Growth inhibition by insulin-like growth factor-binding protein-3 in T47D breast cancer cells requires transforming growth factor-beta (TGF-beta ) and the type II TGF-beta receptor.

Abstract

This study explores the relationship between anti-proliferative signaling by transforming growth factor-beta (TGF-beta) and insulin-like growth factor-binding protein-3 (IGFBP-3) in human breast cancer cells. In MCF-7 cells, the expression of recombinant IGFBP-3 inhibited proliferation and sensitized the cells to further inhibition by TGF-beta1. To investigate the mechanism, we used T47D cells that lack type II TGF-beta receptor (TGF-betaRII) and are insensitive to TGF-beta1. After introducing the TGF-betaRII by transfection, the basal proliferation rate was significantly decreased. Exogenous TGF-beta1 caused no further growth inhibition, but immunoneutralization of endogenous TGF-beta1 restored the proliferation rate almost to the control level. The addition of IGFBP-3 did not inhibit the proliferation of control cells but caused dose-dependent inhibition in TGF-betaRII-expressing cells when exogenous TGF-beta1 was also present. Similarly, receptor-expressing cells showed dose-dependent sensitivity to exogenous TGF-beta1 only in the presence of exogenous IGFBP-3. This indicates that in these cells, anti-proliferative signaling by exogenous IGFBP-3 requires both the TGF-betaRII and exogenous TGF-beta1. To investigate this synergism, the phosphorylation of TGF-beta signaling intermediates, Smad2 and Smad3, was measured. Phosphorylation of each Smad was stimulated by TGF-beta1 and, independently, by IGFBP-3 with the two agents together showing a cumulative effect. These data suggest that IGFBP-3 inhibitory signaling requires an active TGF-beta signaling pathway and implicate Smad2 and Smad3 in IGFBP-3 signal transduction.

• Authors: S Fanayan, S M Firth, A J Butt, R C Baxter
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 275 Issue 50 Pg. 39146-51 (Dec 15 2000) ISSN: 0021-9258 [Print] United States
• PMID: 10993898 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• DNA, Complementary
• DNA-Binding Proteins
• Insulin-Like Growth Factor Binding Protein 3
• Receptors, Transforming Growth Factor beta
• Recombinant Proteins
• SMAD2 protein, human
• SMAD3 protein, human
• Smad2 Protein
• Smad3 Protein
• Trans-Activators
• Transforming Growth Factor beta
• Protein Serine-Threonine Kinases
• Receptor, Transforming Growth Factor-beta Type II

Topics

• Blotting, Northern
• Breast Neoplasms (metabolism)
• Cell Division
• DNA, Complementary (metabolism)
• DNA-Binding Proteins (metabolism)
• Dose-Response Relationship, Drug
• Enzyme-Linked Immunosorbent Assay
• Humans
• Insulin-Like Growth Factor Binding Protein 3 (metabolism)
• Phosphorylation
• Precipitin Tests
• Protein Serine-Threonine Kinases
• Receptor, Transforming Growth Factor-beta Type II
• Receptors, Transforming Growth Factor beta (metabolism)
• Recombinant Proteins (metabolism)
• Signal Transduction
• Smad2 Protein
• Smad3 Protein
• Time Factors
• Trans-Activators (metabolism)
• Transfection
• Transforming Growth Factor beta (metabolism)
• Tumor Cells, Cultured