title: Comparative proteomic analysis implicates eEF2 as a novel target of PI3Kγ in the MDA-MB-231 metastatic breast cancer cell line.
abstract: BACKGROUND
  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 PI3Kγ as an important migration signalling molecule downstream of receptor transactivation in MDA-MB-231 cells. To identify PI3Kγ-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.
  
  
  RESULTS
  These experiments identified eukaryotic elongation factor 2 (eEF2) as a novel downstream target of PI3Kγ 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 PI3Kγ activity.
  
  
  CONCLUSIONS
  Our data imply a novel role for PI3Kγ in facilitating cell migration by regulating phosphorylation of eEF2.
authors: School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA 5005, Australia.
authors: Meizhi
authors: M
authors: Niu
authors: School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA 5005, Australia.
authors: Manuela
authors: M
authors: Klingler-Hoffmann
authors: School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA 5005, Australia.|Current address: Immunology Group, Paterson Institute for cancer research, The University of Manchester, Manchester, M20 4BX, England.
authors: Julie A
authors: JA
authors: Brazzatti
authors: School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA 5005, Australia.
authors: Briony
authors: B
authors: Forbes
authors: School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA 5005, Australia.|Current address: Department of Medical Technology, Thammasat University, Patumtani, 121212, Thailand.
authors: Chareeporn
authors: C
authors: Akekawatchai
authors: School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA 5005, Australia.
authors: Peter
authors: P
authors: Hoffmann
authors: School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA 5005, Australia.
authors: Shaun R
authors: SR
authors: McColl