Dynamin 2 Mediates PDGFRα-SHP-2-Promoted Glioblastoma Growth and Invasion

Dynamin 2 (Dyn2), a large GTPase, is involved in receptor tyrosine kinase (RTK)-promoted cell migration. However, molecular mechanisms by which Dyn2 regulates RTK-induced cell migration have not been established. Recently we reported that SHP-2 and PI3K mediate PDGFRα-promoted glioma tumor growth and invasion. Here, we show that Dyn2 is an effector downstream of the PDGFRα-PI3K/SHP-2 signaling in glioma cells. Depletion of endogenous Dyn2 by shRNAs inhibited PDGFRα-stimulated phosphorylation of Akt, Erk1/2, Rac1 and Cdc42 activities, glioma cell migration and survival in vitro, tumor growth and invasion in the brains of mice. Dyn2 binds to SHP-2, PI3K and co-localizes with PDGFRα at the invasive fronts in PDGF-A-stimulated glioma cells. Inhibition of SHP-2 by siRNA knockdown abrogated Dyn2 association with activated PDGFRα and PDGFRα activation of Rac1 and Cdc42, glioma cell migration, thereby establishing a link between SHP-2 interaction with Dyn2 and the PDGFRα signaling. Furthermore, a dominant negative SHP-2 C459S mutant inhibited PDGF-A-stimulated glioma cell migration, phosphorylation of Dyn2 and concomitantly blocked PDGFRα-induced Src activation. Inhibition of Src by Src inhibitors attenuated PDGF-A-stimulated phosphorylation of Akt and Dyn2 and glioma cell migration. Additionally, mutations of binding sites to PI3K, SHP-2 or Src of PDGFRα impaired PDGFRα-stimulated phosphorylation of Akt and Dyn2, and Dyn2 association with activated PDGFRα. Taken together, this study identifies Dyn2 as an effector that mediates PDGFRα-SHP-2-induced glioma tumor growth and invasion, suggesting that targeting the PDGFRα-SHP-2-Dyn2 pathway may be beneficial to patients with malignant glioblastomas.