1-Ethoxycarbonyl-beta-carboline inhibits the M2 polarization of tumor-associated macrophages: A study based on network pharmacology and molecular docking analyses

<div>Abstract<p>The immunologic effects of chemotherapy-induced tumor cell death are not completely understood. Accumulating evidence suggests that phagocytic clearance of apoptotic tumor cells, also known as efferocytosis, is an immunologically silent process, thus maintaining an immunosuppressive tumor microenvironment (TME). Here we report that, in the breast tumor microenvironment, thymosin α-1 (Tα-1) significantly reverses M2 polarization of IL10-producing tumor-associated macrophages (TAM) during efferocytosis induced by apoptotic cells. Mechanistically, Tα-1, which bound to phosphatidylserine on the surface of apoptotic tumor cells and was internalized by macrophages, triggered the activation of SH2-containing inositol 5′-phosphatase 1 (SHIP1) through the lysosomal Toll-like receptor 7 (TLR7)/MyD88 pathway, subsequently resulting in dephosphorylation of efferocytosis-activated TBK1 and reduction of efferocytosis-induced IL10. Tα-1 combined with epirubicin chemotherapy markedly suppressed tumor growth in an <i>in vivo</i> breast cancer model by reducing macrophage-derived IL10 and enhancing the number and function of tumor-infiltrating CD4<sup>+</sup> and CD8<sup>+</sup> T cells. In conclusion, Tα-1 improved the curative effect of chemotherapy by reversing M2 polarization of efferocytosis-activated macrophages, suggesting that Tα-1 injection immediately after chemotherapy may contribute to highly synergistic antitumor effects in patients with breast cancer.</p>Significance:<p>Thymosin α-1 improves the curative effect of chemotherapy by reversing efferocytosis-induced M2 polarization of macrophages via activation of a TLR7/SHIP1 axis.</p></div>

<div>Abstract<p>The immunologic effects of chemotherapy-induced tumor cell death are not completely understood. Accumulating evidence suggests that phagocytic clearance of apoptotic tumor cells, also known as efferocytosis, is an immunologically silent process, thus maintaining an immunosuppressive tumor microenvironment (TME). Here we report that, in the breast tumor microenvironment, thymosin α-1 (Tα-1) significantly reverses M2 polarization of IL10-producing tumor-associated macrophages (TAM) during efferocytosis induced by apoptotic cells. Mechanistically, Tα-1, which bound to phosphatidylserine on the surface of apoptotic tumor cells and was internalized by macrophages, triggered the activation of SH2-containing inositol 5′-phosphatase 1 (SHIP1) through the lysosomal Toll-like receptor 7 (TLR7)/MyD88 pathway, subsequently resulting in dephosphorylation of efferocytosis-activated TBK1 and reduction of efferocytosis-induced IL10. Tα-1 combined with epirubicin chemotherapy markedly suppressed tumor growth in an <i>in vivo</i> breast cancer model by reducing macrophage-derived IL10 and enhancing the number and function of tumor-infiltrating CD4<sup>+</sup> and CD8<sup>+</sup> T cells. In conclusion, Tα-1 improved the curative effect of chemotherapy by reversing M2 polarization of efferocytosis-activated macrophages, suggesting that Tα-1 injection immediately after chemotherapy may contribute to highly synergistic antitumor effects in patients with breast cancer.</p>Significance:<p>Thymosin α-1 improves the curative effect of chemotherapy by reversing efferocytosis-induced M2 polarization of macrophages via activation of a TLR7/SHIP1 axis.</p></div>

We focused on investigating the role and mechanism of ganodermanontriol (GAN) in regulating the M2 polarization of tumor-associated macrophages in the gastric cancer microenvironment. M2 polarization of RAW264.7 macrophages was induced by IL-4 or co-culture with MFC, and the expression levels of M1 macrophage markers (TNF-α, IFN-γ, IL-1β) and M2 macrophage markers (IL-10, TGF-β, Arg-1) were detected by enzyme-linked immunosorbed assay (ELISA). The protein expression was assayed by Western-Blotting. For in vitro experiments, a tumor-bearing mouse model was established, with which the CD206 level was detected by histochemistry, and the binding mode between GAN and STAT6 was simulated through molecular dynamics. Both IL-4 and MFC could induce the M2 polarization of macrophages. GAN could inhibit such polarization, which produced unobvious effects on M1 markers, but could suppress the levels of M2 markers. GAN could inhibit the phosphorylated expression of STAT6, and M2 macrophages treated by it had a weakened ability to promote malignant behavior of MFC. According to the results of in vitro experiments, GAN could inhibit tumor growth, suppress the tissue infiltration of CD206 cells, and inhibit the phosphorylated expression of STAT6. Our results show that GAN can inhibit the M2 macrophage polarization in gastric cancer microenvironment, whose mechanism of action is associated with the regulation of STAT6 phosphorylation.

