Macrophages In Tumor Microenvironment Research Articles

Peritoneal resident macrophages in tumor metastasis and immunotherapy.

Macrophages residing in various tissues play crucial roles in innate immunity, tissue repair, and immune homeostasis. The development and differentiation of macrophages in non-lymphoid tissues are highly regulated by the tissue microenvironment. Peritoneum provides a unique metastatic niche for certain types of tumor cells. As the dominant immune cell type in peritoneal cavity, macrophages control the immune response to tumor and influence the efficacy of anti-tumor therapy. Considering the heterogeneity of macrophages in origin, metabolism, and function, it is always challenging to define the precise roles of macrophages in tumor microenvironment. We review here recent progresses in peritoneal resident macrophage research in the context of physiological and metastatic tumor conditions, which may benefit the development of new anti-tumor therapies through targeting macrophages.

Carbonic anhydrase XII mediates the survival and prometastatic functions of macrophages in human hepatocellular carcinoma.

Macrophages constitute a major immune component in tumor tissues, but how these cells adapt to and survive in the nutrient-depleted and lactic acid–induced acidic tumor microenvironments is not yet fully understood. Here, we found that levels of carbonic anhydrase XII (CA12) expression were significantly and selectively upregulated on macrophages in human hepatocellular carcinoma (HCC). Transient glycolytic activation of peritumoral monocytes induced sustained expression of CA12 on tumor-infiltrating macrophages via autocrine cytokines and HIF1α pathways. On the one hand, CA12 mediated the survival of macrophages in relatively acidic tumor microenvironments, while on the other hand, it induced macrophage production of large amounts of C-C motif chemokine ligand 8 (CCL8), which enhanced cancer cell epithelial-mesenchymal transition (EMT) and facilitated tumor metastasis. Consistently, the accumulation of CA12+ macrophages in tumor tissues was associated with increased tumor metastatic potential and reduced survival of patients with HCC. Selective targeting of tumor-infiltrating macrophages with a CA12 inhibitor reduced tumor growth in mice and was sufficient to synergistically enhance the therapeutic efficacy of immune-checkpoint blockade. We suggest that CA12 activity is a previously unappreciated mechanism regulating the accumulation and functions of macrophages in tumor microenvironments and therefore represents a selective vulnerability that could be exploited in future designs for antitumor immunotherapeutic strategies.

Monocytes in tumor: The perspectives of single-cell analysis

Infiltration of mononuclear phagocytes into the tumor microenvironment (TME) is known to orchestrate the tumor progression and is generally considered to interfere with the efficacy of immune checkpoint blockade therapies. For a more precise definition of monocytes, we review some recent advances in the functions of monocytes and macrophages in TME based on single-cell analysis. We also summarize the details of the different subpopulations of monocytes and macrophages involved in immunotherapy and their potential applications in clinical studies. In this review, we briefly introduce the developmental trajectory of mononuclear phagocytes, including monocytes, tumor-associated macrophages, dendritic cells and myeloid-derived suppressive cells, and their functions in TME. In this review, the potential of monocytes and their derived cells as diagnostic and therapeutic targets, with regard to the interaction between monocytes and immune checkpoint therapies, is also summarized.

Colorectal Cancer-Derived Small Extracellular Vesicles Promote Tumor Immune Evasion by Upregulating PD-L1 Expression in Tumor-Associated Macrophages.

