Vascular communication in metastatic brain colonization

描述(申请人提供)：乳腺癌细胞通常通过尚未完全了解的机制转移到大脑。由于没有有效的治疗方法，而且手术治疗往往是有问题的，发生脑转移的乳腺癌患者的存活率很低(&lt；10个月)。最近的研究表明，只有附着在大脑血管表面的转移性乳腺癌细胞才能存活下来，形成微肿瘤。侵入脑实质深处的细胞不会存活。这些发现表明，脑微血管系统为乳腺癌细胞的生存和繁殖提供了独特的利基环境。然而，目前尚不清楚乳腺癌细胞如何附着在血管壁上并与内皮细胞通信。我们最近发表的发现和这项提议中提出的初步结果表明，Cx43介导的缝隙连接(GJ)与脑血管系统的黏附和通信是脑转移所必需的。此外，我们发现脑归巢转移细胞代表了具有干细胞样特性的肿瘤细胞亚群(称为乳腺癌干细胞，BCSCs)。重要的是，BCSCs特异性地表达Cx43，它促进了Cx43-GJS与富含Cx43的脑血管系统的强健形成。这些发现很重要，因为它提供了一个看似合理的解释，解释了为什么乳腺癌细胞通常位于大脑中，并与脑血管系统一起生长。我们的发现还提供了一种独特的机制，通过已有的GJ疗法，如甘草酸(CBX)和功能阻断(细胞通透性多肽)，靶向大脑中的转移细胞，目前正在进行临床试验评估。因此，这项提议将准确地确定异质细胞GJ的通讯和信号转导如何调节脑血管系统的BCSC集落。在这些研究中，我们将使用强大的荧光干细胞报告结构和特定的功能获得或丧失功能Cx43基因突变，结合独特的临床前动物模型，促进活体跟踪和分析BCSC在脑内的转移。我们的工作将为BCSCs如何使用GJ通讯在大脑中定植提供一个基本的了解，并确定这种通讯网络的扰动是否可以用于治疗脑转移疾病。

DESCRIPTION (provided by applicant): Breast cancer cells commonly metastasize to the brain using mechanisms that are not fully understood. Because there are no effective therapeutics and surgical treatments are often problematic, the survival rate of breast cancer patients that develop brain metastases is dismal (<10 months). Recent work indicates that only metastatic breast cancer cells that attach to the vascular surface in the brain survive to form microtumors. Cells that invade deep into the brain parenchyma do not survive. These findings indicate the brain microvasculature provides a unique niche for breast cancer cell survival and propagation. However, it is not known how breast cancer cells attach to the vessel wall and communicate with the endothelium. Our recent published findings and preliminary results presented in this proposal demonstrate that Cx43-mediated gap junction (GJ) adhesion and communication with the brain vasculature is required for brain metastasis. Furthermore, we find that brain homing, metastatic cells, represent a subpopulation of tumor cells with stem cell-like properties (referred to as breast cancer stem cells, BCSCs). Importantly, BCSCs specifically express Cx43, which facilitates robust formation of Cx43-GJs with the Cx43-enriched brain vasculature. These findings are important because it provides a plausible explanation for why breast cancer cells commonly home to the brain and grow in association with the brain vasculature. Our findings also provide a unique mechanism to target metastatic cells in the brain with established GJ therapeutics such as carbenoxolone (CBX) and function blocking, cell-permeable peptides, which are currently being evaluated in clinical trials. Therefore, work i this proposal will determine precisely how heterocellular GJ communication and signal transduction regulates BCSC olonization of the brain vasculature. For these studies, we will use powerful fluorescent stem cell reporter constructs and specific gain or loss of function cx43 gene mutants in combination with unique preclinical animal models that facilitate intravital tracking and analysis of BCSC metastasis in the brain. Our work will provide a fundamental understanding of how BCSCs colonize the brain using GJ communication and determine if perturbation of this communication network can be used to treat metastatic disease in the brain.