Expression of WT1 protein in fetal kidneys and Wilms tumors

• Published in: Laboratory investigation Vol. 71; no. 4; pp. 472 - 479
• Main Authors: GRUBB, G. R, KANKATSU YUN, WILLIAMS, B. R. G, ECCLES, M. R, REEVE, A. E
• Format: Journal Article
• Language: English
• Published: New York, NY Nature Publishing 01.10.1994
• Subjects: Biological and medical sciences; Blotting, Western; DNA - analysis; DNA - genetics; DNA, Neoplasm - analysis; DNA, Neoplasm - genetics; DNA-Binding Proteins - analysis; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Fluorescent Antibody Technique; Gene Expression Regulation; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; In Situ Hybridization; Kidney - chemistry; Kidney - embryology; Kidney - metabolism; Kidney Neoplasms - chemistry; Kidney Neoplasms - genetics; Kidney Neoplasms - metabolism; Kidneys; Medical sciences; Nephrology. Urinary tract diseases; RNA, Messenger - analysis; RNA, Messenger - genetics; Transcription, Genetic; Tumors of the urinary system; Wilms Tumor - chemistry; Wilms Tumor - genetics; Wilms Tumor - metabolism; WT1 Proteins; Immunohistochemistry; Molecular hybridization; Urinary system disease; In situ; Wilms tumor; Renal disease; Tumorigenicity; Malignant tumor; Kidney
• ISSN: 0023-6837; 1530-0307

Wilms' tumors are embryonic kidney neoplasms believed to result from a perturbation in the development of the metanephric blastema. A candidate gene (WT1) has been cloned that has been found to be mutated in a number of Wilms' tumors, consistent with its suggested role as a tumor suppressor gene. This gene has been shown to be essential to the normal development of the embryonic kidney. The aim of the present study was to provide information on the level at which the WT1 gene is regulated. Immunohistochemistry, immunofluorescence, and in situ hybridization was used to examine the localization of WT1 protein and mRNA, respectively. We further used immunofluorescence to examine the WT1 expression in seven Wilms' tumors. In fetal kidneys, WT1 transcripts were detected with increasing levels of hybridization signal in induced blastemal cells, renal vesicles, pre-podocytes of comma- and S-shaped bodies, and podocytes of glomeruli. WT1 protein, detected by an antibody raised against recombinant WT1 fusion protein, was seen in the nuclei of the same cell types mentioned above, and the staining intensity was comparable to the levels of WT1 transcripts. Immunostaining of seven Wilms tumors demonstrated that WT1 protein was expressed only in neoplastic structures whose normal counterparts also expressed WT1 protein. Neither stromal cells nor rhabdomyoblasts contained WT1 protein. The results show that in fetal kidney, WT1 transcripts and protein are coordinately expressed, and strongly associated with differentiation of metanephric blastemal cells into epithelial cells. Furthermore, the finding that WT1 transcripts and protein are coordinately expressed, suggests that WT1 gene expression is primarily regulated at the level of transcription.