Tumor-associated macrophages, potential targets for cancer treatment

Candida albicans-Derived β-Glucan as a Novel Modulator of Tumor Microenvironment: Targeting Macrophage Polarization and Inducing Ferroptosis in Lung Cancer

Introduction

Tumor-associated macrophages (TAMs) play a crucial role in the tumor microenvironment (TME), and their polarization state significantly influences patient outcomes. This study investigates the inhibitory effects of β-glucan extracted from Candida albicans on lung cancer progression, focusing on its impact on TAM polarization and the induction of ferroptosis, a form of regulated cell death.

Methods

Utilizing both in vivo animal models and in vitro cellular assays, we assessed the impact of β-glucan on tumor growth, cellular proliferation, and migration. We evaluated TAM polarization by analyzing the expression of M1 and M2 markers and identified differentially expressed genes (DEGs) related to ferroptosis. The role of ferroptosis in TAM polarization was further confirmed by assessing the protein levels of ACSL4 and GPX4, intracellular ferrous ion levels, and lipid peroxides.

Results

β-glucan treatment significantly reduced tumor size and weight, along with cellular proliferation and migration, suggesting a potent suppressive effect on lung cancer cell growth. β-glucan promoted an M1-like phenotype in TAMs, as evidenced by increased CD86 expression and decreased CD206 expression, and modulated cytokine mRNA levels. RNA sequencing analysis post β-glucan treatment identified a substantial number of DEGs enriched in the ferroptosis pathway. The induction of ferroptosis by β-glucan was further confirmed through the significant upregulation of ACSL4 and downregulation of GPX4, alongside increased intracellular ferrous ion levels and lipid peroxides. The ferroptosis inhibitor Fer-1 abrogated these effects, highlighting the specificity of β-glucan-mediated polarization.

Conclusion

These results collectively provide novel insights into the immunotherapeutic potential of β-glucan from Candida albicans and its role in modulating TAM polarization and lung cancer growth, offering a promising avenue for cancer treatment strategies.

SPDYC serves as a prognostic biomarker related to lipid metabolism and the immune microenvironment in breast cancer

Breast cancer remains the most common malignant carcinoma among women globally and is resistant to several therapeutic agents. There is a need for novel targets to improve the prognosis of patients with breast cancer. Bioinformatics analyses were conducted to explore potentially relevant prognostic genes in breast cancer using The Cancer Genome Atlas (TCGA) and The Gene Expression Omnibus (GEO) databases. Gene subtypes were categorized by machine learning algorithms. The machine learning-related breast cancer (MLBC) score was evaluated through principal component analysis (PCA) of clinical patients' pathological statuses and subtypes. Immune cell infiltration was analyzed using the xCell and CIBERSORT algorithms. Kyoto Encyclopedia of Genes and Genomes enrichment analysis elucidated regulatory pathways related to speedy/RINGO cell cycle regulator family member C (SPDYC) in breast cancer. The biological functions and lipid metabolic status of breast cancer cell lines were validated via quantitative real-time polymerase chain reaction (RT‒qPCR) assays, western blotting, CCK-8 assays, PI‒Annexin V fluorescence staining, transwell assays, wound healing assays, and Oil Red O staining. Key differentially expressed genes (DEGs) in breast cancer from the TCGA and GEO databases were screened and utilized to establish the MLBC score. Moreover, the MLBC score we established was negatively correlated with poor prognosis in breast cancer patients. Furthermore, the impacts of SPDYC on the tumor immune microenvironment and lipid metabolism in breast cancer were revealed and validated. SPDYC is closely related to activated dendritic cells and macrophages and is simultaneously correlated with the immune checkpoints CD47, cytotoxic T lymphocyte antigen-4 (CTLA-4), and poliovirus receptor (PVR). SPDYC strongly correlated with C-C motif chemokine ligand 7 (CCL7), a chemokine that influences breast cancer patient prognosis. A significant relationship was discovered between key genes involved in lipid metabolism and SPDYC, such as ELOVL fatty acid elongase 2 (ELOVL2), malic enzyme 1 (ME1), and squalene epoxidase (SQLE). Potent inhibitors targeting SPDYC in breast cancer were also discovered, including JNK inhibitor VIII, AICAR, and JW-7-52-1. Downregulation of SPDYC expression in vitro decreased proliferation, increased the apoptotic rate, decreased migration, and reduced lipid droplets. SPDYC possibly influences the tumor immune microenvironment and regulates lipid metabolism in breast cancer. Hence, this study identified SPDYC as a pivotal biomarker for developing therapeutic strategies for breast cancer.

Unveiling the contribution of tumor-associated macrophages in driving epithelial-mesenchymal transition: a review of mechanisms and therapeutic Strategies

Tumor-associated macrophages (TAMs), fundamental constituents of the tumor microenvironment (TME), significantly influence cancer development, primarily by promoting epithelial-mesenchymal transition (EMT). EMT endows cancer cells with increased motility, invasiveness, and resistance to therapies, marking a pivotal juncture in cancer progression. The review begins with a detailed exposition on the origins of TAMs and their functional heterogeneity, providing a foundational understanding of TAM characteristics. Next, it delves into the specific molecular mechanisms through which TAMs induce EMT, including cytokines, chemokines and stromal cross-talking. Following this, the review explores TAM-induced EMT features in select cancer types with notable EMT characteristics, highlighting recent insights and the impact of TAMs on cancer progression. Finally, the review concludes with a discussion of potential therapeutic targets and strategies aimed at mitigating TAM infiltration and disrupting the EMT signaling network, thereby underscoring the potential of emerging treatments to combat TAM-mediated EMT in cancer. This comprehensive analysis reaffirms the necessity for continued exploration into TAMs' regulatory roles within cancer biology to refine therapeutic approaches and improve patient outcomes.

The role of CD8+ T-cells in colorectal cancer immunotherapy

Immunotherapy has been an advanced and effective approach to treating various types of solid tumors in recent years, and the most successful strategy is immune checkpoint inhibitors (ICIs), which have shown beneficial effects in patients with colorectal cancer (CRC). Drug resistance to ICIs is usually associated with CD8+ T-cells targeting tumor antigens; thus, CD8+ T-cells play an important role in immunotherapy. Unfortunately, Under continuous antigen stimulation, tumor microenvironment(TME), hypoxia and other problems it leads to insufficient infiltration of CD8+ T-cells, low efficacy and mechanism exhaustion, which have become obstacles to immunotherapy. Thus, this article describes the relationship between CRC and the immune system, focuses on the process of CD8+ T-cells production, activation, transport, killing, and exhaustion, and expounds on related mechanisms leading to CD8+ T-cells exhaustion. Finally, this article summarizes the latest strategies and methods in recent years, focusing on improving the infiltration, efficacy, and exhaustion of CD8+ T-cells, which may help to overcome the barriers to immunotherapy.

Tumor-Targeted Codelivery of CpG and siRNA by a Dual-Ligand-Functionalized Curdlan Nanoparticle

The simultaneous delivery of CpG oligonucleotide along with short interfering RNA (siRNA) has the potential to significantly boost the anticancer impact of siRNA medications. Our previous research demonstrated that Curdlan nanoparticles functionalized with adenosine are capable of selectively delivering therapeutic siRNA to cancerous cells through endocytosis mediated by adenosine receptors. Herein, we synthesized a dual-ligand-functionalized Curdlan polymer (denoted by CuMAN) to simultaneously target tumor cells and tumor-associated macrophages (TAMs). CuMAN nanoparticles containing CpG and siRNA demonstrated enhanced uptake by B16F10 tumor cells and bone marrow-derived macrophages, which are facilitated by AR on tumor cells and mannose receptor on macrophages. This led to increased release of pro-inflammatory cytokines in both in vitro and in vivo settings. The synergistic effect of CpG on TAMs and RNAi on tumor cells mediated by the CuMAN nanoparticle not only suppressed the tumor growth but also strongly inhibited the lung metastasis. Our findings indicate that the CuMAN nanoparticle has potential as an effective dual-targeting delivery system for nucleic acid therapeutics.

