Immunology in the clinic review series; focus on cancer: tumour-associated macrophages: undisputed stars of the inflammatory tumour microenvironment

Tumor Microenvironment: A Niche for Cancer Stem Cell Immunotherapy

Tumorigenic Cancer Stem Cells (CSCs), often called tumor-initiating cells (TICs), represent a unique subset of cells within the tumor milieu. They stand apart from the bulk of tumor cells due to their exceptional self-renewal, metastatic, and differentiation capabilities. Despite significant progress in classifying CSCs, these cells remain notably resilient to conventional radiotherapy and chemotherapy, contributing to cancer recurrence. In this review, our objective is to explore novel avenues of research that delve into the distinctive characteristics of CSCs within their surrounding tumor microenvironment (TME). We will start with an overview of the defining features of CSCs and then delve into their intricate interactions with cells from the lymphoid lineage, namely T cells, B cells, and natural killer (NK) cells. Furthermore, we will discuss their dynamic interplay with myeloid lineage cells, including macrophages, neutrophils, and myeloid-derived suppressor cells (MDSCs). Moreover, we will illuminate the crosstalk between CSCs and cells of mesenchymal origin, specifically fibroblasts, adipocytes, and endothelial cells. Subsequently, we will underscore the pivotal role of CSCs within the context of the tumor-associated extracellular matrix (ECM). Finally, we will highlight pre-clinical and clinical studies that target CSCs within the intricate landscape of the TME, including CAR-T therapy, oncolytic viruses, and CSC-vaccines, with the ultimate goal of uncovering novel avenues for CSC-based cancer immunotherapy.

Targeting vascular normalization: a promising strategy to improve immune-vascular crosstalk in cancer immunotherapy

Blood vessels are a key target for cancer therapy. Compared with the healthy vasculature, tumor blood vessels are extremely immature, highly permeable, and deficient in pericytes. The aberrantly vascularized tumor microenvironment is characterized by hypoxia, low pH, high interstitial pressure, and immunosuppression. The efficacy of chemotherapy, radiotherapy, and immunotherapy is affected by abnormal blood vessels. Some anti-angiogenic drugs show vascular normalization effects in addition to targeting angiogenesis. Reversing the abnormal state of blood vessels creates a normal microenvironment, essential for various cancer treatments, specifically immunotherapy. In addition, immune cells and molecules are involved in the regulation of angiogenesis. Therefore, combining vascular normalization with immunotherapy may increase the efficacy of immunotherapy and reduce the risk of adverse reactions. In this review, we discussed the structure, function, and formation of abnormal vessels. In addition, we elaborated on the role of the immunosuppressive microenvironment in the formation of abnormal vessels. Finally, we described the clinical challenges associated with the combination of immunotherapy with vascular normalization, and highlighted future research directions in this therapeutic area.

Crotoxin Modulates Macrophage Phenotypic Reprogramming

Macrophage plasticity is a fundamental feature of the immune response since it favors the rapid and adequate change of the functional phenotype in response to the pathogen or the microenvironment. Several studies have shown that Crotoxin (CTX), the major toxin of the Crotalus durissus terrificus snake venom, has a long-lasting antitumor effect both in experimental models and in clinical trials. In this study, we show the CTX effect on the phenotypic reprogramming of macrophages in the mesenchymal tumor microenvironment or those obtained from the peritoneal cavity of healthy animals. CTX (0.9 or 5 μg/animal subcutaneously) administered concomitantly with intraperitoneal inoculation of tumor cells (1 × 107/0.5 mL, injected intraperitoneally) of Ehrlich Ascitic Tumor (EAT) modulated the macrophages phenotype (M1), accompanied by increased NO• production by cells from ascites, and was evaluated after 13 days. On the other hand, in healthy animals, the phenotypic profile of macrophages was modulated in a dose-dependent way at 0.9 μg/animal: M1 and at 5.0 μg/animal: M2; this was accompanied by increased NO• production by peritoneal macrophages only for the dose of 0.9 μg/animal of CTX. This study shows that a single administration of CTX interferes with the phenotypic reprogramming of macrophages, as well as with the secretory state of cells from ascites, influencing events involved with mesenchymal tumor progression. These findings may favor the selection of new therapeutic targets to correct compromised immunity in different systems.