Tumor‐associated macrophages (TAMs) are one of the most abundant cell types in colorectal cancer (CRC) tumor microenvironment (TME). Recent studies observed complicated “cross‐talks” between cancer cells and macrophages in TME. However, the underlying mechanisms are still poorly elucidated. Here, PD‐L1 levels are very low in CRC cells but highly abundant in TAMs, and a specific PD‐L1+CD206+ macrophage subpopulation are identified, which is induced by tumor cells and associated with a poor prognosis. Mechanistic investigations reveal that CRC cells can secrete small extracellular vesicles (sEVs) taken up by macrophages that induce M2 like polarization and PD‐L1 expression, resulting in increased PD‐L1+CD206+ macrophage abundance and decreased T cell activity in CRC TME. sEV‐derived miR‐21‐5p and miR‐200a are identified as key signaling molecules mediating the regulatory effects of CRC on macrophages. Further studies reveal that CRC‐derived miR‐21‐5p and miR‐200a synergistically induces macrophage M2 like polarization and PD‐L1 expression by regulating the PTEN/AKT and SCOS1/STAT1 pathways, resulting in decreased CD8+ T cell activity and increased tumor growth. This study suggests that inhibiting the secretion of specific sEV‐miRNAs from CRC and targeting PD‐L1 in TAMs may serve as novel methods for CRC treatment as well as a sensitization method for anti‐PD‐L1 therapy in CRC.

The GRP94 Inhibitor PU-WS13 Decreases M2-like Macrophages in Murine TNBC Tumors: A Pharmaco-Imaging Study with 99mTc-Tilmanocept SPECT.

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancers and is not eligible for hormone and anti-HER2 therapies. Identifying therapeutic targets and associated biomarkers in TNBC is a clinical challenge to improve patients’ outcome and management. High infiltration of CD206+ M2-like macrophages in the tumor microenvironment (TME) indicates poor prognosis and survival in TNBC patients. As we previously showed that membrane expression of GRP94, an endoplasmic reticulum chaperone, was associated with the anti-inflammatory profile of human PBMC-derived M2 macrophages, we hypothesized that intra-tumoral CD206+ M2 macrophages expressing GRP94 may represent innovative targets in TNBC for theranostic purposes. We demonstrate in a preclinical model of 4T1 breast tumor-bearing BALB/c mice that (i) CD206-expressing M2-like macrophages in the TME of TNBC can be specifically detected and quantified using in vivo SPECT imaging with 99mTc-Tilmanocept, and (ii) the inhibition of GRP94 with the chemical inhibitor PU-WS13 induces a decrease in CD206-expressing M2-like macrophages in TME. This result correlated with reduced tumor growth and collagen content, as well as an increase in CD8+ cells in the TME. 99mTc-Tilmanocept SPECT imaging might represent an innovative non-invasive strategy to quantify CD206+ tumor-associated macrophages as a biomarker of anti-GRP94 therapy efficacy and TNBC tumor aggressiveness.

Monocytes secrete CXCL7 to promote breast cancer progression

Certain immune cells and inflammatory cytokines are essential components in the tumor microenvironment to promote breast cancer progression. To identify key immune players in the tumor microenvironment, we applied highly invasive MDA-MB-231 breast cancer cell lines to co-culture with human monocyte THP-1 cells and identified CXCL7 by cytokine array as one of the increasingly secreted cytokines by THP-1 cells. Further investigations indicated that upon co-culturing, breast cancer cells secreted CSF1 to induce expression and release of CXCL7 from monocytes, which in turn acted on cancer cells to promote FAK activation, MMP13 expression, migration, and invasion. In a xenograft mouse model, administration of CXCL7 antibodies significantly reduced abundance of M2 macrophages in tumor microenvironment, as well as decreased tumor growth and distant metastasis. Clinical investigation further suggested that high CXCL7 expression is correlated with breast cancer progression and poor overall survival of patients. Overall, our study unveils an important immune cytokine, CXCL7, which is secreted by tumor infiltrating monocytes, to stimulate cancer cell migration, invasion, and metastasis, contributing to the promotion of breast cancer progression.

