Tumor-associated Macrophages In Tumor Microenvironment Research Articles

Engineering nanoparticles-enabled tumor-associated macrophages repolarization and phagocytosis restoration for enhanced cancer immunotherapy

Tumor-associated macrophages (TAMs) are pivotal within the immunosuppressive tumor microenvironment (TME), and recently, have attracted intensive attention for cancer treatment. However, concurrently to promote TAMs repolarization and phagocytosis of cancer cells remains challenging. Here, a TAMs-targeted albumin nanoparticles-based delivery system (M@SINPs) was constructed for the co-delivery of photosensitizer IR820 and SHP2 inhibitor SHP099 to potentiate macrophage-mediated cancer immunotherapy. M@SINPs under laser irradiation can generate the intracellular reactive oxygen species (ROS) and facilitate M2-TAMs to an M1 phenotype. Meanwhile, inhibition of SHP2 could block the CD47-SIRPa pathway to restore M1 macrophage phagocytic activity. M@SINPs-mediated TAMs remodeling resulted in the immunostimulatory TME by repolarizing TAMs to an M1 phenotype, restoring its phagocytic function and facilitating intratumoral CTLs infiltration, which significantly inhibited tumor growth. Furthermore, M@SINPs in combination with anti-PD−1 antibody could also improve the treatment outcomes of PD−1 blockade and exert the synergistic anticancer effects. Thus, the macrophage repolarization/phagocytosis restoration combination through M@SINPs holds promise as a strategy to concurrently remodel TAMs in TME for improving the antitumor efficiency of immune checkpoint block and conventional therapy.

IFI35 regulates non-canonical NF-κB signaling to maintain glioblastoma stem cells and recruit tumor-associated macrophages.

Glioblastoma (GBM) is the most aggressive malignant primary brain tumor characterized by a highly heterogeneous and immunosuppressive tumor microenvironment (TME). The symbiotic interactions between glioblastoma stem cells (GSCs) and tumor-associated macrophages (TAM) in the TME are critical for tumor progression. Here, we identified that IFI35, a transcriptional regulatory factor, plays both cell-intrinsic and cell-extrinsic roles in maintaining GSCs and the immunosuppressive TME. IFI35 induced non-canonical NF-kB signaling through proteasomal processing of p105 to the DNA-binding transcription factor p50, which heterodimerizes with RELB (RELB/p50), and activated cell chemotaxis in a cell-autonomous manner. Further, IFI35 induced recruitment and maintenance of M2-like TAMs in TME in a paracrine manner. Targeting IFI35 effectively suppressed in vivo tumor growth and prolonged survival of orthotopic xenograft-bearing mice. Collectively, these findings reveal the tumor-promoting functions of IFI35 and suggest that targeting IFI35 or its downstream effectors may provide effective approaches to improve GBM treatment.

Specific molecular weight of Lycium barbarum polysaccharide for robust breast cancer regression by repolarizing tumor-associated macrophages

The pro-tumorigenic M2-type tumor-associated macrophages (TAMs) in the immunosuppressive tumor microenvironment (TME) promote the progression, angiogenesis, and metastasis of breast cancer. The repolarization of TAMs from an M2-type toward an M1-type holds great potential for the inhibition of breast cancer. Here, we report that Lycium barbarum polysaccharides (LBPs) can significantly reconstruct the TME by modulating the function of TAMs. Specifically, we separated four distinct molecular weight segments of LBPs and compared their repolarization effects on TAMs in TME. The results showed that LBP segments within 50–100 kDa molecular weight range exhibited the prime effect on the macrophage repolarization, augmented phagocytosis effect of the repolarized macrophages on breast cancer cells, and regression of breast tumor in a tumor-bearing mouse model. In addition, RNA-sequencing confirms that this segment of LBP displays an enhanced anti-breast cancer effect through innate immune responses. This study highlights the therapeutic potential of LBP segments within the 50–100 kDa molecular weight range for macrophage repolarization, paving ways to offer new strategies for the treatment of breast cancer.

