Tumor cell-derived exosomes regulate macrophage polarization: Emerging directions in the study of tumor genesis and development

Exosome-mediated effects of BRCA1 on cardiovascular artery disease

The progression of coronary artery disease atherosclerosis (CAD) is closely associated with cardiomyocyte apoptosis and inflammatory responses. This study focused on investigating the impact of BRCA1 in exosomes (Exo) derived from M1 macrophages on CAD. Through the analysis of single-cell RNA-seq datasets, significant communication between macrophages and cardiomyocytes in CAD patients was observed. BRCA1, identified as a significant apoptosis-related gene, was pinpointed through the assessment of differential gene expression and weighted gene co-expression network analysis (WGCNA). Experimental procedures involved BRCA1 lentivirus transfection of M1 macrophages, isolation of Exo for application to cardiomyocytes and smooth muscle cells, cell viability assessments, and characterization of Exo. The results showed that BRCA1-Exo from M1 macrophages induced cardiomyocyte apoptosis and affected smooth muscle cell behavior. In vivo studies further supported the exacerbating effects of BRCA1-Exo on CAD progression. Overall, the involvement of Exo carrying BRCA1 from M1 macrophages is evident in the induction of cardiomyocyte apoptosis and the regulation of smooth muscle cell behaviors, thereby contributing to CAD atherosclerosis progression. These findings unveil novel molecular targets that could have potential implications for CAD treatment strategies.

Prognostic value of FCER1G expression and M2 macrophage infiltration in esophageal squamous cell carcinoma

BACKGROUND

FCER1G as an immune-associated protein, which belongs to the immunoglobulin superfamily and is involved in mediating and executing antibody-mediated immune responses. However, the role of FCER1G in cancers remains controversial. Our objectives were to study the association between FCER1G and tumor- infiltrating immune cells (TIICs) as well as the predictive significance of FCER1G.

METHODS

The expression of FCER1G and its prognostic value in ESCC was examined by The Cancer Genome Atlas and Gene Expression Omnibus databases. We also evaluated the relationship between FCER1G expression and 22 TIICs. Immunohistochemistry was used to detect the expression and distribution of FCER1G. Double immunofluorescence was used to detect the co-expression of FCER1G and CD163 positive cells. Kaplan-Meier survival curves and Cox regression analysis was performed to determine the prognostic significance of FCER1G and CD163.

RESULTS

The analysis revealed that FCER1G was upregulated in ESCC, which was distributed more in the intra-tumor mesenchyme than in the cancer nests. The more infiltration in intra-tumor mesenchyme the worse the overall survival (OS) for patients with ESCC. The infiltration of FCER1G+ cells was positively correlated with that of M2 macrophages and most of the CD163+ M2 macrophages expressed FCER1G. The more the infiltration of FCER1G+ M2 macrophages, the worse the OS of ESCC patients. FCER1G and TNM stage were identified as independent risk factors affecting the OS of ESCC patients.

CONCLUSIONS

FCER1G+ cells infiltration may help to predict the prognosis of ESCC. The combined detection of FCER1G and CD163 has a higher prognostic value.

Cell Membrane-Integrated Neuroligin-1 Regulates the Anti-Inflammatory Effects of CRC Cell-Derived Exosomes

Tumor-associated macrophages (TAMs) are one of the most abundant cell types in the colorectal cancer (CRC) tumor microenvironment (TME). CRC cell-derived exosomes support macrophage polarization toward an M2-like phenotype, which leads to tumor growth and metastasis. Neuroligin 1 (NLG1) is a transmembrane protein critical in synaptic function. We reported that NLG1 via an autocrine manner promotes CRC progression by modulating the APC/β-catenin pathway. This study aimed to answer whether NLG1 is involved in the exosome-mediated intercellular cross-talk between CRC and TAMs. Our results showed that exosomes of NLG1-expressing CRC cells induce M2-like (CD206high CD80low) polarization in macrophages. On the other hand, we found that the exosomes of the NLG1 knocked-down CRC cells reinforce the expression of CD80 and pro-inflammatory genes, including IL8, IL1β, and TNFα, in the macrophages, indicating an M1-like phenotype polarization. In conclusion, NLG1, as a cell-membrane-integrated protein, could be a therapeutic target on the surface of the CRC cells for developing clinical treatments to inhibit exosome-induced anti-inflammatory immune responses in TME.

Identification of M2 macrophage-related genes for establishing a prognostic model in pancreatic cancer: FCGR3A as key gene

Background

Pancreatic ductal adenocarcinoma (PDAC) has a rich and complex tumor immune microenvironment (TIME). M2 macrophages are among the most extensively infiltrated immune cells in the TIME and are necessary for the growth and migration of cancers. However, the mechanisms and targets mediating M2 macrophage infiltration in pancreatic cancer remain elusive.

