同半胱胺酸對於人類臍靜脈血管內皮細胞之細胞週期與附著分子表現之影響

Effects of Homocysteine on Cell Cycle Progress and Adhesion Molecules Expression in Human Umbilical Vein Endothelial Cells

傅瓊慧(Chiung-Hui Fu)

指導教授 ： 張基隆

高雄醫學大學/醫學院/醫學研究所/碩士(2006年)

https://doi.org/10.6832/KMU.2006.00128

摘要

根據衛生署統計，近年來心臟和腦血管疾病高居國人十大死因之第二、三名。造成心血管疾病致死的主要原因是發生粥狀動脈硬化 所引起。動脈粥狀硬化是一種慢性發炎疾病，起初會引起血管內皮細胞發生功能異常。已有研究指出，血液中同半胱胺酸濃度過高，是引發心血管疾病的危險因子之一。同時，高濃度的同半胱胺酸確實會引起血管內皮細胞的傷害，但詳細的分子作用機制並不十分清楚。我們先前研究發現，高濃度的同半胱胺酸會活化單核球細胞並促進發炎相關的細胞激素的分泌。因此，本研究欲探討高濃度的同半胱胺酸對於人類臍靜脈的血管內皮細胞之生理活性的影響，包括細胞存活、細胞週期以及黏著分子的表現等。有研究指出同半胱胺酸會造成血管內皮細胞的氧化壓力，當細胞受到氧化性傷害時，會大量表現HO-1 (heme oxygenase-1) 用以保護細胞免於氧化性傷害，但對於同半胱胺酸與HO-1的作用是否相關連則有待更進一步解明。所以，本研究亦使用Hemin作為HO-1誘導劑促使HO-1的合成，並檢測是否能影響ICAM-1的表現，進而探討其與同半胱胺酸是否引發促進粥狀動脈硬化的發生是否具關連性﹖
研究結果顯示，以人類臍靜脈血管內皮細胞進行實驗，在以高濃度同半胱胺酸的處理時，造成血管內皮細胞的生長受到抑制甚至死亡，細胞型態發生改變，並由原來的多角形轉變為細長形。在細胞週期的調控方面，發現同半胱胺酸促使細胞週期停滯在G0/G1期，而G1/S checkpoint相關的蛋白質：cyclin D1、cdk4表現受到抑制，p27表現量則增加。同半胱胺酸會促進血管內皮細胞表面ICAM-1的表現，但對於VCAM-1表現影響則不明顯。當添加Hemin時可以抑制同半胱胺酸引起的細胞週期停滯和ICAM-1的表現。
由上述研究結果得知，同半胱胺酸可經由抑制細胞週期的進行而導致血管內皮細胞生長停滯，亦會促進血管內皮細胞表面的黏著分子的表現，促進血管內皮細胞和白血球之間的接觸並結合，引起更多的白血球進入血管內皮下基質，引起發炎反應，促進粥狀動脈硬化的發生。實驗結果亦得知，HO-1的表現可以阻止同半胱胺酸對於內皮細胞的細胞週期和ICAM-1表現的作用。
這些研究成果將有助於我們能更深入地了解高同半胱胺酸血症引發心血管疾病的相關分子機制，對心血管疾病的預防與治療策略的研究上，亦能提供重要學術及臨床參考價值。

關鍵字

同半胱胺酸 ； 粥狀動脈硬化 ； 血管內皮細胞 ； 附著分子 ； 血色素氧化酶

並列摘要

According to recent report of the Department of Health, heart and brain vascular disease are the top two and three of the ten major causes of death in Taiwan respectively. Previous studies indicated that hyperhomocysteinemia is one of risk factors for cardiovascular disease. The main cause of cardiovascular disease is atherosclerosis which can be referred to as a chronic inflammatory disease. In the initiation of atherosclerosis, endothelial cells of the blood vessel loss function firstly. Previous studies indicated hyperhomoysteinemia actually induced vascular endothelial cell’s injury, however, the detail molecular mechanisms were not well understood. Our recent study showed at pathophysiologic concentrations, homocysteine would activate human monocyte and induce cytokine expression. The present study was designed to explore the effects of homocysteine on human umbilical vein endothelial cells (HUVECs) focusing on the cell viability, cell cycle regulation, and adhesion molecules expression. Since previous studies indicated that homocysteine could increase endothelial cell’s oxidative stress; and HO-1 (heme oxygenase-1) expression was induced against the oxidative stress, we also explored the relations between this homocystein-induced oxidative stress and HO-1expression in HUVECs.
Our results showed, at higher concentrations, homocysteine inhibited the endothelial cell’s growth and changed cell morphology from original polygonal shape to elongated shape. Homocysteine also induced HUVEC’s cell cycle arrest in G0/G1 phase. Some G1/S checkpoint-related proteins, including cyclin D1 and cdk4, expressions were repressed but p27 protein expression was up-regulated. On the other hand, homocysteine promoted surface ICAM-1 expression but had little effect on surface VCAM-1 expression. Addition of hemin, a HO-1 inducer, could inhibit homocysteine’s effects on cell cycle regulation and ICAM-1 expression. Through the ways of inhibiting endothelial cells’ growth and increase in surface ICAM-1 expression, homocysteine can induce peripheral blood mononuclear cells bound to endothelial cells and results in promoting atherosclerotic progress.
From this approach, some molecular mechanisms of homocysteinemia-induced atherosclerosis were exposed and provided the knowledge that HO-1 can release homocysteine’s effect on endothelial cells. These should be benefit for developing the prevention strategy and treatment for homocysteinemia-induced cardiovascular disease.

並列關鍵字

homocysteine ； atherosclerosis ； HUVEC ； adhesion molecules ； heme oxygenase

參考文獻

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