Low molecular weight fucoidan LF2 improves the immunosuppressive tumor microenvironment and enhances the anti-pancreatic cancer activity of oxaliplatin

Chemotherapy remains the cornerstone of pancreatic cancer treatment. However, the dense interstitial and immunosuppressive microenvironment frequently render the ineffective anti-tumor activity of chemotherapeutic agents. Macrophages play a key role in the tumor immunomodulation. In this study, we found that low molecular weight of fucoidan (LF2) directly regulated the differentiation of mononuclear macrophages into the CD86+ M1 phenotype. LF2 significantly upregulated the expressions of M1 macrophage-specific cytokines, including iNOS, IL-6, TNFα and IL-12. LF2 modulated macrophage phenotypic transformation through activation of TLR4-NFκB pathway. Furthermore, we observed that LF2 enhanced the pro-apoptotic activity of oxaliplatin (OXA) in vitro by converting macrophages to a tumoricidal M1 phenotype. Meanwhile, LF2 increased intratumoral M1 macrophage infiltration and ameliorated the immunosuppressed tumor microenvironment, which in turn enhanced the anti-pancreatic ductal adenocarcinoma (PDAC) activity of OXA in vivo. Taken together, our results suggested that LF2 could act as a TLR4 agonist targeting macrophages and has a synergistic effect against PDAC when combined with OXA.

RUNX1 promotes angiogenesis in colorectal cancer by regulating the crosstalk between tumor cells and tumor associated macrophages

Colorectal cancer (CRC) is a common malignancy worldwide. Angiogenesis and metastasis are the critical hallmarks of malignant tumor. Runt-related transcription factor 1 (RUNX1), an efficient transcription factor, facilitates CRC proliferation, metastasis and chemotherapy resistance. We aimed to investigate the RUNX1 mediated crosstalk between tumor cells and M2 polarized tumor associated macrophages (TAMs) in CRC, as well as its relationship with neoplastic angiogenesis. We found that RUNX1 recruited macrophages and induced M2 polarized TAMs in CRC by promoting the production of chemokine 2 (CCL2) and the activation of Hedgehog pathway. In addition, we found that the M2 macrophage-specific generated cytokine, platelet-derived growth factor (PDGF)-BB, promoted vessel formation both in vitro and vivo. PDGF-BB was also found to enhance the expression of RUNX1 in CRC cell lines, and promote its migration and invasion in vitro. A positive feedback loop of RUNX1 and PDGF-BB was thus formed. In conclusion, our data suggest that RUNX1 promotes CRC angiogenesis by regulating M2 macrophages during the complex crosstalk between tumor cells and TAMs. This observation provides a potential combined therapy strategy targeting RUNX1 and TAMs-related PDGF-BB in CRC.

Discovery of novel tumor-targeted near-infrared probes with 6-substituted pyrrolo[2,3-d]pyrimidines as targeting ligands

Since the overexpression of folate receptors (FRs) in certain types of cancers, a variety of FR-targeted fluorescent probes for tumor detection have been developed. However, the reported probes almost all have the same targeting ligand of folic acid with various fluorophores and/or linkers. In the present study, a series of novel tumor-targeted near-infrared (NIR) molecular fluorescent probes were designed and synthesized based on previously reported 6-substituted pyrrolo[2,3-d]pyrimidine antifolates. All newly synthesized probes showed specific FR binding in vitro, whereas GT-NIR-4 and GT-NIR-5 with a benzene and a thiophene ring, respectively, on the side chain of pyrrolo[2,3-d]pyrimidine exhibited better FR binding affinity than that of GT-NIR-6 with folic acid as targeting ligand. GT-NIR-4 also showed high tumor uptake in KB tumor-bearing mice with good pharmacokinetic properties and biological safety. This work demonstrates the first attempt to replace folic acid with antifolates as targeting ligands for tumor-targeted NIR probes.

Targeting toll-like receptor 7/8 for immunotherapy: recent advances and prospectives

Toll-like receptors (TLRs) are a large family of proteins that are expressed in immune cells and various tumor cells. TLR7/8 are located in the intracellular endosomes, participate in tumor immune surveillance and play different roles in tumor growth. Activation of TLRs 7 and 8 triggers induction of a Th1 type innate immune response in the highly sophisticated process of innate immunity signaling with the recent research advances involving the small molecule activation of TLR 7 and 8. The wide range of expression and clinical significance of TLR7/TLR8 in different kinds of cancers have been extensively explored. TLR7/TLR8 can be used as novel diagnostic biomarkers, progression and prognostic indicators, and immunotherapeutic targets for various tumors. Although the mechanism of action of TLR7/8 in cancer immunotherapy is still incomplete, TLRs on T cells are involved in the regulation of T cell function and serve as co-stimulatory molecules and activate T cell immunity. TLR agonists can activate T cell-mediated antitumor responses with both innate and adaptive immune responses to improve tumor therapy. Recently, novel drugs of TLR7 or TLR8 agonists with different scaffolds have been developed. These agonists lead to the induction of certain cytokines and chemokines that can be applied to the treatment of some diseases and can be used as good adjutants for vaccines. Furthermore, TLR7/8 agonists as potential therapeutics for tumor-targeted immunotherapy have been developed. In this review, we summarize the recent advances in the development of immunotherapy strategies targeting TLR7/8 in patients with various cancers and chronic hepatitis B.

Exosomal lncRNA HOTAIR induce macrophages to M2 polarization via PI3K/ p-AKT /AKT pathway and promote EMT and metastasis in laryngeal squamous cell carcinoma

Exosomes are a new way of the communication between the tumor cell and macrophage in the micro-environment. The macrophage can be induced to different phenotypes according to the different tumors. In the present study, long-chain noncoding RNA HOTAIR (lncRNA HOTAIR) was highly expressed in LSCC and exosomes. The pathway of exosomal lncRNA HOTAIR inducing macrophage to M2 polarization in the LSCC was investigated. The carcinoma tissues and adjacent tissues were collected from 104 LSCC cases, and the positive relationship between CD163-/CD206-M2 macrophage infiltration and clinical phase, lymph node spreading and pathological phase in LSCC was observed. To examine the role of exosomal lncRNA HOTAIR, macrophages were co-cultured with LSCC-exosomes of high lncRNA HOTAIR expression or transferred with HOTAIR mimics. It was suggested that exosomal lncRNA HOTAIR can induce macrophages to M2 polarization by PI3K/p-AKT/AKT signaling pathway. Furthermore, exo-treated M2 macrophages facilitate the migration, proliferation, and EMT of LSCC.

Tumor-promoting myeloid cells in the pathogenesis of human oncoviruses: potential targets for immunotherapy

Oncoviruses, known as cancer-causing viruses, are typically involved in cancer progression by inhibiting tumor suppressor pathways and uncontrolled cell division. Myeloid cells are the most frequent populations recruited to the tumor microenvironment (TME) and play a critical role in cancer development and metastasis of malignant tumors. Tumor-infiltrating myeloid cells, including tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), tumor-associated dendritic cells (TADCs), and tumor-associated neutrophils (TANs) exert different states from anti-tumorigenic to pro-tumorigenic phenotypes in TME. Although their role in the anti-tumorigenic state is well introduced, their opposing roles, pro-tumorigenic activities, such as anti-inflammatory cytokine and reactive oxygen species (ROS) production, should not be ignored since they result in inflammation, tumor progression, angiogenesis, and evasion. Since the blockade of these cells had promising results against cancer progression, their inhibition might be helpful in various cancer immunotherapies. This review highlights the promoting role of tumor-associated myeloid cells (TAMCs) in the pathophysiology of human virus tumorigenesis.

