Both estrogen and raloxifene cause G1 arrest of vascular smooth muscle cells
Both estrogen and raloxifene cause G1 arrest of vascular smooth muscle cells
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DOI：
10.1677/joe.0.1780319
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发表时间：
2003-08-01
影响因子：
4
通讯作者：
Kurachi, H
中科院分区：
文献类型：
--
作者：
Takahashi, K;Ohmichi, M;Kurachi, H
血管平滑肌细胞（VSMC）的增殖是动脉粥样硬化发生发展的重要病理生理过程。虽然雌激素是已知的抑制VSMC的增殖，负责这种效果的机制仍有待阐明。此外，雷洛昔芬对VSMC的影响尚不清楚。我们在此发现，17 β-雌二醇（E-2）和雷洛昔芬显著抑制血小板衍生生长因子（PDGF）刺激的培养人VSMC增殖。流式细胞术显示，PDGF刺激的VSMC细胞周期的S期进程也被E-2或雷洛昔芬抑制。我们发现，PDGF诱导的视网膜母细胞瘤蛋白（pRb）的磷酸化，其过度磷酸化是细胞周期中G1-S转换的标志，被E-2和雷洛昔芬显著抑制。这些作用与细胞周期蛋白D1表达的减少有关，而细胞周期蛋白依赖性激酶4或细胞周期蛋白依赖性激酶抑制剂p27（kip 1）表达没有变化。ICI 182，780消除了E-2和雷洛昔芬对PDGF诱导的pRb磷酸化的抑制作用。接下来，我们研究了雌激素受体（ER）是必要的E-2和雷洛昔芬的这些影响。由于VSMC表达ER α和ER β，因此使用A10，一种表达ER β但不表达ER α的大鼠主动脉平滑肌细胞系。与VSMC中获得的结果相反，E-2或雷洛昔芬并未抑制PDGF对A10细胞增殖的剂量依赖性刺激。此外，E2和雷洛昔芬显着抑制PDGF诱导的细胞周期蛋白D1的启动子活性在A10细胞转染ER α的cDNA，但不是在亲本细胞。这些结果表明，E-2和雷洛昔芬至少部分通过抑制pRb磷酸化而在用PDGF处理的VSMC中发挥抗增殖作用，并且E-2和雷洛昔芬的抑制作用可能主要由ER α介导。
The proliferation of vascular smooth muscle cells (VSMC) is a crucial pathophysiological process in the development of atherosclerosis. Although estrogen is known to inhibit the proliferation of VSMC, the mechanism responsible for this effect remains to be elucidated. In addition, the effect of raloxifene on VSMC remains unknown. We have shown here that 17beta-estradiol (E-2 and raloxifene significantly inhibited the platelet-derived growth factor (PDGF)-stimulated proliferation of cultured human VSMC. Flow cytometry demonstrated that PDGF-stimulated S-phase progression of the cell cycle in VSMC was also suppressed by E-2 or raloxifene. We found that PDGF-induced phosphorylation of retinoblastoma protein (pRb), whose hyperphosphorylation is a hallmark of the G1-S transition in the cell cycle, was significantly inhibited by E-2 and raloxifene. These effects were associated with a decrease in cyclin D1 expression, without a change in cyclin-dependent kinase 4 or cyclin-dependent kinase inhibitor, p27(kip1) expression. ICI 182,780 abolished the inhibitory effects of E-2 and raloxifene on PDGF-induced pRb phosphorylation. Next, we examined which estrogen receptor (ER) is necessary for these effects of E-2 and raloxifene. Since VSMC express both ERalpha and ERbeta, A10, a rat aortic smooth muscle cell line that expresses ERbeta but not ERalpha, was used. The dose-dependent stimulation of A10 cell proliferation by PDGF was not inhibited by E-2 or raloxifene in contrast to the results obtained in VSMC. Moreover, E2 and raloxifene significantly inhibited the PDGF-induced cyclin D1 promoter activity in A10 cells transfected with cDNA for ERalpha but not in the parental cells. These results suggested that E, and raloxifene exert an antiproliferative effect in VSMC treated with PDGF, at least in part through inhibition of pRb phosphorylation, and that the inhibitory effects of E-2 and raloxifene may be mainly mediated by ERalpha.