Comparative proteomic analysis implicates eEF2 as a novel target of PI3K[gamma] in the MDA-MB-231 metastatic breast cancer cell line

• Published in: Proteome science 2013-01, Vol.11
• Main Authors: Niu, Meizhi, Klingler-Hoffmann, Manuela, Brazzatti, Julie A, Forbes, Briony, Akekawatchai, Chareeporn, Hoffmann, Peter, McColl, Shaun R
• Format: Article
• Language: English
• Subjects: Breast cancer; Comparative analysis; Insulin-like growth factors; Kinases; Mass spectrometry; Medical research; Metastasis; Proteins; Tyrosine
• ISSN: 1477-5956; 1477-5956
• DOI: 10.1186/1477-5956-11-4

Cancer cell migration is fundamentally required for breast tumour invasion and metastasis. The insulin-like growth factor 1 tyrosine kinase receptor (IGF-1R) and the chemokine G-protein coupled receptor, CXCR4 have been shown to play an important role in breast cancer metastasis. Our previous study has shown that IGF-1R can transactivate CXCR4 via a physical association in the human MDA-MB-231 metastatic breast cancer cell line and that this plays a key role in IGF-I-induced migration of these cells. In the present study we used pharmacological inhibition and RNAi to identify PI3K[gamma] as an important migration signalling molecule downstream of receptor transactivation in MDA-MB-231 cells. To identify PI3K[gamma]-regulated proteins upon transactivation of CXCR4 by IGF-I, we undertook a comparative proteomics approach using 2-D- Fluorescence Difference Gel Electrophoresis (DIGE) and identified the proteins by mass spectrometry. These experiments identified eukaryotic elongation factor 2 (eEF2) as a novel downstream target of PI3K[gamma] after activation of the IGF-1R-CXCR4 heterodimer by IGF-I. Further analysis demonstrated that eEF2 is phosphorylated in MDA-MB-231 cells in response to IGF-I and that this is dependent on PI3K[gamma] activity. Our data imply a novel role for PI3K[gamma] in facilitating cell migration by regulating phosphorylation of eEF2.