Pigment-epithelium-derived factor (PEDF) inhibits angiotensin-II-induced vascular endothelial growth factor (VEGF) expression in MOLT-3 T cells through anti-oxidative properties

Angiotensin II (Ang II), the dominant effector of the renin-angiotensin system, elicits numerous inflammatory-proliferative responses, thereby being involved in angiogenesis. T cells play an important role in angiogenesis as well by delivering vascular endothelial growth factor (VEGF) to inflammatory sites. Since we have previously shown that pigment-epithelium-derived factor (PEDF) blocks the Ang II signaling in endothelial cells, we studied here whether PEDF could inhibit the Ang-II-induced VEGF expression in MOLT-3 T and examined the potential mechanism of PEDF inhibitory effects. Ang II significantly up-regulated VEGF mRNA levels in MOLT-3 T cells, which was inhibited by PEDF or olmesartan, an Ang II type 1 receptor blocker. PEDF blocked the Ang-II-induced reactive oxygen species (ROS) generation in MOLT-3 T cells. Furthermore, H₂O₂ was found to up-regulate VEGF mRNA levels in MOLT-3 T cells in a dose-dependent manner. These results demonstrate that PEDF could inhibit the Ang-II-induced VEGF expression in MOLT-3 T cells via suppression of ROS generation. Blockade by PEDF of VEGF expression in T cells may become a novel therapeutic target for pathological angiogenesis.