Brain Advance Access published online on September 26, 2008
Brain, doi:10.1093/brain/awn233
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Array analysis of epilepsy-associated gangliogliomas reveals expression patterns related to aberrant development of neuronal precursors
1Department of Neuropathology, 2Department of Pathology, University of Bonn Medical Center, Bonn, 3Gene Center, Ludwig-Maximilians-University, Munich, 4Department of Epileptology and 5Department of Neurosurgery, University of Bonn Medical Center, Bonn, Germany
Correspondence to:
Albert J. Becker, MD, Department of Neuropathology, University of Bonn Medical Center, Sigmund-Freud-Strasse 25, D-53105 Bonn, Germany E-mail: albert_becker{at}uni-bonn.de
Gangliogliomas, the most frequent neoplasms in patients with pharmacoresistant focal epilepsies, are characterized by histological combinations of glial and dysplastic neuronal elements, a highly differentiated phenotype and rare gene mutations. Their molecular basis and relationship to other low-grade brain tumours are not completely understood. Systematic investigations of altered gene expression in gangliogliomas have been hampered by their cellular complexity, the lack of suitable control tissue and of sensitive expression profiling approaches. Here, we have used discrete microdissected ganglioglioma and adjacent control brain tissue obtained from the neurosurgical access to the tumour of identical patients (n = 6) carefully matched for equivalent glial and neuronal elements in an amount sufficient for oligonucleotide microarray hybridization without repetitive amplification. Multivariate statistical analysis identified a rich profile of genes with altered expression in gangliogliomas. Many differentially expressed transcripts related to intra- and intercellular signalling including protein kinase C and its target NELL2 in identical ganglioglioma cell components as determined by real-time quantitative RT–PCR (qRT–PCR) and in situ hybridization. We observed the LIM-domain-binding 2 (LDB2) transcript, critical for brain development during embryogenesis, as one of the strongest reduced mRNAs in gangliogliomas. Subsequent qRT–PCR in dysembryoplastic neuroepithelial tumours (n = 7) revealed partial expression similarities as well as marked differences from gangliogliomas. The demonstrated gene expression profile differentiates gangliogliomas from other low-grade primary brain tumours. shRNA-mediated silencing of LDB2 resulted in substantially aberrant dendritic arborization in cultured developing primary hippocampal neurons. The present data characterize novel molecular mechanisms operating in gangliogliomas that contribute to the development of dysplastic neurons and an aberrant neuronal network.
Key Words: glioneuronal; development; migration; network; epilepsy; dysplastic
Abbreviations:
ARF3, ADP-ribosylation factor 3; DNETs, dysembryoplastic neuroepithelial tumours; GFP, green fluorescent protein; HSJ2, heat shock 40 kDa protein 4; LDB2, LIM-domain-binding 2; LMO4, LIM domain only 4; MMP2, matrix metallopeptidase 2; NGFR, nerve growth factor receptor; PRKCB1, protein kinase C β-1; ST6GalNAc4, 
-N-acetyl-neuraminyl-2,3-β-galactosyl-1,3-N-acetyl-galactosaminide -2,6-sialyltransferase; TRIB1, tribbles homolog 1
Received February 7, 2008. Revised August 19, 2008. Accepted August 20, 2008.