Crosstalk between colon cancer cells and macrophages via inflammatory mediators and CD47 promotes tumour cell migration. Eur J Cancer. 2013;49:3320-3334. [PMID: 23810249 DOI: 10.1016/j.ejca.2013.06.005]

Regulation and Function of Tumor-Associated Macrophages (TAMs) in Colorectal Cancer (CRC): The Role of the SRIF System in Macrophage Regulation

Colorectal cancer (CRC) remains the leading cause of morbidity and mortality for both men and women worldwide. Tumor-associated macrophages (TAMs) are the most abundant immune cells in the tumor microenvironment (TME) of solid tumors, including CRC. These macrophages are found in the pro-inflammatory M1 and anti-inflammatory M2 forms, with the latter increasingly recognized for its tumor-promoting phenotypes. Many signaling molecules and pathways, including AMPK, EGFR, STAT3/6, mTOR, NF-κB, MAPK/ERK, and HIFs, are involved in regulating TAM polarization. Consequently, researchers are investigating several potential predictive and prognostic markers, and novel TAM-based therapeutic targets, especially in combination therapies for CRC. Macrophages of the gastrointestinal tract, including the normal colon and rectum, produce growth hormone-releasing inhibitory peptide/somatostatin (SRIF/SST) and five SST receptors (SSTRs, SST1-5). While the immunosuppressive function of the SRIF system is primarily known for various tissues, its role within CRC-associated TAMs remains underexplored. This review focuses on the following three aspects of TAMs: first, the role of macrophages in the normal colon and rectum within the broader context of macrophage biology; second, the various bioactive factors and signaling pathways associated with TAM function, along with potential strategies targeting TAMs in CRC; and third, the interaction between the SRIF system and macrophages in both normal tissues and the CRC microenvironment.

The colorectal cancer microenvironment: Preclinical progress in identifying targets for cancer therapy

Colorectal cancer (CRC) is a common cancer with high mortality rates. Despite progress in treatment, it remains an incurable disease for many patients. In CRC, the tumor microenvironment (TME) plays critical roles in tumor growth, progression, patients' prognosis, and response to treatments. Understanding TME complexities is important for developing effective therapies. In vitro and in vivo preclinical models are critical in understanding the disease, discovering potential targets, and developing effective therapeutics. In this review, we focus on preclinical research studies associated with modulation of the TME in CRC. These models give insights into understanding the role of stroma and immune cell components of the TME in CRC and improve clinical responses, providing insights in novel treatment options. Various studies have focused on targeting the TME in CRC to improve responses to different therapeutic approaches. These include identifying targets for cancer therapies, targeting molecular signaling, and enhancing the efficacy of immunotherapeutic modalities. Furthermore, targeting stromal and angiogenic factors in the TME may provide new therapeutic options. Overall, understanding and targeting the TME in CRC is a promising approach for improving therapeutic outcomes.

Therapeutic strategies targeting CD47-SIRPα signaling pathway in gastrointestinal cancers treatment

Gastrointestinal (GI) cancers are prevalent globally, with leading incidence and mortality rates among malignant tumors. Despite notable advancements in surgical resection, radiotherapy, and chemotherapy, the overall survival rates remain low. Hence, it is imperative to explore alternative approaches that enhance patient outcomes. Cluster of differentiation 47 (CD47), serving as an early diagnostic marker, is predominantly overexpressed in GI cancers and associated with poor prognosis. Targeting the CD47-signal regulatory protein alpha (SIRPα) signaling pathway may provide a novel strategy for GI cancers treatment. This study summarizes current knowledge of the structure and function of CD47 and SIRPα, their roles in signaling pathways, the prognostic significance of CD47, therapeutic strategies targeting the CD47-SIRPα signaling pathway in GI cancer, and highlights key issues for future investigations.

Translating CD47-targeted therapy in gastrointestinal cancers: Insights from preclinical to clinical studies

This review presents a thorough investigation of the role of CD47 in gastrointestinal cancers. We performed a comprehensive, in-depth review of over 100 preclinical and clinical studies focused on inhibiting CD47. The research highlights the potential of targeted CD47 to enhance existing treatments by boosting the immune response to cancer cells. Considering the essential need to balance the toxicity and efficacy of CD47 inhibition, our review emphasizes the need to optimize CD47 inhibitors. We also demonstrate the necessity of combining CD47 antibodies with conventional chemotherapy, radiotherapy, or other targeted therapies to enhance treatment effectiveness. Finally, we propose the integration of CD47-targeted therapies into treatment plans as a promising approach to reshape the therapeutic landscape of gastrointestinal cancers. Continued research in this field holds great potential for improving the outcomes of gastrointestinal cancer patients and overcoming the challenges associated with this formidable spectrum of diseases.

NRF-1 transcription factor regulates expression of an innate immunity checkpoint, CD47, during melanomagenesis

Transmembrane integrin-associated protein CD47 functions as a potent innate immunity checkpoint and is upregulated by many types of malignant cells, including melanoma during tumor progression. Binding of CD47 to its target receptor, SIRPα, on myeloid cell lineages leads to the initiation of the downstream signaling cascades that inhibit innate immunity anti-tumor responses. Molecular mechanisms underlying upregulation of CD47 during melanoma progression remain largely unknown. In this report, we performed ATAC-Sequencing on patient-derived melanoma cells, as well as, the analysis of ATAC-Seq datasets covering clinical melanoma samples to demonstrate a significant increase in chromatin accessibility for the CD47 promoter region in comparison to normal cells and tissues. Additionally, profiling of multiple CD47 transcript isoforms established that upregulation of CD47 in malignant cells occurs at the mRNA level. Using chromatin immunoprecipitation (ChIP) approaches along with the analysis of ChIP-Seq cancer datasets, we identified the transcription factor NRF-1 which binds at multiple sites within the proximal CD47 promoter region. In combination with serial deletions of CD47 promoter, we defined the minimal DNA region required for its activation, as well as, specific DNA locations within that region, which are preferentially occupied by NRF-1 in tumor cells.

P4HA3 promotes colon cancer cell escape from macrophage phagocytosis by increasing phagocytosis immune checkpoint CD47 expression

Cancer immunotherapies have greatly changed the prospects for the therapy of many malignancies, including colon cancer. Macrophages as the effectors of cancer immunotherapy provide considerable promise for cancer treatment. Prolyl 4-hydroxylase subunit alpha 3 (P4HA3) plays a cancer-promoting role in a variety of cancers, including colon cancer. In the present work, we provided evidence for the first time that P4HA3 promoted colon cancer cell escape from macrophage phagocytosis, and preliminarily explored its possible molecular mechanism. Immunohistochemistry was used to detect the expression of P4HA3 in tissues. Bioinformatics methods were used to analyze the tumor public databases (including TCGA database and GEO database). Macrophage phagocytosis assay and flow cytometric analysis were used to detect the phagocytic capacity of macrophages. Western blot and qRT-PCR were used to detect the expression of related markers (such as P4HA3, CD47, CD24, IL-34, and M-CSF). First, we found that P4HA3 was significantly and highly expressed in both colon cancer tissues and cells, and that P4HA3 had a positive correlation with lymph node metastasis, Dukes stage and also strongly correlated with poorer survival. Subsequently, we found that P4HA3 was strongly associated with the macrophage infiltration level in colon cancer. Immediately we also found that decreasing P4HA3 expression promoted macrophage phagocytosis in colon cancer cells, whereas P4HA3 overexpression produced the opposite effect. Finally, we demonstrated that P4HA3 promoted the expression of cluster of differentiation 47 (CD47) in colon cancer cells. Moreover, P4HA3 caused colon cancer cells to secrete Interleukin 34 (IL34) and Macrophage colony stimulating factor (M-CSF), which further induced macrophages to differentiate to M2 type and thereby contributed to the progression of colon cancer. We have demonstrated that P4HA3-driven CD47 overexpression may act as an escape mechanism, causing colon cancer cells to evade phagocytosis from macrophages.