Reversing tumor immunosuppressive microenvironment via targeting codelivery of CpG ODNs/PD-L1 peptide antagonists to enhance the immune checkpoint blockade-based anti-tumor effect

In order to reverse tumor immunosuppressive microenvironment and improve antitumor immune effect based on immune checkpoint blocking, a mannose-modified liposome-based CpG ODNs and PD-L1 antagonistic peptides (P) co-delivery system (HA/M-Lipo CpG-P) was constructed, in which hyaluronic acid (HA) coating was supposed to improve the systemic circulation stability and thereby promote its accumulation in tumor tissues. When the HA/M-Lipo CpG-P complexes enter the tumor tissues, HA will be hydrolyzed under the action of hyaluronidase, exposing P peptides. Then, P peptides linked by octapeptides that can be cleaved by matrix metalloproteinases (MMPs) are released into tumor tissues under the action of MMPs, exerting a blocking effect in the PD-1/PD-L1 pathway. The M-Lipo CpG complexes can recognize macrophage surface mannose receptors through its surface modified mannose molecules, and promote the intracellular delivery of CpG ODNs, thereby activating macrophages. The results showed that HA/M-Lipo CpG-P complexes successfully reversed M2-type macrophages in tumor microenvironment (TME) to M1, thereby activating anti-tumor related immune cells and inhibiting tumor growth. Moreover, the HA/M-Lipo CpG-P complexes showed a better tumor inhibitory effect than the HA/M-Lipo CpG or the HA/M-Lipo-P (monotherapy) treatment groups. Overall, HA/M-Lipo CpG-P complexes provide a promising co-delivery strategy for targeting tumors to improve the antitumor effect based on immune checkpoint blockade.

Wrapping Porphyromonas gingivalis for tumor microenvironment immunomodulation and photothermal immunotherapy

Tumorigenic M2 phenotype macrophages, which are polarized by stimulating factors in the tumor microenvironment (TME), could facilitate tumor growth. They take participants in limiting T cells functions, tumor angiogenesis, tumor invasion, and metastasis. Increasing the ratio of M1 over M2 macrophages in TME is a promising strategy for cancer immunotherapy. Porphyromonas gingivalis (Pg) from the oral cavity could secrete melanin steadily, recruit macrophages and accelerate the conversion of macrophages to M1 phenotype. Here, we report a wrapping Porphyromonas gingivalis coated with the red blood cell membrane (cm) to generate cmPg to tune the ratio of M1 over M2 macrophages for cancer immunotherapy. The cm coating improves bacteria's size distribution, reduces their uptake by macrophages, and sustains the polarization behavior. In addition, the melanin in cmPg serves as photothermal therapy (PTT) agent under laser irradiation, enables cmPg to convert light to heat, and facilitates photothermal-induced immunogenic cell death (ICD) of cancer cells. Our bioinspired immunomodulatory bacteria can inhibit the growth of the primary and secondary tumor in B16F10 melanoma and CT26 colon cancer with the help of laser and anti-PD-1. Our work offers a straightforward strategy to upcycle Pg as biocompatible materials for combined photothermal immunotherapy.

Predicting the herbal medicine triggering innate anti-tumor immunity from a system pharmacology perspective

Although the main focus of immuno-oncology has been manipulating the adaptive immune system, tumor associated macrophages (TAMs) are the main infiltrating component in the tumor microenvironment (TME) and play a critical role in cancer progression. TAMs are mainly divided into two different subtypes: macrophages with antitumor or killing activity are called M1 while tumor-promoting or healing macrophages are named M2. Therefore, controlling the polarization of TAMs is an important strategy for cancer treatment, but there is no particularly effective means to regulate the polarization process. Here, combined systems pharmacology targets and pathways analysis strategy, we uncovered Scutellariae Radix (SR) has the potential to regulate TAMs polarization to inhibit the growth of non-small cell lung cancer (NSCLC). Firstly, systems pharmacology approach was used to reveal the active components of SR targeting macrophages in TME through compound target prediction and target-microenvironment phenotypic association analysis. Secondly, in vitro experiment verified that WBB (wogonin, baicalein and baicalin), major active ingredients of SR are significantly related to macrophages and survival, initiated macrophages programming to M1-like macrophages to promoted the apoptosis of tumor cells. Finally, we evidenced that WBB effectively inhibited tumor growth in LLC (Lewis lung carcinoma) tumor-bearing mice and increased the infiltration of M1-type macrophages in TME. Overall, the systems pharmacology strategy offers a paradigm to understand the mechanism of polypharmacology of natural products targeting TME.

