复合蛋白聚糖-1促进乳腺癌M2型巨噬细胞的细胞程序性死亡-配体1表达上调及其机制

SDC-1 promotes the upregulation of PD-L1 expression in M2 macrophages of breast cancer

摘要

目的 探究调控乳腺癌M2型巨噬细胞中细胞程序性死亡-配体1(programmed cell death ligand 1, PD-L1)表达的关键分子及其相关作用机制。方法 通过UCSE XEAN网站和癌症基因组图谱(TCGA)数据网站收集乳腺癌单细胞(GSE176078数据集)测序及临床数据,并进行细胞注释分析,分析PD-L1在各细胞亚群中的表达变化及PD-L1与M2型巨噬细胞相关性分析。将恶性肿瘤细胞(Malignant)分为CD274⁺组与CD274^-组,分析两组与不同亚群细胞的通讯信号差异。通过差异基因表达分析、Kaplan-Meier生存分析及与PD-L1的相关性分析筛选出关键调控分子。应用Western blotting检测关键调控分子复合蛋白聚糖-1(syndecan-1, SDC-1)在M2型巨噬细胞中的表达;通过外源性加入SDC-1重组蛋白进行干预,并另设SDC-1抑制剂处理组及对照组,比较各组PD-L1蛋白的表达变化,以评估SDC-1对PD-L1表达的调控作用;并应用Western blotting探讨SDC-1对M2型巨噬细胞PD-L1表达的影响。结果 细胞功能注释分析显示,GSE176078数据集中大多为Malignant细胞与M2型巨噬细胞。PD-L1在M2型巨噬细胞中平均表达较高且与M2型巨噬细胞浸润程度呈正相关。CD274⁺组与M2型巨噬细胞的关联性更强,CD274⁺组与CD274^-组的差异性细胞通讯信号主要富集于胶原蛋白(collagen)、层粘连蛋白(laminin)和血管生成素样蛋白(angiopoietin-like proteins, ANGPTL)等信号分子。差异基因表达分析发现SDC-1为表达差异基因,且与患者生存预后和PD-L1的表达显著相关。Western blotting实验发现,SDC-1在M2型巨噬细胞中的表达更高;加入SDC-1重组蛋白组细胞PD-L1蛋白表达高于对照组;抑制剂组的PD-L1蛋白表达明显低于对照组。结论 乳腺癌SDC-1的高表达通过促进M2型巨噬细胞增加PD-L1的表达促进乳腺癌进展,这为乳腺癌发病机制提供了新的见解。

Abstract

Objective To investigate the key regulatory molecules and underlying mechanisms governing programmed cell death ligand 1 (PD-L1) expression in M2 macrophages in breast cancer. Methods Single-cell sequencing data and clinical information of breast cancer (GSE176078 dataset) were obtained from the UCSE XENA platform and The Cancer Genome Atlas (TCGA) database. Cell annotation analysis was performed to evaluate PD-L1 expression across different cell subpopulations and to assess its correlation with M2 macrophages. Malignant tumor cells were stratified into CD274⁺ and CD274^- groups, and differences in intercellular communication between these groups and various cell types were analyzed. Key regulatory molecules were screened through differential gene expression analysis, Kaplan-Meier survival analysis, and correlation analysis with PD-L1. The expression of syndecan-1 (SDC-1) in M2 macrophages was examined by Western blotting. Recombinant SDC-1 protein was exogenously added for intervention, with SDC-1 inhibitor-treated and corresponding control groups established. PD-L1 protein expression under different treatment conditions was compared to evaluate the regulatory role of SDC-1. Results Cell functional annotation indicated that the GSE176078 dataset was mainly composed of malignant cells and M2 macrophages. PD-L1 expression was relatively higher in M2 macrophages and positively correlated with the extent of M2 macrophage infiltration. The CD274⁺ group showed a closer association with M2 macrophages. Differential cell communication analysis revealed that signaling pathways were primarily enriched in collagen, laminin, and angiopoietin-like proteins (ANGPTL). Differential expression analysis identified SDC-1 as a key gene significantly associated with patient prognosis and PD-L1 expression. Western blotting demonstrated that SDC-1 expression was elevated in M2 macrophages; exogenous addition of recombinant SDC-1 protein increased PD-L1 protein expression, whereas treatment with an SDC-1 inhibitor significantly reduced PD-L1 expression compared with the non-inhibitor group. Conclusion In breast cancer, elevated SDC-1 expression may promote tumor progression by upregulating PD-L1 expression in M2 macrophages and it provide new insights into the molecular mechanisms underlying breast cancer progression.

关键词

乳腺癌 / M2型巨噬细胞 / 程序性死亡-配体1(PD-L1) / 复合蛋白聚糖-1(SDC-1)

Key words

breast cancer / M2 macrophage / programmed cell death ligand 1 (PD-L1) / syndecan-1 (SDC-1)

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