Macrophage-based cancer immunotherapy: Challenges and opportunities

Macrophages play crucial roles in the tumor microenvironment (TME), exerting diverse functions ranging from promoting tumor growth and metastasis to orchestrating anti-tumor immune responses. Their plasticity allows them to adopt distinct activation states, often called M1-like (pro-inflammatory) and M2-like (anti-inflammatory or pro-tumoral), significantly influencing tumor progression and response to therapy. Harnessing the potential of macrophages in cancer immunotherapy has emerged as a promising strategy, with increasing interest in targeting these cells directly or modulating their functions within the TME. This review explores the intricate interplay between macrophages, the TME, and immunotherapeutic approaches. We discuss the dynamic phenotypic and functional heterogeneity of tumor-associated macrophages (TAMs), their impact on disease progression, and the mechanisms underlying their response to immunotherapy. Furthermore, we highlight recent advancements in macrophage-based immunotherapeutic strategies, including macrophage-targeting agents, adoptive cell transfer, and engineering approaches. Understanding the complex crosstalk between macrophages and the TME is essential for developing effective immunotherapeutic interventions that exploit the immunomodulatory functions of macrophages to enhance anti-tumor immunity and improve clinical outcomes for cancer patients.

The human CD47 checkpoint is targeted by an immunosuppressive Aedes aegypti salivary factor to enhance arboviral skin infectivity

The Aedes aegypti mosquito is a vector of many infectious agents, including flaviviruses such as Zika virus. Components of mosquito saliva have pleomorphic effects on the vertebrate host to enhance blood feeding, and these changes also create a favorable niche for pathogen replication and dissemination. Here, we demonstrate that human CD47, which is known to be involved in various immune processes, interacts with a 34-kilodalton mosquito salivary protein named Nest1. Nest1 is up-regulated in blood-fed female A. aegypti and facilitates Zika virus dissemination in human skin explants. Nest1 has a stronger affinity for CD47 than its natural ligand, signal regulatory protein α, competing for binding at the same interface. The interaction between Nest1 with CD47 suppresses phagocytosis by human macrophages and inhibits proinflammatory responses by white blood cells, thereby suppressing antiviral responses in the skin. This interaction elucidates how an arthropod protein alters the human response to promote arbovirus infectivity.

CD47-mediated immune evasion in early-stage lung cancer progression

Alveolar and interstitial macrophages play crucial roles in eradicating pathogens and transformed cells in the lungs. The immune checkpoint CD47, found on normal and malignant cells, interacts with the SIRPα ligand on macrophages, inhibiting phagocytosis, antigen presentation, and promoting immune evasion. In this study, we demonstrated that CD47 is not only a transmembrane protein, but that it is also highly concentrated in extracellular vesicles from lung cancer cell lines and patient plasma. Abundant CD47 was observed in the cytoplasm of lung cancer cells, aligning with our finding that it was packed into extracellular vesicles for physiological and pathological functions. In our clinical cohort, extracellular vesicle CD47 was significantly higher in the patients with early-stage lung cancer, emphasizing innate immunity inactivation in early tumor progression. To validate our hypothesis, we established an orthotopic xenograft model mimicking lung cancer development, which showed increased serum soluble CD47 and elevated IL-10/TNF-α ratio, indicating an immune-suppressive tumor microenvironment. CD47 expression led to reduced tumor-infiltrating macrophages during progression, while there was a post-xenograft increase in tumor-associated macrophages. In conclusion, CD47 is pivotal in early lung cancer progression, with soluble CD47 emerging as a key pathological effector.

The Role of Adipocytes Recruited as Part of Tumor Microenvironment in Promoting Colorectal Cancer Metastases

Adipose tissue dysfunction, which is associated with an increased risk of colorectal cancer (CRC), is a significant factor in the pathophysiology of obesity. Obesity-related inflammation and extracellular matrix (ECM) remodeling promote colorectal cancer metastasis (CRCM) by shaping the tumor microenvironment (TME). When CRC occurs, the metabolic symbiosis of tumor cells recruits adjacent adipocytes into the TME to supply energy. Meanwhile, abundant immune cells, from adipose tissue and blood, are recruited into the TME, which is stimulated by pro-inflammatory factors and triggers a chronic local pro-inflammatory TME. Dysregulated ECM proteins and cell surface adhesion molecules enhance ECM remodeling and further increase contractibility between tumor and stromal cells, which promotes epithelial-mesenchymal transition (EMT). EMT increases tumor migration and invasion into surrounding tissues or vessels and accelerates CRCM. Colorectal symbiotic microbiota also plays an important role in the promotion of CRCM. In this review, we provide adipose tissue and its contributions to CRC, with a special emphasis on the role of adipocytes, macrophages, neutrophils, T cells, ECM, and symbiotic gut microbiota in the progression of CRC and their contributions to the CRC microenvironment. We highlight the interactions between adipocytes and tumor cells, and potential therapeutic approaches to target these interactions.

The role of innate immune cells in the colorectal cancer tumor microenvironment and advances in anti-tumor therapy research

Innate immune cells in the colorectal cancer microenvironment mainly include macrophages, neutrophils, natural killer cells, dendritic cells and bone marrow-derived suppressor cells. They play a pivotal role in tumor initiation and progression through the secretion of diverse cytokines, chemokines, and other factors that govern these processes. Colorectal cancer is a common malignancy of the gastrointestinal tract, and understanding the role of innate immune cells in the microenvironment of CRC may help to improve therapeutic approaches to CRC and increase the good prognosis. In this review, we comprehensively explore the pivotal role of innate immune cells in the initiation and progression of colorectal cancer (CRC), alongside an extensive evaluation of the current landscape of innate immune cell-based immunotherapies, thereby offering valuable insights for future research strategies and clinical trials.

Advances in molecular mechanisms of inflammatory bowel disease‑associated colorectal cancer (Review)

The link between inflammation and cancer is well documented and colonic inflammation caused by inflammatory bowel disease (IBD) is thought to be a high-risk factor for the development of colorectal cancer (CRC). The complex crosstalk between epithelial and inflammatory cells is thought to underlie the progression from inflammation to cancer. The present review collates and summarises recent advances in the understanding of the pathogenesis of IBD-associated CRC (IBD-CRC), including the oncogenic mechanisms of the main inflammatory signalling pathways and genetic alterations induced by oxidative stress during colonic inflammation, and discusses the crosstalk between the tumour microenvironment, intestinal flora and host immune factors during inflammatory oncogenesis in colitis-associated CRC. In addition, the therapeutic implications of anti-inflammatory therapy for IBD-CRC were discussed, intending to provide new insight into improve clinical practice.

Tumor-associated macrophages: an effective player of the tumor microenvironment

Cancer progression is primarily caused by interactions between transformed cells and the components of the tumor microenvironment (TME). TAMs (tumor-associated macrophages) make up the majority of the invading immune components, which are further categorized as anti-tumor M1 and pro-tumor M2 subtypes. While M1 is known to have anti-cancer properties, M2 is recognized to extend a protective role to the tumor. As a result, the tumor manipulates the TME in such a way that it induces macrophage infiltration and M1 to M2 switching bias to secure its survival. This M2-TAM bias in the TME promotes cancer cell proliferation, neoangiogenesis, lymphangiogenesis, epithelial-to-mesenchymal transition, matrix remodeling for metastatic support, and TME manipulation to an immunosuppressive state. TAMs additionally promote the emergence of cancer stem cells (CSCs), which are known for their ability to originate, metastasize, and relapse into tumors. CSCs also help M2-TAM by revealing immune escape and survival strategies during the initiation and relapse phases. This review describes the reasons for immunotherapy failure and, thereby, devises better strategies to impair the tumor-TAM crosstalk. This study will shed light on the understudied TAM-mediated tumor progression and address the much-needed holistic approach to anti-cancer therapy, which encompasses targeting cancer cells, CSCs, and TAMs all at the same time.

