ABSTRACT: Chemotherapy induced terminal muscle differentiation in WT1 mutant Wilms tumors is associated with cell cycle exit and a loss of growth potential
Project description:Patients with Wilms tumors are efficiently treated by chemotherapy; however, tumors with mutant WT1 genes show a poor volume response. Here we used an unbiased gene expression profiling approach and identified a novel mechanism of conventional chemotherapy that explains how the cure of these patients is brought about. Transcription profiling of an untreated WT1 mutant Wilms tumor (Wilms10) and a corresponding lung metastasis that was detected after long-term chemotherapy, revealed the induction of a myogenic transcriptional network with concomitant down-regulation of cell cycle genes. Cell culture experiments showed convincingly that the Wilms10 tumor cells from this lung metastasis had lost their growth potential due to an induction of terminal skeletal muscle differentiation by chemotherapy. These results were confirmed using a set of Wilms tumors with mutant WT1 genes that were treated by preoperative chemotherapy. We conclude here that chemotherapy-induced terminal skeletal muscle differentiation of Wilms tumors with concomitant loss of growth potential enables the cure of Wilms tumor patients with WT1 mutations in the clinical setting. We have shown before that cell lines derived from Wilms tumors with WT1 mutations have characteristic features of mesenchymal stem cells and it will be of great interest to evaluate whether other tumor types with stem cell features show a differentiation reponse to chemotherapy.
Project description:Gain-of-function mutations in exon 3 of beta-catenin (CTNNB1) are specific for Wilms' tumors that have lost WT1, but 50% of WT1-mutant cases lack such "hot spot" mutations. To ask whether stabilization of beta-catenin might be essential after WT1 loss, and to identify downstream target genes, we compared expression profiles in WT1-mutant versus WT1 wild-type Wilms' tumors. Supervised and nonsupervised hierarchical clustering of the expression data separated these two classes of Wilms' tumor. The WT1-mutant tumors overexpressed genes encoding myogenic and other transcription factors (MOX2, LBX1, SIM2), signaling molecules (TGFB2, FST, BMP2A), extracellular Wnt inhibitors (WIF1, SFRP4), and known beta-catenin/TCF targets (FST, CSPG2, CMYC). Beta-Catenin/TCF target genes were overexpressed in the WT1-mutant tumors even in the absence of CTNNB1 exon 3 mutations, and complete sequencing revealed gain-of-function mutations elsewhere in the CTNNB1 gene in some of these tumors, increasing the overall mutation frequency to 75%. Lastly, we identified and validated a novel direct beta-catenin target gene, GAD1, among the WT1-mutant signature genes. These data highlight two molecular classes of Wilms' tumor, and indicate strong selection for stabilization of beta-catenin in the WT1-mutant class. Beta-Catenin stabilization can initiate tumorigenesis in other systems, and this mechanism is likely critical in tumor formation after loss of WT1. Experiment Overall Design: Identification of WNT/Beta-Catenin or WT1 target genes. 39 individual samples.
Project description:The Wilms tumor 1 (WT1) gene encodes a zinc finger transcription factor important for normal kidney development. WT1 is a suppressor for Wilms tumor development and an oncogene for diverse malignant tumors. We recently established cell lines from primary Wilms tumors and identified the corresponding WT1 mutations (see GSE18058). To investigate the function of mutant WT1 proteins we performed WT1 knockdown experiments in primary Wilms tumor cell lines with a frameshift/extension (p.V432fsX87 = Wilms3) and a stop mutation (p.P362X = Wilms2) of WT1, followed by genome wide gene expression analysis. A detailed analysis of these gene expression data using MetaCore enabled us to classify the WT1 mutations as gain of function mutations. The mutant WT1Wilms2 and WT1Wilms3 proteins acquired an ability to modulate the expression of a highly significant number of genes from the G2/M phase of the cell cycle, and WT1 knockdown experiments showed that they are required for Wilms tumor cell proliferation. Data from the literature show that p53 negatively regulates the activity of a large number of these genes which are also part of a core proliferation cluster in diverse human cancers. Our data strongly suggest that mutant WT1 proteins facilitate expression of these cell cycle genes by antagonizing transcriptional repression mediated by p53. In light of this it is important to note that mutant WT1 has an ability to physically interact with the tumor suppressor p53. Together the findings show for the first time, that mutant WT1 proteins have a gain of function and act as oncogenes for Wilms tumor development by regulating Wilms tumor cell proliferation.
