Phosphorylation of dedicator of cytokinesis 1 (Dock180) at tyrosine residue Y722 by Src family kinases mediates EGFRvIII-driven glioblastoma tumorigenesis

Haizhong Feng, Bo Hu, Michael J. Jarzynka, Yanxin Li, Susan Keezer, Terrance G. Johns, Careen K. Tang, Ronald L. Hamilton, Kristiina Vuori, Ryo Nishikawa, Jann N. Sarkaria, Tim Fenton, Tao Cheng, Frank B. Furnari, Webster K. Cavenee, Shi Yuan Cheng

Research output: Contribution to journalArticlepeer-review

61 Citations (Scopus)


Glioblastoma, the most common primary malignant cancer of the brain, is characterized by rapid tumor growth and infiltration of tumor cells throughout the brain. These traits cause glioblastomas to be highly resistant to current therapies with a resultant poor prognosis. Although aberrant oncogenic signaling driven by signature genetic alterations, such as EGF receptor (EGFR) gene amplification and mutation, plays a major role in glioblastoma pathogenesis, the responsible downstream mechanisms remain less clear. Here, we report that EGFRvIII (also known as ΔEGFR and de2-7EGFR), a constitutively active EGFR mutant that is frequently co-overexpressed with EGFR in human glioblastoma, promotes tumorigenesis through Src family kinase (SFK)-dependent phosphorylation of Dock180, a guanine nucleotide exchange factor for Rac1. EGFRvIII induces phosphorylation of Dock180 at tyrosine residue 722 (Dock180 Y722) and stimulates Rac1-signaling, glioblastoma cell survival and migration. Consistent with this being causal, siRNA knockdown of Dock180 or expression of a Dock180 Y722F mutant inhibits each of these EGFRvIII-stimulated activities. The SFKs, Src, Fyn, and Lyn, induce phosphorylation of Dock180 Y722 and inhibition of these SFKs by pharmacological inhibitors or shRNA depletion markedly attenuates EGFRvIII-induced phosphorylation of Dock180 Y722, Rac1 activity, and glioblastoma cell migration. Finally, phosphorylated Dock180 Y722 is coexpressed with EGFRvIII and phosphorylated Src Y418 in clinical specimens, and such coexpression correlates with an extremely poor survival in glioblastoma patients. These results suggest that targeting the SFK-p-Dock180 Y722-Rac1 signaling pathway may offer a novel therapeutic strategy for glioblastomas with EGFRvIII overexpression.

Original languageEnglish
Pages (from-to)3018-3023
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number8
Publication statusPublished - 21 Feb 2012
Externally publishedYes


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