Tumor-associated Macrophages In Colorectal Cancer Research Articles

Wnt5a/CaMKII/ERK/CCL2 axis is required for tumor-associated macrophages to promote colorectal cancer progression.

Tumor-associated macrophages (TAMs) are closely correlated with tumor occurrence, invasion, and metastasis. However, factors affecting the biological functions of TAMs in colorectal cancer (CRC) are incompletely understood. Here, we found that Wnt5a was mainly expressed on TAMs of tumor stroma but not on CRC cells. Subsequently, we found that Wnt5a+ TAMs facilitated tumor cell proliferation and migration, and recruited macrophages infiltration. Furthermore, Wnt5a knockdown impaired the pro-tumor roles of TAMs in vivo and in vitro. Mechanistically, the cancer-promoting roles of Wnt5a in TAMs depended on CaMKII-ERK pathway-mediated CCL2 secretion. Our data reveal the crucial role played by TAM-expressed Wnt5a in CRC tumorigenesis through paracrine secretion of CCL2. We first report the connection between Wnt5a/CaMKII/ERK/CCL2 axis and biological functions of TAMs in tumor microenvironment, indicating that Wnt5a may be a novel therapeutic target for CRC.

STUDY OF TUMOR MICROENVIRONMENT AND HOST RESPONSE IN COLORECTAL CANCER: IMMUNOHISTOCHEMICAL AND CLINICOPATHOLOGICAL APPROACH

Objective: This study aimed to evaluate the immunohistochemical expression of forkhead boxP3 (Foxp3), CD8, CD68, and CD21 in stroma between tumor cells of colorectal cancer (CRC) patients and examines the relationship between these variables and clinicopathological parameter and patients’ prognosis.
 Methods: In this work, 50 cases of colorectal carcinomas were included and immunohistochemical evaluation of Foxp3, CD8, CD68, and CD21 in tumor tissue samples.
 Results: Tumor-infiltrating lymphocytes (TILs) including cytotoxic T cells and regulatory T cells as well as tumor-associated macrophages and follicular dendritic cells (FDCs) were studied in the stroma of the tumor using immunostaining technique for CD8, Foxp3, CD68, and CD21, respectively. Cases were followed up. CD8-positive cytotoxic T cells, Foxp3-positive regulatory T cells, and CD21 positive-FDCs were significantly more pronounced in early tumors and those with longer overall survival. On the other hand, CD68 positive macrophages were more encountered in late stage and metastatic tumors as well as tumors with shorter overall survival, but these results not reached the level of significance.
 Conclusion: We concluded that (TILs) and FDCs are conferring better prognosis in CRCs, they may act synergistically in stimulating a protective immune response in the tumor microenvironment that hinders tumor progression, while the role of tumor-associated macrophages in CRCs is still controversial and needs further studies.

Abstract 502: Circulating exosomal miR-203 is associated with metastasis via inducing tumor-associated macrophages in colorectal cancer

