Calcineurin-NFAT regulates endothelial activation in pre-metastatic sites

 描述(申请人提供)：转移是大多数癌症相关死亡的原因，尽管它仍然是一个鲜为人知的过程。转移性肿瘤细胞从原发肿瘤渗出，并在远处组织中定植，对定植的调控机制知之甚少。血管系统在转移前部位和转移进展中的作用还没有被广泛研究。我们实验室最近的工作表明，在检测到优先转移到肺的肿瘤细胞之前，钙调神经磷酸酶-NFAT通路在肺内皮细胞中被特异性地激活。我们的初步数据表明，内皮细胞激活是转移定植的先决条件，这种作用至少部分通过激活钙调神经磷酸酶-NFAT信号通路来实现。钙调神经磷酸酶是一种丝氨酸/酪氨酸磷酸酶，可激活NFAT家族转录因子，调节多种组织的发育。我们和其他人已经证明，钙调神经磷酸酶-NFAT通路是内皮细胞和血管生成中血管内皮生长因子-A信号的关键细胞内中介。在唐氏综合征(DS)患者中观察到的对实体瘤的显著保护表明了钙调神经磷酸酶信号在肿瘤血管生成中的重要性。我们先前在唐氏综合征小鼠模型中发表的研究表明，肿瘤血管生成缺陷导致肿瘤生长显著减少，部分原因是该途径的21号染色体编码抑制物唐氏综合症候选区域1(Dscr1)和双特异性激酶1A(Dyrk1A)表达增加，导致内皮细胞钙调神经磷酸酶信号减弱。在这里，我们建议探索这一信号通路和两个特定的下游靶点--凝血酶敏感蛋白-1(TSP-1)和血管生成素-2(Ang-2)在激活肺和肝脏转移前部位的血管内皮细胞中的临床相关作用。我们假设内皮细胞的激活启动了转移前的位置，为转移的肿瘤细胞的植入和存活提供了一个接受性的微环境。我们将从遗传学和药理学角度调控钙调神经磷酸酶-NFAT通路、血管内皮细胞TSP-1和Ang-2的表达，以确定其在肺和肝转移中的作用。我们将利用自发转移到肺或肝的原发肿瘤的转基因小鼠模型以及肺和肝的定植试验来研究转移性肿瘤细胞的植入。我们的研究将更好地阐明钙调神经磷酸酶-NFAT-TSP-1和Ang-2信号在转移部位内皮细胞中的生物学作用以及转移肿瘤细胞在远处组织定植的机制。这些发现还可能导致新的治疗方法，以防止广泛的肺和肝转移。

 DESCRIPTION (provided by applicant): Metastasis is responsible for most cancer-related mortality although it remains a poorly understood process. Metastatic tumor cells extravasate from the primary tumor and colonize in distant tissues with little understanding about mechanisms regulating colonization. The role of the vasculature in pre-metastatic sites and metastatic progression has not been extensively examined. Recent work from our lab shows that the calcineurin-NFAT pathway is activated specifically in lung endothelium prior to the detection of tumor cells that preferentially metastasize to the lung. Our preliminary data implicates endothelial activation as a prerequisite for metastatic colonization with this effect mediated at least partially via activation of the calcineurin-NFAT signaling pathway. Calcineurin, a ser/thr phosphatase, activates NFAT family transcription factors to regulate the development of many tissues. We and others have shown that the calcineurin-NFAT pathway is a key intracellular mediator of VEGF-A signaling in endothelial cells and angiogenesis. The importance of calcineurin signaling in tumor angiogenesis is illustrated by the remarkable protection against solid tumors observed in Down syndrome (DS) individuals. Our previously published studies in a Down syndrome mouse model indicate that defects in tumor angiogenesis resulting in significantly decreased tumor growth is due in part to attenuation of calcineurin signaling in endothelial cell by the increased expression of chromosome 21-encoded inhibitors of this pathway, Down syndrome candidate region-1 (Dscr1) and Dual specificity kinase 1A (Dyrk1A). Here we propose to explore novel clinically relevant roles for this signaling pathway and two specific downstream targets, thrombospondin-1 (TSP-1) and angiopoietin-2 (ANG-2) in activating the vascular endothelium in pre-metastatic sites in the lung and liver. We hypothesize that endothelial activation primes pre-metastatic sites providing a receptive microenvironment for the engraftment and survival of metastatic tumor cells. We will genetically and pharmacologically manipulate the calcineurin-NFAT pathway, TSP-1 and ANG-2 expression in endothelial cells to determine the effects on lung and liver metastasis. We will utilize transgenic mouse models of primary tumors that spontaneously metastasize to the lung or liver as well as lung and liver colonization assays to investigate metastatic tumor cell engraftment. Our studies will better elucidate the biology of calcineurin-NFAT-TSP-1 and ANG-2 signaling in endothelial cells at metastatic sites and mechanisms underlying metastatic tumor cell colonization in distant tissues. These findings may also lead to new therapies to prevent widespread lung and liver metastasis.