Hyperproliferation of PKD1 cystic cells is induced by insulin-like growth factor-1 activation of the Ras/Raf signalling system

Kidney Int. 2007 Jul;72(2):157-65. doi: 10.1038/sj.ki.5002229. Epub 2007 Mar 28.


Autosomal dominant polycystic kidney disease (ADPKD) largely results from mutations in the PKD1 gene leading to hyperproliferation of renal tubular epithelial cells and consequent cyst formation. Rodent models of PKD suggest that the multifunctional hormone insulin-like growth factor-1 (IGF-1) could play a pathogenic role in renal cyst formation. In order to test this possibility, conditionally immortalized renal epithelial cells were prepared from normal individuals and from ADPKD patients with known germline mutations in PKD1. All patient cell lines had a decreased or absence of polycystin-1 but not polycystin-2. These cells had an increased sensitivity to IGF-1 and to cyclic AMP, which required phosphatidylinositol-3 (PI3)-kinase and the mitogen-activated protein kinase, extracellular signal-regulated protein kinase (ERK) for enhanced growth. Inhibition of Ras or Raf abolished the stimulated cell proliferation. Our results suggest that haploinsufficiency of polycystin-1 lowers the activation threshold of the Ras/Raf signalling system leading to growth factor-induced hyperproliferation. Inhibition of Ras or Raf activity may be a therapeutic option for decreasing tubular cell proliferation in ADPKD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Cell Proliferation / drug effects*
  • Cysts / pathology
  • Germ-Line Mutation
  • Humans
  • Insulin-Like Growth Factor I / pharmacology*
  • Insulin-Like Growth Factor I / physiology
  • Kidney Tubules / pathology
  • Polycystic Kidney, Autosomal Dominant / drug therapy
  • Polycystic Kidney, Autosomal Dominant / metabolism
  • Polycystic Kidney, Autosomal Dominant / pathology*
  • Signal Transduction / drug effects
  • TRPP Cation Channels*
  • raf Kinases / drug effects*
  • raf Kinases / metabolism
  • ras GTPase-Activating Proteins / drug effects*
  • ras GTPase-Activating Proteins / metabolism


  • TRPP Cation Channels
  • polycystic kidney disease 1 protein
  • ras GTPase-Activating Proteins
  • Insulin-Like Growth Factor I
  • raf Kinases