The cross-talk between macrophages and tumor cells as a target for cancer treatment

Macrophages represent an important component of the innate immune system. Under physiological conditions, macrophages, which are essential phagocytes, maintain a proinflammatory response and repair damaged tissue. However, these processes are often impaired upon tumorigenesis, in which tumor-associated macrophages (TAMs) protect and support the growth, proliferation, and invasion of tumor cells and promote suppression of antitumor immunity. TAM abundance is closely associated with poor outcome of cancer, with impediment of chemotherapy effectiveness and ultimately a dismal therapy response and inferior overall survival. Thus, cross-talk between cancer cells and TAMs is an important target for immune checkpoint therapies and metabolic interventions, spurring interest in it as a therapeutic vulnerability for both hematological cancers and solid tumors. Furthermore, targeting of this cross-talk has emerged as a promising strategy for cancer treatment with the antibody against CD47 protein, a critical macrophage checkpoint recognized as the "don't eat me" signal, as well as other metabolism-focused strategies. Therapies targeting CD47 constitute an important milestone in the advancement of anticancer research and have had promising effects on not only phagocytosis activation but also innate and adaptive immune system activation, effectively counteracting tumor cells' evasion of therapy as shown in the context of myeloid cancers. Targeting of CD47 signaling is only one of several possibilities to reverse the immunosuppressive and tumor-protective tumor environment with the aim of enhancing the antitumor response. Several preclinical studies identified signaling pathways that regulate the recruitment, polarization, or metabolism of TAMs. In this review, we summarize the current understanding of the role of macrophages in cancer progression and the mechanisms by which they communicate with tumor cells. Additionally, we dissect various therapeutic strategies developed to target macrophage-tumor cell cross-talk, including modulation of macrophage polarization, blockade of signaling pathways, and disruption of physical interactions between leukemia cells and macrophages. Finally, we highlight the challenges associated with tumor hypoxia and acidosis as barriers to effective cancer therapy and discuss opportunities for future research in this field.

SIRPα: A key player in innate immunity

Signal regulatory protein alpha (SIRPα) is a crucial inhibitory regulator expressed on the surface of myeloid cells, including macrophages, dendritic cells, monocytes, neutrophils, and microglia. SIRPα plays an indispensable role in innate immune and adoptive immune responses in cancer immunology, tissue homeostasis, and other physiological or phycological conditions. This review provides an overview of the research history, ligands, signal transduction pathways, and functional mechanisms associated with SIRPα. Additionally, we summarize the therapeutic implications of targeting SIRPα as a promising novel strategy in immuno-oncology.

CAP2 promotes gastric cancer metastasis by mediating the interaction between tumor cells and tumor-associated macrophages

The metastasis of cancer cells is the main cause of death in patients with gastric cancer (GC). Mounting evidence has demonstrated the vital importance of tumor-associated macrophages in promoting tumor invasion and metastasis; however, the interaction between tumor cells and macrophages in GC is largely unknown. In this study, we demonstrated that cyclase-associated protein 2 (CAP2) was upregulated in GC, especially in cases with lymph node metastasis, and was correlated with a poorer prognosis. The transcription factor JUN directly bound to the promoter region of CAP2 and activated CAP2 transcription. The N-terminal domain of CAP2 bound to the WD5 to WD7 domains of receptor for activated C kinase 1 (RACK1) and induced M2 macrophage polarization by activating the SRC/focal adhesion kinase (FAK)/ERK signaling pathway, which resulted in IL-4 and IL-10 secretion. Polarized M2 macrophages induced premetastatic niche formation and promoted GC metastasis by secreting TGFB1, which created a TGFB1/JUN/CAP2 positive-feedback loop to activate CAP2 expression continuously. Furthermore, we identified salvianolic acid B as an inhibitor of CAP2, which effectively inhibited GC cell invasion capabilities by suppressing the SRC/FAK/ERK signaling pathway. Our data suggest that CAP2, a key molecule mediating the interaction between GC cells and tumor-associated macrophages, may be a promising therapeutic target for suppressing tumor metastasis in GC.

Loss of HES1 expression is associated with extracellular matrix remodeling and tumor immune suppression in KRAS mutant colon adenocarcinomas

The loss of HES1, a canonical Notch signaling target, may cooperate with KRAS mutations to remodel the extracellular matrix and to suppress the anti-tumor immune response. While HES1 expression is normal in benign hyperplastic polyps and normal colon tissue, HES1 expression is often lost in sessile serrated adenomas/polyps (SSAs/SSPs) and colorectal cancers (CRCs) such as those right-sided CRCs that commonly harbor BRAF or KRAS mutations. To develop a deeper understanding of interaction between KRAS and HES1 in colorectal carcinogenesis, we selected microsatellite stable (MSS) and KRAS mutant or KRAS wild type CRCs that show aberrant expression of HES1 by immunohistochemistry. By comparing the transcriptional landscapes of microsatellite stable (MSS) CRCs with or without nuclear HES1 expression, we investigated differentially expressed genes and activated pathways. We identified pathways and markers in the extracellular matrix and immune microenvironment that are associated with mutations in KRAS. We found that loss of HES1 expression positively correlated with matrix remodeling and epithelial-mesenchymal transition but negatively correlated with tumor cell proliferation. Furthermore, loss of HES1 expression in KRAS mutant CRCs correlates with a higher M2 macrophage polarization and activation of IL6 and IL10 immunosuppressive signature. Identifying these HES1-related markers may be useful for prognosis stratification and developing treatment for KRAS-mutant CRCs.

Synthetic bacterial therapies for intestinal diseases based on quorum-sensing circuits

Bacterial therapy has become a key strategy against intestinal infectious diseases in recent years. Moreover, regulating the gut microbiota through traditional fecal microbiota transplantation and supplementation of probiotics faces controllability, efficacy, and safety challenges. The infiltration and emergence of synthetic biology and microbiome provide an operational and safe treatment platform for live bacterial biotherapies. Synthetic bacterial therapy can artificially manipulate bacteria to produce and deliver therapeutic drug molecules. This method has the advantages of solid controllability, low toxicity, strong therapeutic effects, and easy operation. As an essential tool for dynamic regulation in synthetic biology, quorum sensing (QS) has been widely used for designing complex genetic circuits to control the behavior of bacterial populations and achieve predefined goals. Therefore, QS-based synthetic bacterial therapy might become a new direction for the treatment of diseases. The pre-programmed QS genetic circuit can achieve a controllable production of therapeutic drugs on particular ecological niches by sensing specific signals released from the digestive system in pathological conditions, thereby realizing the integration of diagnosis and treatment. Based on this as well as the modular idea of synthetic biology, QS-based synthetic bacterial therapies are divided into an environmental signal sensing module (senses gut disease physiological signals), a therapeutic molecule producing module (plays a therapeutic role against diseases), and a population behavior regulating module (QS system). This review article summarized the structure and function of these three modules and discussed the rational design of QS gene circuits as a novel intervention strategy for intestinal diseases. Moreover, the application prospects of QS-based synthetic bacterial therapy were summarized. Finally, the challenges faced by these methods were analyzed to make the targeted recommendations for developing a successful therapeutic strategy for intestinal diseases.

Immune Profile of Exosomes in African American Breast Cancer Patients Is Mediated by Kaiso/THBS1/CD47 Signaling

African American (AA) women with breast cancer are more likely to have higher inflammation and a stronger overall immune response, which correlate with poorer outcomes. In this report, we applied the nanostring immune panel to identify differences in inflammatory and immune gene expression by race. We observed a higher expression of multiple cytokines in AA patients compared to EA patients, with high expression of CD47, TGFB1, and NFKB1 associated with the transcriptional repressor Kaiso. To investigate the mechanism associated with this expression pattern, we observed that Kaiso depletion results in decreased expression of CD47, and its ligand SIRPA. Furthermore, Kaiso appears to directly bind to the methylated sequences of the THBS1 promotor and repress gene expression. Similarly, Kaiso depletion attenuated tumor formation in athymic nude mice, and these Kaiso-depleted xenograft tissues showed significantly higher phagocytosis and increased infiltration of M1 macrophages. In vitro validation using MCF7 and THP1 macrophages treated with Kaiso-depleted exosomes showed a reduced expression of immune-related markers (CD47 and SIRPA) and macrophage polarization towards the M1 phenotype compared to MCF7 cells treated with exosomes isolated from high-Kaiso cells. Lastly, analysis of TCGA breast cancer patient data demonstrates that this gene signature is most prominent in the basal-like subtype, which is more frequently observed in AA breast cancer patients.

