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Colorectal cancer (CRC) exhibits a substantial morbidity and mortality rate, with its aetiology and pathogenesis remain elusive. It holds significant importance within the tumour microenvironment (TME) and exerts a crucial regulatory influence on tumorigenesis, progression, and metastasis. TAMs possess the capability to foster CRC pathogenesis, proliferation, invasion, and metastasis, as well as angiogenesis, immune evasion, and tumour resistance. Furthermore, TAMs can mediate the prognosis of CRC. In this paper, we review the mechanisms by which natural compounds target TAMs to exert anti-CRC effects from the perspective of the promotional effects of TAMs on CRC, mainly regulating the polarization of TAMs, reducing the infiltration and recruitment of TAMs, enhancing the phagocytosis of macrophages, and regulating the signalling pathways and cytokines, and discuss the potential value and therapeutic strategies of natural compounds-targeting the TAMs pathway in CRC clinical treatment. [ABSTRACT FROM AUTHOR]

Abstract Objective This study aims to investigate the effect of CD206 on the progression of hepatocellular carcinoma (HCC) and the regulation of the tumour immune microenvironment. Methods A subcutaneous mouse model of HCC was established and treated with CD206-overexpressing adenovirus by tail vein injection or CD206 antibody C068C2 by intratumoral injection. The hepatocarcinoma-bearing mice were divided into four groups (IgG+ tail vein adenovirus group, IgG group, C068C2+ tail vein adenovirus group and C068C2 group) to observe the changes in tumour weight and volume with different expression levels of CD206. The proportion of M2-type tumour-associated macrophages (TAMs) was detected by flow cytometry and immunofluorescence. The apoptosis of tumour cells was detected using terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) staining, and inflammatory factors in serum and tissues were detected using the ENZYME-LINKED IMMUNOSORBENT ASSAY. Results Compared with the mice with low CD206 expression, the hepatocarcinoma-bearing mice with high CD206 expression in HCC exhibited faster tumour growth and more aggressive progression. Flow cytometry and immunofluorescence staining revealed that the expression level of CD206-positive M2-type TAMs was highest in the IgG + adenovirus group and lowest in the C068C2 group (p

INTRODUCTION: Recent breast cancer research has focused on tumour microenvironment (TME). Tumour-associated macrophages (TAMs) are the key players in TME as they provide pro-tumorigenic milieu for tumour progression and metastasis. These macrophages are primarily regulated by colony-stimulating factor-1 (CSF-1) secreted by breast cancer cells. This study investigated the association of localization of TAMs infiltration within breast carcinoma and CSF-1 expression by cancer cells with the pathological prognostic parameters. MATERIALS AND METHODS: TAMs were assessed in 128 cases of invasive breast carcinoma by CD163 immunohistochemical expression. The median TAM density in both the tumour nest and tumour stroma was utilized to classify TAMs into categories of low and high infiltration. The cancer cells were immunostained with anti-CSF-1 antibody and the staining intensity was evaluated as low or high expression. RESULTS: High nest and stromal TAMs were associated with higher tumour grades (p=0.005 and p=0.0001, respectively) whereas only high stromal TAMs showed significant association with negative oestrogen and progesterone receptors status (p=0.001 and 0.001, respectively); and triple-negative subtype (p=0.002). High CSF-1 expression was significantly associated with high stromal TAMs (p=0.031). High CSF-1 expression was associated with tumour grade and positive HER2 status (p=0.008 and 0.007, respectively). CONCLUSION: TAMs in tumour nest and stroma showed varying degrees of association with the clinicopathological parameters. High CSF-1 expression was associated with unfavourable prognostic parameters. Therefore, the evaluation of TAMs and CSF-1 expressions could potentially serve as prognostic markers and cellular targets for novel treatment modality in invasive breast cancers. [ABSTRACT FROM AUTHOR]

AbstractEliciting tumour microenvironment (TME) activation in triple-negative breast cancer (TNBC) is crucial for effective anti-tumour therapies. The aim of this study is to employ pharmaceutical approaches to precisely deliver Ganoderma polysaccharide (GPS) to tumour sites, thereby enhancing TME activation. We first established a direct link between the accumulation of GPS within tumours and its efficacy in the TME activation. Building upon this insight, we then engineered a mannose/hyaluronic acid dual-coated GPS-loaded superparamagnetic iron oxide nanocomplex (Man/HA/GPS-SPIONs) with a particle size of 33.8 ± 1.6 nm and a zeta potential of −22.4 ± 3.5 mV, capable of precise tumour accumulation through magnet-assisted targeting and internalisation by tumour-associated macrophages (TAMs) and tumour cells, facilitated by dual ligand modification. In vitro, Man/HA/GPS-SPIONs effectively induced M1 polarisation of macrophages (CD86+ cells: 38.6 ± 2.8%), curbed 4T1 cell proliferation (viability: 47.3 ± 2.9%) and heightened Th1 cytokine release. Significantly, in vivo, Man/HA/GPS-SPIONs notably suppressed tumour growth (tumour index: 0.048 ± 0.005), fostered M1 polarisation of TAMs (CD45+F4/80+CD86+ cells: 26.1 ± 7.2%), consequently bolstering intratumoural T cytotoxic cells. This enhancement was intricately tied to the efficient co-delivery of GPS and iron ions to the tumours, made possible by the Man/HA/GPS-SPIONs delivery system. The synergistic effects with paclitaxel (PTX, inhibition rate: 61.2 ± 4.3%) and PD-1 inhibitors (inhibition rate: 69.8 ± 7.6%) underscored the translational potential of this approach. By harnessing a well-conceived iron-based drug delivery strategy, this study amplifies the tumour immune modulatory potential of natural polysaccharides, offering insightful guidance for interventions in the TME and synergistic therapies. [ABSTRACT FROM AUTHOR]

Objective: This study aims to investigate the effect of CD206 on the progression of hepatocellular carcinoma (HCC) and the regulation of the tumour immune microenvironment. Methods: A subcutaneous mouse model of HCC was established and treated with CD206-overexpressing adenovirus by tail vein injection or CD206 antibody C068C2 by intratumoral injection. The hepatocarcinoma-bearing mice were divided into four groups (IgG+ tail vein adenovirus group, IgG group, C068C2+ tail vein adenovirus group and C068C2 group) to observe the changes in tumour weight and volume with different expression levels of CD206. The proportion of M2-type tumour-associated macrophages (TAMs) was detected by flow cytometry and immunofluorescence. The apoptosis of tumour cells was detected using terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) staining, and inflammatory factors in serum and tissues were detected using the ENZYME-LINKED IMMUNOSORBENT ASSAY. Results: Compared with the mice with low CD206 expression, the hepatocarcinoma-bearing mice with high CD206 expression in HCC exhibited faster tumour growth and more aggressive progression. Flow cytometry and immunofluorescence staining revealed that the expression level of CD206-positive M2-type TAMs was highest in the IgG + adenovirus group and lowest in the C068C2 group (p < 0.001). Compared with the IgG + adenovirus group, the proportion of TUNEL-positive cells in tumour cells was significantly reduced in the C068C2 group. The IgG + adenovirus group had the highest concentrations of transforming growth factor-β (TGF-β) and interleukin 6 (IL-6) in both serum and tumour tissues. Conclusion: The overexpression of CD206 accelerates the progression of HCC and changes the tumour immune microenvironment. The high expression of CD206 in HCC increases the M2-type polarisation of TAMs and induces the expression of both TGF-β and IL-6 in tumour tissues and serum, thereby promoting HCC progression. [ABSTRACT FROM AUTHOR]

The deregulation of monounsaturated, polyunsaturated, and saturated fatty acids (MUFAs, PUFAs, SFAs) from de novo synthesis and hypoxia are central metabolic features of breast tumour. Early response markers for neoadjuvant chemotherapy (NACT) are critical for stratified treatment for patients with breast cancer, and restoration of lipid metabolism and normoxia might precede observable structural change. In this study, we hypothesised that peri-tumoural lipid composition and hypoxia might be predictive and early response markers in patients with breast cancer undergoing NACT. Female patients with breast cancer were scanned on a 3T clinical MRI scanner at baseline and Cycle1, with acquisition of lipid composition maps of MUFAs, PUFAs, and SFAs, and hypoxia maps of effective transverse relaxation rate R2*. The percentage change in lipid composition and hypoxia at Cycle1 was calculated with reference to baseline. Tumour-associated macrophages were analysed based on immunostaining of CD163 from biopsy and resection, with the percentage change in the resected tumour calculated across the entire NACT. We found no significant difference in lipid composition and R2* between good and poor responders at baseline and Cycle1; however, the correlation between the percentage change in MUFAs and PUFAs against CD163 suggested the modulation in lipids with altered immune response might support the development of targeted therapies. [ABSTRACT FROM AUTHOR]

