ABSTRACT
PURPOSE: Ependymomas are glial tumors of presumably radial glial origin that share morphologic similarities with ependymal cells. The molecular genetics of ependymomas of supratentorial, infratentorial, and spinal location is heterogeneous. We aimed at identifying pathways operative in the development of infratentorial ependymomas. EXPERIMENTAL DESIGN: To do so, gene expression profiles of tumor cells laser microdissected from infratentorial ependymomas (n = 15) were compared with that of nonneoplastic ependymal cells laser microdissected from autopsy tissue (n = 7). RESULTS: Among 31 genes significantly overexpressed (>5-fold) in ependymomas, transcription factor EVI1 (ecotropic viral integration site 1) showed the highest overexpression (35-fold). Evi-1 protein expression could be confirmed in formalin-fixed, paraffin-embedded samples of 26 of 28 infratentorial ependymomas but only in 7 of 47 nonependymal glial tumors (P < 0.001). Furthermore, MDS1/EVI1 fusion transcripts were detectable in 17 of 28 infratentorial ependymomas and significantly correlated with MGMT (O6-methylguanine-DNA-methyltransferase) promoter hypermethylation (P < 0.05). In primary infratentorial ependymoma cells, transfection with EVI1-specific siRNAs resulted in significant growth inhibition [48 hours: 87% ± 2% and 74% ± 10% as compared with control (mean ± SD; P < 0.001)]. The prognostic role of EVI1 could further be validated in an independent cohort of 39 infratentorial and 26 supratentorial ependymomas on the basis of mRNA expression profiling. Although in supratentorial ependymomas EVI1 expression status had no prognostic impact, in infratentorial ependymomas, high EVI1 expression was associated with shorter overall survival and progression-free survival. CONCLUSIONS: To conclude, the transcription factor Evi-1 is overexpressed in infratentorial ependymomas, promotes proliferation of ependymal tumor cells, and is prognostically unfavorable.
Subject(s)
Cell Proliferation , DNA-Binding Proteins/biosynthesis , Ependymoma/metabolism , Infratentorial Neoplasms/metabolism , Transcription Factors/biosynthesis , DNA Methylation , DNA-Binding Proteins/genetics , Ependymoma/pathology , Female , Gene Expression Profiling , Gene Expression Regulation, Neoplastic , Humans , Infratentorial Neoplasms/pathology , MDS1 and EVI1 Complex Locus Protein , Male , O(6)-Methylguanine-DNA Methyltransferase/genetics , Oncogene Proteins, Fusion/metabolism , Prognosis , Promoter Regions, Genetic/genetics , Proto-Oncogenes/genetics , Reverse Transcriptase Polymerase Chain Reaction , Transcription Factors/genetics , Tumor Cells, CulturedABSTRACT
The pathogenesis of choroid plexus papillomas, intraventricular papillary neoplasms most often occurring sporadically in children and young adults, remains poorly understood. To identify pathways operative in the development of choroid plexus papillomas, gene expression profiles obtained from laser-microdissected human choroid plexus papilloma cells (n = 7) were compared with that of normal choroid plexus epithelial cells laser microdissected from autopsy tissue (n = 8). On DNA microarray data analysis, 53 probe sets were differentially expressed in choroid plexus papilloma tumor cells (>7-fold). Up-regulation of TWIST1, WIF1, TRPM3, BCLAF1, and AJAP1, as well as down-regulation of IL6ST was confirmed using quantitative reverse transcription-PCR. Knockdown of Twist1 gene expression in the rat choroid plexus epithelial cell line Z310 significantly reduced proliferation as assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and cell invasion in a Matrigel assay, whereas cell migration was not affected. Screening for expressional changes of cancer-related genes upon Twist1 knockdown revealed up-regulation of Cdkn1a, Cflar, and Serpinb2 and down-regulation of Figf. To conclude, using gene expression profiling, several genes differentially expressed in human choroid plexus papillomas could be identified. Among those, TWIST1 is highly expressed in choroid plexus papillomas and promotes proliferation and invasion.
Subject(s)
Nuclear Proteins/biosynthesis , Papilloma, Choroid Plexus/metabolism , Papilloma, Choroid Plexus/pathology , Twist-Related Protein 1/biosynthesis , Adolescent , Adult , Animals , Cell Growth Processes/physiology , Cell Movement/physiology , Child , Child, Preschool , Epithelial Cells/metabolism , Epithelial Cells/pathology , Female , Gene Expression Profiling , Humans , Infant , Infant, Newborn , Male , Microdissection , Middle Aged , Neoplasm Invasiveness , Nuclear Proteins/genetics , Papilloma, Choroid Plexus/genetics , Rats , Twist-Related Protein 1/genetics , Young AdultABSTRACT
Granulocyte-colony stimulating factor (G-CSF) receptor signaling counteracts detrimental pathways in ischemic stroke. In rodents, neuroprotection provided by the G-CSF system involves up-regulation of the G-CSF receptor and its ligand, G-CSF, during cerebral ischemia. The confirmation of a similar response in the human brain would be an important rationale for the use of G-CSF in clinical stroke trials. Therefore, the temporal and cellular profile of G-CSF and G-CSF receptor expression was examined in a series of human stroke brains. The median age of the 21 stroke patients was 67 years; median time from death to autopsy was 24 h (range: 10-67 h). In acute ischemic stroke, strong neuronal G-CSF receptor immunoreactivity was encountered in the infarct area and the peri-infarct rim as compared to the contralateral cortex. In subacute infarctions, microglial and macrophage G-CSF receptor immunoreactivity predominated, whereas chronic infarction was characterized by the presence of G-CSF receptor expressing reactive astrocytes. Neuronal G-CSF expression was encountered very early upon ischemic stroke. At later time-points, an up-regulation of vascular G-CSF expression in the peri-infarct area prevailed. In conclusion, the observed up-regulation of G-CSF receptors and G-CSF points towards a role in the pathophysiology of human ischemic stroke.