RNA-seq shows Angiopoietin-like 4 promotes hepatocellular carcinoma progression by inducing M2 polarization of tumor-associated macrophages.

BackgroundSphingosine kinase 1 (SphK1) has distinct roles in the activation of Kupffer cells (KCs) and hepatic stellate cells (HSCs) in liver fibrosis. This study aims to examine the role of...

LINC00665 interacts with BACH1 to activate Wnt1 and mediates the M2 polarization of tumor-associated macrophages in GC

Objective To explore the mechanism of ubiquitin specific peptidase 21 (USP21) increasing the stability of forkhead box protein M1 (FOXM1) and promoting M2 polarization of macrophages in endometriosis (EM). Methods Eutopic endometrial stromal cells (EESC) collected from patients and normal endometrial stromal cells (NESC) from routine health examiners were cultured in vitro, and the expression levels of USP21 and FOXM1 were detected using RT-qPCR and Western blot. EESCs were co-cultured with macrophages. M1 polarization markers of interleukin 6 (IL-6) and CXC chemokine ligand 10 (CXCL10) and M2 polarization markers of CD206 and fibronectin 1 (FN1) were tested using RT-qPCR. M2 marker CD206 was further detected by flow cytometry. IL-6, tumor necrosis factor-alpha (TNF-α), IL-10, and transforming growth factor-beta (TGF-β) levels in cell supernatant were detected by ELISA. Co-immunoprecipitation was used to assess the interaction between USP21 and FOXM1, and the ubiquitination level of FOXM1. FOXM1 protein stability was detected through cycloheximide (CHX) assay. Results USP21 and FOXM1 expression levels in the EESC group were significantly increased compared with those in the NESC group; compared with the NESC + M0 group, the EESC + M0 group showed no significant difference in the expression of M1 polarization markers (IL-6 and CXCL10), but increased expression of M2 polarization markers (CD206 and FN1), along with notably increased number of M2 macrophages; there was no significant difference in IL-6 and TNF-α levels, but increased levels of IL-10 and TGF-β in the cell supernatant. The above findings indicated that the deubiquitinase USP21 was highly expressed in EM, promoting M2 polarization of macrophages. Knocking down USP21 or FOXM1 can inhibit M2 polarization of EM macrophages. USP21 interacted with FOXM1 in EESC, leading to a decrease in FOXM1 ubiquitination level and an increase in FOXM1 protein stability. Overexpression of FOXM1 reversed the inhibitory effect of knocking down USP21 on M2 polarization of EM macrophages. Conclusion The deubiquitinase USP21 interacts with FOXM1 to increase the stability of FOXM1 and promote M2 polarization of EM macrophages.

Circular RNAs (circRNAs) are reported to be involved in the tumorigenesis of lung adenocarcinoma (LUAD). Here, this study focused on studying the function and mechanism of circHSPB6 in LUAD progression. Levels of genes and proteins were tested using qRT-PCR and western blotting analyses. The 5-ethynyl-2'-deoxyuridine (EdU), colony formation, flow cytometry, and transwell assays were adopted for in vitro assays. In vivo assay was conducted using mouse xenograft models. The binding between let-7a-2-3p and circHSPB6 or CCL2 was validated using RIP and dual-luciferase reporter assays. The M2 polarization of tumor-associated macrophages (TAMs) was analyzed by flow cytometry. LUAD tissues and cells showed high circHSPB6 expression, knockdown of circHSPB6-suppressed LUAD cell proliferation, migration, invasion, and induced cell apoptosis in vitro, as well as hindered tumor growth in vivo. Mechanistically, circHSPB6/let-7a-2-3p/CCL2 forms a feedback loop. CircHSPB6 could regulate CCL2 expression via sponging let-7a-2-3p. Further rescue assays showed that the effects of circHSPB6 silencing on LUAD cells were reversed by let-7a-2-3p inhibition or CCL2 overexpression. Moreover, circHSPB6 promoted the M2 polarization and infiltration of TAMs by CCL2. Functionally, circHSPB6 knockdown in A549 and H1299 cells inhibited TAM M2 polarization and then suppressed cell proliferation, migration, invasion, and emergency medical technicians (EMT) progression, while these effects were reversed by CCL2 up-regulation CircHSPB6 induced TAM M2 polarization to promote LUAD cell proliferation, migration, invasion, and EMT progression through let-7a-2-3p/CCL2 axis.

