Distinct FAK-Src activation events promote α5β1 and α4β1 integrin-stimulated neuroblastoma cell motility

L Wu, JA Bernard-Trifilo, Y Lim, ST Lim, SK Mitra… - Oncogene, 2008 - nature.com
L Wu, JA Bernard-Trifilo, Y Lim, ST Lim, SK Mitra, S Uryu, M Chen, CJ Pallen, NKV Cheung
Oncogene, 2008nature.com
Signals from fibronectin-binding integrins promote neural crest cell motility during
development in part through protein-tyrosine kinase (PTK) activation. Neuroblastoma (NB) is
a neural crest malignancy with high metastatic potential. We find that α4 and α5 integrins are
present in late-stage NB tumors and cell lines derived thereof. To determine the signaling
connections promoting either α4β1-or α5β1-initiated NB cell motility, pharmacological,
dominant negative and short-hairpin RNA (shRNA) inhibitory approaches were undertaken …
Abstract
Signals from fibronectin-binding integrins promote neural crest cell motility during development in part through protein-tyrosine kinase (PTK) activation. Neuroblastoma (NB) is a neural crest malignancy with high metastatic potential. We find that α4 and α5 integrins are present in late-stage NB tumors and cell lines derived thereof. To determine the signaling connections promoting either α4β1-or α5β1-initiated NB cell motility, pharmacological, dominant negative and short-hairpin RNA (shRNA) inhibitory approaches were undertaken. shRNA knockdown revealed that α5β1-stimulated NB motility is dependent upon focal adhesion kinase (FAK) PTK, Src PTK and p130Cas adapter protein expression. Cell reconstitution showed that FAK catalytic activity is required for α5β1-stimulated Src activation in part through direct FAK phosphorylation of Src at Tyr-418. Alternatively, α4β1-stimulated NB cell motility is dependent upon Src and p130Cas but FAK is not essential. Catalytically inactive receptor protein-tyrosine phosphatase-α overexpression inhibited α4β1-stimulated NB motility and Src activation consistent with α4-regulated Src activity occurring through Src Tyr-529 dephosphorylation. In α4 shRNA-expressing NB cells, α4β1-stimulated Src activation and NB cell motility were rescued by wild type but not cytoplasmic domain-truncated α4 re-expression. These studies, supported by results using reconstituted fibroblasts, reveal that α4β1-mediated Src activation is mechanistically distinct from FAK-mediated Src activation during α5β1-mediated NB migration and support the evaluation of inhibitors to α4, Src and FAK in the control of NB tumor progression.
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