En Route to Metastasis: Circulating Tumor Cell Clusters and Epithelial-to-Mesenchymal Transition

Blood-borne metastasis accounts for the vast majority of cancer-related deaths and it is fueled by the generation of circulating tumor cells (CTCs) from a primary tumor deposit. Recent technological advances have made it possible to characterize human CTCs as they travel within the bloodstream. CTCs are found both as single cells and as clusters of cells held together by intercellular junctions. Although less prevalent, CTC clusters appear to have greater metastatic potential than single CTCs in the circulation. Both may exhibit shifts in expression of epithelial and mesenchymal markers, which may show dynamic changes during cancer progression. In this review we discuss recent insights into the biological properties of individual and clustered cancer cells in the circulation.

血行转移导致了绝大多数癌症相关的死亡，它是由原发性肿瘤病灶产生循环肿瘤细胞（CTCs）所推动的。近期的技术进步使得在人类循环肿瘤细胞在血液中流动时对其进行特征分析成为可能。循环肿瘤细胞既以单细胞形式存在，也以通过细胞间连接聚集在一起的细胞簇形式存在。尽管不太常见，但循环中的循环肿瘤细胞簇似乎比单个循环肿瘤细胞具有更强的转移潜能。两者都可能在上皮和间充质标志物的表达上发生变化，这种变化在癌症进展过程中可能呈现动态改变。在这篇综述中，我们讨论了对循环中单个和聚集的癌细胞生物学特性的最新见解。