Methods

The M2 macrophage infiltration score of patients was assessed using the xCell algorithm. Using weighted gene co-expression network analysis (WGCNA), module genes associated with M2 macrophages were identified, and a predictive model was designed. The variations in immunological cell patterns, cancer mutations, and enrichment pathways between the cohorts with the high- and low-risk were examined. Additionally, the expression of FCGR3A and RNASE2, as well as their association with M2 macrophages were evaluated using the HPA, TNMplot, and GEPIA2 databases and verified by tissue immunofluorescence staining. Moreover, in vitro cell experiments were conducted, where FCGR3A was knocked down in pancreatic cancer cells using siRNA to analyze its effects on M2 macrophage infiltration, tumor proliferation, and metastasis.

Results

The prognosis of patients in high-risk and low-risk groups was successfully distinguished using a prognostic risk score model of M2 macrophage-related genes (p = 0.024). Between the high- and low-risk cohorts, there have been notable variations in immune cell infiltration patterns, tumor mutations, and biological functions. The risk score was linked to the manifestation of prevalent immunological checkpoints, immunological scores, and stroma values (all p < 0.05). In vitro experiments and tissue immunofluorescence staining revealed that FCGR3A can promote the infiltration or polarization of M2 macrophages and enhance tumor proliferation and migration.

Conclusions

In this study, an M2 macrophage-related pancreatic cancer risk score model was established, and found that FCGR3A was correlated with tumor formation, metastasis, and M2 macrophage infiltration.

Reprogramming tumor-associated macrophages using exosomes from M1 macrophages

Macrophages, abundant in tumors, are classified as M1 or M2 types with M2 dominating the tumor microenvironment. Shifting macrophages from M2 to M1 using exosomes is a promising intervention. The properties of exosomes depend on their source cells. M1-exosomes are expected to polarize macrophages towards M1 phenotype. We compared M1-exosomes and M0-exosomes' effects on M2 macrophage polarization. The RAW264.7 cells were cultured and one group of them was exposed to LPS. The serum-free medium was collected and exosomes were extracted. Exosomes were analyzed by scanning and transmission electron microscopy, dynamic light scattering and Western blot. Subsequently, M1 or M0 exosomes were applied to M2 macrophages induced by IL4. The macrophages polarization, including M1 and M2 genes and surface markers expression, cytokines secretion, and phagocytosis ability were evaluated. It was demonstrated that M1-exosomes induced macrophage polarization toward the M1 phenotype, characterized by an upregulation of M1-specific markers and a downregulation of M2 markers. Furthermore, the secretion of TNF-α was increased, while the secretion of IL-10 was decreased. The phagocytosis ability of M1-exosome-treated macrophages was also augmented. This research suggested that M1-exosomes might be promising candidates for modulating immune response in situations marked by an overabundance of M2 polarization, like in cancer.

Identification of Transcriptomic Signatures of Pancreatic Ductal Adenocarcinoma-Derived Exosomes That Promote Macrophage M2 Polarization and Predict Prognosis: S100A9 Reveals Tumor Progression

Background

Exosomes play a role in intercellular communication and participate in the interaction between pancreatic ductal adenocarcinoma (PDAC) cells and immune cells. Macrophages can receive tumor cell-derived exosomes to polarize into M2-type macrophages, which can enhance the invasion and metastasis of pancreatic cancer, leading to poor prognosis. However, the mechanism by which pancreatic cancer cell-derived exosomes promote M2-type macrophages is still unclear.

Methods

M2 macrophage-associated exosome-derived key module genes were identified by differentially expressed genes (DEGs) and weighted gene co-expression network analysis (WGCNA) analysis using exoRbase 2.0, The Cancer Genome Atlas (TCGA), and The International Cancer Genome Consortium (ICGC) databases. Multivariate Cox regression analysis was used to identify key prognostic genes and obtain regression coefficients to establish prognostic signature. Immune infiltration, tumor mutations, and GSEA among different risk groups were compared. exoRbase 2.0, Gene Expression Profiling Interactive Analysis 2 (GEPIA2), HPA, and TISCH2 databases were used to further analyze the expression pattern of S100A9 in pancreatic cancer. In vitro experiments, cell-derived exosome isolation, quantitative polymerase chain reaction (qPCR), western blot, flow cytometry analysis, cell transfection, transwell assay, and CCK-8 assay were applied to investigate the roles of S100A9 in macrophage M2 polarization and tumor progression.

Results

The key genes of PDAC-derived exosomes promoting M2-type macrophage polarization were identified, and a risk score model was established. The risk score is related to the expression of common immune checkpoints, immune score, and stromal score, and the tumor mutational burden and biological function of high- and low-risk groups were also different. S100A9 was positively correlated with M2-type macrophage marker. In addition, scRNA-seq data from the TISCH2 database revealed that S100A9 is predominantly expressed in pancreatic cancer cells and mono/macrophage cells, suggesting that S100A9 in pancreatic cancer cells could be received by macrophages, thereby inducing macrophage polarization. In vitro, we used exosomes from BxPC-3 cell lines to coculture macrophages and found that macrophages were mainly polarized toward M2 type, which further promoted the proliferation and metastasis of PDAC.

Conclusions

Our study established a reliable risk score model for PDAC-derived exosomes and M2 macrophages, identified the important role of S100A9 in macrophage M2 polarization, which provides a new strategy for the diagnosis and treatment of PDAC, and strengthened the understanding of the mechanism of tumor development and metastasis.