Background Tumor-associated macrophages (TAMs) are major components of tumor microenvironment that frequently associated with tumor metastasis in human cancers. Circulating tumor cell (CTC), originating from primary tumor sites, is considered to be the precursors of tumor metastasis. However, the regulatory mechanism of TAMs in CTC-mediated tumor metastasis still remains unclear. Methods Immunohistochemical staining was used to detect the macrophages infiltration (CD68 and CD163), epithelial–mesenchymal transition (EMT) markers (E-cadherin and Vimentin) expression in serial sections of human colorectal cancer (CRC) specimens. Then, the correlations between macrophages infiltration and clinicopathologic features, mesenchymal CTC ratio, and patients’ prognosis were analyzed. A co-culture assay in vitro was used to evaluate the role of TAMs on CRC EMT, migration and invasion, and ELISA, luciferase reporter assay and CHIP were performed to uncover the underlying mechanism. Furthermore, an in vivo model was carried out to confirm the effect of TAMs on mesenchymal CTC-mediated metastasis. Results Clinically, CD163 + TAMs infiltrated in invasive front was associated with EMT, mesenchymal CTC ratio, and poor prognosis in patients with CRC. CRC–conditioned macrophages regulated EMT program to enhance CRC cells migration and invasion by secreting IL6. TAMs-derived IL6 activated the JAK2/STAT3 pathway, and activated STAT3 transcriptionally inhibited the tumor suppressor miR-506-3p in CRC cells. miR-506-3p, a key miRNA regulating FoxQ1, was downregulated in CRC cells, resulting in increased FoxQ1 expression, which in turn led to the production of CCL2 that promoted macrophage recruitment. Inhibition of CCL2 or IL6 broke this loop and reduced macrophage migration and mesenchymal CTC-mediated metastasis, respectively. Conclusions Our data indicates that TAMs induce EMT program to enhance CRC migration, invasion, and CTC-mediated metastasis by regulating the JAK2/STAT3/miR-506-3p/FoxQ1 axis, which in turn leads to the production of CCL2 that promote macrophage recruitment, revealing a new cross-talk between immune cells and tumor cells in CRC microenvironment. Electronic supplementary material The online version of this article (10.1186/s12943-019-0976-4) contains supplementary material, which is available to authorized users.

BackgroundWith persistent inconsistencies in colorectal cancer (CRC) miRNAs expression data, it is crucial to shift toward inclusion of a “pre-laboratory” integrated analysis to expedite effective precision medicine and translational research. Aberrant expression of hsa-miRNA-195 (miR-195) which is distinguished as a clinically noteworthy miRNA has previously been observed in multiple cancers, yet its role in CRC remains unclear.MethodsIn this study, we performed an integrated analysis of seven CRC miRNAs expression datasets. The expression of miR-195 was validated in The Cancer Genome Atlas (TCGA) datasets, and an independent validation sample cohort. Colon cancer cells were transfected with miR-195 mimic and inhibitor, after which cell proliferation, colony formation, migration, invasion, and dual luciferase reporter were assayed. Xenograft mouse models were used to determine the role of miR-195 in CRC tumorigenicity in vivo.ResultsFour downregulated miRNAs (hsa-let-7a, hsa-miR-125b, hsa-miR-145, and hsa-miR-195) were demonstrated to be potentially useful diagnostic markers in the clinical setting. CRC patients with a decreased level of miR-195-5p in tumor tissues had significantly shortened survival as revealed by the TCGA colon adenocarcinoma (COAD) dataset and our CRC cohort. Overexpression of miR-195-5p in DLD1 and HCT116 cells repressed cell growth, colony formation, invasion, and migration. Inhibition of miR-195-5p function contributed to aberrant cell proliferation, migration, invasion, and epithelial mesenchymal transition (EMT). We identified miR-195-5p binding sites within the 3’-untranslated region (3′-UTR) of the human yes-associated protein (YAP) mRNA. YAP1 expression was downregulated after miR-195-5p treatment by qRT-PCR analysis and western blot.ConclusionsFour downregulated miRNAs were shown to be prime candidates for a panel of biomarkers with sufficient diagnostic accuracy for CRC in a clinical setting. Our integrated microRNA profiling approach identified miR-195-5p independently associated with prognosis in CRC. Our results demonstrated that miR-195-5p was a potent suppressor of YAP1, and miR-195-5p-mediated downregulation of YAP1 significantly reduced tumor development in a mouse CRC xenograft model. In the clinic, miR-195-5p can serve as a prognostic marker to predict the outcome of the CRC patients.Electronic supplementary materialThe online version of this article (doi:10.1186/s13045-017-0445-8) contains supplementary material, which is available to authorized users.