Abstract Objective To assess the infiltration characteristics of tumour-associated macrophages (TAMs) in buccal mucosa carcinoma (BMC) and the correlation of these features with clinicopathological factors. Materials and methods Immunohistochemistry was used to detect the expression of TAM-related markers (CD68, CD163, CD206), CD8+ T cell markers, PD-L1, and epidermal growth factor receptor (EGFR) in 46 patients with mucosal cancer after radical surgery. In addition, the correlation between TAM infiltration and clinical characteristics, PD-L1 expression, and EGFR expression was analysed. Results A high infiltration level of M2-polarized (CD206+) TAMs and M2-polarized (CD163+) TAMs was more common in stage T3–T4, N+, III–IV patients than in other patient groups (P

Abstract Macrophages infiltrating tumour tissues or residing in the microenvironment of solid tumours are known as tumour-associated macrophages (TAMs). These specialized immune cells play crucial roles in tumour growth, angiogenesis, immune regulation, metastasis, and chemoresistance. TAMs encompass various subpopulations, primarily classified into M1 and M2 subtypes based on their differentiation and activities. M1 macrophages, characterized by a pro-inflammatory phenotype, exert anti-tumoural effects, while M2 macrophages, with an anti-inflammatory phenotype, function as protumoural regulators. These highly versatile cells respond to stimuli from tumour cells and other constituents within the tumour microenvironment (TME), such as growth factors, cytokines, chemokines, and enzymes. These stimuli induce their polarization towards one phenotype or another, leading to complex interactions with TME components and influencing both pro-tumour and anti-tumour processes. This review comprehensively and deeply covers the literature on macrophages, their origin and function as well as the intricate interplay between macrophages and the TME, influencing the dual nature of TAMs in promoting both pro- and anti-tumour processes. Moreover, the review delves into the primary pathways implicated in macrophage polarization, examining the diverse stimuli that regulate this process. These stimuli play a crucial role in shaping the phenotype and functions of macrophages. In addition, the advantages and limitations of current macrophage based clinical interventions are reviewed, including enhancing TAM phagocytosis, inducing TAM exhaustion, inhibiting TAM recruitment, and polarizing TAMs towards an M1-like phenotype. In conclusion, while the treatment strategies targeting macrophages in precision medicine show promise, overcoming several obstacles is still necessary to achieve an accessible and efficient immunotherapy.

Objective: To assess the infiltration characteristics of tumour-associated macrophages (TAMs) in buccal mucosa carcinoma (BMC) and the correlation of these features with clinicopathological factors. Materials and methods: Immunohistochemistry was used to detect the expression of TAM-related markers (CD68, CD163, CD206), CD8+ T cell markers, PD-L1, and epidermal growth factor receptor (EGFR) in 46 patients with mucosal cancer after radical surgery. In addition, the correlation between TAM infiltration and clinical characteristics, PD-L1 expression, and EGFR expression was analysed. Results: A high infiltration level of M2-polarized (CD206+) TAMs and M2-polarized (CD163+) TAMs was more common in stage T3–T4, N+, III–IV patients than in other patient groups (P < 0.05). The infiltration degree of M2-polarized (CD68+) TAMs was positively correlated with the PD-L1 TPS (P = 0.0331). The infiltration level of M2-polarized (CD206+) TAMs was higher in the EGFR high expression group than in the EGFR low expression group (P = 0.040). Conclusion: High infiltration of M2-polarized TAMs is highly associated with advanced disease stage and higher expression of PD-L1 and EGFR in BMCs, suggesting that M2-polarized TAMs infiltration can serve as a potential therapeutic target. [ABSTRACT FROM AUTHOR]

Macrophages play essential roles in maintaining tissue homeostasis and immune defence. However, their extensive infiltration into tumours has been linked to adverse outcomes in multiple human cancers. Within the tumour microenvironment (TME), tumour-associated macrophages (TAMs) promote tumour growth and metastasis, making them prime targets for cancer immunotherapy. Recent single-cell analysis suggest that proliferating TAMs accumulate in human cancers, yet their origins and differentiation pathways remain uncertain. Here, we show that a subpopulation of CD163+ TAMs proliferates in situ within the TME of melanoma, lung cancer, and breast cancer. Consistent with their potential role in suppressing anti-tumour activities of T cells, CD163+ TAMs express a range of potent immunosuppressive molecules, including PD-L1, PD-L2, IL-10, and TGF-β. Other phenotypic markers strongly suggested that these cells originate from CD14+ CCR2+ monocytes, a cell population believed to have minimal capacity for proliferation. However, we demonstrate in vitro that certain myelopoietic cytokines commonly available within the TME induce robust proliferation of human monocytes, especially the combination of interleukin 3 (IL-3) and Macrophage Colony-Stimulating Factor 1 (M-CSF). Monocytic cells cultured with these cytokines efficiently modulate T cell proliferation, and their molecular phenotype recapitulates that of CD163+ TAMs. IL-3-driven proliferation of monocytic cells can be completely blocked by IL-4, associated with the induction of CDKN1A, alongside the upregulation of transcription factors linked to dendritic cell function, such as BATF3 and IRF4. Taken together, our work suggests several novel therapeutic routes to reducing immunosuppressive TAMs in human tumours, from blocking chemokinemediated recruitment of monocytes to blocking their proliferation. [ABSTRACT FROM AUTHOR]

Macrophages infiltrating tumour tissues or residing in the microenvironment of solid tumours are known as tumour-associated macrophages (TAMs). These specialized immune cells play crucial roles in tumour growth, angiogenesis, immune regulation, metastasis, and chemoresistance. TAMs encompass various subpopulations, primarily classified into M1 and M2 subtypes based on their differentiation and activities. M1 macrophages, characterized by a pro-inflammatory phenotype, exert anti-tumoural effects, while M2 macrophages, with an anti-inflammatory phenotype, function as protumoural regulators. These highly versatile cells respond to stimuli from tumour cells and other constituents within the tumour microenvironment (TME), such as growth factors, cytokines, chemokines, and enzymes. These stimuli induce their polarization towards one phenotype or another, leading to complex interactions with TME components and influencing both pro-tumour and anti-tumour processes. This review comprehensively and deeply covers the literature on macrophages, their origin and function as well as the intricate interplay between macrophages and the TME, influencing the dual nature of TAMs in promoting both pro- and anti-tumour processes. Moreover, the review delves into the primary pathways implicated in macrophage polarization, examining the diverse stimuli that regulate this process. These stimuli play a crucial role in shaping the phenotype and functions of macrophages. In addition, the advantages and limitations of current macrophage based clinical interventions are reviewed, including enhancing TAM phagocytosis, inducing TAM exhaustion, inhibiting TAM recruitment, and polarizing TAMs towards an M1-like phenotype. In conclusion, while the treatment strategies targeting macrophages in precision medicine show promise, overcoming several obstacles is still necessary to achieve an accessible and efficient immunotherapy. [ABSTRACT FROM AUTHOR]

Immunotherapy is a promising and safer alternative to conventional cancer therapies. It involves adaptive T-cell therapy, cancer vaccines, monoclonal antibodies, immune checkpoint blockade (ICB), and chimeric antigen receptor (CAR) based therapies. However, most of these modalities encounter restrictions in solid tumours owing to a dense, highly hypoxic and immune-suppressive microenvironment as well as the heterogeneity of tumour antigens. The elevated intra-tumoural pressure and mutational rates within fast-growing solid tumours present challenges in efficient drug targeting and delivery. The tumour microenvironment is a dynamic niche infiltrated by a variety of immune cells, most of which are macrophages. Since they form a part of the innate immune system, targeting macrophages has become a plausible immunotherapeutic approach. In this review, we discuss several versatile approaches (both at pre-clinical and clinical stages) such as the direct killing of tumour-associated macrophages, reprogramming pro-tumour macrophages to anti-tumour phenotypes, inhibition of macrophage recruitment into the tumour microenvironment, novel CAR macrophages, and genetically engineered macrophages that have been devised thus far. These strategies comprise a strong and adaptable macrophage-toolkit in the ongoing fight against cancer and by understanding their significance, we may unlock the full potential of these immune cells in cancer therapy. [ABSTRACT FROM AUTHOR]

