Fassunke Jana, Majores Michael, Tresch Achim, Niehusmann Pitt, Grote Alexander, Schoch Susanne, Becker Albert J
Department of Neuropathology, University of Bonn Medical Center, Bonn, Germany.
Brain. 2008 Nov;131(Pt 11):3034-50. doi: 10.1093/brain/awn233. Epub 2008 Sep 26.
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.
神经节胶质瘤是药物难治性局灶性癫痫患者中最常见的肿瘤，其特征在于神经胶质和发育异常的神经元成分的组织学组合、高度分化的表型以及罕见的基因突变。它们的分子基础以及与其他低级别脑肿瘤的关系尚未完全明确。由于神经节胶质瘤的细胞复杂性、缺乏合适的对照组织以及敏感的表达谱分析方法，对其基因表达改变的系统性研究受到了阻碍。在此，我们使用了从神经外科手术获取的离散显微切割的神经节胶质瘤及相邻对照脑组织，这些组织来自相同患者（n = 6），在神经胶质和神经元成分方面经过仔细匹配，数量足以进行寡核苷酸微阵列杂交且无需重复扩增。多变量统计分析确定了神经节胶质瘤中大量表达改变的基因。通过实时定量逆转录聚合酶链反应（qRT-PCR）和原位杂交确定，许多差异表达的转录本与细胞内和细胞间信号传导相关，包括蛋白激酶C及其靶点NELL2，它们存在于相同的神经节胶质瘤细胞成分中。我们观察到在胚胎发育过程中对脑发育至关重要的LIM结构域结合蛋白2（LDB2）转录本是神经节胶质瘤中表达降低最为显著的mRNA之一。随后对胚胎发育不良性神经上皮肿瘤（n = 7）进行的qRT-PCR显示，其与神经节胶质瘤存在部分表达相似性以及明显差异。所展示的基因表达谱将神经节胶质瘤与其他低级别原发性脑肿瘤区分开来。shRNA介导的LDB2沉默导致培养的发育中的原代海马神经元出现明显异常的树突分支。目前的数据揭示了神经节胶质瘤中存在的新分子机制，这些机制促成了发育异常的神经元和异常神经网络的形成。