Background: The interaction and crosstalk between tumor-associated macrophages (TAMs) and epithelial-mesenchymal transition (EMT) has been demonstrated to play a critical role in the progression and metastasis of multiple cancers. However, the roles of the M2-polarized TAMs in different tumor location in EMT and prognosis of colorectal cancer (CRC) have not been elucidated. Therefore, the present study was designed to set up a reliable ratio of CD163 + /CD68 + to assess M2-polarized TAMs infiltration in the tumor center (TC) and tumor invasive front (TF) and to further evaluate their prognostic value and biological effects on tumor cells in CRC. Methods: TAMs markers (CD68 and CD163) and EMT markers (E-cadherin and Vimentin) expression were evaluated by immunohistochemistry in 81 patients with CRC. Circulating tumor cells (CTCs) of peripheral blood from above patients was also isolated. The correlation of CD163 + /CD68 + ratio in different locations, EMT and CTCs counts were further analyses. Kaplan-Meier and the model analyses of univariate Cox proportional hazards were utilized to compare the survival of patients with high CD163 + /CD68 + ratio with those with low CD163 + /CD68 + ratio. Furthermore, the effects of the M2-polarized TAMs on growth, migration and invasion of CRC cells were explored in vivo and in vitro co-culture system. Results : The results showed that the level of CD163 + /CD68 + ratio in TF was significant higher than that in TC, and higher CD163 + /CD68 + TF ratio were closely correlated with enhanced lymphovascular invasion, tumor invasion and TNM stage. Interestingly, higher CD163 + /CD68 + TF ratio were also significantly associated with EMT program and CTCs counts. Meanwhile, Kaplan-Meier analysis showed that CD163 + /CD68 + TF was associated with both recurrence-free survival (RFS) and overall survival (OS) of patients with CRC. Multivariate Cox regression analyses demonstrated that CD163 + /CD68 + TF remained an independent prognostic factor for RFS and OS. Further receiver operating characteristic (ROC) curve analysis found that CD163 + /CD68 + TF was a better prognosticator compared with CD68 + TF and CD163 + TF for CRC patients. What's more, M2-polarized TAMs secreted TGF-β to facilitate the EMT, growth, proliferation and invasion of CRC cells by in vivo and ...

Background: Tumor-associated macrophages (TAMs) in the tumor microenvironment influence tumor initiation, invasion and metastasis. Several studies have shown that Wnt5a is mainly expressed in the tumor stroma, especially in TAMs. However, whether Wnt5a regulates the polarization and biological function of TAMs in colorectal cancer (CRC) is incompletely understood. Methods: Immunofluorescence staining was performed to detect CD68 and Wnt5a expression in colorectal tissues from patients (63 CRC specimens VS 20 normal tissues). RT-qPCR, flow cytometry, ELISA and inhibitors were carried out to explore the role of Wnt5a in the polarization of TAMs. Clone formation and transwell assays were performed to determine the effects of Wnt5a-treated macrophages on tumor proliferation, migration and invasion in vitro. Finally, a xenograft model was applied to confirm the effects of Wnt5a + TAMs on CRC tumorigenesis. Results: We found that high Wnt5a + CD68 + /CD68 + TAMs ratio was significantly associated with poor prognosis in CRC patients and Wnt5a + TAM was an M2-like TAM subtype. Subsequently, we found that Wnt5a induced macrophages to secrete IL-10, which then acted as an autocrine cytokine to induce M2 polarization of these macrophages. IL-10 neutralizing antibody completely reversed the pro-M2 effect of Wnt5a. Mechanistically, the CaKMII-ERK1/2-STAT3 pathway was required for Wnt5a-mediated IL-10 expression in macrophages. Furthermore, Wnt5a-induced M2 macrophages promoted CRC cells proliferation, migration and invasion; knockdown of Wnt5a in TAMs significantly impaired the pro-tumor functions of TAMs. Conclusions: Our data indicate that Wnt5a could induce M2 polarization of TAMs by regulating CaKMII-ERK1/2-STAT3 pathway-mediated IL-10 secretion, ultimately promoting tumor growth and metastasis of CRC.