BackgroundLncRNAs have been proved to play an important role in human cancers. The M2 polarization of tumor associated macrophages (TAMs) is also reported to promote cancer progression. However, the specific role of cancer derived exosomal lncRNA in the M2 polarization of macrophages remains largely unknown.MethodsBioinformatic analysis was used to screen out the differentially expressed lncRNAs in colorectal cancer (CRC). Single-cell RNA sequencing was conducted to investigate the different distribution of cell type in tumor and para-tumor tissues. Function gain and loss assays were performed both in vitro and in vivo to verify the specific role of target genes. The involvement of exosomes was verified by transmission electron microscopy, nano-sight particle tracking analysis and Cre-LoxP system. RNA immunoprecipitation, RNA pull-down, truncation experiment, dual-luciferase reporter assay, chromatin immunoprecipitation, qRT-PCR and Western blot were used to explore the interactions between LINC01615, RBMX and EZH2.ResultsLINC01615 was highly expressed in CRC and contributed to the M2 polarization of TAMs and progression of CRC. Mechanistically, LINC01615 could be transported from CRC cells to TAMs via exosomes. The exosomal LINC01615 acted as a scaffold to mediate the combination between RBMX and EZH2 mRNA and EZH2 promoter, which promoted EZH2 expression and M2 polarization of TAMs, thus promoting CRC progression.ConclusionCancer-derived exosomal LINC01615 induces M2 polarization of TAMs via RBMX-EZH2 axis to promote CRC progression, which may be a reliable diagnostic marker and potential therapeutic target for CRC.

Dietary restriction has been recognized as a healthy and natural therapy for cancer. It is reported that different forms of dietary restriction can promote anti-tumor immunity. However, it is not clear how fasting affects tumor-associated macrophages (TAMs). This study aims to investigate the relationship between fasting and antitumor immunity in terms of tumor-associated macrophages. In vivo, the results showed that alternate day fasting for 2 weeks inhibitted the tumor growth of mice without causing a reduction of body weight. Meanwhile, M2 polarization of tumor-associated macrophages in tumor tissues of alternate day fasting group was also decreased. In vitro, fasting induced the autophagy of CT26 cells, decreased the generation of extracellular adenosine by supressing the expression of CD73 in CT26 cells. Decreasing adenosine inhibitted M2 polarization of RAW264.7 cells through inactivating JAK1/STAT3 signal pathway in fasting condition. Eventually, the proliferation of CT26 cancer cells declined on account of fasting-facilitated antitumor immunity. These results suggested that fasting suppressed M2 polarization of tumor-associated macrophages to inhibit tumor growth through decreasing the level of adenosine in the tumor microenvironment both in vivo and in vitro. This process was associated with increasing autophagy of tumor cells.

<div>Abstract<p>Secretion of the powerful angiogenic factor MFG-E8 by pericytes can bypass the therapeutic effects of anti-VEGF therapy, but the mechanisms by which MFG-E8 acts are not fully understood. In this study, we investigated how this factor acts to promote the growth of melanomas that express it. We found that mouse bone marrow–derived mesenchymal stromal cells (MSC) expressed a substantial amount of MFG-E8. To assess its expression from this cell type, we implanted melanoma cells and MSC derived from wild type (WT) or MFG-E8 deficient [knockout (KO)] into mice and monitored tumor growth. Tumor growth and M2 macrophages were each attenuated in subjects coimplanted with KO-MSC compared with WT-MSC. In both xenograft tumors and clinical specimens of melanoma, we found that MFG-E8 expression was heightened near blood vessels where MSC could be found. Through <i>in vitro</i> assays, we confirmed that WT-MSC–conditioned medium was more potent at inducing M2 macrophage polarization, compared with KO-MSC–conditioned medium. VEGF and ET-1 expression in KO-MSC was significantly lower than in WT-MSC, correlating <i>in vivo</i> with reduced tumor growth and numbers of pericytes and M2 macrophages within tumors. Overall, our results suggested that MFG-E8 acts at two levels, by increasing VEGF and ET-1 expression in MSC and by enhancing M2 polarization of macrophages, to increase tumor angiogenesis. <i>Cancer Res; 76(14); 4283–92. ©2016 AACR</i>.</p></div>