Fucoidan, as an immunostimulator promotes M1 macrophage differentiation and enhances the chemotherapeutic sensitivity of capecitabine in colon cancer

Chemotherapy resistance is one of the most critical challenges in colorectal cancer (CRC) treatment. The occurrence and development of chemotherapy resistance closely related to the tumor immune microenvironment (TIME). As the most important immunosuppressive immune cells infiltrating into the TIME, macrophages are essential for chemotherapy resistance in CRC treatment. In this study, we found that a kind of fucoidan (FPS1M) induced macrophages differentiation to the M1 phenotype, and this transformation promoted cancer cells apoptosis both in vitro and in vivo. TNFα is a key mediator of FPS1M-induced tumorcidal activity of macrophages. Mechanistically, as a stimulator of TLR4, FPS1M enhanced macrophages glycolysis and regulated macrophages differentiation to the M1 phenotype by the activation of TLR4 mediated PI3K/AKT/mTOR signaling axis. In addition, FPS1M improved the immunosuppressed tumor microenvironment by increasing the infiltration of M1 macrophages in tumor tissue, which was conducive to improving the sensitivity of tumor to chemotherapy. Collectively, our findings demonstrated that FPS1M has the great potential to be used in tumor immunotherapy. The results also suggested that the combination of FPS1M with capecitabine is an alternative therapy method for colon cancer.

Similarities between wound re-epithelialization and Metastasis in ESCC and the crucial involvement of macrophages: A review

In cancer, tumor-associated macrophages (TAMs) possess crucial functions in facilitating epithelial-mesenchymal transition (EMT). EMT is a crucial process in tumor metastasis. Tumor metastasis is one of the hallmarks of cancer and leads to patient mortality. Cancer cells often find ways to evade being detected and attacked by the immune system. This is achieved by cross-talk between cancer cells and the altered microenvironment. The accumulation of tumor-associated macrophages (TAMs) in the tumor microenvironment (TME) creates an immunosuppressive and tumor-supportive environment. Circulating monocytes and macrophages which are recruited into tumors are defined as tumor-associated macrophages once in the TME. Based on the activated stimuli and function, macrophages can be divided into M1 macrophages and M2 macrophages. M1 macrophages, also known as classically activated macrophages, exhibit pro-inflammatory and antitumor activities. M2 macrophages, also known as alternatively activated macrophages, exhibit anti-inflammatory, pro-tumorigenic, and wound healing activities. TAMs are considered to be of the M2 phenotype. The TME polarizes recruited macrophages into M2 macrophages as they provide an immunosuppressive pro-tumoral environment. Accumulating studies show that the presence of TAMs in esophageal squamous cell carcinoma (ESCC) leads to tumor progression. In this review, we discuss how EMT can be used by TAMs to cause tumor migration and metastasis in ESCC. We also discuss the potential therapies targeting TAMs.

Cervical Cancer Outcome and Tumor-Associated Macrophages: Research Evidence

Inflammation is a key factor in cancer promotion. Tumor-associated macrophages (TAMs), as part of the tumor microenvironment, are often associated with the progression of tumors and a worse prognosis in many cancers, namely on cervical cancer. This work exhaustively summarizes the conclusions of the different studies published concerning TAMs function in cervical cancer, from in vitro studies using cancer cell lines to the clinical perspective (histological samples-based studies). Most studies have led to the conclusion that TAMs increased density is directly related to increased severity of a malignant cervical lesion. Additionally, TAMs are normally polarized into an M2 phenotype, benefiting and promoting tumor progression, resulting in a worse disease outcome. The tumor microenvironment is also a highly critical contributor that not only influences tumor natural history but also modulates the specific immune response.

Leveraging macrophages for cancer theranostics

As fundamental immune cells in innate and adaptive immunity, macrophages engage in a double-edged relationship with cancer. Dissecting the character of macrophages in cancer development facilitates the emergence of macrophages-based new strategies that encompass macrophages as theranostic targets/tools of interest for treating cancer. Herein, we provide a concise overview of the mixed roles of macrophages in cancer pathogenesis and invasion as a foundation for the review discussions. We survey the latest progress on macrophage-based cancer theranostic strategies, emphasizing two major strategies, including targeting the endogenous tumor-associated macrophages (TAMs) and engineering the adoptive macrophages to reverse the immunosuppressive environment and augment the cancer theranostic efficacy. We also discuss and provide insights on the major challenges along with exciting opportunities for the future of macrophage-based cancer theranostic approaches.

The Emerging Role of Tissue-Resident Memory CD8+ T Lymphocytes in Human Digestive Tract Cancers

Malignant digestive tract tumors are a great threat to human public health. In addition to surgery, immunotherapy brings hope for the treatment of these tumors. Tissue-resident memory CD8⁺ T (Trm) cells are a focus of tumor immunology research and treatment due to their powerful cytotoxic effects, ability to directly kill epithelial-derived tumor cells, and overall impact on maintaining mucosal homeostasis and antitumor function in the digestive tract. They are a group of noncirculating immune cells expressing adhesion and migration molecules such as CD69, CD103, and CD49a that primarily reside on the barrier epithelium of nonlymphoid organs and respond rapidly to both viral and bacterial infection and tumorigenesis. This review highlights new research exploring the role of CD8⁺ Trm cells in a variety of digestive tract malignant tumors, including esophageal cancer, gastric cancer, colorectal cancer, and hepatocellular carcinoma. A summary of CD8⁺ Trm cell phenotypes and characteristics, tissue distribution, and antitumor functions in different tumor environments is provided, illustrating how these cells may be used in immunotherapies against digestive tract tumors.

Prognostic Value of Macrophage-Associated Long Non-Coding RNA Expression for Hepatocellular Carcinoma

Background

There is ample evidence that macrophages play a crucial role in the biological processes of hepatocellular carcinoma (HCC). This study was designed to establish a novel macrophage-associated prognostic model for HCC.

Methods

Long non-coding RNA (lncRNA) microarrays and clinical data in The Cancer Genome Atlas (TCGA) database were analysed using a univariate Cox proportional regression model to select macrophage-associated prognostic lncRNAs. Multivariate Cox proportional regression models and survival analysis were used to establish a prognosis index (PI) model. Furthermore, to better understand the biological functions of differentially expressed macrophage-associated lncRNAs (MALs) in HCC, enrichment analysis was performed. Finally, the correlation between MALs and clinical features was further analysed in HCC.

Results

We identified eight MALs with significant prognostic values for HCC. Next, a PI model for HCC was developed, and patients were classified into the high-risk or low-risk group based on risk scores. The overall survival (OS) of high-risk patients was significantly shorter than that of low-risk patients (P < 0.001). Univariate and multivariate factors indicate that risk scores can be used as independent prognostic factors for patients with HCC. Multiple receiver operating characteristic (ROC) plots show that the area under the ROC curve (AUC) of the risk score is higher than that of other clinical features. The C-index of our nomogram was 0.768.

Conclusion

The PI model has a prognostic efficacy superior to that of other clinical features.

Immunotherapy for Hepatocellular Carcinoma: New Prospects for the Cancer Therapy

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related death worldwide. HCC patients may benefit from liver transplantation, hepatic resection, radiofrequency ablation, transcatheter arterial chemoembolization, and targeted therapies. The increased infiltration of immunosuppressive immune cells and the elevated expression of immunosuppressive factors in the HCC microenvironment are the main culprits of the immunosuppressive nature of the HCC milieu. The immunosuppressive tumor microenvironment can substantially attenuate antitumoral immune responses and facilitate the immune evasion of tumoral cells. Immunotherapy is an innovative treatment method that has been promising in treating HCC. Immune checkpoint inhibitors (ICIs), adoptive cell transfer (ACT), and cell-based (primarily dendritic cells) and non-cell-based vaccines are the most common immunotherapeutic approaches for HCC treatment. However, these therapeutic approaches have not generally induced robust antitumoral responses in clinical settings. To answer to this, growing evidence has characterized immune cell populations and delineated intercellular cross-talk using single-cell RNA sequencing (scRNA-seq) technologies. This review aims to discuss the various types of tumor-infiltrating immune cells and highlight their roles in HCC development. Besides, we discuss the recent advances in immunotherapeutic approaches for treating HCC, e.g., ICIs, dendritic cell (DC)-based vaccines, non-cell-based vaccines, oncolytic viruses (OVs), and ACT. Finally, we discuss the potentiality of scRNA-seq to improve the response rate of HCC patients to immunotherapeutic approaches.