Ligustilide counteracts carcinogenesis and hepatocellular carcinoma cell-evoked macrophage M2 polarization by regulating yes-associatedprotein-mediated interleukin-6 secretion.

Cross-communication between cancer cells and macrophages within the tumor microenvironment fulfills the critical roles in the progression of cancers, including hepatocellular carcinoma (HCC). Ligustilide exerts anti-inflammation, anti-injury, and anti-tumor pleiotropic pharmacological functions. Nevertheless, its roles in HCC cells and tumor microenvironment remain elusive. In the current study, ligustilide dramatically restrained HCC cell viability and migration but had little cytotoxicity to normal hepatocytes. Importantly, ligustilide antagonized HCC cell co-culture-induced macrophage recruitment and M2 polarization by enhancing the percentage of CD14+CD206+ cells and macrophage M2 markers (CD163, Arg1, CD206, CCL22, IL-10, and TGF-β). Mechanistically, ligustilide repressed yes-associatedprotein (YAP) activation by reducing nuclear translocation, protein expression, transcriptional regulatory activity of YAP, and increasing p-YAP levels. Noticeably, blocking the YAP offset the suppressive effects of ligustilide on macrophage recruitment and M2 polarization evoked by HCC cells. Moreover, the release of interleukin-6 (IL-6) was mitigated by ligustilide in a YAP-dependent manner in HCC cells, concomitant with inhibition of IL-6R/STAT3 signaling activation. Of interest, interdicting the IL-6 aggravated ligustilide-mediated suppression in HCC-induced macrophage recruitment and M2 polarization; whereas exogenous IL-6 treatment reversed the above effects. Additionally, blockage of IL-6R signaling also overturned IL-6-induced macrophage recruitment and M2 phenotype. Consequently, these findings support a notion that ligustilide not only restrains HCC cell malignancy but also antagonizes HCC cell-evoked macrophage recruitment and M2 polarization by inhibiting YAP/IL-6 release-induced activation of the IL-6 receptor/signal transducer and activator of transcription 3 (IL-6R/STAT3) signaling. Thus, ligustilide may be a promising therapeutic agent to fight HCC by regulating cancer cells and cross-talk between tumor cells and macrophages in tumor microenvironment.

Multi-functional carboxymethyl chitin-based nanoparticles for modulation of tumor-associated macrophage polarity

Current challenge of using cytokines is its poor distribution and systemic side effects. To avoid this issue, we prepared the tumor-targeted and microenvironment-responsive nanocarriers (TRN), which were consisted of α-tocopheryl succinate (α-TOS) loaded mesoporous silica nanoparticles as cores, and surface-modified by thioketal-linkage, electrostatically coated with carboxymethyl chitin, and further anchored glucose-regulated protein 78-binding peptide as shells for encapsulating IL-12. TRN showed a size of 260 nm after encapsulated IL-12 and α-TOS with loading content of 0.0206% and 7.21%, respectively, and exhibited good biocompatibility to 4 T1 cells and macrophages. Moreover, IL-12/α-TOS loaded TRN displayed obvious anti-tumor efficacy on BALB/c nude mice bearing 4 T1 tumors, which was derived from promoted targeting to tumor tissue, endocytosed by macrophages and locally release IL-12 to subsequently repolarize tumor-associated macrophages into tumoricidal M1 phenotype with reduced side effects. The nanosystem exhibited as a promising strategy with functional conversion of macrophages in tumor microenvironment for anti-tumor therapy.