Glioma is the most prevalent malignant brain tumour. Currently, reshaping its tumour microenvironment has emerged as an appealing strategy to enhance therapeutic efficacy. As the largest group of transmembrane transport proteins, solute carrier proteins (SLCs) are responsible for the transmembrane transport of various metabolites and ions. They play a crucial role in regulating the metabolism and functions of malignant cells and immune cells within the tumour microenvironment, making them a promising target in cancer therapy. Through multidimensional data analysis and experimental validation, we investigated the genetic landscape of SLCs in glioma. We established a classification system comprising 7‐SLCs to predict the prognosis of glioma patients and their potential responses to immunotherapy and chemotherapy. Our findings unveiled specific SLC expression patterns and their correlation with the immune‐suppressive microenvironment and metabolic status. The 7‐SLC classification system was validated in distinguishing subgroups within the microenvironment, specifically identifying subsets involving malignant cells and tumour‐associated macrophages. Furthermore, the orphan protein SLC43A3, a core member of the 7‐SLC classification system, was identified as a key facilitator of tumour cell proliferation and migration, suggesting its potential as a novel target for cancer therapy. [ABSTRACT FROM AUTHOR]

Tumour immune microenvironment (TIME) plays an indispensable role in tumour progression, and tumour‐associated macrophages (TAMs) are the most abundant immune cells in TIME. Non‐apoptotic regulated cell death (RCD) can avoid the influence of tumour apoptosis resistance on anti‐tumour immune response. Specifically, autophagy, ferroptosis, pyroptosis and necroptosis mediate the crosstalk between TAMs and tumour cells in TIME, thus reprogram TIME and affect the progress of tumour. In addition, although some achievements have been made in immune checkpoint inhibitors (ICIs), there is still defect that ICIs are only effective for some people because non‐apoptotic RCD can bypass the apoptosis resistance of tumour. As a result, ICIs combined with targeting non‐apoptotic RCD may be a promising solution. In this paper, the basic molecular mechanism of non‐apoptotic RCD, the way in which non‐apoptotic RCD mediates crosstalk between TAMs and tumour cells to reprogram TIME, and the latest research progress in targeting non‐apoptotic RCD and ICIs are reviewed. [ABSTRACT FROM AUTHOR]

Aims: The neutrophil–lymphocyte ratio (NLR) is a systemic reflection of cancer‐associated inflammation and a prognostic marker for breast cancer. For the local tumour microenvironment, tumour‐infiltrating lymphocytes (TILs) and tumour‐associated macrophages (TAMs) are also highly correlated with breast cancer survival. This study aimed to explore the relationship between the circulating and local immune microenvironment, and to further delineate the prognostic role of NLR in breast cancer patients receiving neoadjuvant chemotherapy (NAC). Methods: A cohort of breast cancer patients receiving NAC with subsequent surgery was retrieved. Clinical data were reviewed. Histological slides and CD8 immunohistochemistry from biopsy (pre‐chemotherapy) and excision (postchemotherapy) specimens were assessed for TILs and TAMs. Results: A total of 146 patients were included. There was a significant positive correlation between pre‐ and postsurgery NLR at a cut‐off of 2.6 (median pre‐chemotherapy NLR) (P < 0.001). NLR pre‐chemotherapy was associated positively with necrosis on biopsy (P = 0.027) and excision (P = 0.021) and TAMs on excision (P = 0.049). NLR 1 year postsurgery was associated with high tumour stage (P = 0.050) and low histological grade (P = 0.008). TIL count was lower in NLR‐high cases at almost all time‐points by histological assessment and CD8 immunostaining (P < 0.050). In multivariate analysis, postsurgery NLR is an independent predictor for overall survival [OS; hazard ratio (HR) = 9.524, P < 0.001], breast cancer‐specific survival (BCSS) (HR = 10.059, P = 0.001) and disease‐free survival (DFS; HR = 2.824, P = 0.016). Conclusions: The association between NLR with tumour necrosis, TAMs and TILs illustrates an interaction between the circulating and local immune microenvironment. Late NLR is a strong indicator of outcome and may be useful for prognostication and disease monitoring. [ABSTRACT FROM AUTHOR]

Tumour-associated macrophages (TAMs) express a continuum of phenotypes ranging from an anti-tumoural M1-like phenotype to a pro-tumoural M2-like phenotype. During cancer progression, TAMs may shift to a more M2-like polarisation state, but the role of TAMs in CRC metastases is unclear. We conducted a comprehensive spatial and prognostic analysis of TAMs in CRC pulmonary metastases and corresponding primary tumours using multiplexed immunohistochemistry and machine learning-based image analysis. We obtained data from 106 resected pulmonary metastases and 74 corresponding primary tumours. TAMs in the resected pulmonary metastases were located closer to the cancer cells and presented a more M2-like polarised state in comparison to the primary tumours. Higher stromal M2-like macrophage densities in the invasive margin of pulmonary metastases were associated with worse 5-year overall survival (HR 3.19, 95% CI 1.35–7.55, p = 0.008). The results of this study highlight the value of multiplexed analysis of macrophage polarisation in cancer metastases and might have clinical implications in future cancer therapy. [ABSTRACT FROM AUTHOR]

Background: Metastasis accounts for the majority of deaths among patients with colorectal cancer (CRC). Here, the regulatory role of tumour‐associated macrophages (TAMs) in CRC metastasis was explored. Methods: Immunohistochemical (IHC) analysis of the TAM biomarker CD163 was conducted to evaluate TAM infiltration in CRC. Transwell assays and an ectopic liver metastasis model were established to evaluate the metastatic ability of tumour cells. RNA sequencing (RNA‐seq) and liquid chromatography‒mass spectrometry (LC‒MS) were applied to identify the differentially expressed genes and proteins in CRC cells and in TAM‐derived extracellular vesicles (EVs). Cholesterol content measurement, a membrane fluidity assay and filipin staining were performed to evaluate cholesterol efflux in CRC cells. Results: Our results showed that TAM infiltration is positively correlated with CRC metastasis. TAMs can facilitate the migration and invasion of MC‐38 and CT‐26 cells via EVs. According to the RNA‐seq data, TAM‐EVs increase cholesterol efflux and enhance membrane fluidity in CRC cells by regulating ABCA1 expression, thus affecting the motility of CRC cells. Mechanistically, DOCK7 packaged in TAM‐EVs can activate RAC1 in CRC cells and subsequently upregulate ABCA1 expression by phosphorylating AKT and FOXO1. Moreover, IHC analysis of ABCA1 in patients with liver‐metastatic CRC indicated that ABCA1 expression is significantly greater in metastatic liver nodules than in primary CRC tumours. Conclusions: Overall, our findings suggest that DOCK7 delivered via TAM‐EVs could regulate cholesterol metabolism in CRC cells and CRC cell metastasis through the RAC1/AKT/FOXO1/ABCA1 axis. DOCK7 could thus be a new therapeutic target for controlling CRC metastasis. [ABSTRACT FROM AUTHOR]

Background and aims: In gastric cancer, the response rate of programmed cell death protein‐1 (PD‐1) inhibitor is far from satisfactory, indicating additional nonredundant pathways might hamper antitumour immunity. V‐domain immunoglobulin suppressor of T‐cell activation (VISTA) has been reported in several malignancies as a novel immune‐checkpoint. Nevertheless, the role of VISTA in gastric cancer still remains obscure. Our purpose is to explore the clinical significance and potential mechanism of VISTA in affecting gastric cancer patients' survival and immunotherapeutic responsiveness. Methods: Our study recruited eight independent cohorts with a total of 1403 gastric cancer patients. Immunohistochemistry, multiplex immunofluorescence, flow cytometry or intracellular flow cytometry, quantitative polymerase chain reaction, western blotting, fluorescence‐activated cell sorting, magnetic‐activated cell sorting, smart‐seq2, in vitro cell co‐culture and ex vivo tumour inhibition assays were applied to investigate the clinical significance and potential mechanism of VISTA in gastric cancer. Results: VISTA was predominantly expressed on tumour‐associated macrophages (TAMs), and indicated poor clinical outcomes and inferior immunotherapeutic responsiveness. VISTA+ TAMs showed a mixed phenotype. Co‐culture of TAMs and CD8+ T cells indicated that VISTA+ TAMs attenuated effective function of CD8+ T cells. Blockade of VISTA reprogrammed TAMs to a proinflammatory phenotype, reactivated CD8+ T cells and promoted apoptosis of tumour cells. Moreover, blockade of VISTA could also enhance the efficacy of PD‐1 inhibitor, suggesting that blockade of VISTA might synergise with PD‐1 inhibitor in gastric cancer. Conclusions: Our data revealed that VISTA was an immune‐checkpoint associated with immunotherapeutic resistance. Blockade of VISTA reprogrammed TAMs, promoted T‐cell‐mediated antitumour immunity, and enhanced efficacy of PD‐1 inhibitor, which might have implications in the treatment of gastric cancer. [ABSTRACT FROM AUTHOR]

Melanoma is considered one of the most aggressive types of cancer due to its high propensy for metastasis, which significantly reduces survival chances when detected late. Moreover, melanoma exhibits strong immunogenic characteristics, complicating its treatment, increasing the need to develop more effective techniques of therapy. In the field of oncology, mathematical modeling enables the analysis and distinction of the various mechanisms involved in tumor progression. This allows the analysis of numer- ous scenarios, which would be impractical experimentally. The main objective of this study is to develop a mathematical model that describes melanoma dynamics in the presence of Tumor-Associated Macrophages (TAM) and Chimeric Antigen Receptor (CAR) T-cell immunotherapy. The goal is to assess why this therapy often falls short in erradicating solid tumors like melanoma and to understand the role of TAM in this failure. This research encompasses stability analysis of the equilibrium points of the model, sensitivity analysis of its parameters, and the examination of numerical solutions. Our results showed that immunosuppression caused by TAM has a negative impact on the effectiveness of the dose and varying the cytotoxicity of CAR T-cells together with dose. Adjusting CAR T-cell cytotoxicity and treatment dosage may enhance tumor control, with the initial tumor burden playing a crucial role in treatment effectiveness.

