Role of estrogen receptor (ER) α in insulin-like growth factor (IGF)-I-induced responses in MCF-7 breast cancer cells

S. Zhang, X. Li, R. Burghardt, R. Smith, S. H. Safe

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


Insulin-like growth factor-I (IGF-I) is a mitogenic polypeptide that induces proliferation of MCF-7 breast cancer cells, and cotreatment with the phosphoinositide 3-kinase (PI3-K) inhibitor LY294002 and the antiestrogen ICI 182780 inhibits IGF-I-induced growth. The role of estrogen receptor α (ERα) in mediating responses induced by IGF-I was investigated in cells transfected with small inhibitory RNA for ERα (iERα). The results showed that IGF-I-dependent phosphorylation of Akt and mitogen-activated protein kinase, induction of G1-S-phase progression and enhanced expression of cyclin D1 and cyclin E were dependent on ERα. Moreover, these same IGF-I-induced responses were also inhibited by the antiestrogen ICI 182780 and this was in contrast to a previous report suggesting that ICI 182780 did not affect IGF-I-dependent activation of PI3-K or induction of cyclin D1 expression. ICI 182780 exhibits antimitogenic activity and iERα inhibits G1-S-phase progression and proliferation of MCF-7 cells treated with IGF-I, suggesting that the effects of the antiestrogen are primarily related to downregulation of ERα.

Original languageEnglish (US)
Pages (from-to)433-447
Number of pages15
JournalJournal of Molecular Endocrinology
Issue number3
StatePublished - Dec 2005

ASJC Scopus subject areas

  • Molecular Biology
  • Endocrinology


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