Epithelial-Mesenchymal Transition Inversely Associates With Immune Activity in Breast Cancer Tumour Immune Microenvironment

The epithelial to mesenchymal transition (EMT) is a major mechanism of resistance to cancer therapy, including immunotherapy in breast cancer. Recent studies highlighted the role of the EMT program in regulating immune checkpoints; however, the overall immune activity during EMT of carcinoma remains to be shown. Using in-silico data analysis on a large cohort of breast cancer samples from The Cancer Genome Atlas (TCGA) and measuring immune activities across various EMT scores, we found that an increasing EMT score reduces immune cells infiltration and activity, turning an immune infiltrated ‘hot’ tumor microenvironment (TME) to a ‘cold’ and less immune infiltrated TME. Remarkably, the high EMT score and expression of EMT related genes negatively associated with infiltration and activity of various immune cells particularly CD8+ T cells, while increased intratumoral heterogeneity level, infiltration of Treg cells, and M2 macrophages in TME. These data revealed the crucial role of the EMT program in regulating immune-suppression in the tumor-immune microenvironment (TIME) by reducing immune activity and highlighting the potential application of EMT score as a biomarker for the responsiveness of breast cancer patients to immunotherapy.

Converged Rab37/IL-6 trafficking and STAT3/PD-1 transcription axes elicit an immunosuppressive lung tumor microenvironment.

Background: Increased IL-6 level, M2 macrophages and PD-1+CD8+ T cells in tumor microenvironments (TME) have been identified to correlate with resistance to checkpoint blockade immunotherapy, yet the mechanism remains poorly understood. Rab small GTPase-mediated trafficking of cytokines is critical in immuno-modulation. We have previously reported dysregulation of Rab37 in lung cancer cells, whereas the roles of Rab37 in tumor-infiltrating immune cells and cancer immunotherapy are unclear.Methods: The tumor growth of the syngeneic mouse allograft in wild type or Rab37 knockout mice was analyzed. Imaging analyses and vesicle isolation were conducted to determine Rab37-mediated IL-6 secretion. STAT3 binding sites at PD-1 promoter in T cells were identified by chromatin immunoprecipitation assay. Multiplex fluorescence immunohistochemistry was performed to detect the protein level of Rab37, IL-6 and PD-1 and localization of the tumor-infiltrating immune cells in allografts from mice or tumor specimens from lung cancer patients.Results: We revealed that Rab37 regulates the secretion of IL-6 in a GTPase-dependent manner in macrophages to trigger M2 polarization. Macrophage-derived IL-6 promotes STAT3-dependent PD-1 mRNA expression in CD8+ T cells. Clinically, tumors with high stromal Rab37 and IL-6 expression coincide with tumor infiltrating M2-macrophages and PD1+CD8+ T cells that predicts poor prognosis in lung cancer patients. In addition, lung cancer patients with an increase in plasma IL-6 level are found to be associated with immunotherapeutic resistance. Importantly, combined blockade of IL-6 and CTLA-4 improves survival of tumor-bearing mice by reducing infiltration of PD1+CD8+ T cells and M2 macrophages in TME.Conclusions: Rab37/IL-6 trafficking pathway links with IL-6/STAT3/PD-1 transcription regulation to foster an immunosuppressive TME and combined IL-6/CTLA-4 blockade therapy exerts potent anti-tumor efficacy.

Colony Stimulating Factor-1 and its Receptor in Gastrointestinal Malignant Tumors.

Gastrointestinal malignant tumor is the fourth most common cancer in the world and the second cause of cancer death. Due to the susceptibility to lymphatic metastasis and liver metastasis, the prognosis of advanced tumor patients is still poor till now. With the development of tumor molecular biology, the tumor microenvironment and the cytokines, which are closely related to the proliferation, infiltration and metastasis, have become a research hotspot in life sciences. Colony stimulating factor-1 (CSF-1), a polypeptide chain cytokine, and its receptor CSF-1R are reported to play important roles in regulating tumor-associated macrophages in tumor microenvironment and participating in the occurrence and development in diversities of cancers. Targeted inhibition of the CSF-1/CSF-1R signal axis has broad application prospects in cancer immunotherapy. Here, we reviewed the biological characters of CSF-1/CSF-1R and their relationship with gastrointestinal malignancies.

