Augmented growth response to IGF-1 via increased IRS-1 in Chinese hamster ovary cells expressing kinase-negative insulin receptors

Diabetologia. 1999 Jun;42(6):763-72. doi: 10.1007/s001250051226.


Aims/hypothesis: Although both increased cell growth and impaired insulin signalling have been associated with diabetes, this association has not been investigated. Insulin-like growth factor-1 (IGF-1), a structural and functional analog of insulin, may play a part in the aberrant insulin receptor-mediated signalling observed in diabetes.

Methods: To investigate the consequence of this impaired signalling on cell proliferation and transformation, we transfected Chinese hamster ovary cells with cDNA encoding a kinase-defective insulin receptor.

Results: In these mutant cells, the mitogenic and metabolic effects of insulin were reduced compared with control cells (p < 0.05) and this was due to a dominant negative effect. In contrast, these mutant cells showed a higher mitogenic response to IGF-1 than control cells, although IGF-1 receptor expression was similar in both cell lines. There was no statistically significant difference in mitogenic response, however, to platelet-derived growth factor, basic fibroblast growth factor and heparin-binding epidermal growth factor-like growth factor. Variables of the IGF-1 signalling pathway, including tyrosine phosphorylation of insulin receptor substrate-1 and activation of mitogen-activated protein kinase and phosphatidyl inositol 3 kinase, were also augmented in mutant cells. Insulin receptor substrate-1 message and protein abundance were higher in mutant than in control cells. Moreover, mutant cells had a higher mitogenic potential in low-serum-containing medium, suggesting that these cells have a transformed phenotype.

Conclusion/interpretation: These findings suggest that an impaired insulin signalling may upregulate insulin receptor substrate-1 and that this, in turn, leads to increased IGF-1 signalling, a phenomenon that is possibly associated with increased cell growth in diabetes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing*
  • Adaptor Proteins, Vesicular Transport*
  • Animals
  • CHO Cells
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism
  • Cricetinae
  • Insulin Receptor Substrate Proteins
  • Insulin-Like Growth Factor I / pharmacology*
  • Intracellular Signaling Peptides and Proteins
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphoproteins / metabolism*
  • Phosphorylation
  • Protein-Tyrosine Kinases / deficiency*
  • Protein-Tyrosine Kinases / genetics
  • Proteins / metabolism
  • Receptor, IGF Type 1 / metabolism
  • Receptor, Insulin / genetics*
  • Receptor, Insulin / metabolism
  • Shc Signaling Adaptor Proteins


  • Adaptor Proteins, Signal Transducing
  • Adaptor Proteins, Vesicular Transport
  • Insulin Receptor Substrate Proteins
  • Intracellular Signaling Peptides and Proteins
  • Phosphoproteins
  • Proteins
  • Shc Signaling Adaptor Proteins
  • Insulin-Like Growth Factor I
  • Phosphatidylinositol 3-Kinases
  • Protein-Tyrosine Kinases
  • Receptor, IGF Type 1
  • Receptor, Insulin
  • Calcium-Calmodulin-Dependent Protein Kinases