<div>Abstract<p>Secretion of the powerful angiogenic factor MFG-E8 by pericytes can bypass the therapeutic effects of anti-VEGF therapy, but the mechanisms by which MFG-E8 acts are not fully understood. In this study, we investigated how this factor acts to promote the growth of melanomas that express it. We found that mouse bone marrow–derived mesenchymal stromal cells (MSC) expressed a substantial amount of MFG-E8. To assess its expression from this cell type, we implanted melanoma cells and MSC derived from wild type (WT) or MFG-E8 deficient [knockout (KO)] into mice and monitored tumor growth. Tumor growth and M2 macrophages were each attenuated in subjects coimplanted with KO-MSC compared with WT-MSC. In both xenograft tumors and clinical specimens of melanoma, we found that MFG-E8 expression was heightened near blood vessels where MSC could be found. Through <i>in vitro</i> assays, we confirmed that WT-MSC–conditioned medium was more potent at inducing M2 macrophage polarization, compared with KO-MSC–conditioned medium. VEGF and ET-1 expression in KO-MSC was significantly lower than in WT-MSC, correlating <i>in vivo</i> with reduced tumor growth and numbers of pericytes and M2 macrophages within tumors. Overall, our results suggested that MFG-E8 acts at two levels, by increasing VEGF and ET-1 expression in MSC and by enhancing M2 polarization of macrophages, to increase tumor angiogenesis. <i>Cancer Res; 76(14); 4283–92. ©2016 AACR</i>.</p></div>

Secretion of the powerful angiogenic factor MFG-E8 by pericytes can bypass the therapeutic effects of anti-VEGF therapy, but the mechanisms by which MFG-E8 acts are not fully understood. In this study, we investigated how this factor acts to promote the growth of melanomas that express it. We found that mouse bone marrow-derived mesenchymal stromal cells (MSC) expressed a substantial amount of MFG-E8. To assess its expression from this cell type, we implanted melanoma cells and MSC derived from wild type (WT) or MFG-E8 deficient [knockout (KO)] into mice and monitored tumor growth. Tumor growth and M2 macrophages were each attenuated in subjects coimplanted with KO-MSC compared with WT-MSC. In both xenograft tumors and clinical specimens of melanoma, we found that MFG-E8 expression was heightened near blood vessels where MSC could be found. Through in vitro assays, we confirmed that WT-MSC-conditioned medium was more potent at inducing M2 macrophage polarization, compared with KO-MSC-conditioned medium. VEGF and ET-1 expression in KO-MSC was significantly lower than in WT-MSC, correlating in vivo with reduced tumor growth and numbers of pericytes and M2 macrophages within tumors. Overall, our results suggested that MFG-E8 acts at two levels, by increasing VEGF and ET-1 expression in MSC and by enhancing M2 polarization of macrophages, to increase tumor angiogenesis. Cancer Res; 76(14); 4283-92. ©2016 AACR.

BackgroundTumor-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.MethodsImmunofluorescence 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.ResultsWe 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.ConclusionsOur 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.

Non-small cell lung cancer (NSCLC) is an aggressive and devastating cancer due to its metastasis induced by increased invasion. Lentinan is a polysaccharide exerting antitumor roles in multiple cancers, including lung cancer. However, the influence of lentinan on cell invasion in NSCLC remains unclear. Cell invasion was detected by transwell analysis. Matrix metallopeptidase 9 (MMP9) levels were measured through immunofluorescence staining. The markers arginase-1 (Arg-1), CD206 and interleukin (IL)-10 (IL-10) of M2 macrophages, Wnt3a, and β-catenin levels were measured by western blot or enzyme linked immunosorbent assay. Lentinan did not affect cell viability and proliferation in NSCLC cells. Lentinan suppressed cell invasion and reduced the expression and secretion of MMP9. Lentinan attenuated also M2 polarization of tumor-associated macrophages. Moreover, lentinan mitigated the M2 macrophage conditioned medium-mediated cell invasion and MMP9 alterations in NSCLC cells. Lentinan inhibited the activation of the Wnt/β-catenin signaling in NSCLC cells. The activated Wnt/β-catenin pathway reversed the suppressive effects of lentinan on cell invasion and MMP9 level in NSCLC cells. In conclusion, lentinan reduces cell invasion in NSCLC cells by inhibiting the M2 polarization of tumor-associated macrophages and the Wnt/β-catenin signaling.