Background: Oesophageal squamous cell carcinoma (ESCC) is a leading cause of cancer-related deaths worldwide because existing treatments are often insufficient. Therefore, new, reliable biomarkers must be identified. CTSL overexpression is closely associated with tumour progression and poor prognosis. However, the role and mechanism of CTSL as an oncogene in ESCC remain unclear. Methods: Genome-wide association study (GWAS) data were used for Mendelian randomization analysis to investigate the possible relationships between CTSL and ESCC. The correlation between CTSL expression and prognosis was analysed using GEO, TCGA, and GEPIA data. We compared CTSL expression among the cell types using single-cell sequencing. Correlations between CTSL and the tumour microenvironment, immune cell infiltration, tumour mutational load, immunological checkpoints, and treatment sensitivity in patients with ESCC were investigated. Finally, using mouse models and cellular investigations, we assessed the effects of CTSL on the growth, apoptosis, and metastasis of ESCC tumour cells. Results: CTSL was overexpressed in ESCC and correlated with prognosis. We also discovered its close association with cell immunity, especially with tumour-associated macrophages and immune checkpoints in the tumour microenvironment. CTSL may play a key role in ESCC development by affecting M2 macrophage polarisation. CTSL and the M2 macrophage marker genes showed significant positive correlations. Mendelian randomization analysis confirmed a relationship between CTSL and ESCC. Finally, our in vitro and in vivo experiments demonstrated that CTSL promoted the proliferation and migration of ESCC cells, validating our bioinformatic analysis. Conclusion: CTSL emerged as a crucial gene in ESCC that influences patient prognosis and immunity, particularly in association with M2 macrophages. Therefore, targeting or modulating CTSL levels may provide new therapeutic strategies for patients with ESCC.

Abstract Background and aims In gastric cancer, the response rate of programmed cell death protein‐1 (PD‐1) inhibitor is far from satisfactory, indicating additional nonredundant pathways might hamper antitumour immunity. V‐domain immunoglobulin suppressor of T‐cell activation (VISTA) has been reported in several malignancies as a novel immune‐checkpoint. Nevertheless, the role of VISTA in gastric cancer still remains obscure. Our purpose is to explore the clinical significance and potential mechanism of VISTA in affecting gastric cancer patients’ survival and immunotherapeutic responsiveness. Methods Our study recruited eight independent cohorts with a total of 1403 gastric cancer patients. Immunohistochemistry, multiplex immunofluorescence, flow cytometry or intracellular flow cytometry, quantitative polymerase chain reaction, western blotting, fluorescence‐activated cell sorting, magnetic‐activated cell sorting, smart‐seq2, in vitro cell co‐culture and ex vivo tumour inhibition assays were applied to investigate the clinical significance and potential mechanism of VISTA in gastric cancer. Results VISTA was predominantly expressed on tumour‐associated macrophages (TAMs), and indicated poor clinical outcomes and inferior immunotherapeutic responsiveness. VISTA+ TAMs showed a mixed phenotype. Co‐culture of TAMs and CD8+ T cells indicated that VISTA+ TAMs attenuated effective function of CD8+ T cells. Blockade of VISTA reprogrammed TAMs to a proinflammatory phenotype, reactivated CD8+ T cells and promoted apoptosis of tumour cells. Moreover, blockade of VISTA could also enhance the efficacy of PD‐1 inhibitor, suggesting that blockade of VISTA might synergise with PD‐1 inhibitor in gastric cancer. Conclusions Our data revealed that VISTA was an immune‐checkpoint associated with immunotherapeutic resistance. Blockade of VISTA reprogrammed TAMs, promoted T‐cell‐mediated antitumour immunity, and enhanced efficacy of PD‐1 inhibitor, which might have implications in the treatment of gastric cancer.

Abstract Background Metastasis accounts for the majority of deaths among patients with colorectal cancer (CRC). Here, the regulatory role of tumour‐associated macrophages (TAMs) in CRC metastasis was explored. Methods Immunohistochemical (IHC) analysis of the TAM biomarker CD163 was conducted to evaluate TAM infiltration in CRC. Transwell assays and an ectopic liver metastasis model were established to evaluate the metastatic ability of tumour cells. RNA sequencing (RNA‐seq) and liquid chromatography‒mass spectrometry (LC‒MS) were applied to identify the differentially expressed genes and proteins in CRC cells and in TAM‐derived extracellular vesicles (EVs). Cholesterol content measurement, a membrane fluidity assay and filipin staining were performed to evaluate cholesterol efflux in CRC cells. Results Our results showed that TAM infiltration is positively correlated with CRC metastasis. TAMs can facilitate the migration and invasion of MC‐38 and CT‐26 cells via EVs. According to the RNA‐seq data, TAM‐EVs increase cholesterol efflux and enhance membrane fluidity in CRC cells by regulating ABCA1 expression, thus affecting the motility of CRC cells. Mechanistically, DOCK7 packaged in TAM‐EVs can activate RAC1 in CRC cells and subsequently upregulate ABCA1 expression by phosphorylating AKT and FOXO1. Moreover, IHC analysis of ABCA1 in patients with liver‐metastatic CRC indicated that ABCA1 expression is significantly greater in metastatic liver nodules than in primary CRC tumours. Conclusions Overall, our findings suggest that DOCK7 delivered via TAM‐EVs could regulate cholesterol metabolism in CRC cells and CRC cell metastasis through the RAC1/AKT/FOXO1/ABCA1 axis. DOCK7 could thus be a new therapeutic target for controlling CRC metastasis.

As one of the deadliest cancers of the gastrointestinal tract, there has been limited improvement in long-term survival rates for gastric cancer (GC) in recent decades. The poor prognosis is attributed to difficulties in early detection, minimal opportunity for radical resection and resistance to chemotherapy and radiation. Macrophages are among the most abundant infiltrating immune cells in the GC stroma. These cells engage in crosstalk with cancer cells, adipocytes and other stromal cells to regulate metabolic, inflammatory and immune status, generating an immunosuppressive tumour microenvironment (TME) and ultimately promoting tumour initiation and progression. In this review, we summarise recent advances in our understanding of the origin of macrophages and their types and polarisation in cancer and provide an overview of the role of macrophages in GC carcinogenesis and development and their interaction with the GC immune microenvironment and flora. In addition, we explore the role of macrophages in preclinical and clinical trials on drug resistance and in treatment of GC to assess their potential therapeutic value in this disease. [ABSTRACT FROM AUTHOR]

Single cell transcriptomics and spatial profiling have revealed that tumor-associated macrophages comprise multiple subtypes (molecularly), and harbor different functions within the tumor microenvironment. This can depend on their spatial localization, tumor type, and disease stage. Six major macrophage clusters might exist in tumors including: inflammatory macrophages, angiogenic macrophages, immunoregulatory macrophages, interferon-mediated regulatory macrophages, immunostimulatory macrophages, and a CD169+ macrophage cluster whose distinct function remains an active area of investigation. Putative therapies aiming to specifically target these functional classes of macrophages are actively being tested preclinically and might begin to show clinical impact. The aim is to block the immunosuppressive, inflammatory, or angiogenic activities of these macrophages. A deeper understanding of the molecular, spatial, and functional heterogeneity of tumor-associated macrophages, within the local TME has driven the development of a new class of therapies directed against such diverse functional subsets. This is leading to impressive antitumor responses in preclinical models and is now being tested in patients when given as monotherapies or in combination with targeted and T cell-based immunotherapies. Macrophages represent a key component of the tumor microenvironment (TME) and are largely associated with poor prognosis. Therapeutic targeting of macrophages has historically focused on inhibiting their recruitment or reprogramming their phenotype from a protumor (M2-like) to an antitumor (M1-like) one. Unfortunately, this approach has not provided clinical breakthroughs that have changed practice. Emerging studies utilizing single-cell RNA-sequencing (scRNA-seq) and spatial transcriptomics have improved our understanding of the ontogeny, phenotype, and functional plasticity of macrophages. Overlaying the wealth of current information regarding macrophage molecular subtypes and functions has also identified novel therapeutic vulnerabilities that might drive better control of tumor-associated macrophages (TAMs). Here, we discuss the functional profiling of macrophages and provide an update of novel macrophage-targeted therapies in development. [ABSTRACT FROM AUTHOR]

