SMOOTH MUSCLE CELL PROLIFERATION IN HUMAN CORONARY ARTERY BYPASS GRAFTS

描述(申请人提供)：冠状动脉疾病，导致心肌梗死和缺血，影响数百万人，是全球发病率和死亡率的主要原因之一。侵入性技术，如使用大隐静脉(SV)或乳内动脉(IMA)的冠状动脉旁路移植术(CABG)被用来减轻动脉闭塞的后遗症。不幸的是，由于移植静脉管道中血管平滑肌细胞(VSMCs)的增殖，再狭窄在几个月到几年内发生，并逐渐降低通畅性。令人惊讶的是，IMA管道没有受到纤维增殖的病理影响。然而，造成这种差异的潜在细胞和分子机制尚不清楚。机械力在静脉移植物疾病的发病机制中起重要作用。剪切力的改变导致血管活性介质的释放，并调节VSMCs的基因表达。最近，我们观察到多功能脂质磷酸酶PTEN的暂时失活导致SV SMC的增殖，并且PTEN的过表达减少了IGF-1受体和细胞的增殖。我们还发现，血管紧张素II(Ang II)和IGF-1刺激SMC后，连接蛋白43(Cx43)的表达增加，与IMA相比，SV SMC的增殖显著增加。由于PTEN调控细胞信号和细胞生长，而涉及Cx43的细胞之间的通讯在内膜增生的发生发展中起着至关重要的作用，现建议研究PTEN在Cx43表达、IGF-1和Ang II激活的信号转导以及相关的促增生通路中的调节作用。中心假说是PTEN以反馈的方式减少IGF-1受体，通过调控PI3K-Akt/PKB促增殖通路和MAPK-AP-1-Cx43的表达来调节血管紧张素II-IGF-1诱导的人冠状动脉旁路移植术后血管内皮细胞的增殖和存活。目的：研究PTEN在胰岛素样生长因子-1(IGF-1)和血管紧张素转换酶II(Ang-II)诱导的血管内皮细胞IGF-1受体表达、PI3K-Akt/PKB和MAPK通路激活中的反馈作用及其对细胞增殖的影响。目的：研究PTEN过表达对胰岛素样生长因子-1(IGF-1)和血管紧张素转换酶II(Ang-II)刺激的人血管内皮细胞(SMC)MAPK-AP-1-Cx43表达和活化的影响及其对细胞增殖的影响。目的：研究PTEN过表达对血管紧张素Ⅱ和胰岛素样生长因子1诱导的血管紧张素Ⅱ和胰岛素样生长因子1诱导的细胞周期蛋白依赖性蛋白抑制物(CKIs；p21、p27和P53)、细胞周期蛋白D和E、Rb蛋白和E2F表达和活化的影响及其对细胞增殖的影响。对SV和IMA搭桥术中发生增生的确切机制进行比较，可以为制定更好的治疗策略提供机会。公共卫生相关性：冠状动脉搭桥术的长期结果受到血管再闭合的影响，血管再闭合主要发生在隐静脉移植物上，而内乳动脉仍然几乎不能再闭合。在这个项目中，建议进行实验，以在细胞和分子水平上检查潜在的精确机制。从这项研究中获得的信息应该为制定更好的治疗方法提供机会。

DESCRIPTION (provided by applicant): Coronary artery disease, leading to myocardial infarction and ischemia, affects millions of people and is one of the leading causes of morbidity and mortality worldwide. Invasive techniques such as coronary artery bypass grafting (CABG) using the saphenous vein (SV) or internal mammary artery (IMA) are used to alleviate the sequelae of arterial occlusion. Unfortunately, restenosis, due to proliferation of vascular smooth muscle cells (VSMCs) in the grafted venous conduit, occurs within months to years with a gradual reduction in patency. Surprisingly, the IMA conduits are spared from the pathologic effects of fibroproliferation. However, the underlying cellular and molecular mechanisms, which are the basis for this difference, are unclear. Mechanical forces play an important role in the pathogenesis of vein graft disease. Alterations in shear stress result in the release of vasoactive mediators and modulate gene expression in VSMCs. Recently, we observed temporal inactivation of PTEN, a multifunctional lipid phosphatase, causing proliferation of SV SMCs, and that PTEN overexpression decreased IGF-1 receptors and cell proliferation. We also found that increased connexin43 (Cx43) expression following stimulation of SMCs with angiotensin II (Ang II) and IGF-1 significantly increases proliferation in the SMCs of SV than in the IMA. Since PTEN modulates cell signaling and cell growth, and communication between cells involving Cx43 plays a crucial role in the development of intimal hyperplasia, investigation of the regulatory role of PTEN in Cx43 expression and IGF-1 and Ang II- activated signaling, along with associated pro-hyperplasia pathways is now proposed. The central hypothesis is that PTEN decreases IGF-1 receptors in a feedback manner to regulate angiotensin II-IGF-1- induced proliferation and survival of smooth muscle cells from human CABG conduits by controlling PI3K-Akt/PKB pro-hyperplasia pathway and MAPK-AP-1-Cx43 expression. AIM 1: To examine the feedback effect of PTEN on IGF-1- and Ang-II-induced IGF-1 receptor expression and activation of the PI3K-Akt/PKB and MAPK pathways in SMCs of human SV and IMA and on the resultant proliferation. AIM 2: To investigate the effect of PTEN overexpression on the expression and activation of MAPK-AP-1-Cx43 in IGF-1- and Ang-II-stimulated SMCs of human SV and IMA, and on the resultant proliferation. AIM 3: To examine the effect of PTEN overexpression on Ang-II and IGF-1-induced expression and activation of cyclin- dependent kinase inhibitors (CKIs; p21, p27, and p53), cyclin D and E, Rb protein and E2F in SMCs of human SV and IMA, and on the resultant proliferation. The comparison of the precise mechanisms involved in the development of hyperplasia in SV and IMA bypass grafts should provide an opportunity to formulate superior therapeutic strategies. PUBLIC HEALTH RELEVANCE: Long term outcome of coronary artery bypass surgeries is compromised by re-closure of the vessels, which predominantly occurs in saphenous vein grafts while the internal mammary artery remains almost resistant to re-closure. In this project experiments are proposed to examine the underlying precise mechanisms at the cellular and molecular level. The information obtained from this study should provide an opportunity to formulate superior therapeutic approaches.