Abstract 4653: Spatial architecture of tumor-infiltrating macrophagesorchestrates tumor immunity and therapeutic response

Abstract Tumor-infiltrating macrophages, a major cellular component in the tumor microenvironment (TME), have been proven to be linked with tumor progression and immunotherapy resistance. Tremendous heterogeneity has been revealed for tumor-associated macrophages (TAMs) in different cancer types, however, how these TAM subtypes are localized and interact with tissue ecosystems remains poorly understood. Here, we perform an integrative analysis of TAMs, malignant and non-malignant cells from 10 cancer types, based on single-cell RNA-seq and spatial transcriptomic data. By interrogating the spatial distributions of different TAM subtypes in situ, we reveal spatially restricted developmental, regulation, and functional heterogeneity of TAMs in TME. Different cancer types show distinct TAM subtype enrichments with specific interface architectures, which is potentially shaped by the cellular compositions and spatial niches of tumor cells. Furthermore, the compartmentalized TAM subpopulations can reflect the spatial architecture of surrounding stromal and immune cells, and thus orchestrate tumor immunity and therapeutic response. Our study demonstrates the cellular and molecular underpinnings of TAM heterogeneity and stochastic regulations of TAMs for TME architecture, tumor progression and immunotherapy responses, which will assist in the identification of possible therapeutic targets. Citation Format: Yuanyuan Zhang, Fuduan Peng, Guangsheng Pei, Yunhe Liu, Guangchun Han, Linghua Wang. Spatial architecture of tumor-infiltrating macrophagesorchestrates tumor immunity and therapeutic response. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4653.

Targeted delivery of pexidartinib to tumor-associated macrophages via legumain-sensitive dual-coating nanoparticles for cancer immunotherapy

Tumor-associated macrophage (TAM) is regarded as an appealing cell target for cancer immunotherapy. However, it remains challenging to selectively eliminate M2-like TAM in tumor microenvironment. In this work, we employed a legumain-sensitive dual-coating nanosystem (s-Tpep-NPs) to deliver CSF-1R inhibitor pexidartinib (PLX3397) for targeting TAM therapy. The PLX3397-loaded NPs exhibited uniform size of ∼240 nm in diameter, good drug loading capacity and efficiency, as well as sustained drug release profile. Compared to non-sensitive counterpart ns-Tpep-NPs, s-Tpep-NPs showed distinguished selectivity upon M1 and M2 macrophage uptake with relation to incubation time and dose. Besides, the selectivity of anti-proliferation effect was also identified for s-Tpep-NPs against M1 and M2 macrophage. In vivo imaging demonstrated that s-Tpep-NPs exhibited much higher tumoral accumulation and TAM recognition specificity as compared to non-sensitive ns-Tpep-NPs. In vivo efficacy verified that s-Tpep-NPs formulation was much more effective than ns-Tpep-NPs and other PLX3397 formulations to treat B16F10 melanoma via targeting TAM depletion and modulating tumor immune microenvironment. Overall, this study provides a robust and promising nanomedicine strategy for TAM-targeted cancer immunotherapy.

Significance of tumor-associated macrophages in bladder cancer development

Bladder cancer is the 2 nd most common urological oncological disease in the worlds. Tumors can be muscle invasive and non-muscle invasive. Recently, tumor microenvironment (TME) became a focus of investigation in malignant tumors of the bladder. According to the currently available data, TME is a specific environment crating optimal conditions for carcinogenesis in the neoplastic lesion. The main parts of TME are extracellular matrix and stroma including vasculature, stromal, and immune cells. Additionally, TME includes cytokines, chemokines, and other compounds activating signal pathways necessary for tumor cells. Tumor-associated macrophages (TAMs) are being extensively studied as representatives of TME in solid tumors of varying locations. These macrophages can be classified into 2 phenotypes: M1 (pro-inflammatory and antitumor) and M2 (anti-inflammatory and protumor). The phenotypes perform different roles, and M2 macrophages regulate the most important processes of oncogenesis (invasion, proliferation, neoangiogenesis, etc.). In the context of bladder cancer, M2 macrophages are the most significant as they are the most numerous TAMs in TME. Aim . To study the role of tumor-associated macrophages in development of bladder tumors, as well as prognostic value of these macrophages.