Simple Summary: Approximately one in seven patients with classical Hodgkin lymphoma have refractory disease or relapse after standard front line chemotherapy. Prognostic biomarkers could help determine candidates for more effective treatment. The latest advances in research techniques have contributed to new insights in understanding the tumour microenvironment of Hodgkin lymphoma and the crucial role it plays in the disease course and response to treatment. Many new potential biomarkers are being explored in this setting and the results of these studies, as well as diagnostic methodologies, are presented in this review. Classical Hodgkin lymphoma (cHL) accounts for 0.4% of all new cancer cases globally. Despite high cure rates with standard treatment, approximately 15% of patients still experience relapsed or refractory (RR) disease, and many of these eventually die from lymphoma-related causes. Exciting new targeted agents such as anti-PD-1 agents and brentuximab vedotin have changed the therapeutic paradigm beyond chemotherapy and radiotherapy alone. Advances in understanding of the molecular biology are providing insights in the context of novel therapies. The signature histology of cHL requires the presence of scant malignant Hodgkin Reed–Sternberg cells (HRSCs) surrounded by a complex immune-rich tumour microenvironment (TME). The TME cellular composition strongly influences outcomes, yet knowledge of the precise characteristics of TME cells and their interactions with HRSCs is evolving. Novel high-throughput technologies and single-cell sequencing allow deeper analyses of the TME and mechanisms elicited by HRSCs to propagate growth and avoid immune response. In this review, we explore the evolution of knowledge on the prognostic role of immune cells within the TME and provide an up-to-date overview of emerging prognostic data on cHL from new technologies that are starting to unwind the complexity of the cHL TME and provide translational insights into how to improve therapy in the clinic. [ABSTRACT FROM AUTHOR]

Abstract Tumour-associated macrophages (TAMs) are crucial components of the tumour microenvironment and play a significant role in tumour development and drug resistance by creating an immunosuppressive microenvironment. Macrophages are essential components of both the innate and adaptive immune systems and contribute to pathogen resistance and the regulation of organism homeostasis. Macrophage function and polarization are closely linked to altered metabolism. Generally, M1 macrophages rely primarily on aerobic glycolysis, whereas M2 macrophages depend on oxidative metabolism. Metabolic studies have revealed that the metabolic signature of TAMs and metabolites in the tumour microenvironment regulate the function and polarization of TAMs. However, the precise effects of metabolic reprogramming on tumours and TAMs remain incompletely understood. In this review, we discuss the impact of metabolic pathways on macrophage function and polarization as well as potential strategies for reprogramming macrophage metabolism in cancer treatment.

Simple Summary: Hepatocellular carcinoma (HCC) is a highly lethal disease with an increasing incidence. Despite the advancements in diagnosis and recent therapeutic options, improving the prognosis of HCC patients remains challenging. One of the reasons of the unsatisfactory outcome of patients with HCC is the complex tumour microenvironment (TME), which is composed of immune and stromal cells, limiting effective treatments. Recent research has highlighted the importance of macrophages in the development and progression of HCC, opening new possibilities for therapy. This review focuses on the heterogeneity of tumour-associated macrophages (TAMs) in HCC, the mechanisms through which HCC tumour cells polarize macrophages, and the therapeutic targets that are currently being tested to explore novel therapies that can improve the prognosis and quality of life of HCC patients. Hepatocellular carcinoma (HCC) is a prevalent and aggressive cancer that comprises a complex tumour microenvironment (TME). Tumour-associated macrophages (TAMs) are one of the most abundant immune cells present in the TME, and play a key role both in the development and in the progression of HCC. Thus, TAM-based immunotherapy has been presented as a promising strategy to complement the currently available therapies for HCC treatment. Among the novel approaches focusing on TAMs, reprogramming their functional state has emerged as a promising option for targeting TAMs as an immunotherapy in combination with the currently available treatment options. Nevertheless, a further understanding of the immunobiology of TAMs is still required. This review synthesizes current insights into the heterogeneous nature of TAMs in HCC and describes the mechanisms behind their pro-tumoural polarization focusing the attention on their interaction with HCC cells. Furthermore, this review underscores the potential involvement of TAMs' reprogramming in HCC therapy and highlights the urgency of advancing our understanding of these cells within the dynamic landscape of HCC. [ABSTRACT FROM AUTHOR]

Dachshund family transcription factor 1 (DACH1) has been shown to exhibit a tumour‐suppressive role in a number of human cancers. However, the role of DACH1 in hypopharyngeal squamous cell carcinoma (HPSCC) and its function in the tumour microenvironment (TME) are still not clear. Crosstalk between cancer cells and tumour‐associated macrophages (TAMs) mediates tumour progression in HPSCC. The expression of DACH1, CD86 and CD163 was detected in 71 matched HPSCC–non‐cancerous tissue pairs using quantitative real‐time polymerase chain reaction and IHC analysis. Cell proliferation, migration and invasion were monitored by colony formation, Transwell and EdU incorporation assays. ChIP‐qPCR and dual‐luciferase reporter assays were applied to verify the targeting relationships between DACH1 and IGF‐1. Stably transfected HPSCC cells were co‐cultured with MΦ macrophages to assess macrophage polarization and secretory signals. DACH1 was decreased in HPSCC tissues and was indicative of a poor prognosis for HPSCC patients. Decreased DACH1 expression in HPSCC was associated with fewer CD86+ TAMs and more CD163+ TAMs. Knockdown of DACH1 inhibited the proliferation, migration and invasion of FaDu cells via Akt/NF‐κB/MMP2/9 signalling. Additionally, DACH1 was found to directly bind to the promoter region of IGF‐1 to downregulate the secretion of IGF‐1, which inhibited TAMs polarization through the IGF‐1R/JAK1/STAT3 axis. Furthermore, in nude mice, the effects of DACH1 inhibition on tumour progression and M2‐like TAMs polarization were confirmed. These findings suggest that IGF‐1 is a critical downstream effector of DACH1 that suppresses cell migration and invasion and inhibits TAMs polarization. DACH1 could be a therapeutic target and prognostic marker for HPSCC. [ABSTRACT FROM AUTHOR]

Numerous studies have shown the positive correlation between high levels of Pi and tumour progression. A critical goal of macrophage‐based cancer therapeutics is to reduce anti‐inflammatory macrophages (M2) and increase proinflammatory antitumour macrophages (M1). This study aimed to investigate the relationship between macrophage polarization and low‐Pi stress. First, the spatial populations of M2 and M1 macrophages in 22 HCC patient specimens were quantified and correlated with the local Pi concentration. The levels of M2 and M1 macrophage markers expressed in the peritumour area were higher than the intratumour levels, and the expression of M2 markers was positively correlated with Pi concentration. Next, monocytes differentiated from THP‐1 cells were polarized against different Pi concentrations to investigate the activation or silencing of the expression of p65, IκB‐α and STAT3 as well as their phosphorylation. Results showed that low‐Pi stress irreversibly repolarizes tumour‐associated macrophages (TAMs) towards the M1 phenotype by silencing stat6 and activating p65. Moreover, HepG‐2 and SMCC‐7721 cells were cultured in conditioned medium to investigate the innate anticancer immune effects on tumour progression. Both cancer cell lines showed reduced proliferation, migration and invasion, as epithelial–mesenchymal transition (EMT) was inactivated. In vivo therapeutic effect on the innate and adaptive immune processes was validated in a subcutaneous liver cancer model by the intratumoural injection of sevelamer. Tumour growth was significantly inhibited by the partial deprivation of intratumoural Pi as the tumour microenvironment under low‐Pi stress is more immunostimulatory. The anticancer immune response, activated by low‐Pi stress, suggests a new macrophage‐based immunotherapeutic modality. [ABSTRACT FROM AUTHOR]

