Activation of Rac1 by Src-dependent phosphorylation of Dock180Y1811 mediates PDGFRα-stimulated glioma tumorigenesis in mice and humans
Haizhong Feng, … , Webster K. Cavenee, Shi-Yuan Cheng
Haizhong Feng, … , Webster K. Cavenee, Shi-Yuan Cheng
Published November 14, 2011
Citation Information: J Clin Invest. 2011;121(12):4670-4684. https://doi.org/10.1172/JCI58559.
View: Text | PDF
Research Article Oncology

Activation of Rac1 by Src-dependent phosphorylation of Dock180Y1811 mediates PDGFRα-stimulated glioma tumorigenesis in mice and humans

Abstract

Two hallmarks of glioblastoma multiforme, the most common malignant brain cancer in humans, are aggressive growth and the ability of single glioma cells to disperse throughout the brain. These characteristics render tumors resistant to current therapies and account for the poor prognosis of patients. Although it is known that oncogenic signaling caused by overexpression of genes such as PDGFRA is responsible for robust glioma growth and cell infiltration, the mechanisms underlying glioblastoma malignancy remain largely elusive. Here, we report that PDGFRα signaling in glioblastomas leads to Src-dependent phosphorylation of the guanine nucleotide exchange factor Dock180 at tyrosine 1811 (Dock180Y1811) that results in activation of the GTPase Rac1 and subsequent cell growth and invasion. In human glioma cells, knockdown of Dock180 and reversion with an RNAi-resistant Dock180Y1811F abrogated, whereas an RNAi-resistant Dock180WT rescued, PDGFRα-promoted glioma growth, survival, and invasion. Phosphorylation of Dock180Y1811 enhanced its association with CrkII and p130Cas, causing activation of Rac1 and consequent cell motility. Dock180 also associated with PDGFRα to promote cell migration. Finally, phosphorylated Dock180Y1811 was detected in clinical samples of gliomas and various types of human cancers, and coexpression of phosphorylated Dock180Y1811, phosphorylated SrcY418, and PDGFRα was predictive of extremely poor prognosis of patients with gliomas. Taken together, our findings provide insight into PDGFRα-stimulated gliomagenesis and suggest that phosphorylated Dock180Y1811 contributes to activation of Rac1 in human cancers with PDGFRA amplification.

Authors

Haizhong Feng, Bo Hu, Kun-Wei Liu, Yanxin Li, Xinghua Lu, Tao Cheng, Jia-Jean Yiin, Songjian Lu, Susan Keezer, Tim Fenton, Frank B. Furnari, Ronald L. Hamilton, Kristiina Vuori, Jann N. Sarkaria, Motoo Nagane, Ryo Nishikawa, Webster K. Cavenee, Shi-Yuan Cheng

×

Figure 7

PDGF-A–induced association of Dock180 with PDGFRα is required for PDGFRα-promoted glioma cell migration.

Options: View larger image (or click on image) Download as PowerPoint
PDGF-A–induced association of Dock180 with PDGFRα is required for PDGFRα...
(A) PDGF-A induced association of Dock180 with PDGFRα in glioma cells. (B) Schematics of Dock180WT and various Dock180 deletion mutants. (C–E) Dock180WT or indicated Dock180 mutants was separately cotransfected with or without PDGFRαΔ8,9 into HEK293T cells. (C and D) Dock180 interacted with PDGFRα through its N-terminal region with aa residues 1–159. (E) Removal of 1–159 aa of Dock180 (Dock180Δ160) inhibited the induced interaction of Dock180 with PDGFRα without affecting p-Y Dock180 in HEK293T cells. (F) Dock180Δ160 inhibited interaction of Dock180 with PDGFRα, ELMO1, and Rac1 activation without affecting p-Y of Dock180 in LN444/PDGF-A cells. (G) In vitro cell migration assays were performed and analyzed as in Figure 1C. (H) The double mutation Dock180Δ160-Y1811F had an additive effect on inhibition of PDGFRα-induced Rac1 activation and cell migration compared with that caused by single Dock180Y1811F or Dock180Δ160 mutation. (A, C–F, and H) Co-IP experiments were performed using anti-PDGFRα, anti-Dock180, anti-Flag, or anti-phosphotyrosine (4G10) antibodies. Data (± SD) represent 3 independent experiments with similar results. *P < 0.05; **P < 0.001.