Peptide-guided resiquimod-loaded lignin nanoparticles convert tumor-associated macrophages from M2 to M1 phenotype for enhanced chemotherapy

Nanomedicines represent innovative and promising alternative technologies to improve the therapeutic effects of different drugs for cancer ablation. Targeting M2-like tumor-associated macrophages (TAMs) has emerged as a favorable therapeutic approach to fight against cancer through the modulation of the tumor microenvironment. However, the immunomodulatory molecules used for this purpose present side effects upon systemic administration, which limits their clinical translation. Here, the biocompatible lignin polymer is used to prepare lignin nanoparticles (LNPs) that carry a dual agonist of the toll-like receptors TLR7/8 (resiquimod, R848). These LNPs are targeted to the CD206-positive M2-like TAMs using the "mUNO" peptide, in order to revert their pro-tumor phenotype into anti-tumor M1-like macrophages in the tumor microenvironment of an aggressive triple-negative in vivo model of breast cancer. Overall, we show that targeting the resiquimod (R848)-loaded LNPs to the M2-like macrophages, using very low doses of R848, induces a profound shift in the immune cells in the tumor microenvironment towards an anti-tumor immune state, by increasing the representation of M1-like macrophages, cytotoxic T cells, and activated dendritic cells. This effect consequently enhances the anticancer effect of the vinblastine (Vin) when co-administered with R848-loaded LNPs. STATEMENT OF SIGNIFICANCE: Lignin-based nanoparticles (LNPs) were successfully developed to target a potent TLR7/8 agonist (R848) of the tumor microenvironment (TME). This was achieved by targeting the mannose receptor (CD206) on the tumor supportive (M2-like) macrophages with the "mUNO" peptide, to reprogram them into an anti-tumor (M1-like) phenotype for enhanced chemotherapy. LNPs modified the biodistribution of the R848, and enhanced its accumulation and efficacy in shifting the immunological profile of the cells in the TME, which was not achieved by systemic administration of free R848. Moreover, a reduction in the tumor volumes was observed at lower equivalent doses of R848 compared with other studies. Therefore, the co-administration of R848@LNPs is a promising chemotherapeutic application in aggressive tumors, such as the triple-negative breast cancer.

IL-33/ST2 as a potential target for tumor immunotherapy

IL-33, a member of the IL-1 family, was initially reported to be expressed constitutively in the nucleus of tissue-lining and structural cells. However, upon tissue damage or injury, IL-33 can be released quickly to bind with its cognate receptor ST2 in response to wound healing and inflammation and act as a DAMP. As a key regulator of Th2 responses, IL-33/ST2 signal is primarily associated with immunity and immune-related disorders. In recent years, IL-33/ST2 signaling pathway has been reported to promote the development of cancer and remodel the tumor microenvironment by expanding immune suppressive cells such as myeloid-derived suppressor cells or regulatory T cells. However, its role remains controversial in some tumor settings. IL-33 could also promote effective infiltration of immune cells such as CD8⁺ T and NK cells, which act as antitumor. These dual effects may limit the clinical application to target this cytokine axis. Therefore, more comprehensive exploration and deeper understanding of IL-33 are required. In this review, we summarized the IL-33/ST2 axis versatile roles in the tumor microenvironment with a focus on the IL-33-target immune cells and downstream signaling pathways. We also discuss how the IL-33/ST2 axis could be used as a potential therapeutic target for cancer immunotherapy.

STAT3 is over-activated within CD163pos bone marrow macrophages in both Multiple Myeloma and the benign pre-condition MGUS

Tumour-associated macrophages (TAMs) support cancer cell survival and suppress anti-tumour immunity. Tumour infiltration by CD163^pos TAMs is associated with poor outcome in several human malignancies, including multiple myeloma (MM). Signal transducer and activator of transcription 3 (STAT3) is over-activated in human cancers, and specifically within TAMs activation of STAT3 may induce an immunosuppressive (M2-like) phenotype. Therefore, STAT3-inhibition in TAMs may be a future therapeutic strategy.We investigated TAM markers CD163, CD206, and activated STAT3 (pSTAT3) in patients with MGUS (n = 32) and MM (n = 45), as well as healthy controls (HCs, n = 13).Blood levels of the macrophage biomarkers sCD163 and sCD206, and circulating cytokines, as well as bone marrow mRNA expression of CD163 and CD206, were generally increased in MGUS and MM patients, compared to HCs, but to highly similar levels. By immunohistochemistry, bone marrow levels of pSTAT3 were increased specifically within CD163^pos cells in both MGUS and MM patients.In conclusion, macrophage-related inflammatory changes, including activation of STAT3, were present already at the MGUS stage, at similar levels as in MM. Specific increase in pSTAT3 levels within CD163^pos cells supports that the CD163 scavenger receptor may be a useful target for future delivery of STAT3-inhibitory drugs to TAMs in MM patients.

Topical arginase inhibition decreases growth of cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinomas (cSCC) are among the most commonly diagnosed malignancies, causing significant morbidity and mortality. Tumor-associated macrophage (TAM) expression of arginase is implicated in tumor progression, and therapeutic use of arginase inhibitors has been studied in various cancers. However, investigating potential cSCC immunotherapies including arginase inhibition in pre-clinical models is hampered by the lack of appropriate tumor models in immunocompetent mice. PDV is a cSCC cell line derived from chemical carcinogenesis of mouse keratinocytes. PDVC57 cells were derived from a PDV tumor in C57BL/6 (B6) mice. Unlike PDV, PDVC57 tumors grow consistently in B6 mice, and have increased TAMs, decreased dendritic and T cell intra-tumor infiltration. Arginase inhibition in cSCC tumors using Nω-hydroxy-nor-arginine (nor-NOHA) reduced tumor growth in B6 mice but not immunodeficient Rag1-deficient mice. nor-NOHA administration increased dendritic and T cell tumor-infiltration and PD-1 expression. The combination of nor-NOHA and anti-PD-1 therapy with nivolumab enhanced anti-PD-1 therapeutic efficacy. This study demonstrates the therapeutic potential of transcutaneous arginase inhibition in cSCC. A competent immune microenvironment is required for tumor growth inhibition using this arginase inhibitor. Synergistic co-inhibition of tumor growth in these results, supports further examination of transcutaneous arginase inhibition as a therapeutic modality for cSCC.

Prognostic Value of Tumor-Associated Macrophages in Clear Cell Renal Cell Carcinoma: A Systematic Review and Meta-Analysis

Background

Tumor-associated macrophages (TAMs) are the major immune cells in tumor microenvironment. The prognostic significance of TAMs has been confirmed in various tumors. However, whether TAMs can be prognostic factors in clear cell renal cell carcinoma (ccRCC) is unclear. In this study, we aimed to clarify the prognostic value of TAMs in ccRCC.

Methods

We searched PubMed, Embase, and the Web of Science for relevant published studies before December 19, 2020. Evidence from enrolled studies were pooled and analyzed by a meta-analysis. Hazard ratios (HRs) and odd ratios (ORs) with 95% confidence intervals (CIs) were computed to evaluate the pooled results.

