Cancer Cell-Derived Granulocyte-Macrophage Colony-Stimulating Factor Is Dispensable for the Progression of 4T1 Murine Breast Cancer

Abstract

We previously reported that 4T1 murine breast cancer cells produce GM-CSF that up-regulates macrophage expression of several cancer promoting genes, including Mcp-1/Ccl2, Ccl17 and Rankl, suggesting a critical role of cancer cell-derived GM-CSF in cancer progression. Here, we attempted to define whether 4T1 cell-derived GM-CSF contributes to the expression of these genes by 4T1tumors, and their subsequent progression. Intraperitoneal injection of anti-GM-CSF neutralizing antibody did not decrease the expression of Mcp-1, Ccl17 or Rankl mRNA by 4T1 tumors. To further examine the role of cancer cell-derived GM-CSF, we generated GM-CSF-deficient 4T1 cells by using the Crisper-Cas9 system. As previously demonstrated, 4T1 cells are a mixture of cells and cloning of cells by itself significantly reduced tumor growth and lung metastasis. By contrast, GM-CSF-deficiency did not affect tumor growth, lung metastasis or the expression of these chemokine and cytokine genes in tumor tissues. By in-situ hybridization, the expression of Mcp-1 mRNA was detected in both F4/80-expressing and non-expressing cells in tumors of GM-CSF-deficient cells. These results indicate that cancer cell-derived GM-CSF is dispensable for the tuning of the 4T1 tumor microenvironment and the production of MCP-1, CCL17 or RANKL in the 4T1 tumor microenvironment is likely regulated by redundant mechanisms.

Overexpression of GLUT3 promotes metastasis of triple‐negative breast cancer by modulating the inflammatory tumor microenvironment

“…For example, Jang et al recently identified that TNBC cells induce inflammasome activation and the M1‐type of macrophage polarization via soluble CD44 (Jang et al, 2020). Likewise, the secretion of colony stimulating factor 1 by TNBC cells is reported to be responsible for induction of iNOS in macrophages (Lin et al, 2010) Moreover, inhibition of glycolysis in TNBC cells suppressed granulocyte‐macrophage colony‐stimulating factor expression (W. Li et al, 2018), which also participates in monocyte maturation by stimulating MCP1/CCL2 (Tanimoto et al, 2008; Yoshimura et al, 2019). The inflammatory microenvironment is a common feature in breast cancer, and high expressions of glycolysis genes in patients with breast cancer are correlated with immune infiltration (W. Li et al, 2020).…”

Curcumin inhibits the growth of liver cancer by impairing myeloid‑derived suppressor cells in murine tumor tissues

“…G-CSF and GM-CSF have been discovered to be the main regulators of the proliferation and differentiation of myeloid cells ( 56 ). A recent study demonstrated that cancer cell-derived GM-CSF serves a key role in cancer progression, and GM-CSF is indispensable for the tuning of the tumor microenvironment and MDSCs ( 57 ). Furthermore, the inflammatory microenvironment in cancer, which is established by multiple inflammatory factors, recruits and activates MDSCs ( 58 ).…”

CCL2: An Important Mediator Between Tumor Cells and Host Cells in Tumor Microenvironment

“…Yoshimura et al identified GM-CSF derived from 4T1 cells as an important inducer of CCL2 expression in macrophages (66). They also recently reported that GM-CSFdeficient tumor cells did not show retarded growth rates and had no effect on overall CCL2 expression levels in 4T1 tumor tissue, indicating that non-myeloid-cell-derived CCL2 is also influenced by GM-CSF deletion (21).…”

“…Hsu et al. studied miR-122, an anti-inflammatory microRNA, and found that its inhibition induced activation of RelB and subsequent release of pro-inflammatory chemokines, including CCL2, by macrophages ( 21 ). Long non-coding RNA LNMAT1 was shown to epigenetically activate the CCL2 gene by attracting hnRNPL to the CCL2 promoter, leading to histone trimethylation ( 22 ).…”

“…Tumor-derived microRNA-375 was found to mediate tumor cell-macrophage interplay via CCL2; specifically, microRNA-375 could promote CCL2 production in tumor cells and induce macrophage migration (20). Hsu et al studied miR-122, an anti-inflammatory microRNA, and found that its inhibition induced activation of RelB and subsequent release of pro-inflammatory chemokines, including CCL2, by macrophages (21). Long non-coding RNA LNMAT1 was shown to epigenetically activate the CCL2 gene by attracting hnRNPL to the CCL2 promoter, leading to histone trimethylation (22).…”