Hypoxia promotes invasive growth by transcriptional activation of the met protooncogene.

Uncontrolled cell survival, growth, angiogenesis and metastasis are essential hallmarks of cancer. Genetic and biochemical data have demonstrated that the growth and motility factor hepatocyte growth factor/scatter factor (HGF/SF) and its receptor, the tyrosine kinase MET, have a causal role in all of these processes, thus providing a strong rationale for targeting these molecules in cancer. Parallel progress in understanding the structure and function of HGF/SF, MET and associated signalling components has led to the successful development of blocking antibodies and a large number of small-molecule MET kinase inhibitors. In this Review, we discuss these advances, as well as results from recent clinical studies that demonstrate that inhibiting MET signalling in several types of solid human tumours has major therapeutic value.

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Targeting MET in cancer: rationale and progress

Rearrangements of the cytoskeleton and cell contacts induce process formation during differentiation of conditionally immortalized mouse podocyte cell lines

How do individual cells organize into multicellular tissues? Here, we propose that the morphogenetic behaviour of epithelial cells is guided by two distinct elements: an intrinsic differentiation programme that drives formation of a lumen-enclosing monolayer, and a growth factor-induced, transient de-differentiation that allows this monolayer to be remodelled.

Building epithelial architecture: insights from three-dimensional culture models

Developmental roles of HGF/SF and its receptor, the c-Met tyrosine kinase.

Several lines of evidence suggest that hepatocyte growth factor/scatter factor (HGF/SF), a soluble protein secreted by embryo fibroblasts and several fibroblast lines, may elicit morphogenesis in adjacent epithelial cells. We investigated the role of HGF/SF and its membrane receptor, the product of the c-met protooncogene, in the early development of the metanephric kidney. At the inception of the mouse metanephros at embryonic day 11, HGF/SF was expressed in the mesenchyme, while met was expressed in both the ureteric bud and the mesenchyme, as assessed by reverse transcription PCR, in situ hybridization, and immunohistochemistry. To further investigate the expression of met in renal mesenchyme, we isolated 13 conditionally immortal clonal cell lines from transgenic mice expressing a temperature-sensitive mutant of the SV-40 large T antigen. Five had the HGF/SF+/met+ phenotype and eight had the HGF/SF-/met+ phenotype. None had the HGF/SF+/met- nor the HGF/SF-/met- phenotypes. Thus the renal mesenchyme contains cells that express HGF/SF and met or met alone. When metanephric rudiments were grown in serum-free organ culture, anti-HGF/SF antibodies (a) inhibited the differentiation of metanephric mesenchymal cells into the epithelial precursors of the nephron; (b) increased cell death within the renal mesenchyme; and (c) perturbed branching morphogenesis of the ureteric bud. These data provide the first demonstration for coexpression of the HGF/SF and met genes in mesenchymal cells during embryonic development and also imply an autocrine and/or paracrine role for HGF/SF and met in the survival of the renal mesenchyme and in the mesenchymal-epithelial transition that occurs during nephrogenesis. They also confirm the postulated paracrine role of HGF/SF in the branching of the ureteric bud.

/pdf/roles-of-hepatocyte-growth-factor-scatter-factor-and-the-met-rojpfkctln.pdf

Roles of hepatocyte growth factor/scatter factor and the met receptor in the early development of the metanephros.

Deregulation of cell survival in cystic and dysplastic renal development.

Development of epithelial organs requires co-ordinated interactions between epithelial and mesenchymal tissues. Studies using null mutant mice have indicated that the ret receptor and its ligand, glia

Glial Cell Line-Derived Neurotrophic Factor Stimulates Ureteric Bud Outgrowth and Enhances Survival of Ureteric Bud Cells in vitro

The adult kidney is highly vascular and receives about 20% of the cardiac output, yet the mode of development of the glomerular capillaries is not fully understood. At the inception of nephrogenesis the condensed metanephric mesenchyme contains no patent capillaries. However, in this current study we detected vascular endothelial growth factor (VEGF) mRNA and protein in uninduced mouse E11 metanephric mesenchyme and in cell lines from this tissue. Moreover, transcripts for receptor tyrosine kinases which are markers of endothelial precursors (VEGFR-1/Flt-1, VEGFR-2/Flk-1 and Tie-1) were expressed by the E11 mesenchyme. In transgenic mice, Tie1/LacZ-expressing cells were identified in E11 renal mesenchyme when patent vessels were absent. Moreover, a similar pattern of transgene expression was detected within intermediate mesoderm condensing to form metanephric mesenchyme. When Tie-1/LacZ E11 metanephroi were transplanted into the nephrogenic cortex of wild-type mice, transgene-expressing capillary loops were detected in glomeruli developing in donor tissue. In contrast, glomerular Tie-1/LacZ-positive vessels never developed in rudiments in organ culture. We postulate that endothelial precursors are present at the inception of the mouse nephrogenesis, and these differentiate and undergo morphogenesis into glomerular capillaries when experimental conditions resemble those found in the metanephros in vivo.

P Hardman

Papers

Roles of hepatocyte growth factor/scatter factor and the met receptor in the early development of the metanephros.

Deregulation of cell survival in cystic and dysplastic renal development.

Glial Cell Line-Derived Neurotrophic Factor Stimulates Ureteric Bud Outgrowth and Enhances Survival of Ureteric Bud Cells in vitro

A molecular and genetic analysis of renalglomerular capillary development.

A molecular and genetic analysis of renal glomerular capillary development