title: Classification of a frameshift/extended and a stop mutation in WT1 as gain-of-function mutations that activate cell cycle genes and promote Wilms tumour cell proliferation.
abstract: The WT1 gene encodes a zinc finger transcription factor important for normal kidney development. WT1 is a suppressor for Wilms tumour development and an oncogene for diverse malignant tumours. We recently established cell lines from primary Wilms tumours with different WT1 mutations. To investigate the function of mutant WT1 proteins, we performed WT1 knockdown experiments in 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. We also expressed wild-type and mutant WT1 proteins in human mesenchymal stem cells and established gene expression profiles. A detailed analysis of gene expression data enabled us to classify the WT1 mutations as gain-of-function mutations. The mutant WT1(Wilms2) and WT1(Wilms3) 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 tumour cell proliferation. p53 negatively regulates the activity of a large number of these genes that 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. We show that mutant WT1 can physically interact with p53. Together the findings show for the first time that mutant WT1 proteins have a gain-of-function and act as oncogenes for Wilms tumour development by regulating Wilms tumour cell proliferation.
authors.affiliation: Institute of Human Genetics and Anthropology, Heinrich-Heine University, Medical Faculty, Düsseldorf D-40225, Germany.
authors.forename: Maike
authors.initials: M
authors.lastname: Busch
authors.affiliation: Institute of Human Genetics and Anthropology, Heinrich-Heine University, Medical Faculty, Düsseldorf D-40225, Germany.
authors.forename: Heinrich
authors.initials: H
authors.lastname: Schwindt
authors.affiliation: Institute of Human Genetics and Anthropology, Heinrich-Heine University, Medical Faculty, Düsseldorf D-40225, Germany.
authors.forename: Artur
authors.initials: A
authors.lastname: Brandt
authors.affiliation: Institute of Human Genetics and Anthropology, Heinrich-Heine University, Medical Faculty, Düsseldorf D-40225, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Beier
authors.affiliation: Institute of Human Genetics and Anthropology, Heinrich-Heine University, Medical Faculty, Düsseldorf D-40225, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Görldt
authors.affiliation: Institute of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada V8P 5C2.
authors.forename: Paul
authors.initials: P
authors.lastname: Romaniuk
authors.affiliation: Department of Biological Sciences, University at Buffalo, Buffalo, NY 14260, USA.
authors.forename: Eneda
authors.initials: E
authors.lastname: Toska
authors.affiliation: Department of Biological Sciences, University at Buffalo, Buffalo, NY 14260, USA.
authors.forename: Stefan
authors.initials: S
authors.lastname: Roberts
authors.affiliation: Institute of Human Genetics and Anthropology, Heinrich-Heine University, Medical Faculty, Düsseldorf D-40225, Germany.
authors.forename: Hans-Dieter
authors.initials: HD
authors.lastname: Royer
authors.affiliation: Institute of Human Genetics and Anthropology, Heinrich-Heine University, Medical Faculty, Düsseldorf D-40225, Germany royer@uni-duesseldorf.de.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Royer-Pokora
mesh_terms: D002453:Cell Cycle / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D053263:Gene Regulatory Networks; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism; D058977:Molecular Sequence Annotation; D009154:Mutation; D061251:Primary Cell Culture; D025941:Protein Interaction Mapping; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism; D025721:WT1 Proteins / Q000235:genetics* / Q000378:metabolism; D009396:Wilms Tumor / Q000235:genetics* / Q000378:metabolism / Q000473:pathology
chemical_list: D020033:Protein Isoforms; D016159:Tumor Suppressor Protein p53; D025721:WT1 Proteins; C583751:WT1 protein, human