Abstract
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 language | English (US) |
---|---|
Pages (from-to) | 433-447 |
Number of pages | 15 |
Journal | Journal of Molecular Endocrinology |
Volume | 35 |
Issue number | 3 |
DOIs | |
State | Published - Dec 2005 |
ASJC Scopus subject areas
- Molecular Biology
- Endocrinology