title: The pluripotent renal stem cell regulator SIX2 is activated in renal neoplasms and influences cellular proliferation and migration.
abstract: Embryonal renal mesenchyme contains pluripotent progenitor cells characterized by expression of SIX2, which suppresses cellular differentiation. Additionally hypomethylation of the promotor region in renal neoplasms indicates a role of SIX2 in tumorigenesis. This study focuses therefore on the investigation of SIX2 in different renal neoplasms and the mode and consequences of SIX2 activation. Expression of SIX2 was determined in renal cell carcinomas, nephroblastomas, and dysplastic kidneys using immunohistochemistry and quantitative real-time polymerase chain reaction. Its potential mode of activation was assessed by measuring upstream activators by quantitative real-time polymerase chain reaction and the level of methylation of the promoter region by quantitative DNA methylation analysis. Consequences of SIX2 activation were investigated by overexpressing SIX2 in a cell line. Forty-seven of 49 renal clear cell carcinomas showed nuclear staining of SIX2, whereas all papillary carcinomas were negative. In nephroblastomas of various subtypes blastema showed a significant up-regulation (P < .01) and a strong nuclear protein expression of SIX2 in contrast to negative epithelial and mesenchymal areas. 11 cases of dysplastic kidneys were entirely negative. Upstream activators of SIX2 indicated an activation of the signal transduction pathway in most samples. No difference of promoter methylation status was observed between blastema and epithelial structures. A significantly higher percentage of cells in the S-phase and an increased migration were detected in the cell-line overexpressing SIX2. Our study suggests that activation of SIX2 might contribute to the pathogenesis of renal clear cell carcinomas and nephroblastomas. SIX2 also appears to be a valuable marker for minimal residual blastema contributing to the prognosis of nephroblastomas.
authors.affiliation: Institute of Pathology, Medical University of Graz, Auenbruggerplatz 25, 8036 Graz, Austria.
authors.forename: Upeka
authors.initials: U
authors.lastname: Senanayake
authors.forename: Karin
authors.initials: K
authors.lastname: Koller
authors.forename: Martin
authors.initials: M
authors.lastname: Pichler
authors.forename: Ivo
authors.initials: I
authors.lastname: Leuschner
authors.forename: Heimo
authors.initials: H
authors.lastname: Strohmaier
authors.forename: Ulrike
authors.initials: U
authors.lastname: Hadler
authors.forename: Suman
authors.initials: S
authors.lastname: Das
authors.forename: Gerald
authors.initials: G
authors.lastname: Hoefler
authors.forename: Barbara
authors.initials: B
authors.lastname: Guertl
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D002292:Carcinoma, Renal Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D002648:Child; D019175:DNA Methylation; D015972:Gene Expression Regulation, Neoplastic; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007680:Kidney Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D021782:Multicystic Dysplastic Kidney / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D039904:Pluripotent Stem Cells / Q000378:metabolism / Q000473:pathology; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction; D015854:Up-Regulation; D009396:Wilms Tumor / Q000235:genetics* / Q000378:metabolism / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; C484762:SIX2 protein, human