Wilms' tumour is a pediatric neoplasm exhibiting histologic features of developing kidney. Although the majority of Wilms' tumour patients are treated effectively, approximately 15% develop metastases and of these, 30% succumb to their disease. The biologic factors governing Wilms' tumour metastasis are largely unknown. Attempts at deriving representative Wilms' tumour cell lines, which could facilitate functional studies, have only been partially successful thus far. We now report on derivation and characterization of a Wilms' tumour cell line, WiT 49, from a first-generation xenograft of a human Wilms' tumour lung metastasis. WiT 49 recapitulates the phenotype of the parent tumours (primary and lung metastasis) and expresses normal WT1, overexpresses IGFII and carries a frequently identified p53 mutation. We recently reported overexpression of hepatocyte growth factor(HGF) and its receptor met in a series of Wilms' tumours with higher levels in homotypic metastatic cases. We therefore examined WiT 49 for expression of HGF/met and for met signaling targets associated with cell adhesion and cytoplasmic mediators of transcription using Western blot, co-immunoprecipitation, immunofluorescence labeling and zymography. Our results show co-expression of HGF and met protein, absence of E-cadherin, high levels of beta-catenin co-immunolocalized to met at the cell membrane and moderate levels of gamma-catenin and ezrin protein expression. After cell fractionation, beta-catenin was detected in the cytoplasm and nuclei of WiT 49 with relatively higher levels in the cytoplasm as compared to nuclei. Examination of MMP expression in WiT 49 showed constitutive activation of MMP 9 and latent MMP 2 supporting possible beta-catenin-mediated transcriptional activation. The WiT 49 cell line responded to recombinant human HGF by an increase in the expression of the met receptor, recruitment of the Gab-1 adapter protein to met and release of bound beta-catenin from met. Our studies therefore establish WiT 49 as a representative Wilms' tumour cell line derived from a lung metastasis that co-expresses HGF/met and shows absence of the cadherin-catenin complex supporting a role for these factors in regulation of the invasive and metastatic phenotype in Wilms' tumour.
Copyright 2003 Wiley-Liss, Inc.