A key driver to promote HCC: Cellular crosstalk in tumor microenvironment

Liver cancer is the third greatest cause of cancer-related mortality, which of the major pathological type is hepatocellular carcinoma (HCC) accounting for more than 90%. HCC is characterized by high mortality and is predisposed to metastasis and relapse, leading to a low five-year survival rate and poor clinical prognosis. Numerous crosstalk among tumor parenchymal cells, anti-tumor cells, stroma cells, and immunosuppressive cells contributes to the immunosuppressive tumor microenvironment (TME), in which the function and frequency of anti-tumor cells are reduced with that of associated pro-tumor cells increasing, accordingly resulting in tumor malignant progression. Indeed, sorting out and understanding the signaling pathways and molecular mechanisms of cellular crosstalk in TME is crucial to discover more key targets and specific biomarkers, so that develop more efficient methods for early diagnosis and individualized treatment of liver cancer. This piece of writing offers insight into the recent advances in HCC-TME and reviews various mechanisms that promote HCC malignant progression from the perspective of mutual crosstalk among different types of cells in TME, aiming to assist in identifying the possible research directions and methods in the future for discovering new targets that could prevent HCC malignant progression.

Emerging phagocytosis checkpoints in cancer immunotherapy

Cancer immunotherapy, mainly including immune checkpoints-targeted therapy and the adoptive transfer of engineered immune cells, has revolutionized the oncology landscape as it utilizes patients' own immune systems in combating the cancer cells. Cancer cells escape immune surveillance by hijacking the corresponding inhibitory pathways via overexpressing checkpoint genes. Phagocytosis checkpoints, such as CD47, CD24, MHC-I, PD-L1, STC-1 and GD2, have emerged as essential checkpoints for cancer immunotherapy by functioning as "don't eat me" signals or interacting with "eat me" signals to suppress immune responses. Phagocytosis checkpoints link innate immunity and adaptive immunity in cancer immunotherapy. Genetic ablation of these phagocytosis checkpoints, as well as blockade of their signaling pathways, robustly augments phagocytosis and reduces tumor size. Among all phagocytosis checkpoints, CD47 is the most thoroughly studied and has emerged as a rising star among targets for cancer treatment. CD47-targeting antibodies and inhibitors have been investigated in various preclinical and clinical trials. However, anemia and thrombocytopenia appear to be formidable challenges since CD47 is ubiquitously expressed on erythrocytes. Here, we review the reported phagocytosis checkpoints by discussing their mechanisms and functions in cancer immunotherapy, highlight clinical progress in targeting these checkpoints and discuss challenges and potential solutions to smooth the way for combination immunotherapeutic strategies that involve both innate and adaptive immune responses.

Knockdown of membrane-bound complement regulatory proteins suppresses colon cancer growth in mice through inducing tumor cell apoptosis

CD46, CD55 and CD59 are membrane-bound complement regulatory proteins (mCRPs) and highly expressed in many tumor tissues. Our analysis by RNA sequencing and qRT-PCR revealed that the expression of mCRPs was significantly elevated in cancer tissues of 15 patients with colon cancer. To further investigate the role of mCRPs in the development of colon cancer, we suppressed the expression of mCRPs by CD46-shRNA, CD55-shRNA and CD59-shRNA in colon cancer cell lines, SW620 and HT-29 cells. The results indicated that CD46-shRNA, CD55-shRNA and CD59-shRNA effectively reduced the expression of mCRPs, accompanied with the increased LDH release and the percentage of Annexin V + 7-AAD- early phase of apoptotic cells. The similar cytotoxic effects were also observed in the cells treated with CD46 neutralizing antibody (aCD46), associated with the increased C5b-9 deposition, cleaved caspase-3 and Bax expression in the treated cells. The cytotoxic effects by mCRPs knock-down were potentiated in the cells co-treated with doxorubicin (Dox). In addition, STAT3, STAT6, and p38 MAPK inhibitors, including C188-9, AS1517499 and SB203580 effectively reduced the expression of CD46 in the treated colon cells, associated with increased cell apoptosis and LDH release. Further study with mouse model revealed that mCRPs knockdown by mCRPs-shRNA significantly reduced colon cancer growth, associated with increased expression of Bax, cleaved caspase-3 and C5b-9 deposition, but reduced expression of Bcl-2, IL-6 and IL-1beta in tumor tissues of nude mice transplanted with SW620 cells. Thereby, mCRPs expression in human colon cancer cells were upregulated by STAT3/STAT6/p38 MAPK signaling and mCRPs knockdown reduced colon cancer growth in mice through inducing tumor cell apoptosis.

HDAC6-dependent deacetylation of TAK1 enhances sIL-6R release to promote macrophage M2 polarization in colon cancer

Histone deacetylase 6 (HDAC6), a member of the HDAC family, has been identified as a potential therapeutic target for tumor therapy, but the function and underlying mechanisms of HDAC6 in colon cancer are incompletely characterized. Our study showed that the infiltration ratio of M2 macrophages was increased in colon cancer tissues with high HDAC6 expression. Similarly, the knockdown of HDAC6 in colon cancer cells inhibited cocultured macrophage M2 polarization in vitro. Analysis of the antibody chip revealed that HDAC6 promoted sIL-6R release to enhance macrophage M2 polarization. Mass spectrometry and immunoprecipitation demonstrated that, mechanistically, HDAC6 interacted with transforming growth factor β-activated kinase 1 (TAK1), deacetylated TAK1 at T178 and promoted TAK1 phosphorylation. TAK1-p38 MAPK signaling could further increase the phosphorylation and activity of ADAM17, which is responsible for shedding of IL-6R. Notably, the expression of phosphorylated TAK1 was positively correlated with HDAC6 expression and macrophage M2 polarization in human colon cancer tissues. Our study revealed a new HDAC6-TAK1-ADAM17 regulatory axis that mediates sIL-6R release and macrophage polarization in colon cancer.

An Immune-Related Prognostic Risk Model in Colon Cancer by Bioinformatics Analysis

Colon cancer is one of the leading malignancies with poor prognosis worldwide. Immune cell infiltration has a potential prognostic value for colon cancer. This study aimed to establish an immune-related prognostic risk model for colon cancer by bioinformatics analysis. A total of 1670 differentially expressed genes (DEGs), including 177 immune-related genes, were identified from The Cancer Genome Atlas (TCGA) dataset. A prognostic risk model was constructed based on six critical immune-related genes (C-X-C motif chemokine ligand 1 (CXCL1), epiregulin (EREG), C-C motif chemokine ligand 24 (CCL24), fatty acid binding protein 4 (FABP4), tropomyosin 2 (TPM2), and semaphorin 3G (SEMA3G)). This model was validated using the microarray dataset GSE35982. In addition, Cox regression analysis showed that age and clinical stage were correlated with prognostic risk scores. Kaplan–Meier survival analysis showed that high risk scores correlated with low survival probabilities in patients with colon cancer. Downregulated TPM2, FABP4, and SEMA3G levels were positively associated with the activated mast cells, monocytes, and macrophages M2. Upregulated CXCL1 and EREG were positively correlated with macrophages M1 and activated T cells CD4 memory, respectively. Based on these results, we can conclude that the proposed prognostic risk model presents promising novel signatures for the diagnosis and prognosis prediction of colon cancer. This model may provide therapeutic benefits for the development of immunotherapy for colon cancer.

Overcoming immunotherapeutic resistance in PDAC: SIRPα-CD47 blockade

A daily increase in the number of new cases of pancreatic ductal adenocarcinoma remains an issue of contention in cancer research. The data revealed that a global cumulated case of about 500, 000 have been reported. This has made PDAC the fourteenth most occurring tumor case in cancer research. Furthermore, PDAC is responsible for about 466,003 deaths annually, representing the seventh prevalent type of cancer mortality. PDAC has no salient symptoms in its early stages. This has exasperated several attempts to produce a perfect therapeutic agent against PDAC. Recently, immunotherapeutic research has shifted focus to the blockade of checkpoint proteins in the management and of some cancers. Investigations have centrally focused on developing therapeutic agents that could at least to a significant extent block the SIRPα-CD47 signaling cascade (a cascade which prevent phagocytosis of tumors by dendritic cells, via the deactivation of innate immunity and subsequently resulting in tumor regression) with minimal side effects. The concept on the blockade of this interaction as a possible mechanism for inhibiting the progression of PDAC is currently being debated. This review examined the structure--function activity of SIRPα-CD47 interaction while discussing in detail the mechanism of tumor resistance in PDAC. Further, this review details how the blockade of SIRPα-CD47 interaction serve as a therapeutic option in the management of PDAC.