Results

Both of high CD68+ TAMs and M2-TAMs were risk factors for poor prognosis in ccRCC patients. The pooled HRs indicated that elevated CD68+ TAMs correlated with poor OS and PFS (HR: 3.97, 95% CI 1.39–11.39; HR: 5.73, 95% CI 2.36–13.90, respectively). For M2-TAMs, the pooled results showed ccRCC patients with high M2-TAMs suffered a worse OS and shorter PFS, with HR 1.32 (95% CI 1.16–1.50) and 1.40 (95% CI 1.14–1.72), respectively. Also, high density of TAMs was associated with advanced clinicopathological features in ccRCC.

Conclusions

TAMs could be potential biomarkers for prognosis and novel targets for immunotherapy in ccRCC. Further researches are warranted to validate our results.

A narrative review of tumor-associated macrophages in lung cancer: regulation of macrophage polarization and therapeutic implications

Lung cancer is the deadliest malignancy worldwide. An inflammatory microenvironment is a key factor contributing to lung tumor progression. Tumor-Associated Macrophages (TAMs) are prominent components of the cancer immune microenvironment with diverse supportive and inhibitory effects on growth, progression, and metastasis of lung tumors. Two main macrophage phenotypes with different functions have been identified. They include inflammatory or classically activated (M1) and anti-inflammatory or alternatively activated (M2) macrophages. The contrasting functions of TAMs in relation to lung neoplasm progression stem from the presence of TAMs with varying tumor-promoting or anti-tumor activities. This wide spectrum of functions is governed by a network of cytokines and chemokines, cell-cell interactions, and signaling pathways. TAMs are promising therapeutic targets for non-small cell lung cancer (NSCLC) treatment. There are several strategies for TAM targeting and utilizing them for therapeutic purposes including limiting monocyte recruitment and localization through various pathways such as CCL2-CCR2, CSF1-CSF1R, and CXCL12-CXCR4, targeting the activation of TAMs, genetic and epigenetic reprogramming of TAMs to antitumor phenotype, and utilizing TAMs as the carrier for anti-cancer drugs. In this review, we will outline the role of macrophages in the lung cancer initiation and progression, pathways regulating their function in lung cancer microenvironment as well as the role of these immune cells in the development of future therapeutic strategies.

A Review of Proteomics Strategies to Study T-Cell Activation and Function in Cancer Disease

Cytotoxic T-cells play a key role in natural response to cancer and in immunotherapy. Understanding in an ever more thorough and complete way the mechanisms underlying their activation and/or those that prevent it is a crucial challenge for the success of the therapy. Proteomics can make a decisive contribution to achieving this goal as it brings together a range of technologies that potentially allow the expression levels of thousands of proteins to be analyzed at the same time. In the first part of this chapter, after an overview of the main mechanisms that determine T-cell dysfunction, new MS-based approaches to characterizing T-cell subpopulations in the tumor microenvironment will be described. The second part of the chapter will focus on the main strategies for cancer immunotherapy, from the selective blockage of inhibitory receptor to CAR T therapy. Examples of proteomics application to tumor microenvironment analysis will be reported to illustrate how these innovative approaches can contribute significantly to understanding the cellular and molecular mechanisms that regulate an effective response to therapy.

Targeting immunosuppressive macrophages overcomes PARP inhibitor resistance in BRCA1-associated triple-negative breast cancer

Despite objective responses to PARP inhibition and improvements in progression-free survival compared to standard chemotherapy in patients with BRCA-associated triple-negative breast cancer (TNBC), benefits are transitory. Using high dimensional single-cell profiling of human TNBC, here we demonstrate that macrophages are the predominant infiltrating immune cell type in BRCA-associated TNBC. Through multi-omics profiling we show that PARP inhibitors enhance both anti- and pro-tumor features of macrophages through glucose and lipid metabolic reprogramming driven by the sterol regulatory element-binding protein 1 (SREBP-1) pathway. Combined PARP inhibitor therapy with CSF-1R blocking antibodies significantly enhanced innate and adaptive anti-tumor immunity and extends survival in BRCA-deficient tumors in vivo and is mediated by CD8+ T-cells. Collectively, our results uncover macrophage-mediated immune suppression as a liability of PARP inhibitor treatment and demonstrate combined PARP inhibition and macrophage targeting therapy induces a durable reprogramming of the tumor microenvironment, thus constituting a promising therapeutic strategy for TNBC.

Co-culture hydrogel micro-chamber array-based plate for anti-tumor drug development at single-element resolution

In response to the need for reliable cellular models that reflect complex tumor microenvironmental properties, and enable more precise testing of anti-cancer therapeutics effects on humans, a co-culture platform for in-vitro model that enhances the physiology of breast cancer (BC) microenvironment is presented. A six well imaging plate wherein each macro-well contains several separate compartments was designed. Three-dimensional (3D) cancer spheroids are generated and cultured in the inner compartment which is embossed with an array of nano-liter micro-chambers made of hydrogel. Stromal cells are cultured in the outer chambers. The two cell types are cultured side-by-side, sharing a common space, thus enabling extra-cellular communication via secreted molecules. As proof of concept, a model of BC tumor microenvironment was recapitulated by co-cultivating 3D MCF7 spheroids in the presence of tumor-associated macrophages (TAMs). The presence of TAMs induced an aggressive phenotype by promoting spheroid growth, enhancing survivin expression levels and enabling invasive behavior. Moreover, TAMs influenced the response of BC spheroids to cytotoxic treatment as well as hormonal drug therapy, and enhanced the effects of nitric oxide donor. The platform enables time-lapse imaging and treatment without losing spatial location of the measured spheroids, thereby allowing measurements and analysis at individual-object resolution in an easy and efficient manner.

Characterising the immune microenvironment in liposarcoma, its impact on prognosis and the impact of radiotherapy

BACKGROUND AND OBJECTIVES

Limited literature exists examining the immune microenvironment in liposarcoma, particularly with regard to the impact of radiotherapy. A major problem is the lack of scoring system for the tumour-infiltrating lymphocytes (TILs) in sarcoma. This study aims to describe the immune environment pre- and postradiotherapy and identify the optimal immune infiltrate scoring system for sarcoma.

METHODS

Thirty-nine paired tissue samples (pre- and postradiotherapy) from patients with liposarcoma were scored by two pathologists for TILs using pre-existing systems (for breast cancer and melanoma) and compared for interobserver reliability. Immunohistochemical staining was performed for various immune markers.

RESULTS

The TIL scoring system for breast cancer yielded perfect agreement (κ = 1.000). 21% of patients had increased TILs after radiotherapy, 87.5% of whom had dedifferentiated liposarcoma. Immune suppressor expression was increased frequently after radiotherapy (CD68 increased in 59.4%, PD-L1 increased in 25%). Immune effector expression (CD8) was unchanged in 84.4%.

CONCLUSIONS

Breast cancer TIL scoring is reproducible in liposarcoma and has high interobserver reliability. Radiotherapy was observed to have a limited impact on immune effectors but seemed to have more impact in upregulating immune suppressors, suggesting radiotherapy may contribute to disease control through immunomodulatory effects. Dedifferentiated liposarcoma represents a uniquely responsive subtype.

Adjuvant Antitumor Immunity Contributes to the Overall Antitumor Effect of Pegylated Liposomal Doxorubicin (Doxil®) in C26 Tumor-Bearing Immunocompetent Mice

Doxorubicin (DXR) has been reported to have direct cytotoxicity against cancer cells and indirect immunotoxicity by modulation of host antitumor immunity. Hence, it may prevent cancer progression by a dual mechanism. Doxil^®, a formulation of DXR encapsulated in polyethylene glycol modified (PEGylated) liposomes, is the most widely used of the clinically approved liposomal anticancer drugs. However, the effect of Doxil^® on host antitumor immunity is not well understood. In this study, Doxil^® efficiently suppressed tumor growth in immunocompetent mice bearing C26 murine colorectal carcinomas, but not in T cell-deficient nude mice, indicating a contribution of T cells to the overall antitumor effect of Doxil^®. In immunocompetent mice, Doxil^® increased major histocompatibility complex (MHC-1) levels in C26 tumors, which may be an indicator of increased immunogenicity of tumor cells, and potentially amplified tumor immunogenicity by decreasing immunosuppressive cells such as regulatory T cells, tumor-associated microphages and myeloid-derived suppressor cells that collectively suppress T cell-mediated antitumor responses. This suggests that encapsulation of DXR into PEGylated liposomes increased the therapeutic efficacy of DXR though effects on host antitumor immunogenicity in addition to direct cytotoxic effects on tumor cells. This report describes the role of host antitumor immunity in the overall therapeutic effects of Doxil^®. Manipulating pharmacokinetics and biodistribution of chemotherapeutic agents with immunomodulatory properties may increase their therapeutic efficacies by amplifying host antitumor immunity in addition to direct cytotoxic effects on tumor cells.

