Regulation of metastatic progression by an endothelial-derived factor

我们以前已经鉴定了一组组织特异性microRNA，它们通过不同的调节转移进展， 癌症类型。在乳腺癌和黑色素瘤中，这种转移调节miRNA通路使 癌细胞贪婪地将内皮细胞募集到原发性肿瘤部位（Png等，Nature，2011; Pencheva et 例如，Cell，2012）。在该领域中未知的关键是由这种被招募的人提供的信号。 影响转移进展的内皮细胞。我们使用了一种创新的无偏见的方法， 肿瘤内皮细胞的核糖体用亲和标签进行遗传标记。这使得能够纯化 肿瘤内皮核糖体沿着与其相关的转录物，然后进行下一代 测序这使我们能够将Slit 2鉴定为在内皮细胞中由高表达的细胞因子显著诱导的基因。 转移细胞Slit 2是神经系统正常建立所需的轴突导向分子 连通性。我们在同基因模型中的初步证据表明， 内皮隔室显著削弱了来自原发肿瘤部位的癌症转移。我们提出了一个 转移细胞在内皮细胞中诱导Slit 2的模型，Slit 2作为促进细胞增殖的信号， 肿瘤内的癌细胞（低Slit 2）向血管系统（高Slit 2）迁移，使血管内渗成为可能 和转移。这一模型得到了初步临床相关证据的支持，这些证据表明， 相对于肿瘤区室，内皮区室中Slit 2的增加与更高的分期相关。 转移复发率更高的肿瘤。在本申请中，我们提出了一系列 用于严格证实这一令人惊讶的模型的补充方法， 我们将通过基因失活的内皮细胞或癌细胞来调节癌细胞对Slit 2信号的感知。 肿瘤Slit 2使用细胞类型特异性基因失活在遗传启动的癌症进展模型中。 我们将采用活体动物多光子显微镜观察Slit 2驱动的肿瘤跨内皮迁移 和内渗。我们的目标是确定肿瘤受体的感觉Slit 2，使用免疫组织化学 研究内皮细胞Slit 2与人类癌症进展和转移之间的关联的方法 复发，并发现诱导内皮Slit 2的肿瘤源性信号。最后，我们将应用这些 通过确定临床使用的治疗方法，我们发现诱导Slit 2促进癌症转移。 这项工作有可能对我们理解癌症进展的机制产生重大影响， 建立内皮细胞作为转移的主要协调者。它可能对人类产生重要影响， 考虑到这种途径控制着高度流行的癌症类型的进展， 人类复发此外，我们采用的细胞类型特异性核糖体分析方法可以用于 更广泛地应用于研究肿瘤微环境中无穷无尽的细胞类型。

We have previously identified sets of tissue-specific microRNAs that regulate metastatic progression by distinct cancer types. In both breast cancer and melanoma, such metastasis regulating miRNA pathways enable cancer cells to avidly recruit endothelial cells into the primary tumor site (Png et al., Nature, 2011; Pencheva et al., Cell, 2012). A key unknown in the field has been the signal(s) that are provided by such recruited endothelial cells that impact metastatic progression. We have used an innovative unbiased approach wherein ribosomes of tumor endothelial cells are genetically marked with an affinity tag. This enables purification of tumor endothelial ribosomes along with their associated transcripts, which then undergo next-generation sequencing. This allowed us to identify Slit2 as a gene significantly induced in endothelial cells by highly metastatic cells. Slit2 is an axon guidance molecule required for the proper establishment of nervous system connectivity. Our preliminary evidence in syngeneic models reveals that genetic inactivation of Slit2 in the endothelial compartment significantly impairs cancer metastasis from the primary tumor site. We propose a model whereby metastatic cells induce Slit2 in endothelial cells, which serves as a signal that promotes migration of cancer cells within the tumor (low Slit2) towards the vasculature (high Slit2), enabling intravasation and metastasis. This model is supported by preliminary clinical association evidence that reveals that increased Slit2 in endothelial compartment relative to the tumoral compartment associates with higher stage tumors that exhibit higher rates of metastatic relapse. In this application, we propose a series of complementary approaches for rigorously confirming this surprising model and further mechanistically dissecting it. We will modulate Slit2 signal sensing by cancer cells through genetic inactivation of endothelial or tumoral Slit2 using cell-type specific genetic inactivation in a genetically initiated model of cancer progression. We will employ live animal multi-photon microscopy to visualize Slit2-driven tumoral trans-endothelial migration and intravasation. We aim to identify the tumoral receptor that senses Slit2, to use immunohistochemical methods to investigate an association between endothelial Slit2 and human cancer progression and metastatic relapse, and to discover the tumor-derived signal that induces endothelial Slit2. Finally, we will apply these insights by determining if a clinically used therapeutic, which we find induces Slit2 promotes cancer metastasis. This work has the potential for major impact on our understanding of mechanisms of cancer progression by establishing endothelial cells as major orchestrators of metastasis. It could have important impact on human disease given that this pathway governs progression of highly prevalent cancer types and associates with human relapse. Moreover, the cell-type specific ribosomal profiling method we have employed could be applied more broadly to study endless cell-types within the tumor microenvironment.