Understanding the feasibility of chemotherapeutic and immunotherapeutic targets against non-small cell lung cancers: an update of resistant responses and recent combinatorial therapies

Despite consistent progress in prompt diagnosis and curative therapies in the last decade, lung cancer (LC) continues to threaten mankind, accounting for nearly twice the casualties compared to prostate, breast, and other cancers. Statistics associate ~25% of 2021 cancer-related deaths with LC, more than 80% of which are explicitly caused by tobacco smoking. Prevailing as small and non-small cell pathologies, with respective occurring frequency of nearly 15% and 80-85%, non-small cell LCs (NSCLCs) are prominently distinguished into lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC), subtypes. Since the first use of epidermal growth factor receptor (EGFR) inhibitor gefitinib for NSCLC treatment in 2002, immense progress has been made for targeted therapies with the next generation of drugs spanning across the chronological generations of small molecule inhibitors. The last two years have overseen the clinical approval of more than 10 therapeutic agents as first-line NSCLC medications. However, uncertain mutational aberrations as well as systemic resistant responses, and abysmal overall survival curtail the combating efficacies. Of late, immune checkpoint inhibitors (ICIs) against various molecules including programmed cell death-1 (PD-1) and its ligand (PD-L1) have been demonstrated as reliable LC treatment targets. Keeping these aspects in mind, this review article discusses the success of NSCLC chemo and immunotherapies with their characteristic effectiveness and future perspectives.

Pegylated Liposomal Alendronate Biodistribution, Immune Modulation, and Tumor Growth Inhibition in a Murine Melanoma Model

While tumor-associated macrophages (TAM) have pro-tumoral activity, the ablation of macrophages in cancer may be undesirable since they also have anti-tumoral functions, including T cell priming and activation against tumor antigens. Alendronate is a potent amino-bisphosphonate that modulates the function of macrophages in vitro, with potential as an immunotherapy if its low systemic bioavailability can be addressed. We repurposed alendronate in a non-leaky and long-circulating liposomal carrier similar to that of the clinically approved pegylated liposomal doxorubicin to facilitate rapid clinical translation. Here, we tested liposomal alendronate (PLA) as an immunotherapeutic agent for cancer in comparison with a standard of care immunotherapy, a PD-1 immune checkpoint inhibitor. We showed that the PLA induced bone marrow-derived murine non-activated macrophages and M2-macrophages to polarize towards an M1-functionality, as evidenced by gene expression, cytokine secretion, and lipidomic profiles. Free alendronate had negligible effects, indicating that liposome encapsulation is necessary for the modulation of macrophage activity. In vivo, the PLA showed significant accumulation in tumor and tumor-draining lymph nodes, sites of tumor immunosuppression that are targets of immunotherapy. The PLA remodeled the tumor microenvironment towards a less immunosuppressive milieu, as indicated by a decrease in TAM and helper T cells, and inhibited the growth of established tumors in the B16-OVA melanoma model. The improved bioavailability and the beneficial effects of PLA on macrophages suggest its potential application as immunotherapy that could synergize with T-cell-targeted therapies and chemotherapies to induce immunogenic cell death. PLA warrants further clinical development, and these clinical trials should incorporate tumor and blood biomarkers or immunophenotyping studies to verify the anti-immunosuppressive effect of PLA in humans.

A multifactorial analysis of FAP to regulate gastrointestinal cancers progression

Background

Fibroblast activation protein (FAP) is a cell-surface serine protease that has both dipeptidyl peptidase as well as endopeptidase activities and could cleave substrates at post-proline bond. Previous findings showed that FAP was hard to be detected in normal tissues but significantly up-regulated in remodeling sites like fibrosis, atherosclerosis, arthritis and embryonic tissues. Though increasing evidence has demonstrated the importance of FAP in cancer progression, no multifactorial analysis has been developed to investigate its function in gastrointestinal cancers until now.

