Section 3.3.3: Tumor-associated macrophages and CSCs (from DOI: 10.1038/s41392-020-0110-5)

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Article	Targeting cancer stem cell pathways for cancer therapy (DOI: 10.1038/s41392-020-0110-5)
Sections in this Publication
Section	Section 1: Introduction (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 2: The concept of CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 2.1: Biological characteristics of CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 2.2: Isolation and identification of CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3: Factors regulating CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.1: Major transcription factors in CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.2: Major signaling pathways in CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.2.1: Wnt signaling pathway in CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.2.2: Notch signaling pathway in CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.2.3: Hh signaling pathway in CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.2.4: NF-kappaB signaling pathway in CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.2.5: JAK-STAT signaling pathway (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.2.6: TGF/SMAD signaling pathway in CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.2.7PI3K/AKT/mTOR signaling pathway in CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.2.8: PPAR signaling pathways in CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.2.9: Interactions between signaling pathways in CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.3: The microenvironment of CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.3.1: Vascular niche microenvironments and CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.3.2: The hypoxia microenvironment and CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.3.3: Tumor-associated macrophages and CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.3.4: Cancer-associated fibroblasts and CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.3.5: Cancer-associated MSCs and CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.3.6: Extracellular matrix and CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 3.3.7: Exosomes in the TME and CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 4: Therapeutic targeting of CSCs (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 4.1: Agents targeting CSC-associated surface biomarkers in clinical trials (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 4.2: Agents targeting CSC-associated signaling pathways in clinical trials (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 4.3: Targeting the CSC microenvironment (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 4.4: CSC-directed immunotherapy (from DOI: 10.1038/s41392-020-0110-5)
Section	Section 5: Conclusions and perspectives (from DOI: 10.1038/s41392-020-0110-5)
Section	Competing interests (from DOI: 10.1038/s41392-020-0110-5)
Section	Bibliography (from DOI: 10.1038/s41392-020-0110-5)
Named Entities in this Section

From publication: "Targeting cancer stem cell pathways for cancer therapy" published as Signal Transduct Target Ther; 2020 ; 5 8; DOI: https://doi.org/10.1038/s41392-020-0110-5

Section 3.3.3: Tumor-associated macrophages and CSCs

Macrophages are an important component of the innate immune response and are a group of cells with plasticity and heterogeneity. Infiltrating and inflammatory macrophages originate from the precursors of bone marrow mononuclear cells. These precursor cells infiltrate various tissues from blood vessels and differentiate into different subtypes in different microenvironments. There are two subtypes of macrophages: the M1 and M2 phenotypes. The M1 phenotype has anti-inflammatory and anti-tumor effects and secretes proinflammatory factors such as interleukin-1 (IL-1), IL-12, IL-23, TNF-alpha, chemokine (C-X-C motif) ligand 5 (CXCL5), CXCL9, and CXCL10. M2 macrophages are generally considered to be the phenotype of tumor-associated macrophages (TAMs), have immunosuppressive and angiogenesis-promoting effects, and are considered to be a tumor-promoting cell type. M2 macrophages secrete CCL17 (C-C chemokine ligand 17), CCL22, and CCL24 and have low expression of IL-12 and high expression of IL-10. Cytokines secreted by macrophages affect the proliferation, tumorigenic transformation, or apoptosis of CSCs through various signaling pathways.

TAMs are closely related to CSCs or stem cell transformation. Renal epithelial cells cocultured with macrophages induce the EMT to transform renal cancer cells into CSCs expressing CD117, Nanog, and CD133. Another study also showed that mucin-1 secreted by M2 macrophages induces the transdifferentiation of non-small-cell lung cancer cells into CSCs that express CD133 and Sox2. Jinushi and colleagues also reported that TAMs secrete MFG-E8, which maintains the self-renewal ability of colon and breast CSCs, and knockout of MFG-E8 significantly inhibits the tumorigenic ability in SCID mice. TAMs are closely related to glioma stem cell growth. TAMs are mainly distributed near CD133+ glioma stem cells and accumulate in pericapillary and hypoxic areas. Glioma stem cells recruit and maintain macrophages by secreting a potent chemokine membrane protein. The ablation of TAMs inhibits the tumorigenesis of glioma stem cells. Recent studies have shown that the interaction between the TME and CSCs is regulated by a variety of signaling pathways. Macrophages enhance the invasion of glioma stem-like cells through the TGF-beta1 signaling pathway. TAMs activate the STAT3/Sox2 signaling pathway in mouse breast CSCs by secreting EGF, which promotes the self-renewal ability of CSCs. IL-8 secreted by TAMs also induces the EMT in hepatocellular cancer cells by activating the JAK2/STAT3/Snail pathway.