Hepatocyte growth factor-stimulated renal tubular mitogenesis: effects on expression of c-myc, c-fos, c-met, VEGF and the VHL tumour-suppressor and related genes.
Hepatocyte growth factor (HGF/SF) is a potent renal proximal tubular cell (PTEC) mitogen involved in renal development. HGF/SF is the functional ligand for the c-met proto-oncogene, and germline c-met mutations are associated with familial papillary renal cell carcinoma. Somatic von Hippel-Lindau disease tumour-suppressor gene (VHL) mutations are frequently detected in sporadic clear cell renal cell carcinomas (RCC), and germline VHL mutations are the commonest cause of familial clear cell RCC. pVHL binds to the positive regulatory components of the trimeric elongin (SIII) complex (elongins B and C) and has been observed to deregulate expression of the vascular endothelial growth factor (VEGF) gene. HGF/SF has similarly been reported to up-regulate expression of the VEGF gene in non-renal experimental systems. To investigate the mechanism of HGF/SF action in PTECs and, specifically, to examine potential interactions between the HGF/c-met and the VHL-mediated pathways for renal tubular growth control, we have isolated untransformed PTECs from normal kidneys, developed conditions for their culture in vitro and used these cells to investigate changes in mRNA levels of the VHL, elongin A, B and C, VEGF, c-myc, c-fos and c-met genes after HGF/SF exposure. Significant elevations in the mRNA levels of VEGF, c-myc, c-fos, c-met and elongins A, B and C, but not VHL, were detected after HGF/SF stimulation of human PTECs (P < 0.02), with a consistent order of peak levels observed over successive replicates (c-fos at 1 h, VEGF at 2-4 h, c-myc, at 4 h, followed by c-met and all three elongin subunits at 8 h). This study highlights the spectrum of changes in gene expression observed in PTECs after HGF/SF stimulation and has identified possible candidate mediators of the HGF/SF-induced mitogenic response. Our evidence would suggest that the changes in PTEC VEGF expression induced by HGF/SF are mediated by a VHL-independent pathway.
Clifford
S C
SC
Department of Pathology, University of Cambridge, UK.
Czapla
K
K
Richards
F M
FM
O'Donoghue
D J
DJ
Maher
E R
ER
D002478:Cells, Cultured / Q000187:drug effects; D000075065:Elongin; D016228:Endothelial Growth Factors / Q000378:metabolism; D005809:Genes, Regulator / Q000187:drug effects*; D016762:Genes, fos / Q000187:drug effects; D016259:Genes, myc / Q000187:drug effects; D017228:Hepatocyte Growth Factor / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects*; D008025:Ligases; D008222:Lymphokines / Q000378:metabolism; D008938:Mitosis / Q000187:drug effects; D011506:Proteins / Q000187:drug effects; D000090063:Proto-Oncogene Mas; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D051794:Von Hippel-Lindau Tumor Suppressor Protein
C000616397:ELOA protein, human; D000075065:Elongin; D016228:Endothelial Growth Factors; D008222:Lymphokines; C000715470:MAS1 protein, human; D011506:Proteins; D000090063:Proto-Oncogene Mas; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D017228:Hepatocyte Growth Factor; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D019859:Proto-Oncogene Proteins c-met; D008025:Ligases; C497446:VHL protein, human