Cannabinoid Receptor-1 suppresses M2 macrophage polarization in colorectal cancer by downregulating EGFR

Cannabinoid receptors, CB1 and CB2, have been implicated as emerging targets for cancer therapy. Herein, we investigated the potential regulation mechanism of CB1 and its implications in colorectal cancer. CB1 and EGFR expression were examined in colorectal cancer cell lines. The effects of CB1 agonist ACEA and its antagonist AM251 on the proliferation, migration and invasion of colorectal cancer cells and the expression of M1 and M2 macrophage markers were examined. EGFR overexpression was performed with plasmids containing EGFR gene. Tumor xenografts were constructed to explore the effects of CB1 activation on tumorigenesis. We showed that CB1 was downregulated while EGFR was upregulated in colorectal cancer cells. The activation of CB1 suppressed the proliferation, migration and invasion of colorectal cancer cells and the differentiation of M2 macrophages, while CB1 inhibition had opposite effects. Moreover, the alterations in tumorigenesis and M2 macrophage activation induced by CB1 activation were counteracted by EGFR overexpression. Besides, CB1 silencing promoted tumor cell proliferation and M2 polarization which was counteracted by EGFR knockdown. In vivo, CB1 activation also repressed tumorigenesis and M2 macrophage activation. The present study demonstrated that CB1 activation suppressed M2 macrophage through EGFR downregulation in colorectal cancers. These findings first unveiled the potential avenue of CB1 as a targeted therapy for colorectal cancer.

High expression of PI4K2A predicted poor prognosis of colon adenocarcinoma (COAD) and correlated with immunity

BACKGROUND

PI4K2A has been found to have a tumor-promoting role in various solid tumors and be involved in various biological procedures. In this article, we aim to investigate the prognostic values of PI4K2A and provide new insights in colon adenocarcinoma (COAD).

METHODS

The Cancer Genome Atlas (TCGA) database, Human Protein Atlas online database, and UALCAN database were used to analyze the expression of PI4K2A in COAD and the survival of patients. Univariate and multifactorial Cox regression analyses were used to assess the prognosis of PI4K2A on COAD. GSEA was used to explore PI4K2A-related signaling pathways. In addition, the effect of PI4K2A on immune checkpoint inhibitors (ICIs) treatment was investigated by constructing a TIDE model and predicting the association between PI4K2A and anticancer drug sensitivity through the CellMiner database.

RESULTS

In the TCGA database, PI4K2A was highly expressed in COAD and the similar results were verified by qRT-PCR. Survival analysis, utilizing Kaplan-Meier curves, revealed that COAD patients with high PI4K2A expression had a worse prognosis. In addition, PI4K2A expression was discovered to have been associated with T-stage, N-stage, and pathological stage by logistic analysis. Next, we utilized univariate and multifactorial Cox regression analyses to identify PI4K2A as an independent predictor. Additionally, GSEA analysis indicates that PI4K2A is enriched in MAPK signaling pathway, Toll-like receptor signaling pathway, etc. In COAD, PI4K2A was remarkably associated with the tumor immune microenvironment. In addition, by constructing a TIDE model, we discovered that COAD patients in the PI4K2A low-expression cohort were better treated with ICI. Finally, analysis of the CellMiner database predicted that PI4K2A was adversely correlated with the sensitivity of various anticancer drugs.

CONCLUSIONS

Our study suggests that PI4K2A may be a potential predictor of poor prognosis in COAD and a potential biomarker for early diagnosis, prognosis, and treatment.

Using Next-Generation Sequencing and Bioinformatic Methods to Predict New Genes That May Be Regulated by CD47 in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is one of the most common cancers in the world, and the incidence and death rate of OSCC in men is twice that of women. CD47 is a ubiquitous cell surface transmembrane protein, also known as integrin-related protein (IAP). Previous studies have pointed out that CD47 can inhibit the growth of OSCC, but the detailed mechanism is not clear. This study aimed to explore the effect of CD47 gene expression profiles in OSCC. The OSCC cell lines, OECM-1 and OC-2, overexpressed CD47, and the expression profiles of mRNAs were analyzed through next-generation sequencing (NGS) with a bioinformatic approach. A total of 14 differentially expressed genes (DEGs) were listed. In addition, ingenuity pathway analysis (IPA) was used to analyze the molecular function (MF), biological process (BP), and cellular component (CC) network signaling. The human protein atlas (HPA) database was used to analyze gene expression and the survivability of human cancer. The results found that HSPA5, HYOU1, and PDIA4 were involved in the IPA network and when highly expressed, mediated the survivability of cancer. In addition, HSPA5 was positively and significantly correlated with CD47 expression (p < 0.0001) and induced by CD47-overexpression in the OECM-1 and OC-2 OSCC cancer cell lines. These findings provide important insights into possible new diagnostic strategies, including unfolded protein for OSCC-targeting CD47.

Multiphoton Microscopy Reveals DAPK1-Dependent Extracellular Matrix Remodeling in a Chorioallantoic Membrane (CAM) Model

Simple Summary

The formation of metastasis is not only intricately orchestrated by cancer cells but is also affected by the surrounding extracellular matrix (ECM). The barrier function of the ECM represents an obstacle that cancer cells have to overcome to disseminate from the primary tumor to form metastasis in distant organs. Here, we demonstrate an approach to studying the remodeling of a collagen-rich ECM by colorectal tumor cells using multiphoton microscopy (MPM). This approach allows the analysis of the invasion front of tumors grown on the CAM in 3D. MPM is superior to conventional histology, which is limited to 2D analysis and needs extensive tissue preparation.

Abstract

Cancer cells facilitate tumor growth by creating favorable tumor micro-environments (TME), altering homeostasis and immune response in the extracellular matrix (ECM) of surrounding tissue. A potential factor that contributes to TME generation and ECM remodeling is the cytoskeleton-associated human death-associated protein kinase 1 (DAPK1). Increased tumor cell motility and de-adhesion (thus, promoting metastasis), as well as upregulated plasminogen-signaling, are shown when functionally analyzing the DAPK1 ko-related proteome. However, the systematic investigation of how tumor cells actively modulate the ECM at the tissue level is experimentally challenging since animal models do not allow direct experimental access while artificial in vitro scaffolds cannot simulate the entire complexity of tissue systems. Here, we used the chorioallantoic membrane (CAM) assay as a natural, collagen-rich tissue model in combination with all-optical experimental access by multiphoton microscopy (MPM) to study the ECM remodeling potential of colorectal tumor cells with and without DAPK1 in situ and even in vivo. This approach demonstrates the suitability of the CAM assay in combination with multiphoton microscopy for studying collagen remodeling during tumor growth. Our results indicate the high ECM remodeling potential of DAPK1 ko tumor cells at the tissue level and support our findings from proteomics.

MiR-126 downregulates CXCL12 expression in intestinal epithelial cells to suppress the recruitment and function of macrophages and tumorigenesis in a murine model of colitis-associated colorectal cancer

Inflammatory bowel disease, characterised by chronic relapsing‐remitting colitis, is a significant risk factor for colorectal cancer (CRC). Previously, we showed that miR‐126 functions as a tumour suppressor in CRC and is inversely correlated with tumour proliferation, metastasis and patient prognosis. In the current study, we documented a protective role for miR‐126 in colitis‐associated CRC (CAC) and its underlying mechanism. We detected downregulated miR‐126 expression during colorectal tumorigenesis in the mouse CAC model and in specimens from patients with CRC. The deficiency of miR‐126 in intestinal epithelial cells (IECs) exacerbated tumorigenesis in mice. We identified CXCL12 as a direct target of miR‐126 in inhibiting the development of colitis and CAC. Moreover, miR‐126 regulated the recruitment of macrophages via CXCL12 and decreased the levels of proinflammatory cytokines (IL‐6, IL‐12 and IL‐23). In addition, IL‐6 secreted by macrophages, which were regulated by cocultured transfected CRC cells, altered the proliferation and migration of colon cells. Our data suggest that miR‐126 exerts an antitumour effect on CAC by regulating the crosstalk between IECs and macrophages via CXCL12‐IL‐6 signalling. Our study contributes to the understanding of cancer progression and suggests miR‐126 as a potential therapy for CRC.