M2 macrophages contribute to the progression of oesophageal squamous cell carcinoma (ESCC); however, the roles of M2 macrophages in early ESCC remain unclear. To clarify the biological mechanisms underlying the interaction between M2 macrophages and oesophageal epithelial cells in early‐stage ESCC, in vitro co‐culture assays between the immortalised oesophageal epithelial cell line Het‐1A and cytokine‐defined M2 macrophages were established. Co‐culture with M2 macrophages promoted the proliferation and migration of Het‐1A cells via the mTOR–p70S6K signalling pathway activated by YKL‐40, also known as chitinase 3‐like 1, and osteopontin (OPN) that were hypersecreted in the co‐culture supernatants. YKL‐40 and OPN promoted the above phenotypes of Het‐1A by making a complex with integrin β4 (β4). Furthermore, YKL‐40 and OPN promoted M2 polarisation, proliferation, and migration of macrophages. To validate the pathological and clinical significances of in vitro experimental results, immunohistochemistry of human early ESCC tissues obtained by endoscopic submucosal dissection (ESD) was performed, confirming the activation of the YKL‐40/OPN–β4–p70S6K axis in the tumour area. Moreover, epithelial expression of β4 and the number of epithelial and stromal infiltrating YKL‐40‐ and OPN‐positive cells correlated with the Lugol‐voiding lesions (LVLs), a well‐known predictor of the incidence of metachronous ESCC. Furthermore, the combination of high expression of β4 and LVLs or high numbers of epithelial and stromal infiltrating YKL‐40‐ and OPN‐positive immune cells could more clearly detect the incidence of metachronous ESCC than each of the parameters alone. Our results demonstrated that the YKL‐40/OPN–β4–p70S6K axis played important roles in early‐stage ESCC, and the high expression levels of β4 and high numbers of infiltrating YKL‐40‐ and OPN‐positive immune cells could be useful predictive parameters for the incidence of metachronous ESCC after ESD. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Tumour-associated macrophages (TAMs) support tumour development and have emerged as important regulators of therapeutic response to cytostatic agents. To target TAMs, we have developed a novel drug delivery approach which induces drug release as it inhibits cysteine cathepsin activity. This inhibitory prodrug (IPD) approach establishes a self-regulated system where drug release stops after all cysteine cathepsins are inhibited. This could improve the therapeutic window for drugs with severe side effects. We demonstrate and characterise this self-regulation concept with a fluorogenic IPD model. Next, we applied this IPD strategy to deliver cytotoxic drugs, as doxorubicin and monomethyl auristatin E, which are efficiently released and dose-dependently eliminate RAW264.7 macrophages. Lastly, by exploiting the increased cathepsin activity in TAM-like M2-polarised primary macrophages, we show that IPD-Dox selectively eliminates M2 over M1 macrophages. This demonstrates the potential of our IPD strategy for selective drug delivery and modulation of the tumour microenvironment.

Tumour-Associated Macrophages (TAMs) are one of the pivotal components of the tumour microenvironment. Their roles in the cancer immunity are complicated, both pro-tumour and anti-cancer activities are reported, including not only angiogenesis, extracellular matrix remodeling, immunosuppression, drug resistance but also phagocytosis and tumour regression. Interestingly, TAMs are highly dynamic and versatile in solid tumours. They show anti-cancer or pro-tumour activities, and interplay between the tumour microenvironment and cancer stem cells and under specific conditions. In addition to the classic M1/M2 phenotypes, a number of novel dedifferentiation phenomena of TAMs are discovered due to the advanced single-cell technology, e.g., macrophage-myofibroblast transition (MMT) and macrophage-neuron transition (MNT). More importantly, emerging information demonstrated the potential of TAMs on cancer immunotherapy, suggesting by the therapeutic efficiency of the checkpoint inhibitors and chimeric antigen receptor engineered cells based on macrophages. Here, we summarized the latest discoveries of TAMs from basic and translational research and discussed their clinical relevance and therapeutic potential for solid cancers.

Tumour-associated macrophages (TAMs) are crucial components of the tumour microenvironment and play a significant role in tumour development and drug resistance by creating an immunosuppressive microenvironment. Macrophages are essential components of both the innate and adaptive immune systems and contribute to pathogen resistance and the regulation of organism homeostasis. Macrophage function and polarization are closely linked to altered metabolism. Generally, M1 macrophages rely primarily on aerobic glycolysis, whereas M2 macrophages depend on oxidative metabolism. Metabolic studies have revealed that the metabolic signature of TAMs and metabolites in the tumour microenvironment regulate the function and polarization of TAMs. However, the precise effects of metabolic reprogramming on tumours and TAMs remain incompletely understood. In this review, we discuss the impact of metabolic pathways on macrophage function and polarization as well as potential strategies for reprogramming macrophage metabolism in cancer treatment. [ABSTRACT FROM AUTHOR]

Tumour‐associated macrophages (TAMs) are highly plastic and are broadly grouped into two major functional states, namely the pro‐inflammatory M1‐type and the pro‐tumoural M2‐type. Conversion of the functional states of TAMs is regulated by various cytokines, chemokines growth factors and other secreted factors in the microenvironment. Dysregulated metabolism is a hallmark of cancer. Emerging evidence suggests that metabolism governs the TAM differentiation and functional conversation in support of tumour growth and metastasis. Aside from the altered metabolism reprogramming in TAMs, extracellular metabolites secreted by cancer, stromal and/or other cells within the tumour microenvironment have been found to regulate TAMs through passive competition for metabolite availability and direct regulation via receptor/transporter‐mediated signalling reaction. In this review, we focus on the regulatory roles of different metabolites and metabolic pathways in TAM conversion and function. We also discuss if the dysregulated metabolism in TAMs can be exploited for the development of new therapeutic strategies against cancer. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) initiated by hepatitis B virus (HBV) infection is a complicated process. MiR‐155 can alter the immune microenvironment to affect the host's anti‐infective ability. This study investigated the mechanism by which miR‐155 affects tumour‐associated macrophage (TAM) polarization at a molecular level, thus affecting the malignant progression of HBV+HCC. MiR‐155 and TAM‐related cytokine expression were analysed by qRT‐PCR. The distribution of TAMs was detected by immunohistochemistry. The effect of the aberrant miR‐155 expression on macrophage polarization was examined by flow cytometry. The targeted relationship was verified by dual‐luciferase assay, and the protein level of src homology 2 domain‐containing inositol polyphosphate 5‐phosphatase 1 (SHIP1) was detected by western blot. The proliferation of HCC cells was examined by CCK‐8 and colony formation assays. Invasion and migration of HCC cells were detected by transwell assay. In HBV+HCC tissues, miR‐155 was significantly highly expressed and the number of CD206‐positive TAM (CD206+ TAM) and CD68‐positive TAM (CD68+ TAM) were higher than those in HBV−HCC tissues. In addition, miR‐155 overexpression significantly promoted M2‐type macrophage polarization, whilst miR‐155 silencing expression significantly promoted M1‐type macrophage polarization. Besides, the miR‐155/SHIP1 axis accelerated HCC cell invasion, proliferation and migration by inducing M2‐type macrophage polarization. MiR‐155 accelerates HCC cell proliferation, migration and invasion by targeting SHIP1 expression and inducing macrophage M2 polarization. This finding provides new insights into the development of novel therapeutic strategies for combatting HBV+HCC and a new reference for exploring anti‐tumour immunotherapy. [ABSTRACT FROM AUTHOR]

Abstract Background DNMT1 has been shown to be highly expressed in a variety of cancers, including breast cancer. However, the mechanism is not very clear. Therefore, we aim to reveal the mechanism of DNMT1 highly express in breast cancer. And we also want to explore the role of DNMT1 in tumour microenvironment promoting breast cancer progression. Results In this study, we demonstrate that DNMT1 is overexpressed in breast cancer and that DNMT1 promotes breast cancer tumorigenesis and metastasis. We discovered that ZEB1 activates DNMT1 expression in breast cancer cells by recruiting P300 binding to the DNMT1 promoter and increasing its acetylation. Moreover, we revealed that tumour-associated macrophages (TAMs) increase DNMT1 expression in breast cancer cells via the IL-6-pSTAT3-ZEB1-DNMT1 axis in the tumour microenvironment. DNMT1 is required for TAM-mediated breast cancer cell migration. In addition, we confirmed that there were positive correlations among CD163 (TAM marker) expression, ZEB1 expression and DNMT1 expression in breast cancer patient tissues. Conclusions Our study indicates that DNMT1 is necessary for TAM-mediated breast cancer metastasis. Decitabine (DAC), as a specific DNA methylation inhibitor and FDA-approved drug, is a bona fide drug for breast cancer treatment.

