Samul-Tang Regulates Cell Cycle and Migration of Vascular Smooth Muscle Cells against TNF-α Stimulation

Samul-Tang (SMT), consisting of four medicinal herbs, is a well-known herbal prescription treating hematological disorders related symptoms. Our previous study demonstrated that SMT attenuated inflammation of vascular endothelial cells. In condition of retained vascular dysfunction, vascular inflammation is initiated and results in activation of smooth muscle cells (SMCs). Activated SMCs lose control of cell cycle regulation and migrate into intima, resulting in formation of atheroma. Here, we further investigated whether SMT suppresses proliferation and migration of SMCs. SMT showed antiproliferative effects on SMCs by suppressing [³H]-thymidine incorporation against TNF-α stimulation. Underlying mechanisms of antiproliferative effects were found to be resulting from cell cycle regulation. SMT downregulated expression of cyclin D1-CDK4 and cyclin E-CDK2 complexes and upregulated p21^waf1/cip1 and p27^kip1. SMT also suppressed migration of SMCs against TNF-α stimulation. This is thought to have resulted from suppressing MMP2 and MMP9 expressions and ROS production. In summary, SMT attenuates abnormal migration of vascular smooth muscle cells via regulating cell cycle and suppressing MMPs expression and ROS production. Our study suggests that SMT, a traditionally used herbal formula, protects vascular smooth muscle cells and might be used as an antiatherosclerotic drug.