Microglia and Macrophages in Neuroprotection, Neurogenesis, and Emerging Therapies for Stroke

Stroke remains the number one cause of morbidity in the United States. Within weeks to months after an ischemic event, there is a resolution of inflammation and evidence of neurogenesis; however, years following a stroke, there is evidence of chronic inflammation in the central nervous system, possibly by the persistence of an autoimmune response to brain antigens as a result of ischemia. The mechanisms underlying the involvement of macrophage and microglial activation after stroke are widely acknowledged as having a role in ischemic stroke pathology; thus, modulating inflammation and neurological recovery is a hopeful strategy for treating the long-term outcomes after ischemic injury. Current treatments fail to provide neuroprotective or neurorestorative benefits after stroke; therefore, to ameliorate brain injury-induced deficits, therapies must alter both the initial response to injury and the subsequent inflammatory process. This review will address differences in macrophage and microglia nomenclature and summarize recent work in elucidating the mechanisms of macrophage and microglial participation in antigen presentation, neuroprotection, angiogenesis, neurogenesis, synaptic remodeling, and immune modulating strategies for treating the long-term outcomes after ischemic injury.

Tumor cell-derived SPON2 promotes M2-polarized tumor-associated macrophage infiltration and cancer progression by activating PYK2 in CRC

Background

Tumor-associated macrophages (TAMs) are key regulators of the complex interplay between cancer and the immune microenvironment. Tumor cell-derived spondin 2 (SPON2) is an extracellular matrix glycoprotein that has complicated roles in recruitment of macrophages and neutrophils during inflammation. Overexpression of SPON2 has been shown to promote tumor cell migration in colorectal cancer (CRC). However, the mechanism by which SPON2 regulates the accumulation of TAMs in the tumor microenvironment (TME) of CRC is unknown.

Methods

Immunohistochemistry was used to examine SPON2 expression in clinical CRC tissues. In vitro migration assays, transendothelial migration assays (iTEM), and cell adhesion assays were used to investigate the effects of SPON2 on monocyte/macrophage migration. Subcutaneous tumor formation and orthotopic implantation assays were performed in C57 BL/6 mice to confirm the effects of SPON2 on TAM infiltration in tumors.

Results

SPON2 expression is positively correlated with M2-TAM infiltration in clinical CRC tumors and poor prognosis of CRC patients. In addition, SPON2 promotes cytoskeletal remodeling and transendothelial migration of monocytes by activating integrin β1/PYK2 axis. SPON2 may indirectly induce M2-polarization through upregulating cytokines including IL10, CCL2 and CSF1 expression in tumor cells. Blocking M2 polarization and Macrophage depletion inhibited the SPON2-induced tumors growth and invasion. Furthermore, blocking the SPON2/integrin β1/PYK2 axis impairs the transendothelial migration of monocytes and cancer-promoting functions of TAMs in vivo.

Conclusions

Our findings demonstrate that SPON2-driven M2-TAM infiltration plays an important role during CRC tumor growth and metastasis. SPON2 may be a valuable biomarker guiding the use of macrophage-targeting strategies and a potential therapeutic target in advanced CRC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02108-0.

The Immunoregulatory Role of the Signal Regulatory Protein Family and CD47 Signaling Pathway in Type 1 Diabetes

Background

The pathogenesis of type 1 diabetes (T1D) involves complex genetic susceptibility that impacts pathways regulating host immunity and the target of autoimmune attack, insulin-producing pancreatic β-cells. Interactions between risk variants and environmental factors result in significant heterogeneity in clinical presentation among those who develop T1D. Although genetic risk is dominated by the human leukocyte antigen (HLA) class II and insulin (INS) gene loci, nearly 150 additional risk variants are significantly associated with the disease, including polymorphisms in immune checkpoint molecules, such as SIRPG.

Scope of Review

In this review, we summarize the literature related to the T1D-associated risk variants in SIRPG, which include a protein-coding variant (rs6043409, G>A; A263V) and an intronic polymorphism (rs2281808, C>T), and their potential impacts on the immunoregulatory signal regulatory protein (SIRP) family:CD47 signaling axis. We discuss how dysregulated expression or function of SIRPs and CD47 in antigen-presenting cells (APCs), T cells, natural killer (NK) cells, and pancreatic β-cells could potentially promote T1D development.

Major Conclusions

We propose a hypothesis, supported by emerging genetic and functional immune studies, which states a loss of proper SIRP:CD47 signaling may result in increased lymphocyte activation and cytotoxicity and enhanced β-cell destruction. Thus, we present several novel therapeutic strategies for modulation of SIRPs and CD47 to intervene in T1D.

The myeloid cell biomarker EMR1 is ectopically expressed in colon cancer

OBJECTIVE

The microenvironment of colon cancer (CC) is heterogeneous including cells of myeloid lineage affecting tumor growth and metastasis. Two functional subtypes of myeloid cells have been identified; one (M1) is tumor-inhibitory and the other one (M2) is tumor-promoting. Whether the three myeloid markers EMR1, CD206 and CD86 are expressed only in the infiltrating myeloid cells or also in the tumor cells was investigated.

METHODS

Expression of the myeloid markers was investigated in CC at the mRNA and protein levels in primary tumors and lymph nodes. mRNA expression was also determined in 5 CC cell lines. Protein expression was investigated by two-color immunofluorescence and consecutive-sections-immune-staining combined with morphometry using specific antibodies for the myeloid cell markers and the epithelial cell markers CEACAM5 and EpCAM.

RESULTS

EMR1 and CD86, but not CD206, mRNA levels were significantly higher in CC primary tumors compared to apparently normal colon tissue (P <  0.0001). EMR1 mRNA levels were significantly higher in both hematoxylin-eosin positive (H&E(+)) and H&E(-) lymph nodes of CC patients compared to control nodes (P = 0.03 and P = 0.01, respectively). EMR1 and CD206 mRNAs were expressed in 4/5 and 5/5 CC cell lines, respectively, while CD86 mRNA was not expressed. Immuno-morphometry revealed that about 20% of the tumor cells expressed EMR1 and CD206. Positive cells were tumor cells as revealed by anti-CEACAM5 and anti-EpCAM staining. The number of EMR1, CD206 and CD86 positive cells were significantly increased in CC primary tumors compared to normal colon tissue (P <  0.0001). However, CD206 was also expressed in normal colonocytes. Only EMR1 showed significantly increased numbers of positive tumor cells in H&E(+) nodes compared to H&E(-) nodes (P = 0.001). EMR1 expression in CC tumor cells correlated with CXCL17 expressing tumor cells.

CONCLUSION

EMR1, like the chemokine CXCL17, is ectopically expressed in colon cancer possibly in the same cancer cells.

Pentraxin-3 inhibits milky spots metastasis of gastric cancer by inhibiting M2 macrophage polarization

Purpose: Recent studies have indicated that Pentraxin-3 (PTX3) is related to invasion, migration and metastasis of gastric cancer cells (GCCs). However, the function of PTX3 in stemness and tumor-associated macrophages (TAMs) polarization in GC has not yet been revealed. Here, we investigated the role of PTX3 in TAMs polarization and stemness in gastric cancer (GC), and further explored the effect of PTX3 on milky spot metastasis of gastric cancer.

Methods: PTX3 expression in human gastric cancer tissues was examined with immunohistochemistry (IHC). The influence on stemness of gastric cancer cells was examined by sphere formation assay and western blot. qRT-PCR, IHC and flow cytometry were used to evaluate M1/M2 macrophage signatures. The effects of PTX3 on TAM polarization and milky spots were investigated in vitro and in vivo. The possible mechanism of PTX3 on targeted cytokines and pathway were analyzed by qRT-PCR and western blot.

Results: We found that PTX3 was low expressed in gastric carcinoma tissues and associated with stemness and polarization of macrophages. The upregulation of PTX3 inhibited the stemness of GCCs. Furthermore, PTX3 suppressed the polarization of M2 macrophages in the milky spots in vivo and in vitro and inhibited the metastasis of GC into milky spots. PTX3 restrained the expression of interleukin-4 (IL-4) and IL-10 via the inhibition of phosphorylation of the c-Jun N-terminal protein kinase 1/2 (JNK1/2) in GCCs.