Background: Tumor-associated macrophages (TAM) are the main component of inflammation along with leukocytes, endothelial cells and fibroblasts together form a tumor microenvironment, with immune cells representing its vital component. Many studies suggested that TAMs cumulating in tumors correlate with a poor prognosis. In prostate cancer, TAMs can increase cancer cell invasion by stimulating tumor angiogenesis, degrading the extracellular matrix, and also suppresses the antitumor functions of cytotoxic T cells resulting in poor prognosis. Aims and Objectives: 1. To determine the expression of M1 (CD68) and M2 (CD163) in prostate carcinoma (Pca). 2. To find the association between M1, M2 macrophage with Gleason's score and stage of Pca. Materials and Methods: This is a retrospective observational study. All transurethral resection prostatic (TURP) chips positive for Pca and the clinical details were collected. Radiologic findings with respect to stage of disease, size of lesion, were noted. Results: Among the 62 cases studied, majority of the cases were in-between the age of 61-70 years. Highest cases were seen in Gleason's score 8, 9, and 10 (62%), prostatic specific antigen (PSA) levels 20-80 ng/mL (64%), tumor size 3-6 cm (51.6%), T3 stage (40.3%), N1 lymph node stage (70.9%). M1 stage of (31%). CD68 and CD163 expression was analyzed with Gleason's score, TNM stage and PSA levels. CD68 score 3 correlated with low distant and nodal metastasis 6.2% and 6.8%, respectively. CD163 score 3 correlated with high metastasis to lymph nodes and distant metastasis of 86.3% and 25%, respectively. On further analysis, statistically convincing association between the CD163 expression and Gleason's score, PSA levels, nodal and distant metastasis was found. Conclusion: CD68 expression was correlated with good prognosis with less nodal and distant metastasis and Cd163 expression has poor outcome with increased chances of nodal and distant metastasis. Further exploration of TAM mechanisms and immune checkpoints in the prostate tumor microenvironment can furnish new light and motives for the treatment of Pca. [ABSTRACT FROM AUTHOR]

Cellular heterogeneity and immune cell molecular phenotypes may be involved in the malignant progression of glioblastoma (GBM). In this study, we aimed to know whether the heterogeneity of tumour-associated macrophages contributes to the recurrence and outcomes of glioblastoma patients. Single-cell RNA sequencing (scRNA-Seq) data were used to assess the heterogeneity of CD45 + immune cells in recurrent GBM and analyse differentially expressed genes (DEGs) in master cells. Then, a prognostic signature based on the identified DEGs was established and validated, the correlation between risk score and tumour microenvironment (TME) was explored. The correlation between immune infiltration and LGMN, an important DEG in GBM tumour-associated macrophages (TAMs) was illuminated, using integrated bioinformatics analyses. Finally, immunohistochemistry and multiplex immunohistochemistry (mIHC) were used to analyse the expression of LGMN in GBM tissues from our hospital. scRNA-Seq analysis showed that the heterogeneity of recurrent GBM mainly comes from TAMs, which can be divided into 8 cell subclusters. Among these subclusters, TAM1 (markers: CXCL10, ADORA3), TAM3 (markers: MRC1, CFP), TAM4 (markers: GPNMB, PLTP), and TAM5 (markers: CCL4, IRAK2) were specifically present in recurrent GBM. After 342 DEGs in TAMs were identified, a prognostic signature was established based on 13 TAM-associated DEGs, and this signature could serve as an excellent prognostic predictor for patients with GBM. LGMN, one of 13 TAM-associated DEGs, was an important gene in lysosome pathway, we found that macrophage infiltration levels were higher after LGMN upregulation. GBM tissues from our hospital were collected for histopathologic validation, then LGMN was co-expressed with CD68, which is associated with the immune regulation of GBM. In conclusion, cell heterogeneity of TAMs is important for recurrent GBM, a prognostic signature based on 13 TAM-related DEGs can predict the survival outcome of GBM patients. An important DEG, LGMN may regulate the immune cell infiltration of GBM. [ABSTRACT FROM AUTHOR]

Tumour-associated macrophages (TAMs) support tumour development and have emerged as important regulators of therapeutic response to cytostatic agents. To target TAMs, we have developed a novel drug delivery approach which induces drug release as it inhibits cysteine cathepsin activity. This inhibitory prodrug (IPD) approach establishes a self-regulated system where drug release stops after all cysteine cathepsins are inhibited. This could improve the therapeutic window for drugs with severe side effects. We demonstrate and characterise this self-regulation concept with a fluorogenic IPD model. Next, we applied this IPD strategy to deliver cytotoxic drugs, as doxorubicin and monomethyl auristatin E, which are efficiently released and dose-dependently eliminate RAW264.7 macrophages. Lastly, by exploiting the increased cathepsin activity in TAM-like M2-polarised primary macrophages, we show that IPD-Dox selectively eliminates M2 over M1 macrophages. This demonstrates the potential of our IPD strategy for selective drug delivery and modulation of the tumour microenvironment. [ABSTRACT FROM AUTHOR]

Abstract Background Gliomas are the most common malignant primary brain tumours with a highly immunosuppressive tumour microenvironment (TME) and poor prognosis. Circular RNAs (circRNA), a newly found type of endogenous noncoding RNA, characterized by high stability, abundance, conservation, have been shown to play an important role in the pathophysiological processes and TME remodelling of various tumours. Methods CircRNA sequencing analysis was performed to explore circRNA expression profiles in normal and glioma tissues. The biological function of a novel circRNA, namely, circNEIL3, in glioma development was confirmed both in vitro and in vivo. Mechanistically, RNA pull-down, mass spectrum, RNA immunoprecipitation (RIP), luciferase reporter, and co-immunoprecipitation assays were conducted. Results We identified circNEIL3, which could be cyclized by EWS RNA-binding protein 1(EWSR1), to be upregulated in glioma tissues and to correlate positively with glioma malignant progression. Functionally, we confirmed that circNEIL3 promotes tumorigenesis and carcinogenic progression of glioma in vitro and in vivo. Mechanistically, circNEIL3 stabilizes IGF2BP3 (insulin-like growth factor 2 mRNA binding protein 3) protein, a known oncogenic protein, by preventing HECTD4-mediated ubiquitination. Moreover, circNEIL3 overexpression glioma cells drives macrophage infiltration into the tumour microenvironment (TME). Finally, circNEIL3 is packaged into exosomes by hnRNPA2B1 and transmitted to infiltrated tumour associated macrophages (TAMs), enabling them to acquire immunosuppressive properties by stabilizing IGF2BP3 and in turn promoting glioma progression. Conclusions This work reveals that circNEIL3 plays a nonnegligible multifaceted role in promoting gliomagenesis, malignant progression and macrophage tumour-promoting phenotypes polarization, highlighting that circNEIL3 is a potential prognostic biomarker and therapeutic target in glioma.

Background: DNMT1 has been shown to be highly expressed in a variety of cancers, including breast cancer. However, the mechanism is not very clear. Therefore, we aim to reveal the mechanism of DNMT1 highly express in breast cancer. And we also want to explore the role of DNMT1 in tumour microenvironment promoting breast cancer progression. Results: In this study, we demonstrate that DNMT1 is overexpressed in breast cancer and that DNMT1 promotes breast cancer tumorigenesis and metastasis. We discovered that ZEB1 activates DNMT1 expression in breast cancer cells by recruiting P300 binding to the DNMT1 promoter and increasing its acetylation. Moreover, we revealed that tumour-associated macrophages (TAMs) increase DNMT1 expression in breast cancer cells via the IL-6-pSTAT3-ZEB1-DNMT1 axis in the tumour microenvironment. DNMT1 is required for TAM-mediated breast cancer cell migration. In addition, we confirmed that there were positive correlations among CD163 (TAM marker) expression, ZEB1 expression and DNMT1 expression in breast cancer patient tissues. Conclusions: Our study indicates that DNMT1 is necessary for TAM-mediated breast cancer metastasis. Decitabine (DAC), as a specific DNA methylation inhibitor and FDA-approved drug, is a bona fide drug for breast cancer treatment. [ABSTRACT FROM AUTHOR]

Osteosarcoma (OS) is a rare malignant primary bone tumours characterized by a high genetic and cell composition heterogeneity. Unfortunately, despite the use of drug combinations and the recent development of immunotherapies, the overall survival has not improved in the last four decades. Due to the key role of the tumour microenvironment in the pathogenesis of OS, a better understanding of its microenvironment is mandatory to develop new therapeutic approaches. From retrospective biological cohorts of OS, we analysed by immunohistochemistry the presence of lipopolysaccharide (LPS)-binding protein (LBP) in diagnostic biopsies with local disease and compared their level of infiltration to patients suffering from metastatic status. LBP is considered as a marker of LPS exposure and can indirectly reflect the presence of Gram-negative microbiota. LBP were detected in the cytoplasm of OS cells as well as in tumour-associated macrophage. Tumour samples of patients with local disease were significantly enriched in LBP compared to tumour tissues of patients with metastatic status. Lung metastatic tissues showed similar level of LBP compared to paired primary tumours. Overall, this study strongly suggests the presence of Gram-negative bacteria in OS tissues and demonstrated their significant differential level according the metastatic status. This tumour-associated microbiome may help in the conceptualisation of new therapeutic approach to trigger efficient therapeutic responses against cancer.