Methods

By comprehensive use of datasets from The Cancer Genome Atlas (TCGA), Clinical Proteomic Tumor Analysis Consortium (CPTAC), scTIME Portal and Human Protein Atlas (HPA), we evaluated the carcinogenesis potential of FAP in gastrointestinal cancers, analyzing the correlation between FAP and poor outcomes, immunology in liver, colon, pancreas as well as stomach cancers. Then liver cancer was selected as example to experimentally validate the pro-tumor and immune regulative role of FAP in gastrointestinal cancers.

Results

FAP was abundantly expressed in gastrointestinal cancers, such as LIHC, COAD, PAAD and STAD. Functional analysis indicated that the highly-expressed FAP in these cancers could affect extracellular matrix organization process and interacted with genes like COL1A1, COL1A2, COL3A1 and POSTN. In addition, it was also observed that FAP was positively correlated to M2 macrophages infiltration across these cancers. To verify these findings in vitro, we used LIHC as example and over-expressed FAP in human hepatic stellate LX2 cells, a main cell type that produce FAP in tumor tissues, and then investigate its role on LIHC cells as well as macrophages. Results showed that the medium from FAP-over-expressed LX2 cells could significantly promote the motility of MHCC97H and SK-Hep1 LIHC cells, increase the invasion of THP-1 macrophages and induce them into pro-tumor M2 phenotype.

Conclusion

In summary, we employed bioinformatic tools and experiments to perform a comprehensive analysis about FAP. Up-regulation of FAP in gastrointestinal cancers was primarily expressed in fibroblasts and contributes to tumor cells motility, macrophages infiltration and M2 polarization, revealing the multifactorial role of FAP in gastrointestinal cancers progression.

Geniposide prevents tumor growth by inhibiting colonic interleukin-1β and monocyte chemoattractant protein-1 via down-regulated expression of cyclooxygenase-2 and thymocyte selection-associated high mobility box proteins TOX/TOX2 in azoxymethane/dextran sulfate sodium-treated mice

Colon cancer was the second leading cause of cancer-related deaths in Japan in 2019. The effects of geniposide isolated from Gardenia jasminoides fructus (Rubiaceae) on the azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced growth of colon tumors and changes in interleukin (IL)-1 β, monocyte chemoattractant protein (MCP)-1, IL-10, and programmed cell death-1 (PD-1) levels in the colon were investigated. The intraperitoneal administration of AOM (10 mg/kg) on days 0 and 27 induced colorectal carcinogenesis. Free access to 1% (w/v) DSS drinking water was given to mice on days 7-15, 32-33, and 35-38. Geniposide (30 and 100 mg/kg) was orally administered on days 1-16, discontinued for 11 days (days 16 to 26), and then administered again on days 27-41. Colonic levels of cytokines, chemokine, and PD-1 were measured using by enzyme-linked immunosorbent assay (ELISA). Increases in colorectal tumor numbers and areas were significantly inhibited by geniposide. In addition, geniposide (100 mg/kg) reduced colonic levels of IL-1 β, MCP-1, PD-1 and IL-10 by 67.4, 57.2, 100%, and 100% respectively. Cyclooxygenase (COX)-2- and thymocyte selection high mobility group box proteins (TOX/TOX2)-positive cell numbers were significantly reduced by geniposide. Geniposide (30 and 100 mg/kg) decreased the phosphorylation of signal transducer and activator of transcription 3 (STAT3) expressions in immunohistochemical analysis by 64.2 and 98.2%, respectively. Thus, the inhibitory effects of geniposide on colon tumor growth may be associated with reductions in the colonic levels of IL-1 β, MCP-1, IL-10, and PD-1 via the down-regulated expression of COX-2 and TOX/TOX2 through the inhibition of Phospho-STAT3 expression (in vivo and in vitro).