The efficacy of etanercept as anti-breast cancer treatment is attenuated by residing macrophages

BackgroundInteraction between microenvironment and breast cancer cells often is not considered at the early stages of drug development leading to failure of many drugs at later clinical stages. Etanercept is a TNF-alpha inhibitor that has been investigated for potential antitumor effect in breast cancer with conflicting results.MethodsSecretome data on MDA-MB-231 cancer cell-line were from public repositories and subjected to gene enrichment analyses. Since MDA-MB-231 cells secrete high levels of Granulocyte-Monocyte Colony Stimulating Factor, which activates macrophages to promote tumor growth, the effect of macrophage co-culturing on anticancer efficacy of Etanercept in breast cancer was evaluated using the Boolean network modeling and in vitro experiments including invasion, cell cycle, Annexin PI, and tetrazolium based viability assays and NFKB activity.ResultsThe secretome profile of MDA-MB-231 cells was similar to the expression of genes following treatment of breast cancer cells with TNF-α. Accordingly, inhibition of TNF-α by Etanercept decreased MDA-MB-231 cell survival, induced apoptosis and cell cycle arrest in vitro and inhibited NFKB activation. The inhibitory effect of Etanercept on cell viability, cell cycle progression, invasion and induction of apoptosis decreased following co-culturing of the cancer cells with macrophages. The Boolean network modeling of the changes in the dynamics of intracellular signaling pathways revealed NFKB activation by secretome of macrophages, leading to a decreased efficacy of Etanercept, suggesting NFKB inhibition as an alternative approach to inhibit cancer cell growth in the presence of macrophage crosstalk.ConclusionThis study indicates that the effect of Etanercept may be influenced by residing macrophages in tumor microenvironment, and suggests a method to predict the effect of drugs in the presence of stromal cells to guide experimental designs in drug development.

Abstract 2682: Extrafollicular high CD163/CD8 ratio is associated with progression of disease within 24 months in follicular lymphoma patients

Abstract Follicular lymphoma (FL) still remains an incurable disease, with most of the patients undergoing subsequent phases of remission and relapse. In the era of immunotherapy, understanding the immunobiology of FL patients who experience progression of disease within 24 months (POD24) and show chemotherapy resistance remains a priority and an unmet clinical need. Tumor-associated macrophages (TAM) are multifaceted cellular components of the tumor microenvironment (TME). In concert with lymphoid-lineage B and T cells at various developmental stages, TAM can mediate enhanced tumor progression, often leading to poor clinical prognosis and impact the clinical response to chemotherapy. Recently, Joshua and colleagues demonstrated that a subset of FL patients with low immune infiltration was enriched in POD24 events. In our work, we characterized the immune repertoire of lymph node biopsies collected retrospectively from 30 patients with histological diagnosis of FL according WHO criteria. Median follow up was 8 years. The expression levels of TAM (CD68, CD163, MS4a4a) and tumor-infiltrating T-lymphocytes (CD8, PD-1 positive subsets) were assessed by immunohistochemistry and summarized using descriptive statistics. Our data highlighted that the subset of patients with a high extrafollicular CD163/CD8 ratio was enriched in POD24 events (p = 0.01). In addition, patients who showed an higher number of intrafollicular CD68+ macrophages, showed a longer disease free survival (p= 0.04). Another difference was related to the number of CD68, CD163, MS4A4A-positive polarized macrophages that resulted higher in bcl-2 negative than bcl-2 positive cases (p< 0.05 for all markers). In the evaluation of T lymphocytes, most relevant associations were found between the content and distribution of PD1+ cells and the treatment response: the higher the number of intrafollicular PD1+ lymphocytes the lower chemotherapy response rates (p= 0.04). No association was found between the number of positive elements in extrafollicular areas, where instead the PD1/CD8 ratio seems to be related with therapy response: the higher the ratio the lower response rate (p= 0.01). This finding could be explained assuming that there may be different types of cellular interactions inside and outside the neoplastic follicles. No other statistically significant difference in terms of expression of these markers was observed in relation to clinical pathological features such as staging, grade and FLIPI score. In conclusion, extrafollicular high CD163/CD8 ratio is associated with POD24 in FL patients, this finding underlines the pathological significance of CD163-expresing macrophages in TME, suggesting this biomarker as a potential therapeutic target in this disease. Citation Format: Clara Bertuzzi, Maria Maddalena Tumedei, Sara Ravaioli, Claudio Agostinelli, Maurizio Puccetti, Sara Bravaccini, Simona Righi, Beatrice Casadei, Andrea Pession, Giovanni Martinelli, Giorgia Simonetti, Elena Sabattini, Serena De Matteis. Extrafollicular high CD163/CD8 ratio is associated with progression of disease within 24 months in follicular lymphoma patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2682.

