Department of General Surgery, The Second Affiliated Hospital of Harbin Medical University, 246 Xuefu Street, Harbin, 150001, China.
Department of Pathology, The Second Affiliated Hospital of Harbin Medical University, 246 Xuefu Street, Harbin, 150001, China.
Cancer Immunol Immunother. 2024 May 7;73(7):117. doi: 10.1007/s00262-024-03699-1.
Estrogen receptor (ER) positive human epidermal growth factor receptor 2 (HER2) negative breast cancer (ER+/HER2-BC) and triple-negative breast cancer (TNBC) are two distinct breast cancer molecular subtypes, especially in tumor immune microenvironment (TIME). The TIME of TNBC is considered to be more inflammatory than that of ER+/HER2-BC. Natural killer (NK) cells are innate lymphocytes that play an important role of tumor eradication in TME. However, studies focusing on the different cell states of NK cells in breast cancer subtypes are still inadequate.
In this study, single-cell mRNA sequencing (scRNA-seq) and bulk mRNA sequencing data from ER+/HER2-BC and TNBC were analyzed. Key regulator of NK cell suppression in ER+/HER2-BC, S100A9, was quantified by qPCR and ELISA in MCF-7, T47D, MDA-MB-468 and MDA-MB-231 cell lines. The prognosis predictability of S100A9 and NK activation markers was evaluated by Kaplan-Meier analyses using TCGA-BRAC data. The phenotype changes of NK cells in ER+/HER2-BC after overexpressing S100A9 in cancer cells were evaluated by the production levels of IFN-gamma, perforin and granzyme B and cytotoxicity assay.
By analyzing scRNA-seq data, we found that multiple genes involved in cellular stress response were upregulated in ER+/HER2-BC compared with TNBC. Moreover, TLR regulation pathway was significantly enriched using differentially expressed genes (DEGs) from comparing the transcriptome data of ER+/HER2-BC and TNBC cancer cells, and NK cell infiltration high/low groups. Among the DEGs, S100A9 was identified as a key regulator. Patients with higher expression levels of S100A9 and NK cell activation markers had better overall survival. Furthermore, we proved that overexpression of S100A9 in ER+/HER2-cells could improve cocultured NK cell function.
In conclusion, the study we presented demonstrated that NK cells in ER+/HER2-BC were hypofunctional, and S100A9 was an important regulator of NK cell function in ER+BC. Our work contributes to elucidate the regulatory networks between cancer cells and NK cells and may provide theoretical basis for novel drug development.
雌激素受体（ER）阳性人表皮生长因子受体 2（HER2）阴性乳腺癌（ER+/HER2-BC）和三阴性乳腺癌（TNBC）是两种不同的乳腺癌分子亚型，尤其是在肿瘤免疫微环境（TIME）中。TNBC 的 TIME 被认为比 ER+/HER2-BC 更具炎症性。自然杀伤（NK）细胞是先天淋巴细胞，在 TME 中发挥着消除肿瘤的重要作用。然而，关于乳腺癌亚型中 NK 细胞不同细胞状态的研究仍然不足。
本研究分析了 ER+/HER2-BC 和 TNBC 的单细胞 mRNA 测序（scRNA-seq）和批量 mRNA 测序数据。通过 qPCR 和 ELISA 在 MCF-7、T47D、MDA-MB-468 和 MDA-MB-231 细胞系中定量检测 ER+/HER2-BC 中 NK 细胞抑制的关键调节因子 S100A9。使用 TCGA-BRAC 数据通过 Kaplan-Meier 分析评估 S100A9 和 NK 激活标志物的预后预测能力。通过测定 IFN-γ、穿孔素和颗粒酶 B 的产生水平和细胞毒性测定评估在癌细胞中过表达 S100A9 后 ER+/HER2-BC 中 NK 细胞表型的变化。
通过分析 scRNA-seq 数据，我们发现与 TNBC 相比，ER+/HER2-BC 中多个涉及细胞应激反应的基因上调。此外，通过比较 ER+/HER2-BC 和 TNBC 癌细胞和 NK 细胞浸润高低组的转录组数据，TLR 调节途径显著富集。在差异表达基因（DEGs）中，S100A9 被鉴定为关键调节因子。S100A9 和 NK 细胞激活标志物表达水平较高的患者总生存率更好。此外，我们证明在 ER+/HER2-细胞中过表达 S100A9 可以改善共培养的 NK 细胞功能。
综上所述，本研究表明 ER+/HER2-BC 中的 NK 细胞功能低下，S100A9 是 ER+BC 中 NK 细胞功能的重要调节因子。我们的工作有助于阐明癌细胞和 NK 细胞之间的调节网络，并为新药开发提供理论依据。
