胶原受体DDR2在肿瘤血管拟态形成中的作用及机制研究

Tumor cell vasculogenic mimicry (VM) refers to the plasticity of aggressive cancer cells forming de novo vascular networks, which thereby contribute to perfusion of rapidly growing tumors, transporting fluid from leaky vessels, and/or connecting with the constitutional endothelial-lined vasculature. The introduction of this new conception is not only a substantial progress in the biology of cancer, but also a hopeful target for antiangiogenic therapy. Although the detailed molecular mechanisms for VM are not fully understood, more and more evidence indicates that VM may be associated with the degradation and remodeling of the extracellular matrix. The discoidin domain receptors(DDRs) are the only RTKs that specifically bind to and are activated by collagen. As one of the two DDRs, DDR2 is involved in remodeling of the extracellular matrix，a process mediated by the activity of matrix metalloproteinases(MMPs). So we have reasons to believe that DDR2 may play a key role in the formation of VM. This study intends to establish in vitro and in vivo model of VM and further study the role of DDR2 in the formation of VM. Through the research of the molecular mechanisms of DDR2 in the process of VM, We hope to find promising clues for the antiangiogenic therapy of cancer. In particular we intend to employ some new methods in the establishment of VM model. As to the in vitro model, we will appraise whether the pipe lined by adenocarcinoma cells in three-dimensional culture is VM or merely acini-like structure by means of it's polarized feature under confocal microscopy，which is immunostained with antibodies to illustrated the polarized orientation of the denocarcinoma cells(for example, antibodies to Golgi apparatus or phospho-ERM). As to the in vivo mouse model, we will estimate the frequency of VM in the transplanted tumor formed by green fluorescent protein-transfected tumor cells, combined with immunohistochemistry for identifying endothelial cells. Altogether, through exploring the role of DDR2 in the formation of cancer cell vasculogenic mimicry, we hope to find more clues in diagnosis and treatment for cancer.

肿瘤血管拟态(vascular mimicry)是指由某些类型的肿瘤细胞自身变形所形成的管网，VM现象的存在提示，在肿瘤抗血管治疗中需同时兼顾内皮依赖性血管与VM。近年的研究表明，VM的发生机制涉及肿瘤EMT及MMP-2介导的细胞外基质重塑。盘状结构域受体2(Discoidin domain receptor 2, DDR2)属于受体型蛋白酪氨酸激酶，配体为胶原，是EMT发生的关键分子，此外还通过调控MMPs的表达参与细胞外基质重塑。因此，我们推测DDR2很有可能通过促进EMT进程及上调MMP-2的表达参与肿瘤VM的发生。本研究拟在细胞水平和动物水平用一种新的检测方法明确DDR2是否参与肿瘤VM的形成并探讨相关的分子机制。该项目不仅能够建立一种分析拟态血管结构及功能的新方法，从而弥补传统研究方法的不足，还能丰富对DDR2功能的认识，从而为靶向DDR2的策略用于抗肿瘤治疗提供理论依据。

肿瘤血管拟态(vascular mimicry)是指由某些类型的肿瘤细胞自身变形所形成的管网，VM现象的存在提示，在肿瘤抗血管治疗中需同时兼顾内皮依赖性血管与VM。近年的研究表明，即使VM这个概念已经被广泛接受，但批判性的怀疑由于技术限制而从未完全消失。我们新建了一种基于荧光探针标记红细胞的方法来示踪VM网络与血液循环系统的连接状态。与已有的VM概念相矛盾的是，在黑色素瘤移植模型中，我们没有发现无内皮细胞的管腔能够运输血液。但当示踪红细胞长时间在荷瘤小鼠体内循环时，可观察到具有典型VM特征的血管腔。但是这些看似VM的结构是与坏死的肿瘤碎片共同定位的，因此我们推测它们可能是功能丧失的木乃伊血管。我们提出了血管消亡的三步骤理论，马赛克血管，被认为是正常肿瘤血管和死亡肿瘤血管之间的中间形态。我们目前的研究不仅为未来确定功能性肿瘤VM结构提供了一种有说服力的方法，而且挑战了当前对VM存在及其生物学意义的看法。

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