Tuberculosis-Cancer Parallels in Immune Response Regulation

Mycobacterium tuberculosis and cancer are two diseases with proclivity for the development of resistance to the host immune system. Mechanisms behind resistance can be host derived or disease mediated, but they usually depend on the balance of pro-inflammatory to anti-inflammatory immune signals. Immunotherapies have been the focus of efforts to shift that balance and drive the response required for diseases eradication. The immune response to tuberculosis has widely been thought to be T cell dependent, with the majority of research focused on T cell responses. However, the past decade has seen greater recognition of the importance of the innate immune response, highlighting factors such as trained innate immunity and macrophage polarization to mycobacterial clearance. At the same time, there has been a renaissance of immunotherapy treatments for cancer since the first checkpoint inhibitor passed clinical trials, in addition to work highlighting the importance of innate immune responses to cancer. However, there is still much to learn about host-derived responses and the development of resistance to new cancer therapies. This review examines the similarities between the immune responses to cancer and tuberculosis with the hope that their commonalities will facilitate research collaboration and discovery.

Long noncoding RNAs in cancer immunity: a new avenue in drug discovery

The central role of the nonprotein-coding portion of the genome, such as long noncoding (lnc)RNAs is emerging as a hidden player manipulating the immune system in cancer. lncRNAs, in association with their interacting partners, regulate the expression of various immune system genes, which are perturbed during cancer. The tissue-specific expression of lncRNAs and their importance in cellular proliferation, the tumor microenvironment (TME), epithelial-mesenchymal transition (EMT), and modulation of the cells of the innate and adaptive immune system have novel therapeutic implications in establishing lncRNAs as biomarkers and targets to overcome cancer-associated immunosuppression. In this review, we establish and strengthen the link between lncRNAs and cancer immunity.

CSF1R methylation is a key regulatory mechanism of tumor-associated macrophages in hepatocellular carcinoma

Tumor-associated macrophages (TAMs) are important in tumor microenvironments and are closely associated with cancer occurrence, metastasis and progression. Colony stimulating factor 1 receptor (CSF1R) serves a crucial role in TAM formation. Whether CSF1R expression is regulated by DNA methylation in hepatocellular carcinoma (HCC) has not been fully elucidated. In the current study, HCC and adjacent non-cancerous tissue (ANT) samples were collected from 160 patients with HCC. CSF1R methylation levels were analyzed using a Mass ARRAY Analyzer to establish the potential impact of CSF1R methylation alternations on HCC clinicopathological characteristics. The mean methylation level of the CSF1R promoter (chr 5:149492491-149492958) was demonstrated to be significantly higher in ANTs compared with HCC tissues (65.3±7.5% vs. 57.3±14.4%, respectively; P<0.0001). CSF1R also exhibited decreased expression in HCC tissues compared with ANTs (P=0.0026). However, CSF1R expression was negatively correlated with CSF1R methylation levels in ANTs (r>0.4; P<0.0001). Further analysis indicated that patients with diabetes exhibited lower methylation levels in ANTs compared with HCC tissues (P=0.0062). Furthermore, CSF1R hypomethylation in ANTs was associated with a larger number of tumors (P=0.0332), larger tumor size (P=0.0494) and higher tumor grade (P=0.0244). Therefore, methylation alternation of the CSF1R promoter region analyzed in the present study was a key regulatory mechanism on CSF1R expression and ANT hypomethylation indicated poor clinicopathological characteristics of HCC. CSF1R may be a potential immunological therapeutic target for HCC.

Functional Implications of Cathelicidin Antimicrobial Protein in Breast Cancer and Tumor-Associated Macrophage Microenvironment

It is well-established that tumor-associated macrophages (TAMs) play an important role in breast cancer development. Accumulating evidence suggested that human cathelicidin antimicrobial protein (CAMP), which is mainly expressed in host defense cells such as macrophages, is crucial not only in combating microorganisms but also promoting tumor growth. Here we report the interaction of CAMP with TAMs in breast cancer. CAMP expression was upregulated in cancer tissues and in the circulation of breast cancer patients. Surgical removal of tumor decreased CAMP peptide serum level. Knockdown of CAMP decreased cell proliferation and migration/invasion ability in breast cancer cells. CAMP expression was altered during macrophage M1/M2 polarization and was expressed predominantly in M2 phenotype. In addition, breast cancer cells co-cultured with macrophages upregulated CAMP expression and also increased cancer cell viability. Xenograft tumors reduced significantly upon CAMP receptor antagonist treatment. Our data implicated that CAMP confers an oncogenic role in breast cancer and plays an important role in the tumor microenvironment between TAMs and breast cancer cells, and blocking the interaction between them would provide a novel therapeutic option for this malignant disease.

Breast Tumor Microenvironment: Emerging target of therapeutic phytochemicals

Triple negative breast cancer (TNBC) is the most aggressive and challenging form of breast cancers. Tumor microenvironment (TME) of TNBC is associated with induction of metastasis, immune system suppression, escaping immune detection and drug resistance. TME is highly complex and heterogeneous, consists of tumor cells, stromal cells and immune cells. The rapid expansion of tumors induce hypoxia, which concerns the reprogramming of TME components. The reciprocal communication of tumor cells and TME cells predisposes cancer cells to metastasis by modulation of developmental pathways, Wnt, notch, hedgehog and their related mechanisms in TME. Dietary phytochemicals are non-toxic and associated with various human health benefits and remarkable spectrum of biological activities. The phytochemicals serve as vital resources for drug discovery and also as a source for breast cancer therapy. The novel properties of dietary phytochemicals propose platform for modulation of tumor signaling, overcoming drug resistance, and targeting TME. Therefore, TME could serve as promising target for the treatment of TNBC. This review presents current status and implications of experimentally evaluated therapeutic phytochemicals as potential targeting agents of TME, potential nanosystems for targeted delivery of phytochemicals and their current challenges and future implications in TNBC treatment. The dietary phytochemicals especially curcumin with significant delivery system could prevent TNBC development as it is considered safe and well tolerated in phase II clinical trials.

7-epi-Clusianone, a Multi-Targeting Natural Product with Potential Chemotherapeutic, Immune-Modulating, and Anti-Angiogenic Properties

Targeted therapies have changed the treatment of cancer, giving new hope to many patients in recent years. The shortcomings of targeted therapies including acquired resistance, limited susceptible patients, high cost, and high toxicities, have led to the necessity of combining these therapies with other targeted or chemotherapeutic treatments. Natural products are uniquely capable of synergizing with targeted and non-targeted anticancer regimens due to their ability to affect multiple cellular pathways simultaneously. Compounds which provide an additive effect to the often combined immune therapies and cytotoxic chemotherapies, are exceedingly rare. These compounds would however provide a strengthening bridge between the two treatment modalities, increasing their effectiveness and improving patient prognoses. In this study, 7-epi-clusianone was investigated for its anticancer properties. While previous studies have suggested clusianone and its conformational isomers, including 7-epi-clusianone, are chemotherapeutic, few cancer types have been demonstrated to exhibit sensitivity to these compounds and little is known about the mechanism. In this study, 7-epi-clusianone was shown to inhibit the growth of 60 cancer cell types and induce significant cell death in 25 cancer cell lines, while simultaneously modulating the immune system, inhibiting angiogenesis, and inhibiting cancer cell invasion, making it a promising lead compound for cancer drug discovery.

