miR-17~92 cluster 调控VSMC表型转化在移植静脉术后再狭窄中的作用及机制研究

Vein grafts failure remains an important and unresolved problem of coronary artery bypass grafting (CABG) surgery. The main pathogenesis of vein graft restenosis is neointimal hyperplasia associated with vascular smooth muscle cell (VSMC) dedifferentiation, migration and proliferation. Phenotypic modulation of VSMC by miRs plays a critical role in the pathogenesis of a variety of proliferative vascular diseases. In the preliminary study, we have identified abundant expression of miR-17~92 cluster in vein graft restenosis rat model and VSMC dedifferentiation model. Smad4 as a potential target gene of miR-17~92 cluster according to its mRNA 3’-UTR complementary to miR-17~92 cluster by searching for Targetscan database. Therefore, the objective of the study was to evaluate the role, if any, of miR-17~92 cluster in VSMC phenotypic switch in vitro and in response to neointimal hyperplasia lesion formation after vein graft in vivo. Furthermore, to verify that Smad4 as a downstream target gene of miR-17~92 cluster by luciferase activity assay in vitro. The findings of this study may represent promising therapeutic targets in vein graft restenosis after coronary artery bypass grafting surgery.

血管平滑肌细胞(VSMC)表型转化、过度增殖迁移所致的内膜增生是冠状动脉旁路移植(CABG)术后移植静脉再狭窄发生的主要病理机制。microRNA(miR)是调控VSMC生物学功能的重要因子，我们前期实验发现miR-17~92 cluster在移植静脉再狭窄动物模型和VSMC表型转化模型中均高表达，且伴随Smad4基因的低表达，进一步理论预测发现miR-17~92 与Smad4 mRNA的3'UTR存在关键结合位点。本课题拟通过细胞和动物实验明确miR-17~92 cluster 是否参与VSMC表型转化、增殖和迁移的调控；通过荧光素酶报告实验明确Smad4是否是miRNA-17~92 cluster调控的直接功能性靶基因；靶向抑制miR-17~92 cluster是否可以有效缓解移植静脉术后内膜增生再狭窄的形成。本课题将为CABG术后移植静脉再狭窄的发生发展机制和防治研究提供新的切入点。

本项目主要内容是以microRNA-17~92为研究切入点，以血管平滑肌细胞（VSMC）表型转化为核心病理生理机制，初步探讨其参与移植静脉术后内膜增生性再狭窄发生发展中的作用。本项目主要明确了miRNA-17~92通过调控VSMC表型转化参与移植静脉术后内膜增生性再狭窄发生这一重要机制；阐明了通过基因治疗靶向抑制miRNA-17~92可有效缓解移植静脉术后内膜增生再狭窄的发生这一重要价值；确定了miRNA-17~92家族中的关键成员miRNA-17通过介导VSMC表型转化、增殖迁移等机制参与移植静脉术后内膜增生性再狭窄发生；更重要的是发现了miRNA-17~92家族中的关键成员miRNA-92a通过内皮间质转化（EndMT）参与调控移植静脉术后内膜增生再狭窄的发生这一新的研究切入点。这提示我们miR-17~92很可能从VSMC表型转化及EndMT两个分子层面参与移植静脉术后内膜增生性再狭窄的发生机制，为该课题的后续研究建立了重要的研究基础。本项目的完成提出了miR-17~92作为调节靶点作为冠脉搭桥术后防止或延缓桥血管再狭窄辅助治疗的可能性，为后续研究提供了重要研究依据和研究切入点。截止结题时，在本项目的资助下，共有6篇论著发表，其中SIC论著4篇，CSCD核心2篇；其中IF＞3的SCI论著4篇，IF＞5的SCI论著2篇，尚有1篇SCI论文正在撰写。以第一完成人正在申请技术专利4项，获优秀论文奖、省市级科研基金及人才项目等。