背景:乳腺癌的内部异质性,特别是由恶性和非恶性细胞组成的肿瘤微环境(TME),近年来进行了广泛的探索。这种复杂的细胞生态系统中的细胞通过表型改变激活或抑制肿瘤免疫,代谢产物的分泌和细胞-细胞通讯网络。巨噬细胞,作为TME中最丰富的免疫细胞,被恶性细胞募集并经历表型重塑。肿瘤相关巨噬细胞(TAMs)表现出多种亚型和功能,在影响肿瘤免疫方面发挥重要作用。然而,它们的精确亚型划分和特定功能仍未充分定义。
方法:将来自8名具有不同分子亚型和分期的乳腺癌患者的49,141个细胞的公开单细胞转录组纳入我们的研究。采用无监督聚类和手动细胞注释来准确地分类TAM亚型。然后,我们进行了功能分析,并构建了TAM亚型的发展轨迹。随后,以内皮细胞(ECs)和T细胞为关键节点,探讨了TAM亚型在TME内细胞间通讯网络中的作用.最后,在另一个独立发表的scRNA数据集中重复分析,以验证我们对TAM表征的发现.
结果:TAM被准确地分为7种亚型,显示抗肿瘤或促肿瘤作用。第一次,我们确定了一种新的能够在乳腺癌中增殖和扩增的TAM亚型-TUBA1B+TAM在TAM的多样性和肿瘤进展中起关键作用.发育轨迹说明了TAM如何在TME内重塑并经历表型和功能变化,在初始点使用TUBA1B+TAM。值得注意的是,主要的TAM亚型因乳腺癌的不同分子亚型和分期而异.此外,我们对细胞-细胞通信网络的研究表明,TAM通过直接调节内在免疫而发挥作用,通过T细胞间接调节适应性免疫,以及通过ECs影响肿瘤血管生成和淋巴管生成。
结论:我们的研究建立了精确的乳腺癌TAMs单细胞图谱,阐明它们在肿瘤生物学中的多方面作用,并为乳腺癌免疫治疗中的靶向TAM提供资源。
BACKGROUND: The internal heterogeneity of breast cancer, notably the tumor microenvironment (TME) consisting of malignant and non-malignant cells, has been extensively explored in recent years. The cells in this complex cellular ecosystem activate or suppress tumor immunity through phenotypic changes, secretion of metabolites and cell-cell communication networks. Macrophages, as the most abundant immune cells within the TME, are recruited by malignant cells and undergo phenotypic remodeling. Tumor-associated macrophages (
TAMs) exhibit a variety of subtypes and functions, playing significant roles in impacting tumor immunity. However, their precise subtype delineation and specific function remain inadequately defined.
METHODS: The publicly available single-cell transcriptomes of 49,141 cells from eight breast cancer patients with different molecular subtypes and stages were incorporated into our study. Unsupervised clustering and manual cell annotation were employed to accurately classify TAM subtypes. We then conducted functional analysis and constructed a developmental trajectory for TAM subtypes. Subsequently, the roles of TAM subtypes in cell-cell communication networks within the TME were explored using endothelial cells (ECs) and T cells as key nodes. Finally, analyses were repeated in another independent publish scRNA datasets to validate our findings for TAM characterization.
RESULTS: TAMs are accurately classified into 7 subtypes, displaying anti-tumor or pro-tumor roles. For the first time, we identified a new TAM subtype capable of proliferation and expansion in breast cancer-TUBA1B+ TAMs playing a crucial role in
TAMs diversity and tumor progression. The developmental trajectory illustrates how
TAMs are remodeled within the TME and undergo phenotypic and functional changes, with TUBA1B+
TAMs at the initial point. Notably, the predominant TAM subtypes varied across different molecular subtypes and stages of breast cancer. Additionally, our research on cell-cell communication networks shows that TAMs exert effects by directly modulating intrinsic immunity, indirectly regulating adaptive immunity through T cells, as well as influencing tumor angiogenesis and lymphangiogenesis through ECs.
CONCLUSIONS: Our study establishes a precise single-cell atlas of breast cancer TAMs, shedding light on their multifaceted roles in tumor biology and providing resources for targeting TAMs in breast cancer immunotherapy.