CircSMARCC1 facilitates tumor progression by disrupting the crosstalk between prostate cancer cells and tumor-associated macrophages via miR-1322/CCL20/CCR6 signaling

BackgroundCircular RNAs (circRNAs) mediate the infiltration of tumor-associated macrophages (TAMs) to facilitate carcinogenesis and development of various types of cancers. However, the role of circRNAs in regulating macrophages in prostate cancer (PCa) remains uncertain.MethodsDifferentially expressed circRNAs in PCa were identified by RNA sequencing. The expression of circSMARCC1 was recognized and evaluated using fluorescence in situ hybridization and quantitative real-time PCR. The oncogenic role of circSMARCC1 in PCa tumor proliferation and metastasis was investigated through a series of in vitro and in vivo assays. Finally, Western blot, biotin-labeled RNA pulldown, luciferase assay, rescue experiments, and co-culture experiments with TAMs were conducted to reveal the mechanistic role of circSMARCC1.ResultsCircSMARCC1 was dramatically up-regulated in PCa cells, plasma and tissues. Overexpression of circSMARCC1 promotes tumor proliferation and metastasis both in vitro and in vivo, whereas knockdown of circSMARCC1 exerts the opposite effects. Mechanistically, circSMARCC1 regulates the expression of CC-chemokine ligand 20 (CCL20) via sponging miR-1322 and activate PI3K-Akt signaling pathway involved in the proliferation and epithelial mesenchymal transformation. More importantly, high expression of circSMARCC1 was positively associated with colonization of CD68+/CD163+/CD206+ TAMs in tumor microenvironment. In addition, overexpression of circSMARCC1 facilitates the expression of CD163 in macrophages through the CCL20-CCR6 axis, induces TAMs infiltration and M2 polarization, thereby leading to PCa progression.ConclusionsCircSMARCC1 up-regulates the chemokine CCL20 secretion by sponging miR-1322, which is involved in the crosstalk between tumor cells and TAMs by targeting CCL20/CCR6 signaling to promote progression of PCa.

Epigenetic regulation of cutaneous T-cell lymphoma is mediated by dysregulated lncRNA MALAT1 through modulation of tumor microenvironment.

Cutaneous T-Cell Lymphoma (CTCL) is a rare non-Hodgkin lymphoma marked by migration of T-lymphocytes to the skin. It has many subtypes some of which are aggressive with documented metastasis. We investigated a possible role of lncRNA MALAT1 in CTCL cells because of its documented involvement in cancer metastasis. A screening of MALAT1 in CTCL patients revealed its elevated levels in the patients, compared to healthy individuals. For our investigation, we employed HH and H9 CTCL cells and silenced MALAT1 to understand the MALAT1 mediated functions. Such silencing of MALAT1 resulted in reversal of EMT and inhibition of cancer stem cell phenotype, along with reduced cell growth and proliferation. EMT reversal was established through increased E-cadherin and reduced N-cadherin while inhibition of cancer stem cell phenotype was evident through reduced Sox2 and Nanog. CTCL patients had higher circulating levels of IL-6, IL-8, IL-10, TGFβ, PGE2 and MMP7 which are factors released by tumor-associated macrophages in tumor microenvironment. MALAT1 sponged miR-124 as this tumor suppressive miRNA was de-repressed upon MALAT1 silencing. Moreover, downregulation of miR-124 attenuated MALAT1 silencing effects. Our study provides a rationale for further studies focused on an evaluation of MALAT1-miR-124 in CTCL progression.

The Role of TAMs in Tumor Microenvironment and New Research Progress.

Tumor-associated macrophages (TAMs) are an important part of tumor microenvironment (TME) and play a key role in TME, participating in the process of tumor occurrence, growth, invasion, and metastasis. Among them, metastasis to tumor tissue is the key step of malignant development of tumor. In this paper, the latest progress in the role of TAMs in the formation of tumor microenvironment is summarized. It is particularly noteworthy that cell and animal experiments show that TAMs can provide a favorable microenvironment for the occurrence and development of tumors. At the same time, clinical pathological experiments show that the accumulation of TAMs in tumor is related to poor clinical efficacy. Finally, this paper discusses the feasibility of TAMs-targeted therapy as a new indirect cancer therapy. This paper provides a theoretical basis for finding a potentially effective macrophage-targeted tumor therapy.

