title: Significant reduction of WT1 gene expression, possibly due to epigenetic alteration in Wilms' tumor.
abstract: WT1 at 11p13 is a tumor suppressor gene, an aberration of which causes Wilms' tumor (WT). Since WT1 expression is reduced in a certain proportion of WTs and its mutation is found only in 10-20% of WTs, we examined WT1 gene silencing due to epigenetic alteration in a total of 22 WTs. WT1 expression was significantly reduced in half of WTs without any mutation in the WT1 gene itself, suggesting that the reduction of expression was possibly epigenetic. We found promoter hypermethylation in one WT with loss of heterozygosity (LOH) and showed that promoter methylation reduced reporter gene activity by a reporter assay. These data suggested that methylation was an epigenetic mechanism leading to WT1 silencing and that the expression-reduced allele by hypermethylation combined with LOH was consistent with the revised two-hit model. In addition, as the beta-catenin mutation is frequently associated with the WT1 mutation, the association of WT1 silencing with the beta-catenin mutation was also investigated. beta-catenin mutated in only one WT without WT1 silencing, suggesting that the beta-catenin mutation was not associated with the reduction of WT1 expression.
authors.affiliation: Division of Molecular Biology and Genetics, Department of Biomolecular Sciences, Saga Medical School, 5-1-1 Nabeshima, Saga 849-8501, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Satoh
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Nakagawachi
authors.forename: Hisaya
authors.initials: H
authors.lastname: Nakadate
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kaneko
authors.forename: Zenjiro
authors.initials: Z
authors.lastname: Masaki
authors.forename: Tsunehiro
authors.initials: T
authors.lastname: Mukai
authors.forename: Hidenobu
authors.initials: H
authors.lastname: Soejima
mesh_terms: D001483:Base Sequence; D044127:Epigenesis, Genetic / Q000235:genetics*; D005333:Fetus / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D007680:Kidney Neoplasms / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D025721:WT1 Proteins / Q000096:biosynthesis / Q000235:genetics*; D009396:Wilms Tumor / Q000235:genetics* / Q000378:metabolism
chemical_list: D025721:WT1 Proteins