Abstract Distant metastasis is the leading cause of mortality in patients with malignant tumor including colorectal cancer (CRC). A primary tumor can create a premetastatic niche in distant organs to facilitate the development of metastasis by communicating with host cells. However, little is known about the communicating mechanism is known. Understanding this mechanism should uncover a new field of cancer therapy through the targeting of the interaction between tumor and host. In this study, we focused on circulating microRNAs (miRs) as the communication tool between host and tumor cells that were mainly carried by exosomes in circulation. As a result of gene expression microarray and gene set enrichment analysis, we identified miR-203 as a putative signaling molecule between tumors and monocytes in metastatic CRC patients. The level of miR-203 expression was significantly upregulated in a TNM stage-dependent manner. High exosomal miR-203 expression in serum was significantly associated with poor DFS and OS (P < 0.01), and was an independent poor prognostic factor. Additionally, high exosomal miR-203 was associated with distant metastasis (P < 0.01). We also found that exosomes carrying miR-203 from CRC cells were incorporated into monocytes and miR-203 promoted the expression of M2 markers such as CD163 and STAT3 in vitro. It suggested that serum exosomal miR-203 released from CRC cells promoted the differentiation of monocytes to M2-tumor-associated macrophages (TAMs) which facilitated premetastatic niche and distant metastasis. Co-injection of miR-203-transfected CRC cells and monocyte increased a ratio of liver metastasis in vivo compared with only control CRC cells or only miR-203-transfected CRC cells injection. On the other hand, overexpression of miR-203 did not increase the proliferation, invasion and migration capacity of CRC cells. This results indicated that serum exosomal miR-203 might create a premetastatic niche whereas did not affect to malignant phenotype of CRC cells. Our study indicated that serum exosomal miR-203 expression could be a novel and feasible biomarker for predicting metastasis, possibly via promoting the differentiation of monocytes to M2-TAMs in CRC. Citation Format: Dai Shimizu, Takaaki Masuda, Yuki Takano, Hisae Imamura, Rui Yamaguchi, Kuniaki Sato, Taro Tobo, Hidenari Hirata, Yosuke Kuroda, Sho Nambara, Naoki Hayashi, Tomohiro Iguchi, Shuhei Ito, Hidetoshi Eguchi, Takahiro Ochiya, Katsuhiko Yanaga, Satoru Miyano, Koshi Mimori. Circulating exosomal miR-203 is associated with metastasis via inducing tumor-associated macrophages in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 502.

Oxygenated lipid signaling in tumor-associated macrophages-focus on colon cancer.

Polyunsaturated fatty acids (PUFAs) are enzymatically converted to a variety of bioactive products through insertion of molecular oxygen. PUFA-derived mediators can have either inflammatory or anti-inflammatory/pro-resolving properties, depending upon their specific structures. The relative harm or benefit of these mediators can also be tissue and context dependent. These mediators play important roles in maintaining homeostasis and their dysregulation is involved in pathogenesis of cancers, especially those associated with chronic inflammation. There is a well-established link between colorectal cancer (CRC) and chronic inflammation. The colon harbors a large population of immune cells, which must be tightly regulated in order to maintain the balance between pathogenic and commensal microbes in the gut. Macrophages are key to the process of distinguishing between potentially harmful antigens/microbes and benign or beneficial signals. Macrophages are often associated with tumors (tumor-associated macrophages (TAMs), including CRC. There is some debate as to the prognostic significance of these TAMs in CRC, with some work suggesting a beneficial impact. The purpose of this review is to give an overview of what is currently known regarding PUFA-derived mediator signaling in tumor-associated macrophages in CRC.

The Immune-microenvironment Confers Chemoresistance of Colorectal Cancer through Macrophage-Derived IL6.

Purpose: Tumor-associated macrophages (TAMs) are frequently associated with poor prognosis in human cancers. However, the effects of TAMs in colorectal cancer are contradictory. We therefore investigated the functions, mechanisms, and clinical significance of TAMs in colorectal cancer.Experimental Design: We measured the macrophage infiltration (CD68), P-gp, and Bcl2 expression in colorectal cancer tissues using IHC staining. Coculture of TAMs and colorectal cancer cells both in vitro and in vivo models was used to evaluate the effects of TAMs on colorectal cancer chemoresistance. Cytokine antibody arrays, ELISA, neutralizing antibody, and luciferase reporter assay were performed to uncover the underlying mechanism.Results: TAM infiltration was associated with chemoresistance in patients with colorectal cancer. Colorectal cancer-conditioned macrophages increased colorectal cancer chemoresistance and reduced drug-induced apoptosis by secreting IL6, which could be blocked by a neutralizing anti-IL6 antibody. Macrophage-derived IL6 activated the IL6R/STAT3 pathway in colorectal cancer cells, and activated STAT3 transcriptionally inhibited the tumor suppressor miR-204-5p. Rescue experiment confirmed that miR-204-5p is a functional target mediating the TAM-induced colorectal cancer chemoresistance. miR-155-5p, a key miRNA regulating C/EBPβ, was frequently downregulated in TAMs, resulting in increased C/EBPβ expression. C/EBPβ transcriptionally activated IL6 in TAMs, and TAM-secreted IL6 then induced chemoresistance by activating the IL6R/STAT3/miR-204-5p pathway in colorectal cancer cells.Conclusions: Our data indicate that the maladjusted miR-155-5p/C/EBPβ/IL6 signaling in TAMs could induce chemoresistance in colorectal cancer cells by regulating the IL6R/STAT3/miR-204-5p axis, revealing a new cross-talk between immune cells and tumor cells in colorectal cancer microenvironment. Clin Cancer Res; 23(23); 7375-87. ©2017 AACR.

