The molecular genetics of Wilms tumor

Wilms' tumour gene (wt1) expression at diagnosis has no prognostic relevance in childhood acute lymphoblastic leukaemia treated by an intensive chemotherapy protocol

Expression of the Wilms' tumour gene (wt1) has been demonstrated in a large proportion of human acute leukaemias and is thought to play a role in leukaemogenesis. Recent observations in adult patients with acute leukaemia suggest that wt1 gene expression is a poor prognostic factor. In childhood acute leukaemia, the clinical role of wt1 gene expression has not been established. We have therefore investigated bone marrow samples from 50 children with acute lymphocytic leukaemia at the time of diagnosis for the presence of wt1 transcripts to determine whether wt1 gene expression is associated with specific characteristics of leukaemic cells and whether it is predictive of response to treatment. All patients were treated according to the ALL-BFM 90 protocol. The median observation time was 30 months. Wt1 transcripts were detected by RT-PCR in 60% of the diagnostic samples. Wt1 PCR positive patients showed a higher median leukocyte and peripheral blast cell count than wt1 negative patients. High and intermediate risk patients more frequently displayed wt1 transcripts than low risk patients. No correlation between wtl gene expression and FAB type, immunophenotype, co-expression of myeloid antigens or karyotype has been observed. Furthermore, there was no correlation between wt1 gene expression at diagnosis and achievement of complete remission (CR) and no difference in disease-free survival (DFS) or overall survival (OS) between wt1 positive and negative patients (p > 0.1). These data indicate that (1) wt1 gene expression at diagnosis is detected more frequently in patients with high leukocyte and peripheral blast cell counts, but is not associated with specific characteristics of leukaemic cells, (2) wt1 gene expression is not an independent prognostic factor for CR, DFS or OS in childhood ALL treated by an intensive therapy protocol.

Wilms' tumor in the adult--report of a case and review of the literature

Wilms' tumor is rare in adults. Its histology, grading and staging are identical to those in children. Investigators agree on a combined modality approach in the treatment of adult Wilms' tumor (AWT), but differ on how aggressive it should be. Some advocate adopting the current pediatric protocols which take into account tumor stage and grade. Others recommend using advanced disease regimens for all stages and grades. We report on an 18 year-old male with stage IV favorable histology Wilms' tumor. The patient underwent radical nephrectomy and received postoperative radiotherapy with intensive four-drug chemotherapy. He had one relapse after 12 months which was successfully treated with chemotherapy and radiotherapy. He remains in remission without relapses 36 months after the initial diagnosis. The genetics of Wilms' tumor has been well studied in children but is practically unknown in adults; karyotype and molecular genetic studies in this case were normal.

Characterization of monoclonal antibodies directed to the amino-terminus of the WT1, Wilms' tumor suppressor protein

We have produced and characterized three monoclonal antibodies (MAbs) directed to the amino terminus of the WT1 Wilms' tumor suppressor transcription factor and compared their properties to rabbit polyclonal sera raised to the same immunogen. A recombinant protein consisting of amino acids 1-181 of human WT1 was overexpressed in E. coli, purified, and used as the immunogen. Three MAbs designated 6F-H2, 6F-H7, and 6F-HC-17--all of the IgG1 subclass--were selected and further characterized. Each recognized all isoforms of the full-length WT1 protein in Western blot assays and immunoprecipitated WT1 in both physiologic buffers and under high detergent/high salt (RIPA) conditions. Preliminary epitope mapping suggests that all three MAbs recognize a region in the amino terminal 84 amino acids of WT1 and that the MAbs do not recognize the polyglycine or polyproline regions of the protein. The WT1 antibodies do not recognize the structurally and functionally related early growth response (EGR)1, EGR2, EGR3, or EGR4 proteins. All WT1 MAbs recognize the murine WT1 protein and immunohistochemical staining of murine embryonic and newborn kidney sections show strong staining of condensing metanephric mesenchyme and primitive podocytes in developing glomeruli. These WT1-specific MAbs should be useful in characterizing the biochemical and developmental roles of WT1 and in defining the emerging role of WT1 as a diagnostic and/or prognostic marker in mesothelioma, leukemias, and breast cancer.

The development of the kidney

This chapter describes the earlier stages of development of the vertebrate metanephric kidney. It focuses on the mouse and descriptive morphology is used for considering both molecular mechanisms, underpinning kidney morphogenesis and differentiation, and the ways in which these processes can go awry and lead to congenital kidney disorders—particularly in humans. The mature kidney is a fairly complex organ attached to an arterial input vessel and two output vessels, the vein and the ureter. Inside, the artery and vein are connected by a complex network of capillaries that invade a large number of glomeruli, the proximal entrance to nephrons, which are filtration units that link to an arborized collecting-duct system that drains into the ureter. The ability of the kidney and isolated metanephrogenic mesenchyme, to develop in culture means that the developing tissues can be subjected to a wide variety of experimental procedures designed to investigate their molecular and cellular properties and to test hypotheses about developmental mechanisms.