TY - JOUR
T1 - EGFRvIII stimulates glioma growth and invasion through PKA-dependent serine phosphorylation of Dock180
AU - Feng, H.
AU - Hu, B.
AU - Vuori, K.
AU - Sarkaria, J. N.
AU - Furnari, F. B.
AU - Cavenee, W. K.
AU - Cheng, S. Y.
N1 - Funding Information:
Most of the studies (and all the animal studies) were performed at the University of Pittsburgh in accordance with a protocol approved by the IACUC of the University of Pittsburgh. We acknowledge the support of University of Pittsburgh Cancer Institute and various core facilities. We also thank M Matsuda, R Tsien, E van Meir and Y Zhou for providing reagents, and Angel Alvarez for proofreading of this manuscript. WK Cavenee is a Fellow of the National Foundation for Cancer Research. This work was supported in part by a NIH grant CA130966, CA158911 to S-Y Cheng, a Zell Scholar Award from the Zell Family Foundation and funds from Northwestern Brain Tumor Institute and Department of Neurology at Northwestern University Feinberg School of Medicine to S-Y Cheng; Brain Cancer Research Awards from the James S McDonnell Foundation to B Hu and F Furnari; a grant with the Pennsylvania Department of Health, and Innovative Research Scholar Awards of the Hillman Foundation to S-Y Cheng and B Hu.
PY - 2014/5/8
Y1 - 2014/5/8
N2 - Glioblastomas (GBMs), the most common and malignant brain tumors, are highly resistant to current therapies. The failure of targeted therapies against aberrantly activated oncogenic signaling, such as that of the EGFR-PI3K/Akt pathway, underscores the urgent need to understand alternative downstream pathways and to identify new molecular targets for the development of more effective treatments for gliomas. Here, we report that EGFRvIII (ΔEGFR/de2-7EGFR), a constitutively active EGFR mutant that is frequently co-overexpressed with EGFR in clinical GBM tumors, promotes glioma growth and invasion through protein kinase A (PKA)-dependent phosphorylation of Dock180, a bipartite guanine nucleotide exchange factor (GEF) for Rac1. We demonstrate that EGFRvIII induces serine phosphorylation of Dock180, stimulates Rac1 activation and glioma cell migration. Treatments of glioma cells using the PKA inhibitors H-89 and KT5720, overexpression of a PKA inhibitor (PKI), and in vitro PKA kinase assays show that EGFRvIII induction of serine phosphorylation of Dock180 is PKA-dependent. Significantly, PKA induces phosphorylation of Dock180 at amino acid residue S1250 that resides within its Rac1-activating DHR-2 domain. Expression of the Dock180 S1250L mutant, but not wild type Dock180 WT, protein in EGFRvIII-expressing glioma cells inhibited receptor-stimulated cell proliferation, survival, migration in vitro and glioma tumor growth and invasion in vivo. Together, our findings describe a novel mechanism by which EGFRvIII drives glioma tumorigenesis and invasion through PKA-dependent phosphorylation of Dock180, thereby suggesting that targeting EGFRvIII-PKA-Dock180-Rac1 signaling axis could provide a novel pathway to develop potential therapeutic strategies for malignant gliomas.
AB - Glioblastomas (GBMs), the most common and malignant brain tumors, are highly resistant to current therapies. The failure of targeted therapies against aberrantly activated oncogenic signaling, such as that of the EGFR-PI3K/Akt pathway, underscores the urgent need to understand alternative downstream pathways and to identify new molecular targets for the development of more effective treatments for gliomas. Here, we report that EGFRvIII (ΔEGFR/de2-7EGFR), a constitutively active EGFR mutant that is frequently co-overexpressed with EGFR in clinical GBM tumors, promotes glioma growth and invasion through protein kinase A (PKA)-dependent phosphorylation of Dock180, a bipartite guanine nucleotide exchange factor (GEF) for Rac1. We demonstrate that EGFRvIII induces serine phosphorylation of Dock180, stimulates Rac1 activation and glioma cell migration. Treatments of glioma cells using the PKA inhibitors H-89 and KT5720, overexpression of a PKA inhibitor (PKI), and in vitro PKA kinase assays show that EGFRvIII induction of serine phosphorylation of Dock180 is PKA-dependent. Significantly, PKA induces phosphorylation of Dock180 at amino acid residue S1250 that resides within its Rac1-activating DHR-2 domain. Expression of the Dock180 S1250L mutant, but not wild type Dock180 WT, protein in EGFRvIII-expressing glioma cells inhibited receptor-stimulated cell proliferation, survival, migration in vitro and glioma tumor growth and invasion in vivo. Together, our findings describe a novel mechanism by which EGFRvIII drives glioma tumorigenesis and invasion through PKA-dependent phosphorylation of Dock180, thereby suggesting that targeting EGFRvIII-PKA-Dock180-Rac1 signaling axis could provide a novel pathway to develop potential therapeutic strategies for malignant gliomas.
KW - Dock180
KW - EGFRvIII
KW - PKA
KW - glioblastomas
KW - phosphorylation
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UR - http://www.scopus.com/inward/citedby.url?scp=84900390547&partnerID=8YFLogxK
U2 - 10.1038/onc.2013.198
DO - 10.1038/onc.2013.198
M3 - Article
C2 - 23728337
AN - SCOPUS:84900390547
SN - 0950-9232
VL - 33
SP - 2504
EP - 2512
JO - Oncogene
JF - Oncogene
IS - 19
ER -