Circulating exosomal microRNA-203 is associated with metastasis possibly via inducing tumor-associated macrophages in colorectal cancer

A primary tumor can create a premetastatic niche in distant organs to facilitate the development of metastasis. The mechanism by which tumor cells communicate with host cells to develop premetastatic niches is unclear. We focused on the role of microRNA (miR) signaling in promoting metastasis. Here, we identified miR-203 as a signaling molecule between tumors and monocytes in metastatic colorectal cancer (CRC) patients. Notably, high expression of serum exosomal miR-203, a major form in circulation, was associated with distant metastasis and an independent poor prognostic factor, whereas low expression in tumor tissues was a poor prognostic factor in CRC patients. We also found that exosomes carrying miR-203 from CRC cells were incorporated into monocytes and miR-203 could promote the expression of M2 markers in vitro, suggesting miR-203 promoted the differentiation of monocytes to M2-tumor-associated macrophages (TAMs). In a xenograft mouse model, miR-203-transfected CRC cells developed more liver metastasis compared to control cells. In conclusion, serum exosomal miR-203 expression is a novel biomarker for predicting metastasis, possibly via promoting the differentiation of monocytes to M2-TAMs in CRC. Furthermore, we propose the concept of site-dependent functions for miR-203 in tumor progression.

Phenotyping of tumor-associated macrophages in colorectal cancer: Impact on single cell invasion (tumor budding) and clinicopathological outcome

ABSTRACTTumor-associated macrophages (TAM) play a controversial role in epithelial–mesenchymal transition (EMT) and prognosis of colorectal cancer (CRC). In particular, the microlocalization, polarization and prognostic impact of TAM in the immediate environment of invading CRC cells has not yet been established. To address this clinically relevant question, intraepithelial (iCD68) and stromal macrophages (sCD68), M1-macrophages (iNOS), M2-macrophages (CD163), cytokeratin-positive cancer cells (tumor buds) and expression of the anti-phagocytic marker CD47 were investigated in primary tumors of 205 well-characterized CRC patients. Cell-to-cell contacts between tumor buds and TAM were detected using high-resolution digital scans. The composition of the tumor microenvironment was analyzed with clinicopathological and molecular features. High CD68 counts predicted long term overall survival independent of microlocalization (iCD68 p=0.0016; sCD68 p=0.03), pT, pN, pM and post-operative therapy. CD68 infiltration correlated with significantly less tumor budding (iCD68 p=0.0066; sCD68 p=0.0091) and absence of lymph node metastasis (sCD68 p=0.0286). Cell-to-cell contact of sCD68 and invading cancer cells was frequent and ameliorated the detrimental prognostic effect of the tumor budding phenotype. Subgroup analysis identified long-term survival with CD47 loss and predominance of CD163+ M2 macrophages (p = 0.0366). CD163+ macrophages represented 40% of the total population, and positively correlated with total CD68 macrophage numbers (r[CD68/CD163] = 0.32; p = 0.0001). Strong CD163 infiltration predicted lower tumor grade (p = 0.0026) and less lymph node metastasis (p = 0.0056). This study provides direct morphological evidence of an interaction between TAM and infiltrating cancer cells. The prognostic impact of TAM is modulated by phenotype, microlocalization and the expression of anti-phagocytic markers in CRC.

