Osteopontin induces AP-1-mediated secretion of urokinase-type plasminogen activator through c-Src-dependent epidermal growth factor receptor transactivation in breast cancer cells.

Abstract

We have recently reported that osteopontin (OPN) stimulates cell motility and nuclear factor kappaB-mediated secretion of urokinase-type plasminogen activator (uPA) through phosphatidylinositol 3-kinase/Akt signaling pathways in breast cancer cells (Das, R., Mahabeleshwar, G. H., and Kundu, G. C. (2003) J. Biol. Chem. 278, 28593-28606). However, the role(s) of OPN on AP-1-mediated uPA secretion and cell motility and the involvement of c-Src/epidermal growth factor receptor (EGFR) in these processes in breast cancer cells are not well defined. In this study we report that OPN induces alpha(v)beta(3) integrin-mediated c-Src kinase activity in both highly invasive (MDA-MB-231) and low invasive (MCF-7) breast cancer cells. Ligation of OPN with alpha(v)beta(3) integrin induces kinase activity and tyrosine phosphorylation of EGFR in MDA-MB-231 and wild type EGFR-transfected MCF-7 cells, and this was inhibited by the dominant negative form of c-Src (dn c-Src) indicating that c-Src kinase plays a crucial role in this process. OPN induces association between alpha(v)beta(3) integrin and EGFR on the cell membrane in a macromolecular form with c-Src. Furthermore, OPN induces alpha(v)beta(3) integrin/EGFR-mediated ERK1/2 phosphorylation and AP-1 activation. Moreover, dn c-Src also suppressed the OPN-induced phosphatidylinositol (PI) 3-kinase activity in these cells indicating that c-Src acts as master switch in regulating MEK/ERK1/2 and phosphatidylinositol 3-kinase/Akt signaling pathways. OPN-induced ERK phosphorylation, AP-1 activation, uPA secretion, and cell motility were suppressed when cells were transfected with dn c-Src or pretreated with alpha(v)beta(3) integrin antibody, c-Src kinase inhibitor (pp2), EGFR tyrosine kinase inhibitor (PD153035), and MEK-1 inhibitor (PD98059). To our knowledge, this is the first report that OPN induces alpha(v)beta(3) integrin-mediated AP-1 activity and uPA secretion by activating c-Src/EGFR/ERK signaling pathways and further demonstrates a functional molecular link between OPN-induced integrin/c-Src-dependent EGFR phosphorylation and ERK/AP-1-mediated uPA secretion, and all of these ultimately control the motility of breast cancer cells.

• Authors: Riku Das, Ganapati H Mahabeleshwar, Gopal C Kundu
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 279 Issue 12 Pg. 11051-64 (Mar 19 2004) ISSN: 0021-9258 [Print] United States
• PMID: 14704150 (Publication Type: Journal Article)

Chemical References

• Integrin alphaVbeta3
• SPP1 protein, human
• Sialoglycoproteins
• Transcription Factor AP-1
• Osteopontin
• ErbB Receptors
• Mitogen-Activated Protein Kinase 1
• Mitogen-Activated Protein Kinase 3
• Mitogen-Activated Protein Kinases
• Urokinase-Type Plasminogen Activator

Topics

• Blotting, Western
• Breast Neoplasms (enzymology, genetics, metabolism, pathology)
• Cell Line, Tumor
• ErbB Receptors (genetics)
• Humans
• Hydrolysis
• Integrin alphaVbeta3 (metabolism)
• Mitogen-Activated Protein Kinase 1 (metabolism)
• Mitogen-Activated Protein Kinase 3
• Mitogen-Activated Protein Kinases (metabolism)
• Neoplasm Invasiveness
• Neoplasm Metastasis
• Osteopontin
• Phosphorylation
• Sialoglycoproteins (physiology)
• Signal Transduction
• Transcription Factor AP-1 (physiology)
• Transcriptional Activation (physiology)
• Urokinase-Type Plasminogen Activator (metabolism)