Mechanisms of 4-hydroxytamoxifen anti-growth factor activity in breast cancer cells: alterations of growth factor receptor binding sites and tyrosine kinase activity

Biochem Biophys Res Commun. 1990 Dec 31;173(3):919-26. doi: 10.1016/s0006-291x(05)80873-3.

Abstract

We previously demonstrated that antiestrogen 4-hydroxytamoxifen (OH-Tam) blocks the mitogenic activity of growth factors in breast cancer. We now investigate this mechanism by evaluating how OH-Tam affects growth factor binding and receptor tyrosine kinase activity. We show here that OH-Tam has an opposite effect on epidermal growth factor (EGF) and insulin-like growth factor-1 (IGF-1) binding in estrogen receptor (ER) positive cells. A decrease in IGF-1 binding sites may explain the reduced IGF-I mitogenic effect, whereas an increase in high affinity EGF binding associated with a decrease in in vitro receptor autophosphorylation rather favors the possibility of an alteration in EGF receptor tyrosine kinase activity. We conclude that OH-Tam may prevent growth factor action in ER+ cells both by modulating the concentration of growth factor binding sites and by altering growth factor receptor functionality.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breast Neoplasms / metabolism*
  • ErbB Receptors / drug effects
  • ErbB Receptors / metabolism*
  • Estrogen Antagonists / pharmacology*
  • Humans
  • Insulin-Like Growth Factor I / drug effects
  • Insulin-Like Growth Factor I / metabolism*
  • Phosphorylation
  • Protein-Tyrosine Kinases / metabolism*
  • Receptors, Estrogen / drug effects
  • Receptors, Estrogen / metabolism*
  • Tamoxifen / analogs & derivatives*
  • Tamoxifen / pharmacology
  • Tumor Cells, Cultured

Substances

  • Estrogen Antagonists
  • Receptors, Estrogen
  • Tamoxifen
  • afimoxifene
  • Insulin-Like Growth Factor I
  • ErbB Receptors
  • Protein-Tyrosine Kinases