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RNA sequencing data from beta-catenin activated, E2-2 wildtype and beta-catenin activated, E2-2 deleted cultured fetal mouse kidneys.

ABSTRACT: Oncogenic stabilizing mutations in the beta-catenin gene CTNNB1 are common in one class of human Wilms tumors. To model these tumors, we crossed mice carrying an inducible Cre recombinase (Rosa26-CreERT2) with a conditional gain-of-function beta-catenin allele (Ctnnb1Ex3flox). We obtained kidneys at embryonic day 13.5 and placed them in organ culture with tamoxifen. Multiple small tumors formed in the Ctnnb1∆Ex3 kidneys while the control kidneys developed normally. Immunostaining for Sall1, a marker of condensing metanephric mesenchyme, indicated that the tumors arise from this tissue compartment, analogous to the origin of human Wilms tumors. Expression profiling identified a set of induced genes overlapping with those up-regulated in human Wilms tumors with CTNNB1 mutations, including genes encoding feedback inhibitors of Wnt/beta-catenin signaling, the epithelial-mesenchymal transition (EMT) inducers, and the transcription factor E2-2 (ITF2/TCF4). A conditional deletion of E2-2 showed that this gene is important for growth of the nephroblastomas, in part via promoting an epithelial to mesenchymal transition downstream of beta-catenin. Given these cross-species validations, and genetic proof of the oncogenic function of a key downstream target gene, we expect that this rapid and efficient organ culture model will be useful for further studies to dissect and inhibit oncogenic Wnt/beta-catenin signaling.

ORGANISM(S): Mus musculus

PROVIDER: GSE63418 | GEO | 2017/02/20

SECONDARY ACCESSION(S): PRJNA268204

REPOSITORIES: GEO

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Project description:Medulloblastoma is the most frequent malignant pediatric brain tumor. Considerable efforts are dedicated to identify markers that help to refine treatment strategies. The activation of the Wnt/beta-catenin pathway occurs in 10-15% of medulloblastomas and has been recently described as a marker for favorable patient outcome. We report a series of 72 pediatric medulloblastomas evaluated for beta-catenin immunostaining, CTNNB1 mutations, and studied by comparative genomic hybridization. Gene expression profiles were also available in a subset of 40 cases. Immunostaining of beta-catenin showed extensive nuclear staining (>50% of the tumor cells) in 6 cases and focal nuclear staining (<10% of cells) in 3 cases. The other cases exhibited either a signal strictly limited to the cytoplasm (58 cases) or were negative (5 cases). CTNNB1 mutations were detected in all beta-catenin extensively nucleopositive cases. The expression profiles of these cases documented a strong activation of the Wnt/beta-catenin pathway. Remarkably, 5 out of these 6 tumors showed a complete loss of chromosome 6. In contrast, cases with focal nuclear beta-catenin staining, as well as tumors with negative or cytoplasmic staining, never demonstrated CTNNB1 mutation, Wnt/beta-catenin pathway activation or chromosome 6 loss. Patients with extensive nuclear staining were significantly older at diagnosis and were in continuous complete remission after a mean follow-up of 75.7 months (range 27.5-121.2) from diagnosis. All three patients with a focal nuclear staining of beta-catenin died within 36 months from diagnosis. Altogether, these data confirm and extend previous observations that CTNNB1-mutated tumors represent a distinct molecular subgroup of medulloblastomas with favorable outcome, indicating that therapy de-escalation should be considered. Yet, international consensus on the definition criteria of this distinct medulloblastoma subgroup should be achieved. A series of 72 pediatric medulloblastoma tumors has been studied at the genomic level (array-CGH), screened for CTNNB1 mutations and beta-catenin expression (immunohistochemistry). A subset of 40 tumor samples has been analyzed at the RNA expression level (Affymetrix HG U133 Plus 2.0). Correlations between the genomic data, the expression data, the mutational screening, the pathological classification and clinical data is presented in the study. note: aCGH data not submitted to GEO

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RNA sequencing data from beta-catenin activated, E2-2 wildtype and beta-catenin activated, E2-2 deleted cultured fetal mouse kidneys.

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