Conclusion: These results revealed a novel mechanism of PTX3 in GC, which may participate in the development and metastasis of GC by affecting stemness and macrophage polarization. PTX3 should be considered as a crucial biomarker and may be potentially used in targeted therapy in GC progression.

Third-Generation Anti-CD47-Specific CAR-T Cells Effectively Kill Cancer Cells and Reduce the Genes Expression in Lung Cancer Cell Metastasis

CD47 is a cell surface glycoprotein molecule, belonging to the immunoglobulin superfamily, binding to various proteins including integrins, thrombospondin-1, and signal regulatory protein α (SIRPα). CD47 is an important tumor antigen for the development and progression of various cancers. This study designed the chimeric antigen receptor T-cell (CAR-T) to bind to the CD47 to inhibit the expression of CD47. We used the complementarity-determining regions (CDRs) of the B6H12 mouse antibody grafted onto the IgG1 framework to create the humanized single-chain variable fragment (scFv) with linker (G4S)x3. scFv was used to design the chimeric antigen receptor with the structure CD8signal-CD47scFv-CD8a hinge-CD4TM-CD28-41BB-CD3ζ, which was then transformed into T lymphocytes by the lentivirus to create third generation of CAR-T. Results revealed that the new CAR-T cells efficiently killed A549 cancer cells. CAR-T inhibited the expression of genes involved in metastasis and invasion of cells A549 including beta actin, calreticulin, and cyclooxygenase 2 at mRNA levels.

Rosmarinic acid represses colitis-associated colon cancer: A pivotal involvement of the TLR4-mediated NF-κB-STAT3 axis

Previously, we found that rosmarinic acid (RA) exerted anti-inflammatory activities in a dextran sulfate sodium (DSS)-induced colitis model. Here, we investigated the anti-tumor effects of RA on colitis-associated colon cancer (CAC) and the underlying molecular mechanisms. We established an azoxymethane (AOM)/DSS-induced CAC murine model for in vivo studies and used a conditioned media (CM) culture system in vitro. H&E staining, immunohistochemistry, western blot assay, enzyme-linked immunosorbent assay, molecular docking, co-immunoprecipitation, and immunofluorescence assay were utilized to investigate how RA prevented colorectal cancer. In the AOM/DSS-induced CAC murine model, RA significantly reduced colitis severity, inflammation-related protein expression, tumor incidence, and colorectal adenoma development. It significantly modulated toll-like receptor-4 (TLR4)-mediated nuclear factor-kappa B (NF-κB) and signal transducer and activator of transcription 3 (STAT3) activation, thus attenuating the expression of anti-apoptotic factors, which mediate transcription factor-dependent tumor growth. In vitro, RA inhibited CM-induced TLR4 overexpression and competitively inhibited TLR4-myeloid differentiation factor 2 complex in an inflammatory microenvironment. Thus, RA suppressed NF-κB and STAT3 activation in colon cancer cells in an inflammatory microenvironment. Therefore, RA suppressed colitis-associated tumorigenesis in the AOM/DSS-induced CAC murine model and abrogated human colon cancer progression in an inflammatory microenvironment by propitiating TLR4-mediated NF-κB and STAT3 activation, pleiotropically.

Integrated microenvironment-associated genomic profiles identify LRRC15 mediating recurrent glioblastoma-associated macrophages infiltration

Glioblastoma (GBM) is the most common malignant intracranial tumour with intrinsic infiltrative characteristics, which could lead to most patients eventually relapse. The prognosis of recurrent GBM patients remains unsatisfactory. Cancer cell infiltration and their interaction with the tumour microenvironment (TME) could promote tumour recurrence and treatment resistance. In our study, we aimed to identify potential tumour target correlated with rGBM microenvironment based on the gene expression profiles and clinical information of rGBM patients from The Cancer Genome Atlas (TCGA) database. LRRC15 gene with prognostic value was screened by univariate and multivariate analysis, and the correlation between macrophages and LRRC15 was identified as well. Furthermore, the prognosis correlation and immune characteristics of LRRC15 were validated using the Chinese Glioma Genome Atlas (CGGA) database and our clinical tissues by immunochemistry assay. Additionally, we utilized the transwell assay and carboxy fluorescein succinimidyl ester (CFSE) tracking to further confirm the effects of LRRC15 on attracting microglia/macrophages and tumour cell proliferation in the TME. Gene profiles‐based rGBM microenvironment identified that LRRC15 could act in collusion with microglia/macrophages in the rGBM microenvironment to promote the poor prognosis, especially in mesenchymal subtype, indicating the strategies of targeting LRRC15 to improve macrophages‐based immunosuppressive effects could be promising for rGBM treatments.

Correlation of CD47 Expression with Adverse Clinicopathologic Features and an Unfavorable Prognosis in Colorectal Adenocarcinoma

CD47, a transmembrane protein, is widely overexpressed on the tumor cell surface. However, the prognostic significance of CD47 expression in colorectal adenocarcinoma (CRA) has not yet been clarified. Here, we investigated the clinicopathologic significance of CD47 expression in CRA. CD47 expression was evaluated via immunohistochemical analysis of microarray sections of 328 CRA tissues. CD47 expression was observed in 53 (16.2%) of the 328 CRA tissues, and positive expression was associated with lymphatic invasion (p = 0.018), perineural invasion (p = 0.024), tumor budding (p = 0.009), the pathologic N stage (p = 0.022), and the American Joint Committee on Cancer (AJCC) stage (p = 0.027). In survival analyses of 329 patients, a positive CD47 expression was associated with a poor recurrence-free survival (RFS) (p = 0.032). In multivariate analysis, however, it was not an independent prognostic factor. In patients who underwent surgical resection without adjuvant treatment, a positive CD47 expression was associated with a shorter RFS (p = 0.001) but not with cancer-specific survival (CSS). In patients who received postoperative adjuvant treatment, no significant differences were found in both RFS and CSS. In conclusion, we investigated CD47 expression in 328 CRA tissues. A positive CD47 expression was observed in a minority (16.2%) of the tissues and was significantly associated with adverse clinicopathologic features and a poor patient outcome.

Hydrogen gas represses the progression of lung cancer via down-regulating CD47

Hydrogen gas (H₂) has been identified to play an anti-tumor role in several kinds of cancers, but the molecular mechanisms remain largely unknown. In our previous study, our project group found that H₂ could decrease the expression of CD47 in lung cancer A549 cells via the next-generation sequencing, indicating that CD47 might be involved in H₂-mediated lung cancer repression. Therefore, the present study aimed to explore the effects of CD47 on H₂-induced lung cancer repression. Western blotting and real-time PCR (RT-PCR) assays were used to detect the levels of proteins and mRNAs, respectively. Cell proliferation, invasion, migration and apoptosis were detected by using the cell counting kit-8 (CCK-8), Transwell chambers, wound healing and flow cytometry assays, respectively. The results showed that H₂ treatment caused decreases in the expression levels of CD47 and cell division control protein 42 (CDC42) in a dose-dependent manner. Up-regulation of CD47 abolished H₂ roles in promoting lung cancer cell apoptosis and repressing cell growth, invasion and migration in both A549 and H1975 cell lines. However, knockdown of CD47 enhanced H₂ role in lung cancer inhibition. Moreover, we also observed that H₂ treatment induced obvious inhibitions in the expression levels of CDC42 and CD47 in mice tumor tissues, as well as reinforced macrophage-mediated phagocytosis in A549 and H1975 cells. In conclusion, the current study reveals that H₂ inhibits the progression of lung cancer via down-regulating CD47, which might be a potent method for lung cancer treatment.

Targeting CD47 Inhibits Tumor Development and Increases Phagocytosis in Oral Squamous Cell Carcinoma

BACKGROUND

Our previous work demonstrated upregulated CD47 in Oral Squamous Cell Carcinoma (OSCC).

OBJECTIVE

In the present study, we aimed to investigate the effects of CD47 on tumor cell development and phagocytosis in OSCC and elucidate the underlying mechanisms.