BML-111 inhibits EMT, migration and metastasis of TAMs-stimulated triple-negative breast cancer cells via ILK pathway

Triple-negative breast cancer (TNBC) has a more aggressive phenotype and higher metastasis and recurrence rates than other breast cancer subtypes. The immune microenvironment and hypoxic microenvironment of breast cancer constitute the survival environment of cancer cells, which is an important environment to support cancer cells. LXA4 and its analog, BML-111 is an important regulator of inflammatory cytokines, which provides a possible way for the treatment of inflammatory-related tumors. Here, in the in vitro experiment, we showed that BML-111 could inhibit the EMT and migration of TAMs-stimulated TNBC by down-regulating ILK as well as p-Akt and p-GSK3β. And it could prevent the formation of breast cancer cell clusters. In the in vivo experiment, BML-111 could inhibit the metastasis of 4T1 breast cancer cells. We also demonstrated that BML-111 could affect macrophages in tumor microenvironment to prevent metastasis. These results showed that BML-111 could be a possible candidate for breast cancer therapy by targeting ILK and TAMs.

Regulation of macrophages in tumor microenvironment by microRNA in T cell lymphoma-bearing mice

Abstract The tumor microenvironment is a complex niche created by cancer cells to survive and evade the immune system. Macrophages (Mϕs) are considered to be one of the most abundant cells in the cancer microenvironment. Studies have shown that cancer cells have predilection for the M2 cell phenotype compared to M1 in the microenvironment, because M2 Mϕs promote immunosuppression and subsequently enhance tumor cell proliferation and angiogenesis. The aim of this study was to compare the gene expression profile of tumor-associated Mϕs (TAMs) and splenic Mϕs from tumor-bearing hosts (TBHs) and determine the epigenetic regulation of altered genes. For this purpose, C57BL/6 mice were injected with 1×106 EL4 cancer cells subcutaneous to induce tumor growth and 10 days later, TAMs and splenic Mϕs were isolated. Cell phenotyping by flow cytometry showed that there was an increase in M2 cells in TAMs when compared to splenic Mϕs in TBHs. TAMs also exhibited increase in IL-10, IL-6, VEGFA, and ARG-1 whereas there was a decrease in the expression of MYD88, PTEN, TGFβ3 and P53 when compared to splenic Mϕs in TBHs. Analysis of the microRNA profile of the Mϕs showed differential regulation and using ingenuity pathway analysis (IPA), we found various miRs (miR-21a, miR-30a, miR-30c, miR-125b, miR-155) were upregulated. These miRs targeted MYD88, PTEN and P53, which leads to the overexpression of IL10, known to skew Mϕ polarization to an M2 phenotype. In summary, these studies demonstrate that several miRs regulate IL10 to polarize TAMs from an M1 to M2 phenotype in the tumor microenvironment. (Supported by NIH P01AT003961, P20GM103641, R01AI129788, R01 ES030144 and R01AI123947)

PGE2-HIF1α reciprocal induction regulates migration, phenotypic alteration and immunosuppressive capacity of macrophages in tumor microenvironment