The immune landscape of chondrosarcoma reveals an immunosuppressive environment in the dedifferentiated subtypes and exposes CSFR1+ macrophages as a promising therapeutic target

Survival rate for Chondrosarcoma (CHS) is at a standstill, more effective treatments are urgently needed. Consequently, a better understanding of CHS biology and its immune environment is crucial to identify new prognostic factors and therapeutic targets. Here, we exhaustively describe the immune landscape of conventional and dedifferentiated CHS. Using IHC and molecular analyses (RT-qPCR), we mapped the expression of immune cell markers (CD3, CD8, CD68, CD163) and immune checkpoints (ICPs) from a cohort of 27 conventional and 49 dedifferentiated CHS. The impact of the density of tumor-infiltrating lymphocytes (TILs), tumor-associated macrophages (TAMs) and immune checkpoints (ICPs) on clinical outcome were analyzed. We reveal that TAMs are the main immune population in CHS. Focusing on dedifferentiated CHS, we found that immune infiltrate composition is correlated with patient outcome, a high CD68+/CD8+ ratio being an independent poor prognostic factor (p < 0.01), and high CD68+ levels being associated with the presence of metastases at diagnosis (p < 0.05). Among the ICPs evaluated, CSF1R, B7H3, SIRPA, TIM3 and LAG3 were expressed at the mRNA level in both CHS subtypes. Furthermore, PDL1 expression was confirmed by IHC exclusively in dedifferentiated CHS (42.6% of the patients) and CSF1R was expressed by TAMs in 89.7% of dedifferentiated CHS (vs 62.9% in conventional). Our results show that the immune infiltrate of CHS is mainly composed of immunosuppressive actors favoring tumor progression. Our results indicate that dedifferentiated CHS could be eligible for anti-PDL1 therapy and more importantly immunomodulation through CSF1R + macrophages could be a promising therapeutic approach for both CHS subtypes.

Conceptual Development of Immunotherapeutic Approaches to Gastrointestinal Cancer

Gastrointestinal (GI) cancer is one of the common causes of cancer-related death worldwide. Chemotherapy and/or immunotherapy are the current treatments, but some patients do not derive clinical benefits. Recently, studies from cancer molecular subtyping have revealed that tumor molecular biomarkers may predict the immunotherapeutic response of GI cancer patients. However, the therapeutic response of patients selected by the predictive biomarkers is suboptimal. The tumor immune-microenvironment apparently plays a key role in modulating these molecular-determinant predictive biomarkers. Therefore, an understanding of the development and recent advances in immunotherapeutic pharmacological intervention targeting tumor immune-microenvironments and their potential predictive biomarkers will be helpful to strengthen patient immunotherapeutic efficacy. The current review focuses on an understanding of how the host-microenvironment interactions and the predictive biomarkers can determine the efficacy of immune checkpoint inhibitors. The contribution of environmental pathogens and host immunity to GI cancer is summarized. A discussion regarding the clinical evidence of predictive biomarkers for clinical trial therapy design, current immunotherapeutic strategies, and the outcomes to GI cancer patients are highlighted. An understanding of the underlying mechanism can predict the immunotherapeutic efficacy and facilitate the future development of personalized therapeutic strategies targeting GI cancers.

Long Non-coding RNAs as Communicators and Mediators Between the Tumor Microenvironment and Cancer Cells

Long non-coding RNAs (lncRNAs) are a class of more than 200 nucleotides RNA transcripts which have limited protein coding capacity. They regulate numerous biological processes in cancers through diverse molecular mechanisms. Aberrant expression of lncRNAs has been frequently associated with human cancer. Furthermore, the tumor microenvironment (TME) is composed of different cells such as cancer-associated fibroblasts (CAFs), endothelial cells and infiltrated immune cells, and all of which participate in communication with tumor cells affecting the progression of tumor. LncRNAs are directly and indirectly involved in the crosstalk between stromal cells and tumor cells and dysregulated lncRNAs expression in these cells could drive tumorigenesis. In this review, we explore the influence of aberrantly expressed lncRNAs in tumor progression, clarify the critical roles of lncRNAs in the TME, summarize findings on crosstalk between infiltrated immune cells, CAFs, endothelial cells, and tumor cells via lncRNAs, and discuss the promise of lncRNAs as tumor diagnostic markers and therapeutic targets.

Specific targeting of CD163+ TAMs mobilizes inflammatory monocytes and promotes T cell-mediated tumor regression

Etzerodt et al. show that the specific targeting of CD163⁺ macrophages in melanoma drives inflammatory monocyte influx and promotes antitumor immunity, illustrating the importance of selective targeting of tumor-associated myeloid cells for achieving optimal therapeutic responses.

Tumor-associated macrophages (TAMs) play critical roles in tumor progression but are also capable of contributing to antitumor immunity. Recent studies have revealed an unprecedented heterogeneity among TAMs in both human cancer and experimental models. Nevertheless, we still understand little about the contribution of different TAM subsets to tumor progression. Here, we demonstrate that CD163-expressing TAMs specifically maintain immune suppression in an experimental model of melanoma that is resistant to anti–PD-1 checkpoint therapy. Specific depletion of the CD163⁺ macrophages results in a massive infiltration of activated T cells and tumor regression. Importantly, the infiltration of cytotoxic T cells was accompanied by the mobilization of inflammatory monocytes that significantly contributed to tumor regression. Thus, the specific targeting of CD163⁺ TAMs reeducates the tumor immune microenvironment and promotes both myeloid and T cell–mediated antitumor immunity, illustrating the importance of selective targeting of tumor-associated myeloid cells in a therapeutic context.

Prognostic Significance of Tumor-Associated Macrophage Content in Head and Neck Squamous Cell Carcinoma: A Meta-Analysis

Background: Head and neck squamous cell carcinoma (HNSCC) exists within a microenvironment rich in immune cells. Macrophages are particularly abundant in and around tumor tissue, and have been implicated in the growth, malignancy, and persistence of HNSCC (1). However, current literature reports variable degrees of association between the density of tumor-associated macrophages (TAMs) and clinicopathologic markers of disease (2, 3). These inconsistent findings may be a result of differences in approach to TAM detection. Authors have measured total TAMs in tumor tissue, while others have stained tumor samples for individual subtypes of TAMs, which include pro-inflammatory (M1-like) and immunosuppressive (M2-like). Our aim is to more clearly define the prognostic significance of the phenotypes of tumor-associated macrophages in HNSCC. Methods: We conducted a meta-analysis of the existing publications investigating the relationship between TAMs (total and M2-like subtype) and T stage, nodal involvement, vascular invasion, lymphatic invasion, and tumor differentiation (Figure 1). A total of 12 studies were included. Forest plots and risk ratios were generated to report overall effect. Results: Higher density of both total and M2-like subtype of TAMs in the tumor microenvironment is associated with advanced T stage, increased rates of nodal positivity, presence of vascular invasion, and presence of lymphatic invasion (p < 0.0001; Figures 2-9). There is no significant association between TAM density, either total or M2-like subtype, and tumor differentiation (Figures 10, 11). Conclusions: Increased density of TAMs, including those of the M2-like phenotype, correlate with poor clinicopathologic markers in HNSCC. Our findings warrant additional investigation into the subpopulations of TAMs, the mechanisms behind their recruitment and differentiation, and the associated influence of each phenotype on tumor growth and invasion. A greater understanding of TAM dynamics in HNSCC is critical for directing further research and employing TAM-targeted adjunct therapies.

