Vascular communication in metastatic brain colonization

描述（由申请人提供）：乳腺癌细胞通常转移到大脑的机制尚不完全清楚。由于没有有效的治疗方法和手术治疗经常存在问题，乳腺癌患者发生脑转移的生存率很低（<10个月）。最近的研究表明，只有转移性乳腺癌细胞附着在大脑血管表面才能存活形成微肿瘤。侵入脑实质深处的细胞无法存活。这些发现表明，脑微血管为乳腺癌细胞的生存和繁殖提供了一个独特的生态位。然而，目前尚不清楚乳腺癌细胞是如何附着在血管壁上并与内皮细胞交流的。我们最近发表的研究结果和本提案提出的初步结果表明，cx43介导的间隙连接（GJ）粘附和与脑血管系统的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特异性表达Cx43，这促进了Cx43- gjs与富含Cx43的脑血管系统的强大形成。这些发现很重要，因为它提供了一个合理的解释，为什么乳腺癌细胞通常在大脑中生长，并与脑血管系统相关。我们的研究结果还提供了一种独特的机制，可以利用现有的GJ治疗方法（如卡贝诺洛酮（CBX）和功能阻断、细胞渗透性肽）靶向脑转移细胞，这些治疗方法目前正在临床试验中进行评估。因此，本提案的工作将精确地确定异细胞GJ通讯和信号转导如何调节BCSC在脑血管系统的定植。在这些研究中，我们将使用强大的荧光干细胞报告构建物和特异性功能获得或丧失的cx43基因突变体，结合独特的临床前动物模型，促进脑内BCSC转移的活体跟踪和分析。我们的工作将提供BCSCs如何利用GJ通讯定植大脑的基本理解，并确定这种通讯网络的扰动是否可用于治疗大脑转移性疾病。

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.