Tumors are complex ecosystems in which heterogeneous cancer cells interact with their microenvironment composed of diverse immune, endothelial, and stromal cells. Cancer biology had been studied using bulk genomic and gene expression profiling, which however mask the cellular diversity and average the variability among individual molecular programs. Recent advances in single-cell transcriptomic sequencing have enabled a detailed dissection of tumor ecosystems and promoted our understanding of tumorigenesis at single-cell resolution. In the present review, we discuss the main topics of recent cancer studies that have implemented single-cell RNA sequencing (scRNA-seq). To study cancer cells, scRNA-seq has provided novel insights into the cancer stem-cell model, treatment resistance, and cancer metastasis. To study the tumor microenvironment, scRNA-seq has portrayed the diverse cell types and complex cellular states of both immune and non-immune cells interacting with cancer cells, with the promise to discover novel targets for future immunotherapy.

肿瘤是复杂的生态系统，其中异质癌细胞与其由多种免疫细胞、内皮细胞和基质细胞组成的微环境相互作用。癌症生物学已经使用大量基因组和基因表达谱进行了研究，然而这掩盖了细胞多样性并平均了单个分子程序之间的变异性。单细胞转录组测序的最新进展使我们能够详细剖析肿瘤生态系统，并促进我们对单细胞分辨率下肿瘤发生的理解。在本综述中，我们讨论了最近实施单细胞 RNA 测序 (scRNA-seq) 的癌症研究的主要主题。为了研究癌细胞，scRNA-seq 为癌症干细胞模型、治疗耐药性和癌症转移提供了新的见解。研究肿瘤微环境，