Abstract Background The immunosuppressive tumour microenvironment is a critical factor in the initiation and progression of glioblastoma (GBM), which is characterized by an abundance of tumour-associated macrophages (TAMs) but a paucity of infiltrating T cells. In this research, we studied whether epithelial membrane protein 3 (EMP3) plays a crucial role in immune modulation in GBM. Methods TCGA and CGGA transcriptomic profiles of wild-type IDH1 GBM were used for bioinformatic analysis. The role of EMP3 in GBM was validated through in vivo and in vitro experiments. Human GBM specimens were collected and evaluated using immunofluorescence analysis. Results EMP3 was associated with immunosuppression in GBM. Elevated EMP3 in GBM areas was accompanied by high expression of PD-L1 and abundant M2 TAM recruitment but a lake of T cell infiltration. We found that EMP3 was a potent protein in M2 TAM polarization and recruitment that impaired the ability of GBM cells to secrete CCL2 and TGF-β1. Furthermore, EMP3 suppressed T cell infiltration into GBM tumours by inhibiting the secretion of CXCL9 and CXCL10 by macrophages and led to an effective response to anti-PD1 therapy. Conclusions EMP3 is thus a critical immunosuppressive factor for recruiting TAMs in GBM and suppressing intratumoural T cell infiltration to facilitate tumour progression and is a potential therapeutic target.

Tertiary lymphoid structures (TLS) can reflect cancer prognosis and clinical outcomes in various tumour tissues. Tumour-associated macrophages (TAMs) are indispensable components of the tumour microenvironment and play crucial roles in tumour development and immunotherapy. TAMs are associated with TLS induction via the modulation of the T cell response, which is a major component of the TLS. Despite their important roles in cancer immunology, the subtypes of TAMs that influence TLS and their correlation with prognosis are not completely understood. Here, we provide novel insights into the role of TAMs in regulating TLS formation. Furthermore, we discuss the prognostic value of these TAM subtypes and TLS, as well as the current antitumour therapies for inducing TLS. This study highlights an entirely new field of TLS regulation that may lead to the development of an innovative perspective on immunotherapy for cancer treatment. [ABSTRACT FROM AUTHOR]

Background: Wilms' tumour (WT) is a malignant tumour of childhood with the typical symptoms of an abdominal mass. Tumour-associated macrophages (TAMs) accumulate and imply a poor prognosis in WT, but the mechanism of how TAMs affect the prognosis has not been fully elucidated. In this study, we aimed to present the molecular mechanisms underlying the protumorigenic capacities of TAMs in WT. Methods: TAMs were polarized into M1- and M2-type macrophages. The two types of macrophages were cocultured with SK-NEP-1 cells, and their cell viability and invasion ability were measured. Matrix metalloproteinase 9 (MMP9) expression was assessed in different types of macrophages, and the role of MMP9 in WT was explored. Then data from children diagnosed with WT in our department between February 2006 and July 2014 were retrospectively analysed, the tumour tissues were analysed to explore the distribution of MMP9. Kaplan–Meier analysis of the relationship between MMP9 expression and follow-up information was performed. Results: The results showed that M2-type macrophages could improve the viability and invasive ability of SK-NEP-1 cells. MMP9 expression in M2-type macrophages was significantly higher than that in M1-type macrophages. MMP9 could activate the AKT/PI3K signalling pathway to initiate the epithelial-mesenchymal transition (EMT) process, and promote the proliferation and invasion of WT. In WT tissue, the MMP9 expression level was elevated and it was located in the tumour stroma, which was the same as M2-type macrophage location, and a high level of MMP9 predicted poor survival. Conclusion: M2-type macrophages facilitate tumour proliferation and metastasis by secreting MMP9 to enhance the EMT process via a PI3K/AKT dependent pathway in Wilms' tumour. [ABSTRACT FROM AUTHOR]

Abstract Background Tumour-associated macrophages (TAMs) in the tumour microenvironment (TME) can promote the progression of hepatocellular carcinoma (HCC). Some tumours can be suppressed by targeting Wnt2b in tumour cells. However, the role of Wnt2b in HCC is still unknown. In particular, the role of Wnt2b-mediated signal activation in macrophage polarization in the HCC microenvironment, and the regulatory effect between Wnt and glycolysis in TAMs has not been described. Methods The expression of Wnt2b in TAMs was detected by qPCR and immunofluorescence. Wnt2b/β-catenin interference in HCC-TAMs was performed by lentivirus carrying targeted shRNA or TLR9 agonist. Markers related to macrophage polarization and the changes of key glycolytic enzymes expression were detected by flow cytometry and qPCR. ECAR was analysed by Seahorse analyser. MTT assay, wound healing assay, western blotting were used to evaluate the promoting effect of different HCC-TAMs on the proliferation, migration and EMT of HCC in vitro. Tumour cells and different HCC-TAMs were injected via subcutaneously into immunodeficient mice to assess the effects of CpG ODN, Wnt2b, or β-catenin on HCC-TAMs in tumour growth in vivo. Results Polarization-promoting factors derived from HCC cells upregulated the expression of Wnt2b in macrophages, which promoted the polarization of TAMs to M2-like macrophages by activating Wnt2b/β-catenin/c-Myc signalling. Furthermore, this process was associated with the activation of glycolysis in HCC-TAMs. These HCC-TAMs could promote the development of EMT, proliferation, and migration of HCC. In addition to silencing Wnt2b or β-catenin expression, TLR9 agonist CpG ODN downregulated the level of glycolysis and inhibited the M2 polarization of HCC-TAMs, reversing the tumour-promoting effects of TAMs in vitro and vivo. Conclusions As a potential target for HCC therapy, Wnt2b may play an important regulatory role for the functions of TAMs in the TME. Moreover, the TLR9 agonist CpG ODN might act as a Wnt2b signal inhibitor and can potentially be employed for HCC therapy by disturbing Wnt2b/β-catenin/c-Myc and inhibiting glycolysis in HCC-TAMs.

Background: The roles of different subtypes of tumour‐associated macrophages (TAMs) in predicting the prognosis of colorectal cancer (CRC) remain controversial. In this study, different subtypes of TAMs were investigated as prognostic and predictive biomarkers for CRC. Methods: Expressions of CD68, CD86 and CD163 were investigated by immunohistochemistry (IHC) and immunofluorescence (IF), and the correlation between the expression of CD86 and CD163 was calculated in colorectal cancer tissues from 64 CRC patients. Results: The results showed that high expressions of CD86+ and CD68+CD86+ TAMs as well as low expression of CD163+ and CD68+CD163+ TAMs were significantly associated with favourable overall survival (OS). The level of CD86 protein expression showed a negative correlation with CD163 protein expression. In addition, CD86 protein expression remarkably negatively correlated with tumour differentiation and tumour node metastasis (TNM) stage, while CD163 protein expression significantly positively correlated with tumour differentiation and tumour size. As an independent risk factor, high expression of CD86 TAMs had prominently favourable prognostic efficacy, while high expression of CD68+CD163+ TAMs had significantly poor prognostic efficacy. Conclusions: These results indicate that CD86+ and CD68+CD163+ TAMs as prognostic and predictive biomarkers for CRC. [ABSTRACT FROM AUTHOR]

Though circulating monocytes are the main source of tumour-associated macrophages (TAMs), the regulatory mechanisms of their recruitment to tumours and further differentiation remain unclear. In the present study, we observed a significant decrease in CXCR2 expression in classical circulating monocytes of patients with colorectal cancer (CRC), particularly those in the late TNM stage. The percentage of CXCR2+ monocytes was negatively associated with systemic inflammatory markers and positively associated with intratumoural immunocyte infiltration. The pro-inflammatory cytokine IFN-γ, which was overexpressed in patients with CRC, down-regulated CXCR2 expression of monocytes/TAMs by promoting GRK-2 expression. In vitro, inhibition of CXCR2 signalling in monocytes led to impaired chemotaxis to the tumour cell line supernatant and lower responsiveness to lipopolysaccharide (LPS) stimulation. Finally, monocytes from patients with CRC with decreased CXCR2 expression showed distinct phenotypes and functions after differentiating into CRC cell line-educated TAMs, including expression of co-stimulatory factors and secretion profile, than those from healthy controls. GRK-2 inhibitor altered the functional characteristics of TAMs. In summary, our findings suggest that CXCR2 expression on circulating monocytes reflects CRC stages and is an important factor determining TAM composition in the tumour microenvironment. [ABSTRACT FROM AUTHOR]