LncRNA-MM2P Identified as a Modulator of Macrophage M2 Polarization

M2 polarization of macrophages is essential for their function in immunologic tolerance, which might promote tumorigenesis. However, the molecular mechanism behind the polarization process is not fully understood. Given that several lines of evidence have suggested that long noncoding RNAs (lncRNAs) could be involved in regulating immune cell differentiation and function, the current study aimed to identify the lncRNAs that specifically modulate M2 macrophage polarization. By utilizing a series of cell-based M2 macrophage polarization models, a total of 25 lncRNAs with altered expression were documented based on lncRNA microarray-based profiling assays. Among them, lncRNA-MM2P was the only lncRNA upregulated during M2 polarization but downregulated in M1 macrophages. Knockdown of lncRNA-MM2P blocked cytokine-driven M2 polarization of macrophages and weakened the angiogenesis-promoting feature of M2 macrophages by reducing phosphorylation on STAT6. Moreover, manipulating lncRNA-MM2P in macrophages impaired macrophage-mediated promotion of tumorigenesis, tumor growth in vivo, and tumor angiogenesis. Collectively, our study identifies lncRNA-MM2P as a modulator required for macrophage M2 polarization and uncovers its role in macrophage-promoted tumorigenesis.

Viewing the Emphasis on State-of-the-Art Magnetic Nanoparticles: Synthesis, Physical Properties, and Applications in Cancer Theranostics

Cancer-related mortality is a leading cause of death among both men and women around the world. Target-specific therapeutic drugs, early diagnosis, and treatment are crucial to reducing the mortality rate. One of the recent trends in modern medicine is "Theranostics," a combination of therapeutics and diagnosis. Extensive interest in magnetic nanoparticles (MNPs) and ultrasmall superparamagnetic iron oxide nanoparticles (NPs) has been increasing due to their biocompatibility, superparamagnetism, less-toxicity, enhanced programmed cell death, and auto-phagocytosis on cancer cells. MNPs act as a multifunctional, noninvasive, ligand conjugated nano-imaging vehicle in targeted drug delivery and diagnosis. In this review, we primarily discuss the significance of the crystal structure, magnetic properties, and the most common method for synthesis of the smaller sized MNPs and their limitations. Next, the recent applications of MNPs in cancer therapy and theranostics are discussed, with certain preclinical and clinical experiments. The focus is on implementation and understanding of the mechanism of action of MNPs in cancer therapy through passive and active targeting drug delivery (magnetic drug targeting and targeting ligand conjugated MNPs). In addition, the theranostic application of MNPs with a dual and multimodal imaging system for early diagnosis and treatment of various cancer types including breast, cervical, glioblastoma, and lung cancer is reviewed. In the near future, the theranostic potential of MNPs with multimodality imaging techniques may enhance the acuity of personalized medicine in the diagnosis and treatment of individual patients.

Fates of CD8+ T cells in Tumor Microenvironment

Studies have reported a positive correlation between elevated CD8+ T cells in the tumor microenvironment (TME) and good prognosis in cancer. However, the mechanisms linking T cell tumor-infiltration and tumor rejection are yet to be fully understood. The cells and factors of the TME facilitate tumor development in various ways. CD8+ T cell function is influenced by a number of factors, including CD8+ T cell trafficking and localization into tumor sites; as well as CD8+ T cell growth and differentiation. This review highlights recent literature as well as currently evolving concepts regarding the fates of CD8+ T cells in the TME from three different aspects CD8+ T cell trafficking, differentiation and function. A thorough understanding of factors contributing to the fates of CD8+ T cells will allow researchers to develop new strategies and improve on already existing strategies to facilitate CD8+ T cell mediated anti-tumor function, impede T cell dysfunction and modulate the TME into a less immunosuppressive TME.

Macrophages in the microenvironment of head and neck cancer: potential targets for cancer therapy

The microenvironment of solid tumors has become a promising target for future therapies modulating immune cells. Patients with advanced head and neck cancer, which still portends a poor outcome, are particularly in need of innovative approaches. In oral squamous cell carcinoma, high density of tumor-associated macrophages (TAMs) appears consistently associated with poor prognosis, whereas data are currently limited for other head and neck sites. Several approaches to block TAMs have been investigated, including TAMs inactivation by means of the colony stimulating factor 1 (CSF-1)/CSF-1 receptor (CSF-1R) inhibitors or strategies to reprogram TAMs from M2 protumoral phenotype toward M1 antitumoral phenotype. This review focuses on both prognostic and therapeutic aspects related to TAMs in head and neck carcinomas.

Tim-3 expression and its role in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common tumors in the world, and its mortality is still on the rise. Limited treatments and low chemotherapy sensitivity of HCC make new therapeutic strategies urgently needed. With the rise of immune checkpoint blockade, anti-CTLA-4 antibodies and anti-PD-1 antibodies have shown therapeutic effects in various tumors. T cell immunoglobulin mucin-3 (Tim-3), a newly discovered immune checkpoint molecule, plays a major role in the development of HCC. Tim-3 can be used to evaluate the prognosis and therapeutic effects in HCC, and Tim-3 intervention has shown anti-tumor effects in preclinical experiments. This review summarizes findings regarding Tim-3 and HCC in recent years and discusses the rationale of Tim-3 as a therapeutic target for HCC.

Immune cell subset differentiation and tissue inflammation

Immune cells were traditionally considered as major pro-inflammatory contributors. Recent advances in molecular immunology prove that immune cell lineages are composed of different subsets capable of a vast array of specialized functions. These immune cell subsets share distinct duties in regulating innate and adaptive immune functions and contribute to both immune activation and immune suppression responses in peripheral tissue. Here, we summarized current understanding of the different subsets of major immune cells, including T cells, B cells, dendritic cells, monocytes, and macrophages. We highlighted molecular characterization, frequency, and tissue distribution of these immune cell subsets in human and mice. In addition, we described specific cytokine production, molecular signaling, biological functions, and tissue population changes of these immune cell subsets in both cardiovascular diseases and cancers. Finally, we presented a working model of the differentiation of inflammatory mononuclear cells, their interaction with endothelial cells, and their contribution to tissue inflammation. In summary, this review offers an updated and comprehensive guideline for immune cell development and subset differentiation, including subset characterization, signaling, modulation, and disease associations. We propose that immune cell subset differentiation and its complex interaction within the internal biological milieu compose a “pathophysiological network,” an interactive cross-talking complex, which plays a critical role in the development of inflammatory diseases and cancers.

Crucial biological functions of CCL7 in cancer

Chemokine (C-C motif) ligand 7 (CCL7), a CC chemokine, is a chemotactic factor and attractant for various kinds of leukocytes, including monocytes and neutrophils. CCL7 is widely expressed in multiple cell types and can participate in anti-inflammatory responses through binding to its receptors to mediate the recruitment of immune cells. Abnormal CCL7 expression is associated with certain immune diseases. Furthermore, CCL7 plays a pivotal role in tumorigenesis. CCL7 promotes tumor progression by supporting the formation of the tumor microenvironment and facilitating tumor invasion and metastasis, although some studies have suggested that CCL7 has tumor suppressor effects. In this review, we summarize the currently available information regarding the influence of CCL7 on tumors.

Macrophages: The Road Less Traveled, Changing Anticancer Therapy

Macrophages are present in all vertebrate tissues and have emerged as multifarious cells with complex roles in development, tissue homeostasis, and disease. Macrophages are a major constituent of the tumor microenvironment, where they either promote or inhibit tumorigenesis and metastasis depending on their state. Successful preclinical strategies to target macrophages for anticancer therapy are now being evaluated in the clinic and provide proof of concept that targeting macrophages may enhance current therapies; however, clinical success has been limited. This review discusses the promise of targeting macrophages for anticancer therapy, yet highlights how much is unknown regarding their ontogeny, regulation, and tissue-specific diversity. Further work might identify subsets of macrophages within different tissues, which could reveal novel therapeutic opportunities for anticancer therapy.