Antiangiogenic mechanisms of simvastatin in retinal endothelial cells

While statins have an anti-angiogenic property, their underlying mechanisms are not fully understood. We investigated intracellular mechanisms of simvastatin-mediated reduction in VEGF-induced signalings. The effects of simvastatin on cell proliferation and viability were evaluated by [(3)H]-thymidine incorporation in retinal endothelial cells (RECs) and cell counting. The impact of simvastatin on VEGF-induced phosphorylation of p44/42 mitogen-activated protein (MAP) kinase, myosin light chain (MLC), and VEGF-receptor (VEGFR) 2 were examined by Western blotting. Involvement of the mevalonate pathway in VEGF-induced signaling was also examined. Simvastatin (1 and 10 A mu M) suppressed VEGF-induced RECs proliferation in a concentration-dependent manner, without affecting cell viability. Simvastatin significantly inhibited VEGF-induced phosphorylation of VEGFR2 and its downstream mediators, p44/42 MAP kinase and MLC. Mevalonate completely reversed VEGF-induced VEGFR2 phosphorylation, but only partially reversed the phosphorylation of p44/42 MAP kinase and MLC. These data indicate that simvastatin exerts its anti-angiogenic effects through the reduction of VEGFR2 phosphorylation in RECs at least in part. However, there seems to be both mevalonate-dependent and independent pathway in simvastatin's anti-angiogenic property.