METHODS

The proliferation, apoptosis, migration, and invasion of oral cancer cells were analyzed after knocking down the expression of CD47. The effects of CD47 on tumor development were also evaluated using a murine model of OSCC. The involvement of CD47 in the phagocytosis of oral cancer cells was identified.

RESULTS

Cell proliferation was suppressed by knocking down the expression of CD47 in human OSCC cell line Cal-27 cells but there was no change in the apoptosis rate. Moreover, impaired expression of CD47 inhibited the migration and invasion of Cal-27 cells. Furthermore, we found that nude mice injected with CD47 knockeddown Cal-27 cells displayed decreased tumor volumes at week 9 compared to xenograft transplantations of blank Cal-27 cells. In addition, in vitro phagocytosis of Cal-27 cells by macrophages was significantly enhanced after the knockdown of CD47, which positively correlated with compromised STAT3/JAK2 signaling.

CONCLUSION

In summary, the knockdown of CD47 downregulated the development of OSCC and increased the phagocytosis of Cal-27 cells, indicating that CD47 might be a promising therapeutic target.

The role of CD47-SIRPα immune checkpoint in tumor immune evasion and innate immunotherapy

As a transmembrane protein, CD47 plays an important role in mediating cell proliferation, migration, phagocytosis, apoptosis, immune homeostasis, inhibition of NO signal transduction and other related reactions. Upon the interaction of innate immune checkpoint CD47-SIRPα occurrence, they send a "don't eat me" signal to the macrophages. This signal ultimately helps tumors achieve immune escape by inhibiting macrophage contraction to prevent tumor cells from phagocytosis. Therefore, the importance of CD47-SIRPα immune checkpoint inhibitors in tumor immunotherapy has attracted more attention in recent years. Based on the cognitive improvement of the effect with CD47 in tumor microenvironment and tumor characteristics, the pace of tumor treatment strategies for CD47-SIRPα immune checkpoint inhibitors has gradually accelerated. In this review, we introduced the high expression of CD47 in cancer cells to avoid phagocytosis by immune cells and the importance of CD47 in the structure of cancer microenvironment and the maintenance of cancer cell characteristics. Given the role of the innate immune system in tumorigenesis and development, an improved understanding of the anti-tumor process of innate immune checkpoint inhibitors can lay the foundation for more effective combinations with other anti-tumor treatment strategies.

Advances in Modeling the Immune Microenvironment of Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer and second leading cause of cancer-related death in the US. CRC frequently metastasizes to the liver and these patients have a particularly poor prognosis. The infiltration of immune cells into CRC tumors and liver metastases accurately predicts disease progression and patient survival. Despite the evident influence of immune cells in the CRC tumor microenvironment (TME), efforts to identify immunotherapies for CRC patients have been limited. Here, we argue that preclinical model systems that recapitulate key features of the tumor microenvironment-including tumor, stromal, and immune cells; the extracellular matrix; and the vasculature-are crucial for studies of immunity in the CRC TME and the utility of immunotherapies for CRC patients. We briefly review the discoveries, advantages, and disadvantages of current in vitro and in vivo model systems, including 2D cell culture models, 3D culture systems, murine models, and organ-on-a-chip technologies.

A Novel Blockade CD47 Antibody With Therapeutic Potential for Cancer

Macrophages as components of the innate immune system play a critical role in antitumor responses. Strategies for targeting CD47 are becoming a hot spot for cancer therapy. The expression of CD47 is exercised by macrophages to make a distinction between “self” or “nonself.” Anti-CD47 antibodies block the interaction between macrophage signal regulatory protein-α (SIRPα) and tumor surface CD47. In this study, we report and assess a novel anti-CD47 blocking antibody named 2C8, which exhibits high affinity and tremendous anticancer effects. More concretely, 2C8 significantly induces macrophages, including protumorigenic subtype M2 macrophages killing tumor cells in vitro, and is revealed to be more effective than commercially available anti-CD47 mAb B6H12.2. In vivo, 2C8 controls tumor growth and extends survival of xenograft mice. The antitumor ability of 2C8 might be applicable to many other cancers. The generation of a novel CD47 antibody contributes to consolidating clinical interest in targeting macrophages for the treatment of malignancy and, moreover, as a supplement therapy when patients are resistant or refractory to other checkpoint therapies or relapse after such treatments.

The Prognostic Role of Macrophage Polarization in the Colorectal Cancer Microenvironment

Macrophages are among the most common cells in the colorectal cancer microenvironment, but their prognostic significance is incompletely understood. Using multiplexed immunofluorescence for CD68, CD86, IRF5, MAF, MRC1 (CD206), and KRT (cytokeratins) combined with digital image analysis and machine learning, we assessed the polarization spectrum of tumor-associated macrophages in 931 colorectal carcinomas. We then applied Cox proportional hazards regression to assess prognostic survival associations of intraepithelial and stromal densities of M1-like and M2-like macrophages while controlling for potential confounders, including stage and microsatellite instability status. We found that high tumor stromal density of M2-like macrophages was associated with worse cancer-specific survival, whereas tumor stromal density of M1-like macrophages was not significantly associated with better cancer-specific survival. High M1:M2 density ratio in tumor stroma was associated with better cancer-specific survival. Overall macrophage densities in tumor intraepithelial or stromal regions were not prognostic. These findings suggested that macrophage polarization state, rather than their overall density, was associated with cancer-specific survival, with M1- and M2-like macrophage phenotypes exhibiting distinct prognostic roles. These results highlight the utility of a multimarker strategy to assess the macrophage polarization at single-cell resolution within the tumor microenvironment.

Enhancing antibody-dependent cellular phagocytosis by Re-education of tumor-associated macrophages with resiquimod-encapsulated liposomes

Tumor-associated macrophages (TAMs) exist in nearly all tumors, and form a major part of the tumor microenvironment. TAMs are divided into two groups: tumor-suppressing M1 type and tumor-promoting M2 type. Most TAMs are educated by the tumor cells to become M2 type, which support tumor growth and make immunotherapy ineffective. Antibody-dependent cellular phagocytosis (ADCP) is an important mechanism for antibody cancer therapy, and this mechanism is dependent on TAMs. In this study, we found that the M1 type macrophages elicit a more efficient ADCP response than the M2 type, which was confirmed by three tumor cell lines, Raji, A431, and SKBR3, along with their corresponding therapeutic antibody Rituximab, anti-EGFR mouse monoclonal antibody (clone 528), and Trastuzumab, respectively. Resiquimod (R848), an immune system activating agent, has been shown to stimulate the M1 type macrophages, and re-educate the TAMs from M2 type to M1 type. By treating TAMs with R848, the ADCP response increased significantly in vitro and in in vivo mouse xenograft models. R848 encapsulated liposomes (R848-LPs) not only accumulated efficiently in the tumor tissues, but also distributed in the TAMs. Synergizing the R848-LPs with the anti-EGFR mouse monoclonal antibody (clone 528) significantly inhibited WiDr-tumor growth in vivo. Our study also revealed that the TAM-targeted delivery of R848 is able to re-educate the TAMs to M1 type, enhance the ADCP effect of the antibodies, and hence, enhance the anti-tumor effect of the therapeutic antibodies.

Potential New Cancer Immunotherapy: Anti-CD47-SIRPα Antibodies

CD47 belongs to immunoglobulin superfamily and is widely expressed on the surface of cell membrane, while another transmembrane protein SIRPα is restricted to the surface of macrophages, dendritic cells, and nerve cells. As a cell surface receptor and ligand, respectively, CD47 and SIRPα interact to regulate cell migration and phagocytic activity, and maintain immune homeostasis. In recent years, studies have found that immunoglobulin superfamily CD47 is overexpressed widely across tumor types, and CD47 plays an important role in suppressing phagocytes activity through binding to the transmembrane protein SIRPα in phagocytic cells. Therefore, targeting CD47 may be a novel strategy for cancer immunotherapy, and a variety of anti-CD47 antibodies have appeared, such as humanized 5F9 antibody, B6H12 antibody, ZF1 antibody, and so on. This review mainly describes the research history of CD47-SIRPα and focuses on macrophage-mediated CD47-SIRPα immunotherapy of tumors.