Expression of type I, but not type II insulin-like growth factor receptor on both undifferentiated and differentiated HT29 human colon carcinoma cell line

J Clin Endocrinol Metab. 1992 Aug;75(2):609-16. doi: 10.1210/jcem.75.2.1322432.


The HT29 human colonic carcinoma cell line secretes insulin-like growth factor (IGF)-II. We have examined these cells for expression of IGF receptors. Competitive binding assays as affinity cross-linking experiments using 125I-IGF-II fail to reveal type II IGF receptors at the cell surface. In contrast, cross-linking studies with either 125I-IGF-I or 125I-IGF-II reveal an M(r) 135,000 protein that follows a peptide binding specificity characteristic of the alpha-subunit of the type I IGF receptor. However, 125I-IGF-II binding to this receptor is not inhibited at 4 C by alpha IR-3, a monoclonal antibody to the type I IGF receptor. Analysis of the competitive binding curves with each one of these radioligands suggests that HT29 cells express both a classical type I IGF receptor (about 6,000/cell; KdIGF-I = 0.48 nmol) and a variant one whose 125I-IGF-II binding is not blocked by alpha IR-3 (about 15,000/cell; KdIGF-II = 4.0 nmol). Endocytosis studies of specific cell-bound 125I-IGF-I or 125I-IGF-II suggest that ligand interaction with the classical, but not the variant, binding site is only able to induce receptor internalization. An identical IGF receptors pattern is observed with HT29-D4 clonal cells induced to differentiate by culture in a glucose-free medium.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Affinity Labels
  • Antibodies, Monoclonal
  • Binding, Competitive
  • Carcinoma / metabolism*
  • Carcinoma / pathology
  • Cell Differentiation
  • Colonic Neoplasms / metabolism*
  • Colonic Neoplasms / pathology
  • Humans
  • Receptors, Cell Surface / classification
  • Receptors, Cell Surface / metabolism*
  • Receptors, Somatomedin
  • Somatomedins / metabolism
  • Temperature
  • Tumor Cells, Cultured


  • Affinity Labels
  • Antibodies, Monoclonal
  • Receptors, Cell Surface
  • Receptors, Somatomedin
  • Somatomedins