Integrin (alpha 6 beta 4) regulation of eIF-4E activity and VEGF translation: a survival mechanism for carcinoma cells
Chung, Jun ; Bachelder, Robin E. ; Lipscomb, Elizabeth A. ; Shaw, Leslie M. ; Mercurio, Arthur M.
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UMass Chan Affiliations
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Keywords
Apoptosis
Breast Neoplasms
Cell Survival
Cytoplasm
Endothelial Growth Factors
Eukaryotic Initiation Factor-4E
*Gene Expression Regulation, Neoplastic
Humans
Integrin alpha6beta4
Integrins
Lymphokines
Oligonucleotides, Antisense
Peptide Initiation Factors
Phosphorylation
Polyribosomes
Protein Structure, Tertiary
Protein Transport
RNA, Bacterial
RNA, Messenger
Reverse Transcriptase Polymerase Chain Reaction
Signal Transduction
Tumor Cells, Cultured
Vascular Endothelial Growth Factor A
Vascular Endothelial Growth Factors
Cancer Biology
Neoplasms
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Abstract
We define a novel mechanism by which integrins regulate growth factor expression and the survival of carcinoma cells. Specifically, we demonstrate that the alpha 6 beta 4 integrin enhances vascular endothelial growth factor (VEGF) translation in breast carcinoma cells. The mechanism involves the ability of this integrin to stimulate the phosphorylation and inactivation of 4E-binding protein (4E-BP1), a translational repressor that inhibits the function of eukaryotic translation initiation factor 4E (eIF-4E). The regulation of 4E-BP1 phosphorylation by alpha 6 beta 4 derives from the ability of this integrin to activate the PI-3K-Akt pathway and, consequently, the rapamycin-sensitive kinase mTOR that can phosphorylate 4E-BP1. Importantly, we show that this alpha 6 beta 4-dependent regulation of VEGF translation plays an important role in the survival of metastatic breast carcinoma cells by sustaining a VEGF autocrine signaling pathway that involves activation of PI-3K and Akt. These findings reveal that integrin-mediated activation of PI-3K-Akt is amplified by integrin-stimulated VEGF expression and they provide a mechanism that substantiates the reported role of alpha 6 beta 4 in carcinoma progression.
Source
J Cell Biol. 2002 Jul 8;158(1):165-74. Epub 2002 Jul 8. Link to article on publisher's site