Characterization of Gut Microbiota and Exploration of Potential Predictive Model for Hepatocellular Carcinoma Microvascular Invasion.

BackgroundThe association between gut microbiota and microvascular invasion (MVI) in patients with hepatocellular carcinoma (HCC) remains unclarified. Hence, the microbiome analysis of patients with HCC might predict MVI development as an accurate, non-invasive, and convenient assessment. The aim of this study was to investigate the characteristics of gut microbiota in patients with HCC-MVI and establish a microbial prediction model of HCC-MVI based on a microbiome study.MethodsFecal samples were collected from 59 patients with HCC (24 of the total with MVI disease and 16 healthy controls) and were further analyzed by 16S rRNA amplicon sequencing followed by a comprehensive bioinformatic analysis. The diagnostic performance of microbiome characteristics in predicting MVI was assessed by receiver operating characteristic (ROC) curves. The correlation between gut microbiota and tumor microenvironment (TME) in the HCC-MVI group was further analyzed by using immunohistochemistry and immunofluorescence assay.ResultsA significant differentiation trend of microbiota composition and structure was observed between the HCC-MVI group and those without vascular invasion (HCC-NVI). Compared with HCC-NVI group and healthy controls, gut bacteria Klebsiella, Proteobacteria, Prevotellaceae, and Enterobacteriaceae were significantly enriched, whereas Firmicutes, Ruminococcus, and Monoglobaceae were significantly decreased in patients with HCC-MVI. Klebsiella was considered to be the key microbiome signature for patients with HCC-MVI. The area under the curve (AUC) of the established HCC-MVI microbial prediction model was 94.81% (95% CI: 87.63–100%). The percentage of M2-type tumor-associated macrophages (TAMs) was increased in the HCC-MVI group compared with the HCC-NVI group (p < 0.001). M2-type TAMs in TME were negatively correlated with Shannon and Simpson index of HCC-MVI gut microbiota (all p < 0.01). In addition, predicted KEGG pathways showed that the functional differences in the metabolic pathways of microbiota varied among the groups.ConclusionThe results indicated that differences existed in the fecal microbiome of patients with HCC-MVI and healthy controls. The prediction model of HCC-MVI established with certain gut bacterial signatures may have the potential to predict HCC-MVI outcome, and the characteristics of the fecal microbiome in patients with HCC may be associated with TME, though future larger-cohort studies are required to validate this supposition.

Identification of Key Genes Driving Tumor Associated Macrophage Migration and Polarization Based on Immune Fingerprints of Lung Adenocarcinoma.

The identification of reliable indicators in the tumor microenvironment (TME) is critical for tumor prognosis. Tumor associated macrophages (TAMs) are the major component of non-tumor stromal cells in TME and have increasingly been recognized as a predictive biomarker for lung adenocarcinoma (LUAD) prognosis. Here, we report the development of a prognosis model for LUAD using three immune-related genes (IRGs) detected in The Cancer Genome Atlas (TCGA) which potentially regulate TAMs in TME. In 497 LUAD patients, higher immune scores conferred better overall survival (OS). We identified 93 hub IRGs out of 234 for further prognostic significance. Among them, three IRGs (BTK, Cd1c, and S100P) were proved to be closely correlated to the prognosis of patients with LUAD. Moreover, the immune risk score (IRS) based on the gene expression level of the three IRGs was an independent prognostic factor for OS. Higher IRS predicted lower OS, higher mortality and worse tumor stage. With a good predictive ability [area under the ROC curve (AUC) in TCGA = 0.701, AUC in GEO = 0.722], the IRS contributed to a good risk stratification ability of the nomogram. Immunologically, the three IRGs were related to M1 macrophages and NK cell subsets in TME. Interestingly, by characterizing these immune components in situ we found that S100P is a driver for tumor cells to induce TAM migration and M2 polarization in the immunosuppressive tumor niche. We identified the key genes driving TAM migration and transformation and elucidated the immune landscape of LUAD. The data suggest that IRGs from TME have the potential to become indicators for estimating cancer prognosis and guiding individualized treatment.

CAFs Interacting With TAMs in Tumor Microenvironment to Enhance Tumorigenesis and Immune Evasion.