BackgroundVery little is known about the role inflammation and mechanism(s) that enables the tumor to evade host's anti-tumor immune function during very initial days of tumor establishment. Our study focuses on the immune response and local inflammation specially the pro-inflammatory and immune modifier components that are responsible for tumor-induced immune-suppression, tumor-associated macrophages (TAM) at tumor microenvironment in mouse model from very early to late phase of tumor progression. Methods1 × 105 Ascites tumor, EAC in Swiss albino or Sarcoma-180 (S-180) in Balb c mice strain were inoculated intra-peritonially and grouped into Control (0 day or no tumor), initial phase (3 day tumor), early (7 Day), Late (14 day) and terminal (21 day tumor) sets. T cell activity, tumor niche macrophage, inflammatory signatures were studied using Confocal microscopy, flowcytometry, ELISA, q-RT PCR and Western blot. ResultsWe observed increased T cell infiltration at a very early stage of tumorigenesis in the tumor site with elevated percentage of activated/memory T cells. But increased cellular death and functional suppression of tumor site T cells during final stages. We observed increased infiltration of TAMs with skewed M2 phenotype. Increased chemokine receptor expression could be noted on these TAMs. Using HIF-1α inhibitor and prostaglandin receptor antagonists we demonstrated crucial role of these factor in functional alteration in TAMs. HIF-1α inhibition and also by prostaglandin receptor inhibition reduced signature pro-inflammatory gene expression, migration of macrophages and T cell suppression capacity of TAMs. We also demonstrated that PGE2 can induce HIF-1α activation in relatively less hypoxic microenvironment during early stages of tumor. ConclusionAltogether, these findings strongly suggest link between prostaglandin mediated early HIF-1α activation and subsequent hypoxia induced HIF-1α activation that further enhances prostaglandin synthesis driving the recruitment and functional alteration of tumor site macrophages.

Dihydroartemisinin Prevents Progression and Metastasis of Head and Neck Squamous Cell Carcinoma by Inhibiting Polarization of Macrophages in Tumor Microenvironment.

BackgroundPolarized M2 macrophages are an important type of tumor-associated macrophage (TAM), with roles in the growth, invasion, and migration of cancer cells in the tumor microenvironment. Dihydroartemisinin (DHA), a traditional Chinese medicine extract, has been shown to inhibit the progression and metastasis of head and neck squamous cell carcinoma (HNSCC); however, the effect of DHA on cancer prevention, and the associated mechanism, has not been investigated in the tumor microenvironment.Materials and MethodsFirst, human Thp-1 monocytes were induced and differentiated into M2 macrophages using phorbol 12-myristate 13-acetate (PMA), interleukin-6 (IL-6), and interleukin-4 (IL-4). Induction success was confirmed by cell morphology evaluation, flow cytometry, and quantitative real-time polymerase chain reaction (qRT-PCR). Then, DHA was applied to interfere with M2 macrophage polarization, and conditioned medium (CM), including conditioned medium from M2 macrophages (M2-CM) and conditioned medium from M2 macrophages with DHA (M2-DHA-CM), was obtained. CM was applied to Fadu or Cal-27 cells, and its effects on cancer invasion, migration, and angiogenesis were evaluated using transwell, wound-healing, and tube formation assays, respectively. Finally, Western blotting was used to evaluate the relationship between signal transducer and activator of transcription 3 (STAT3) signaling pathway activation and M2 macrophage polarization.ResultsHuman Thp-1 monocytes were successfully polarized into M2-like TAMs using PMA, IL-6, and IL-4. We found that M2-like TAMs promoted the invasion, migration, and angiogenesis of HNSCC cells; however, DHA significantly inhibited IL-4/IL-6-induced M2 macrophage polarization. Additionally, as DHA induced a decrease in the number of M2-like TAMs, M2-DHA-CM inhibited the induction of invasion, migration, and angiogenesis of Fadu and Cal-27 cells. Finally, DHA inhibited M2 macrophage polarization by blocking STAT3 pathway activation in macrophages.ConclusionDHA inhibits the invasion, migration, and angiogenesis of HNSCC by preventing M2 macrophage polarization via blocking STAT3 phosphorylation.