Gene Transfer of Redox Factor-1 Inhibits Neointimal Formation Involvement of Platelet-Derived Growth Factor-β Receptor Signaling via the Inhibition of the Reactive Oxygen Species-Mediated Syk Pathway

The role of apurinic/apyrimidinic endonuclease-1/redox factor-1 (Ref-1) in vascular smooth muscle cells has yet to be clearly elucidated. Therefore, we attempted to determine the roles of Ref-1 in the migration induced by platelet-derived growth factor (PDGF)-BB and in its signaling in rat aortic smooth muscle cells (RASMCs). Cellular migration, superoxide (O-2(-center dot)) production, Rac-1 activity, and neointima formation were determined in cells transfected with adenoviruses encoding for Ref-1 (AdRef-1) and small interference RNA of Ref-1. Overexpression of Ref-1 induced by treatment with RASMCs coupled with AdRef-1 inhibited the migration induced by PDGF-BB. PDGF-BB also increased the phosphorylation of the PDGF beta receptor, spleen tyrosine kinase (Syk), mitogen-activated protein kinase, and heat shock protein 27, but these increases were significantly inhibited by AdRef-1 treatment. PDGF-BB increased O-2(-center dot) production and Rac-1 activity, and these were diminished in cells transfected with AdRef-1. In contrast, RASMC migration, phosphorylation of Syk and O-2(-center dot) production in response to PDGF-BB were increased by the knock down of Ref-1 with small interference RNA. The phosphorylation of PDGF beta receptor in response to PDGF-BB was inhibited completely by the Syk inhibitor and was partly attenuated by a NADPH oxidase inhibitor. PDGF-BB increased the sprout outgrowth of the aortic ring ex vivo, which was inhibited in the AdRef-1-infected RASMCs as compared with the controls. Balloon injury-induced neointimal formation was significantly attenuated by the gene transfer of AdRef-1. These results indicate that Ref-1 inhibits the PDGF-mediated migration signal via the inhibition of reactive oxygen species-mediated Syk activity in RASMCs. (Circ Res. 2009; 104: 219-227.)