Research progress of tumor-associated macrophages in colorectal cancer

Research progress of tumor-associated macrophages in colorectal cancer

Tumor-Associated Macrophages Recruit CCR6+ Regulatory T Cells and Promote the Development of Colorectal Cancer via Enhancing CCL20 Production in Mice

BackgroundTumor-associated macrophages (TAMs) remodel the colorectal cancer (CRC) microenvironment. Yet, findings on the role of TAMs in CRC seem to be contradictory compared with other cancers. FoxP3+ regulatory T (Treg)-cells dominantly infiltrate CRC. However, the underlying molecular mechanism in which TAMs may contribute to the trafficking of Treg-cells to the tumor mass remains unknown.Methodology/Principal FindingsCRC was either induced by N-methyl-N-nitrosourea (MNU) and H. pylori or established by subcutaneous injection of mouse colorectal tumor cell line (CMT93) in mice. CMT93 cells were co-cultured with primary macrophages in a transwell apparatus. Recruitment of FoxP3 green fluorescence protein positive (FoxP3GFP+) Treg-cells was assessed using the IVIS Imaging System or immunofluorescence staining. A role for macrophages in trafficking of Treg-cells and in the development of CRC was investigated in CD11b diphtheria toxin receptor (CD11b-DTR) transgenic C57BL/6J mice in which macrophages can be selectively depleted. Treg-cells remarkably infiltrated solid tumor, and predominantly expressed the homing chemokine receptor (CCR) 6 in the induced CRC model. Both CMT93 cancer cells and macrophages produced a large amount of CCL20, the sole ligand of CCR6 in vitro and in vivo. Injection of recombinant mouse CCL20 into tumor sites promoted its development with a marked recruitment of Treg-cells in the graft CRC model. Conditional macrophage ablation decreased CCL20 levels, blocked Treg-cell recruitment and inhibited tumor growth in CD11b-DTR mice grafted with CMT93.Conclusions/SignificanceTAMs recruit CCR6+ Treg-cells to tumor mass and promote its development via enhancing the production of CCL20 in a CRC mouse model.

Tumor-associated macrophages recruit CCR6+ regulatory T cells and promote the development of colorectal cancer via enhancing CCL20 production in mice (66.33)

Abstract Background: Tumor-associated macrophages (TAMs) remodel the colorectal cancer (CRC) microenvironment. Yet, findings on the role of TAMs in CRC seem to be contradictory compared with other cancers. Regulatory T (Treg)-cells dominantly infiltrate CRC. However, the underlying molecular mechanism in which TAMs may contribute to the trafficking of Treg-cells to the tumor mass remains unknown. Methodology/Principal Findings: CRC was either induced by MNU and H. pylori or established by subcutaneous injection of mouse colorectal tumor cell line (CMT93) in mice. Recruitment of FoxP3GFP+ Treg-cells was assessed using the IVIS Imaging System. A role for macrophages in trafficking of Treg-cells and in the development of CRC was investigated in CD11b diphtheria toxin receptor (CD11b-DTR) transgenic mice in which macrophages can be selectively depleted. Treg-cells remarkably infiltrated solid tumor, and predominantly expressed the homing chemokine receptor (CCR) 6 in the induced CRC model. Macrophages produced a large amount of CCL20, the sole ligand of CCR6 when co-cultured with CRC cells. Injection of recombinant CCL20 into tumor sites promoted its development with a marked recruitment of Treg-cells. Conditional macrophage ablation decreased CCL20 levels, blocked Treg-cell recruitment and inhibited tumor growth in CD11b-DTR mice. Conclusions/Significance: TAMs recruit CCR6+ Treg-cells to tumor mass and promote its development via enhancing the production of CCL20 in a CRC mouse model.