Journal
CANCER RESEARCH
Volume 73, Issue 14, Pages 4521-4532Publisher
AMER ASSOC CANCER RESEARCH
DOI: 10.1158/0008-5472.CAN-12-4178
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Funding
- CIHR grant [MOP-111143]
- CCSRI [2011-700790]
- AICR [11-0204]
- CIHR [MOP-13466, MOP-6849]
- Terry Fox Foundation/CIHR [TFF 105268]
- Terry Fox New Frontiers Program
- McGill Integrated Program Training Program (MICRTP)
- FRSQ
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ShcA (SHC1) is an adapter protein that possesses an SH2 and a PTB phosphotyrosine-binding motif. ShcA generally uses its PTB domain to engage activated receptor tyrosine kinases (RTK), but there has not been a definitive determination of the role of this domain in tumorigenesis. To address this question, we employed a ShcA mutant (R175Q) that no longer binds phosphotyrosine residues via its PTB domain. Here, we report that transgenic expression of this mutant delays onset of mammary tumors in the MMTV-PyMT mouse model of breast cancer. Paradoxically, we observed a robust increase in the growth and angiogenesis of mammary tumors expressing ShcR175Q, which displayed increased secretion of fibronectin and expression of integrin alpha 5/beta 1, the principal fibronectin receptor. Sustained integrin engagement activated Src, which in turn phosphorylated proangiogenic RTKs, including platelet-derived growth factor receptor, fibroblast growth factor receptor, and Met, leading to increased VEGF secretion from ShcR175Q-expressing breast cancer cells. We defined a ShcR175Q-dependent gene signature that could stratify breast cancer patients with a high microvessel density. This study offers the first in vivo evidence of a critical role for intracellular signaling pathways downstream of the ShcA PTB domain, which both positively and negatively regulate tumorigenesis during various stages of breast cancer progression.
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