PMC抑制 PMA引起的血管平滑肌細胞增生經由

抑制 protein kinase C-alpha的活性

動脈粥狀硬化在心血管疾病中扮演相當重要的角色，經由動脈粥狀硬化的產生，造成冠心病及因血管壁上斑塊的脫落，造成了血管的栓塞，導致急性心肌梗塞、不穩定型心絞痛以及中風等。血管平滑肌細胞增生在動脈粥狀硬化的形成及血管成型術後所造成血管再狹窄化的病程中，均扮演了相當重要的角色。本篇論文在探討一種 Vitamin E的衍生物， PMC (2, 2, 5, 7, 8-pentamethyl-6-hydroxychromane)，對大鼠血管平滑肌細胞 (Vascular smooth muscle cell, VSMC)增生的影響。首先在MTT assay中發現 PMC能有效且呈濃度相關的抑制血管平滑肌細胞增生，而利用流式細胞儀偵測血管平滑肌細胞週期的進行，發現 PMC能有效抑制血管平滑肌細胞進入 S phase。血管平滑肌細胞增殖的機轉中， PKC-alpha佔了很重要的地位。故本次實驗在觀察 PMC是否經由對 PKC-alpha的影響來抑制血管平滑肌細胞增殖。實驗以 PKC活化劑 phorbol 12-myristate 13-acetate (PMA,1 uM)刺激 VSMC中 PKC-alpha的活化， PKC-alpha在 PMA刺激十分鐘後，明顯的從細胞質轉移到細胞膜，此種 translocation的現象為 PKC-alpha活化的表現。而預先給予 PMC處理 20分鐘再以 PMA刺激10分鐘的狀態下，發現 PMC能有效的抑制 PKC-alpha的 translocation現象，且利用免疫螢光染色法觀察細胞中 PKC-alpha的分布，亦呈現相同的結果。本次實驗發現 PMC可能經由有效抑制 PKC-alpha的 translocation來抑制血管平滑肌細胞增殖現象。未來在心血管疾病治療策略上，特別是動脈粥狀硬化方面及血管成型術後所造成血管再狹窄化的病程中，提供發展的新方向。

Coronary atherosclerotic heart disease is the most common cause of cardiovascula

r disability in Taiwan, and postangioplasty restenosis is a complicating factor in the treatment of atherosclerotic heart disease. The ability to alter the pathophysiology of coronary artery disease or control the proliferative events that lead to restenosis would be a major advancement in the treatment of the disease. Our study use PMC (2, 2, 5, 7, 8-pentamethyl-6-hydroxychromane), a potent alpha-tocopherol analogue, inhibits rat vascular smooth cell proliferation through PKC-alpha in MTT assay study.We found PMC also can inhibit effectively rat vascular smooth cell into S phase. PKC-alpha intimately involved in the proliferation, migration, growth, and survival of VSMC, and these factors have been shown to be important in the development of atherosclerotic lesions as well as restenosis after vascular injury. We use PMA, as a PKC-alpha activator, to stimulate PKC-alpha in the smooth muscle cell of blood vessels; translocation phenomenon of PKC-alpha from cytoplasm to cell membrane was obvious. Then PMC can effectively inhibit translocation phenomenon of PKC-alpha from cytoplasm to cell membrane after PMA stimulation. And the immune fluorescence study showed same result as above. So, we found PMC can inhibits rat vascular smooth muscle cell proliferation through PKC-alpha. This study can provide new therapeutic strategy for atherosclerosis and post angioplastic restenosis.

PMC Inhibits PMA-induced Vascular Smooth Muscle Cell Proliferation through inhibiting Protein Kinase C-alpha activity