Cancer associated fibroblasts (CAFs) and tumor associated macrophages (TAMs) are among the most important and abundant players of the tumor microenvironment. CAFs as well as TAMs are known to play pivotal supportive roles in tumor growth and progression. The number of CAF or TAM cells is mostly correlated with poor prognosis. Both CAFs and TAMs are in a reciprocal communication with the tumor cells in the tumor milieu. In addition to such interactions, CAFs and TAMs are also involved in a dynamic and reciprocal interrelationship with each other. Both CAFs and TAMs are capable of altering each other’s functions. Here, the current understanding of the distinct mechanisms about the complex interplay between CAFs and TAMs are summarized. In addition, the consequences of such a mutual relationship especially for tumor progression and tumor immune evasion are highlighted, focusing on the synergistic pleiotropic effects. CAFs and TAMs are crucial components of the tumor microenvironment; thus, they may prove to be potential therapeutic targets. A better understanding of the tri-directional interactions of CAFs, TAMs and cancer cells in terms of tumor progression will pave the way for the identification of novel theranostic cues in order to better target the crucial mechanisms of carcinogenesis.

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.

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.

Crosstalk between cancer and immune cells: Role of tumor-associated macrophages in the tumor microenvironment.

Tumor microenvironment is a complex system that contains multiple cells and cytokines. Among the multiple immune cells, macrophage is particularly abundant and plays an important role throughout the tumor progression process, namely, tumor‐associated macrophage (TAM) in this special tumor microenvironment. Many kinds of cytokines from TAMs and other immune cells in tumor niche are involved in the linkage of inflammation, immunity and tumorigenesis. Inflammatory responses induced by TAMs are crucial to tumor development of different stages. This review highlights the critical role of TAMs in the linkage of inflammation, immunity, and cancer. It outlines the molecules of inflammatory cytokines, chemokines, and growth factors mainly from TAMs in tumor microenvironment and their functions in tumor development during the major issues of angiogenesis, chronic inflammation, and immune suppression. Additionally, the signaling pathways involved in tumor progression and the crosstalk between them are also summarized.

Tumor-driven like macrophages induced by conditioned media from pancreatic ductal adenocarcinoma promote tumor metastasis via secreting IL-8.

Tumor‐associated macrophages (TAMs) are abundant population of inflammatory cells which play an essential role in remodeling tumor microenvironment and tumor progression. Previously, we found the high density of TAMs was correlated with lymph node metastasis and poor prognosis in pancreatic ductal adenocarcinoma (PDAC). Therefore, this study was designed to investigate the mechanisms of interaction between TAMs and PDAC. THP‐1 monocytes were the exposure to conditioned media (CM) produced by PDAC cells; then, monocyte recruitment and macrophage differentiation were assessed. CM from PDAC attracted and polarized THP‐1 monocytes to tumor‐driven like macrophages. mRNA expression cytokine profiling and ELISA identified the IL‐8 secretion was increasing in tumor‐driven like macrophages, and STAT3 pathway was involved. Addition of exogenous recombinant human IL‐8 promoted PDAC cells motility in vitro and metastasis in vivo via upregulating Twist expression, which mediated epithelial‐mesenchymal transition in cancer cells. What is more, IL‐8 expression level in tumor stroma by immunohistochemical analysis was related to lymph node metastasis, the number of tumor CD68 but not CD163 positive macrophages and patient outcome. Taken together, these findings shed light on the important interplay between cancer cells and TAMs in tumor microenvironment and suggested that IL‐8 signaling might be a potential therapeutic target for PDAC.

Macrophage Polarization: Anti-Cancer Strategies to Target Tumor-Associated Macrophage in Breast Cancer.

