Investigating how the metastatic niche impairs NK cell cytotoxicity in early lung metastasis from breast cancer

自然杀伤（NK）细胞是乳腺癌肿瘤微环境（TME）中具有重要抗癌功能的先天性淋巴细胞。虽然NK细胞具有消除转移部位的播散性癌细胞的能力，但其细胞毒性活性在成功转移中受损。我们假设TME中的其他成分在转移性定殖的早期阶段抑制NK细胞活化和对抗癌细胞的功能。因此，我们使用Cherry-niche，一种体内标记工具，来阐明TME细胞在乳腺癌肺微转移中如何变化和相互作用。我们的单细胞RNA测序（scRNA-seq）分析鉴定了在转移性小生境中富集的成纤维细胞和单核细胞的亚群和NK细胞的活性信号分子。接下来，我们开发了2D和3D共培养系统来研究NK细胞、成纤维细胞和单核细胞之间的串扰。我们目前正在使用这些系统来测试NK细胞和成纤维细胞/单核细胞之间的选定分子相互作用的作用，我们使用生物信息学工具（如CellChat和NicheNet）通过计算机识别。这项研究将揭示新的细胞间动力学发生在转移的小生境，以及分子靶点，可能恢复NK细胞的细胞毒性，在早期转移与免疫抑制的潜力。

Natural killer (NK) cells are innate lymphocytes with important anti-cancer functions in the tumour microenvironment (TME) of breast cancer. Although NK cells have the capacity to eliminate disseminated cancer cells at the metastatic site, their cytotoxic activity is impaired in successful metastasis. We hypothesise that other components within the TME inhibit NK cell activation and function against cancer cells at the early stage of metastatic colonisation. Therefore, we have used Cherry-niche, an in vivo labelling tool, to characterise how TME cells change and interact with each other in lung micro-metastases from breast cancer. Our single-cell RNA sequencing (scRNA-seq) analysis identified subpopulations of fibroblasts and monocytes that are enriched in the metastatic niche and active signallers to NK cells. Next, we have developed 2D and 3D co-culture systems to study the crosstalk between NK cells, fibroblasts and monocytes. We are currently using these systems to test the role of selected molecular interactions between NK cells and fibroblasts/monocytes that we identified in silico using bioinformatic tools, such as CellChat and NicheNet. This study will reveal novel inter-cellular dynamics occurring in the metastatic niche, as well as molecular targets that may restore NK cell cytotoxicity in early metastasis with immunotherapeutic potential.