adeninenucleotide transporter (ANT). Recently, we found that high levels of PBR ligand binding in glioma celllines correlate with in vitro tumorigenicity. To study whether enhanced PBR expression is causative orin response to cancer, we genetically modified C6 glioma cells. Antisense knockdown of the IBP resultedin more than 50% reductions in PBR ligand binding both in the mitochondrial and whole cell fractions,accompanied by similar reductions in IBP levels in these respective fractions. The IBP knockdown wasaccompanied by a 25% increase in cell number in confluent cultures. This correlated with an 8-fold increasein in vitro tumorigenicity, as assessed by anchorage independent growth. Cell cycle analysis indicatedthat knockdown of the IBP resulted in a 60% reduction in the number of cells in the pre-G1 apoptosisphase. This paralleled the reduction seen in apoptosis and cell death shown by DNA fragmentation andTrypan blue assays, respectively. Furthermore, knockdown of the IBP appeared to prevent induction ofapoptosis by the antineoplastic agent, erucylphosphocholine. In addition, IBP knockdown preventedprocessing of the caspase 3 component of the apoptosis cascade by the erucylphosphocholine congener,erucylphospho-N,N,N-trimethylammonium. In conclusion, our results suggest that enhanced IBP expression,including enhanced PBR ligand binding, such as occurring in untreated C6 glioma cells, may provide amechanism to increase apoptotic rates of cancer cells.