Tumor-associated macrophages (TAMs) are the most abundant inflammatory cells and orchestrate different stages of breast cancer development. TAMs participate in the tumor angiogenesis, matrix remodeling, invasion, immunosuppression, metastasis, and chemoresistance in breast cancer. Several clinical studies indicate the association between the high influx of TAMs in tumor with poor prognosis in hepatocellular, ovarian, cervical, and breast cancer. Previously developed hypotheses have proposed that TAMs participate in antitumor responses of the body, while recently many clinical and experimental studies have revealed that TAMs in tumor microenvironment predominantly resemble with M2-like polarized macrophages and produce a high amount of anti-inflammatory factors which are directly responsible for the development of tumor. Various studies have shown that TAMs in tumor either enhance or antagonize the anti-tumor efficacy of cytotoxic agents, antibodies-targeting cancer cells, and therapeutic agents depending on the nature of treatment. Thereby, multiple roles of TAMs suggests that it is very important to develop novel therapeutic strategies to target TAMs in breast tumor. In this review, we have discussed the functional role of TAMs in breast cancer and summarized available recent advances potential therapeutic strategies that effectively target to TAMs cells. J. Cell. Biochem. 118: 2484-2501, 2017. © 2017 Wiley Periodicals, Inc.

CD163+ Tumor Associated Macrophages Predict Inferior Outcome in Patients with Diffuse Large B-Cell Lymphoma Treated with R-CHOP

Tumor-associated macrophages (TAMs), as the major component in tumor microenvironment, have been reported to correlate with the prognosis in diffuse large B-cell lymphoma (DLBCL). However due to the different subtypes of TAMs and the given therapy regimen, the prognostic value of TAMs in DLBCL patients remains controversial. To explore the prognostic significance of different TAMs subtypes in DLBCL patients treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone), we retrospectively analyzed 77 de novo DLBCL patients in present study.TAM markers including CD68 and CD163 were evaluated by immunohistochemistry. The cutoff value of CD68, CD163 and CD163/CD68 ratio was determined by receiver operating characteristic curve. In a total of 77 patients, CD68 high expression was found in71.4 %( 55/77) DLBCL patients and CD163 high expression in 51.4 %( 40/77 patients. Patients with high CD163 expression were more present with extranodal sites (P =0.049). However other clinical parameters including age, gender, Ann Arbor stage, performance stage, B symptoms, LDH and international prognostic index (IPI) showed no difference in patients with high and low CD68 or CD163 expression (P >0.05). CD68 expression has less effect on overall survival (OS) and event-free survival (EFS) (P =0.852, 0.782). However, high CD163 expression showed poor OS and EFS in DLBCL patients (P =0.006, 0.004) and also high CD163/CD68 ratio (P <0.001, 0.001). The multivariate analysis revealed that the high CD163 expression and CD163/CD68 ratio remained unfavorable factors for both OS (P =0.094, 0.002) and EFS (P =0.044, 0.016) independent of IPI. In conclusion, our date suggest that high CD163+ TAMs in tumor microenvironment may imply poor outcome in DLBCL patients treated with R-CHOP, but not CD68+ TAMs. DisclosuresNo relevant conflicts of interest to declare.

Abstract B199: Novel anti-angiogenic cancer therapeutic strategy by targeting differentiated macrophage lineage cells through N-myc downstream regulated gene 1 (NDRG1)

