Unknown,Transcriptomics,Genomics,Proteomics

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Analysis of TALE homeobox genes in neuroblastic tumors: ganglioneuroblastoma and ganglioneuroma

ABSTRACT: A large proportion of patients suffering from the malignant pediatric tumor neuroblastoma die of progressive disease despite intensive therapy. Neuroblastomas belong to the group of neuroblastic tumors, together with the more benign, differentiated ganglioneuroblastomas and ganglioneuromas. Little is known of the genes driving the differentiation processes in these tumor types. A search for the transcription factors differentially expressed between ganglioneuromas, ganglioneuroblastomas, and neuroblastomas in a series of 110 neuroblastic tumors (NB110) identified a large number of HOX- and TALE (Three Amino acid Loop Extension)-class homeobox transcription factor genes. The MEIS1-3, PBX1 and -3, and PKNOX1 TALE genes showed highest expression in neuroblastomas and lowest in ganglioneuromas and ganglioneuroblastomas. The PKNOX2 and TGIF1-2 genes showed the opposite expression pattern. This suggests an involvement of TALE genes in neuroblastoma differentiation. Expression of MEIS1, a known oncogene in haematopoietic tumors, was high in all neuroblastomas, and strongly correlated with undifferentiated histology. Consequently, we generated IMR-32 neuroblastoma cells capable of inducible shRNA-mediated MEIS1 knockdown. We observed differentiation, growth arrest and induction of apoptosis upon MEIS1 down-regulation. Affymetrix profiling of time-course experiments using these cells allowed the identification of MEIS1 target genes. Analysis of the target genes in the NB110 series showed that 323 of these were also significantly correlated to MEIS1 expression and to tumor differentiation in neuroblastic tumors. Genes involved in the cell cycle and in developmental pathways were over-represented in this gene set. We conclude that MEIS1 governs several of the signal transduction routes important for neuroblastoma survival and differentiation. 12 ganglioneuroma (gn) and 10 ganglioneuroblastoma (gnb) were analyzed.

ORGANISM(S): Homo sapiens

SUBMITTER: Rogier Versteeg

PROVIDER: E-GEOD-18271 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Neuroblastoma tumors frequently show loss of heterozygosity of chromosome 11q with a shortest region of overlap in the 11q23 region. These deletions are thought to cause inactivation of tumor suppressor genes leading to haploinsufficiency. Alternatively, micro-deletions could lead to gene fusion products that are tumor-driving. To identify such events we analyzed a series of neuroblastomas by comparative genomic hybridization (CGH) and single nucleotide polymorphism (SNP) arrays and integrated these data with Affymetrix mRNA profiling data with the bioinformatic tool R2 (http://r2.amc.nl). We identified three neuroblastoma samples with small interstitial deletions at 11q23, upstream of the forkhead-box transcription factor FOXR1. Genes at the proximal side of the deletion were fused to FOXR1, resulting in fusion transcripts of MLL-FOXR1 and PAFAH1B2-FOXR1. FOXR1 expression has only been detected in early embryogenesis. Affymetrix microarray analysis showed high FOXR1 mRNA expression exclusively in the neuroblastomas with micro-deletions and rare cases of other tumor types, including osteosarcoma cell line HOS. RNAi silencing of FOXR1 strongly inhibited proliferation of HOS cells and triggered apoptosis. Expression profiling of these cells and reporter assays suggested that FOXR1 is a negative regulator of forkhead-box factor mediated transcription. The neural crest stem cell line JoMa1 proliferates in culture conditional to activity of a MYC-ER transgene. Over-expression of the wild-type FOXR1 could functionally replace MYC and drive proliferation of JoMa1. We conclude that FOXR1 is recurrently activated in neuroblastoma by intrachromosomal deletion/fusion events, resulting in over-expression of fusion transcripts. Forkhead-box transcription factors have not been previously implicated in neuroblastoma pathogenesis. Furthermore, this is the first identification of intrachromosomal fusion genes in neuroblastoma. Time series Affymetrix U133p2 profiling of Osteosarcoma HOS cells transduced with FOXR1 targeted shRNAs or control shRNA

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Analysis of TALE homeobox genes in neuroblastic tumors: ganglioneuroblastoma and ganglioneuroma

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