Project description:The Wilms tumor 1 (WT1) gene encodes a zinc finger transcription factor important for normal kidney development. WT1 is a suppressor for Wilms tumor development and an oncogene for diverse malignant tumors. We recently established cell lines from primary Wilms tumors and identified the corresponding WT1 mutations (see GSE18058). To investigate the function of mutant WT1 proteins we performed WT1 knockdown experiments in primary Wilms tumor cell lines with a frameshift/extension (p.V432fsX87 = Wilms3) and a stop mutation (p.P362X = Wilms2) of WT1, followed by genome wide gene expression analysis. A detailed analysis of these gene expression data using MetaCore enabled us to classify the WT1 mutations as gain of function mutations. The mutant WT1Wilms2 and WT1Wilms3 proteins acquired an ability to modulate the expression of a highly significant number of genes from the G2/M phase of the cell cycle, and WT1 knockdown experiments showed that they are required for Wilms tumor cell proliferation. Data from the literature show that p53 negatively regulates the activity of a large number of these genes which are also part of a core proliferation cluster in diverse human cancers. Our data strongly suggest that mutant WT1 proteins facilitate expression of these cell cycle genes by antagonizing transcriptional repression mediated by p53. In light of this it is important to note that mutant WT1 has an ability to physically interact with the tumor suppressor p53. Together the findings show for the first time, that mutant WT1 proteins have a gain of function and act as oncogenes for Wilms tumor development by regulating Wilms tumor cell proliferation. siWT1 mediated knockdown in two Wilms tumor cell lines one and two days after transfection versus non-silencing controls
Project description:Gain-of-function mutations in exon 3 of beta-catenin (CTNNB1) are specific for Wilms' tumors that have lost WT1, but 50% of WT1-mutant cases lack such "hot spot" mutations. To ask whether stabilization of beta-catenin might be essential after WT1 loss, and to identify downstream target genes, we compared expression profiles in WT1-mutant versus WT1 wild-type Wilms' tumors. Supervised and nonsupervised hierarchical clustering of the expression data separated these two classes of Wilms' tumor. The WT1-mutant tumors overexpressed genes encoding myogenic and other transcription factors (MOX2, LBX1, SIM2), signaling molecules (TGFB2, FST, BMP2A), extracellular Wnt inhibitors (WIF1, SFRP4), and known beta-catenin/TCF targets (FST, CSPG2, CMYC). Beta-Catenin/TCF target genes were overexpressed in the WT1-mutant tumors even in the absence of CTNNB1 exon 3 mutations, and complete sequencing revealed gain-of-function mutations elsewhere in the CTNNB1 gene in some of these tumors, increasing the overall mutation frequency to 75%. Lastly, we identified and validated a novel direct beta-catenin target gene, GAD1, among the WT1-mutant signature genes. These data highlight two molecular classes of Wilms' tumor, and indicate strong selection for stabilization of beta-catenin in the WT1-mutant class. Beta-Catenin stabilization can initiate tumorigenesis in other systems, and this mechanism is likely critical in tumor formation after loss of WT1. Keywords: single channel
Project description:A ""Cartes d'Identite des Tumeurs"" (CIT) project from the french Ligue Nationale Contre le Cancer (http://cit.ligue-cancer.net). 73 samples (60 tumoral, 6 normal kidneys (NK), 3 fetal kidneys (FK) and 4 cell lines (L)), hybridized on Affymetrix HG-U133A GeneChips.Tumor classification based on a characterization of WT1 and Betacatenin. Identification of major differences between two categories of Wilms' Tumors defined according to WT1 and CTNNB1 genomic and expression features. First large scale study based on post-chemotherapy resected tumors, according to the SIOP protocoles.
Project description:Wilms tumors are genetically heterogeneous kidney tumors whose cells of origin are unknown. Tumors with WT1 mutations and concomitant loss of the wild-type allele represent a distinct subgroup, frequently associated with mutations in CTNNB1. Here we describe the establishment and characterization of long-term cell cultures derived from five individual Wilms tumors with WT1 mutations. Three of these tumor cell lines also had CTNNB1 mutations and an activated canonical Wnt signaling pathway as measured by β-catenin/TCF transcriptional activity. Four of the five Wilms cell lines had a stable normal karyotype for at least 25 passages, and four lines showed loss of heterozygosity of chromosome 11p due to mitotic recombination in 11p11. Gene expression profiling revealed that the Wilms tumor cell lines are highly similar to human mesenchymal stem cells (MSCs) and FACS analysis demonstrated expression of MSC-specific surface proteins CD105, CD90 and CD73. The stem cell like nature of the Wilms tumor cells is further supported by their adipogenic, chondrogenic, osteogenic and myogenic differentiation potentials. By generating multipotent mesenchymal precursors from paraxial mesoderm (PAM) in tissue culture using embryonal stem cells, gene expression profiles of PAM and MSCs were described. Using these published gene sets we found coexpression of a large number of genes in Wilms tumor cell lines, PAM and MSCs. Lineage plasticity is indicated by the simultaneous expression of genes from the mesendodermal and neuroectodermal lineages. We conclude that Wilms tumors with WT1 mutations have specific traits of PAM, which is the source of kidney stromal cells.
Project description:We describe a stromal predominant Wilms tumor with a complex, tumor specific chromosome 11 aberration: a homozygous deletion of the entire WT1 gene within a heterozygous 11p13 deletion and an additional region of uniparental disomy (UPD) limited to 11p15.5-p15.2 including the IGF2 gene. The tumor carried a heterozygous p.T41A mutation in CTNNB1. Cells established from the tumor carried the same chromosome 11 aberration, but a different, homozygous p.S45Î CTNNB1 mutation. Uniparental disomy (UPD) 3p21.3pter lead to the homozygous CTNNB1 mutation. The tumor cell line was immortalized with telomerase (TERT) and a novel triple ts mutant SV40 large T antigen (LT). This cell line is cytogenetically stable and can be grown indefinitely. It is a valuable tool to study the effect of a complete lack of WT1 in tumor cells. The tumor cell line and the immortalized cells have a limited potential for muscle/osteogenic/adipogenic differentiation similar to all other WT1 mutant cell lines. Array expression experiment of Wilms tumor cell lines
Project description:The Wilms tumor gene, Wt1, is specifically expressed in Sertoli cells (SCs) which support spermatogenesis. Germ cell loss was found in Wt1 knockout mice. In vitro studies demonstrated that Wt1 was essential for cell polarity maintenance in SCs. We used Digital Gene Expression Tag Profiling to detail the global programme of gene expression after Wt1 deletion in sertoli cell and identified 710 gene expression level change more than 2 times.