Abstract [Background] Angiogenesis is essential for malignant progression of cancer. Over the last couple of decades, it was highlighted that the progenitor cells derived from bone marrow (BM) differentiated, became part of the tumor stroma, and involved in tumor angiogenesis. In particular, macrophages, which differentiated into tumor-associated macrophages in tumor microenvironment, are known to play crucial roles in tumor angiogenesis. However, the specific molecules and markers of these “angiogenesis-supporting macrophages” have not been fully defined (Qian and Pollard, Cell. 2010). N-myc downstream regulated gene 1 (NDRG1), a gene responsible for a hereditary motor and sensory neuropathy (Lon-Charcot-Marie disease), plays pleiotropic roles in cell proliferation, development, differentiation, and tumorigenesis. We have previously reported that NDRG1 expression levels in cancer cells were closely correlated with tumor angiogenesis (Maruyama et al., Cancer Res. 2006; Hosoi et al., Cancer Res. 2009; Ureshino et al., PLoS One. 2012; Murakami et al., J Biol Chem. 2013). However, how NDRG1 could affect tumor angiogenesis remains unclear. In this study, we asked how NDRG1 could specifically modulate tumor angiogenesis through its differentiation control of macrophage lineage cells by using NDRG1 knock out (KO) mice. [Material and methods] NDRG1 KO mice: The NDRG1 KO mice on C57BL6 background have been kindly donated by Dr. Toshiyuki Miyata (National Cerebral and Cardiovascular Center) (Okuda et al., Mol Cell Biol., 2004). Preparation of BM derived macrophages (BMDMs): BMDMs were obtained by flushing mouse femurs from mice. Cells were seeded in dishes and washed twice 3 hours later. Adherent cells were incubated in DMEM supplemented with 10% FBS and 20ng/ml M-CSF for 7 days. Matrigel plug assay in BM suppression mice: wild type (WT) recipient mice were exposed to 3-Gy sublethal whole-body irradiation to suppress BM and temporarily deplete leukocytes. Seven days after the irradiation, the mice were injected subcutaneously with growth factor-reduced Matrigel containing B16/BL6 cells, with or without BMDMs from WT or NDRG1 KO mice. [Results] In NDRG1 KO mice as compared to their WT counterparts, [1] serum levels of M-CSF and macrophage-related cytokines were all decreased, and BM cells showed much slower growth rates in response to M-CSF in vitro; [2] trabecular bone mass and number of osteoclasts were decreased in vivo; [3] tumor growth and angiogenesis were markedly suppressed, accompanying by decreased infiltration of tumor-associated macrophages; [4] the transfer of BMDMs from KO mice into BM-eradicated WT mice induced much less tumor angiogenesis than observed in WT mice; [5] VEGF-A expression in BMDMs from KO mice were much less than those in cells from WT mice when stimulated by LPS or IL-1β. [Conclusion] We discovered the central role of NDRG1 in differentiation of macrophage lineage cells, which affected bone remodeling and tumor angiogenesis. We will discuss which molecules are specifically regulated by NDRG1 during differentiation processes of monocytes/macrophages into angiogenesis-supporting macrophages, and whether these molecules in macrophages could have potentially important target for anti-angiogenesis cancer therapeutics. Citation Format: Kosuke Watari, Tomohiro Shibata, Hiroshi Nabeshima, Ai Shinoda, Yuichi Fukunaga, Akihiko Kawahara, Kazuyuki Karasuyama, Jun-ichi Fukushi, Yuichi Murakami, Michihiko Kuwano, Mayumi Ono. Novel anti-angiogenic cancer therapeutic strategy by targeting differentiated macrophage lineage cells through N-myc downstream regulated gene 1 (NDRG1). [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B199.

Abstract 474: Regulation of epithelial plasticity of cancer cells by tumor-associated macrophages

Abstract Epithelial plasticity of cancer cells is considered to be critical for the metastatic process of cancer cells. Epithelial-mesenchymal transition (EMT) has been proved to associate with cancer metastatic dissemination from primary tumor site to distal metastatic organ. In contrast, accumulated evidence showed that the reversal process of EMT, i.e., mesenchymal-epithelial transition (MET), is critical for metastatic colonization. However, the mechanism for controlling the epithelial plasticity during metastatic process is unclear. Tumor-associated macrophages (TAMs) are the most abundant host immune cells in tumor microenvironments. TAMs have been shown to modulate cancer progression through regulating cancer cell growth and metastasis, and remodeling extracellular matrix. However, it is still unclear about the roles of TAMs in regulating epithelial plasticity during cancer metastasis. Here, we demonstrate the distinct characteristics of that the TAMs in primary and metastatic tumors. The TAMs in metastatic tumors carry a M2-like phenotype; in contrast, the TAMs in primary tumors are composed of heterogeneous population containing both M1-like and M2-like cells. Furthermore, we polarize human monocytes into M1-like and M2-like macrophages and treat cancer cells with M1 and M2 macrophages conditioned medium. We find that different macrophage subtypes have a distinct effect in modulating epithelial plasticity of cancer cells. Interestingly, polarized macrophages regulate cancer cell morphological changes through epigenetic regulation. Therefore, we propose that TAMs in tumor microenvironment may polarize into different subtypes and facilitate cancer metastatic dissemination. These findings have implications for designing alternative strategies aimed at preventing and inhibiting cancer metastasis. Citation Format: CHIH-CHAN LEE, Muh-Hwa Yang. Regulation of epithelial plasticity of cancer cells by tumor-associated macrophages. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 474. doi:10.1158/1538-7445.AM2015-474