Effects of Baicalein, KS-5 and YD-3 on Growth Regulation in Vascular Smooth Muscle Cells and Endothelial Cells, and Therapeutic Evaluation in Models of Restenosis and Angiogenesis

• Main Authors: Chieh-Yu Peng, 彭婕妤
• Other Authors: Che-Ming Teng
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/89451110702908227657

博士 === 國立臺灣大學 === 藥理學研究所 === 96 === Arterial reconstruction procedures, including balloon angioplasty, stenting and coronary artery bypass, are used to restore blood flow in atherosclerotic arteries. Restenosis of these arteries is a major limitation of the application of these procedures. Post-angioplasty restenosis results from two major processes: neointimal formation and constrictive remodelling. Neointimal formation is initiated by arterial injury with a resultant loss of contractile phenotype in tunica media, leading to VSMC migration and proliferation. In this dissertation, we study the effects of some biologically active chemical compounds on the proliferation of VSMC and endothelail cells and trying to elucidate their action mechanisms. In the first chapter, we investigate baicalein-mediated inhibitory effects on VSMCs proliferation and intimal hyperplasia after balloon angioplasty in the rat. Baicalein significantly inhibits serum-induced cell proliferation via decreasing the phosphorylation of ERK1/2 and Akt proteins. Baicalein inhibits cyclin D1 expression resulting in the blockade of cell cycle progression. Furthermore, bacalein attenuates serum-induced DNA binding activity of NF-κB. It also inhibits intimal hyperplasia after balloon vascular injury in rat, implying its therapeutic potential for treating restenosis after angioplasty. Angiogenesis, the process of new blood vessel formation from pre-existing ones, plays a key role in various physiological and pathological conditions, including embryonic development, wound repair, inflammation, and tumor growth. Moreover, proliferating endothelial cells undergoing DNA synthesis are a common hallmark of angiogenic microvascular spouts. In the next two chapters, we investigate the effects of KS-5 and YD-3 on bFGF- and thrombin-induced angiogenesis in cultured human umbilical vein endothelial cells (HUVECs) in vitro and in vivo. KS-5, an acridone-derivative compound, inhibits bFGF-induced cell proliferation in a concentration-dependent manner without exhibiting any significant cytotoxicity. The inhibitory effect is associated with decreasing DNA synthesis and abrogating ERK1/2 and Akt protein phosphorylation in endothelial cells. In addition, KS-5 also inhibits bFGF-induced phosphorylation of mTOR and the major downstream effectors, eIF4E and p70S6K, and leading to decreasing protein synthesis. Most importantly, KS-5 treatment in nude mice inhibited in vivo angiogenesis as revealed by matrigel implant assay. YD-3 [1-benzyl-3(ethoxycarbonylphenyl)-indazole], a selective thrombin inhibitor, inhibits neovascularization in vivo induced by thrombin, protease-activated receptor (PAR) -1, and PAR-4, but not by vascular endothelial growth factor (VEGF). YD-3 also inhibits thrombin-, PAR-1- and PAR-4-, but not PAR-2-induced cell proliferation. YD-3 predominantly inhibits thrombin-induced VEGF receptor 2 (Flk-1) up-regulation, but not phosphorylation of ERK1/2 protein. Moreover, in a murine xenograft tumor model, YD-3 administered orally reveals significant antitumor activity without cytotoxicity. In conclusion, the present study suggests that baicalein, KS-5 and YD-3 have antiproliferative effects both in vitro and in vivo and worthy of further development into drug candidates for treating restenosis and angiogenesis-dependent diseases.