Mechanobiology of cancer cell responsiveness to chemotherapy and immunotherapy: Mechanistic insights and biomaterial platforms

Mechanical forces are central to how cancer treatments such as chemotherapeutics and immunotherapies interact with cells and tissues. At the simplest level, electrostatic forces underlie the binding events that are critical to therapeutic function. However, a growing body of literature points to mechanical factors that also affect whether a drug or an immune cell can reach a target, and to interactions between a cell and its environment affecting therapeutic efficacy. These factors affect cell processes ranging from cytoskeletal and extracellular matrix remodeling to transduction of signals by the nucleus to metastasis of cells. This review presents and critiques the state of the art of our understanding of how mechanobiology impacts drug and immunotherapy resistance and responsiveness, and of the in vitro systems that have been of value in the discovery of these effects.

Regulatory cells and the effect of cancer immunotherapy

Several mechanisms and cell types are involved in the regulation of the immune response. These include mostly regulatory T cells (Tregs), regulatory macrophages (Mregs), myeloid suppressor cells (MDSCs) and other regulatory cell types such as tolerogenic dendritic cells (tolDCs), regulatory B cells (Bregs), and mesenchymal stem cells (MSCs). These regulatory cells, known for their ability to suppress immune responses, can also suppress the anti-tumor immune response. The infiltration of many regulatory cells into tumor tissues is therefore associated with a poor prognosis. There is growing evidence that elimination of Tregs enhances anti-tumor immune responses. However, the systemic depletion of Treg cells can simultaneously cause deleterious autoimmunity. Furthermore, since regulatory cells are characterized by their high level of expression of immune checkpoints, it is also expected that immune checkpoint inhibitors perform part of their function by blocking these molecules and enhancing the immune response. This indicates that immunotherapy does not only act by activating specific effector T cells but can also directly or indirectly attenuate the suppressive activity of regulatory cells in tumor tissues. This review aims to draw together our current knowledge about the effect of immunotherapy on the various types of regulatory cells, and how these effects may be beneficial in the response to immunotherapy.

An Overview of Epithelial-to-Mesenchymal Transition and Mesenchymal-to-Epithelial Transition in Canine Tumors: How Far Have We Come?

Historically, pre-clinical and clinical studies in human medicine have provided new insights, pushing forward the contemporary knowledge. The new results represented a motivation for investigators in specific fields of veterinary medicine, who addressed the same research topics from different perspectives in studies based on experimental and spontaneous animal disease models. The study of different pheno-genotypic contexts contributes to the confirmation of translational models of pathologic mechanisms. This review provides an overview of EMT and MET processes in both human and canine species. While human medicine rapidly advances, having a large amount of information available, veterinary medicine is not at the same level. This situation should provide motivation for the veterinary medicine research field, to apply the knowledge on humans to research in pets. By merging the knowledge of these two disciplines, better and faster results can be achieved, thus improving human and canine health.

Advances in the Lung Cancer Immunotherapy Approaches

Despite the progress in the comprehension of LC progression, risk, immunologic control, and treatment choices, it is still the primary cause of cancer-related death. LC cells possess a very low and heterogeneous antigenicity, which allows them to passively evade the anticancer defense of the immune system by educating cytotoxic lymphocytes (CTLs), tumor-infiltrating lymphocytes (TILs), regulatory T cells (Treg), immune checkpoint inhibitors (ICIs), and myeloid-derived suppressor cells (MDSCs). Though ICIs are an important candidate in first-line therapy, consolidation therapy, adjuvant therapy, and other combination therapies involving traditional therapies, the need for new predictive immunotherapy biomarkers remains. Furthermore, ICI-induced resistance after an initial response makes it vital to seek and exploit new targets to benefit greatly from immunotherapy. As ICIs, tumor mutation burden (TMB), and microsatellite instability (MSI) are not ideal LC predictive markers, a multi-parameter analysis of the immune system considering tumor, stroma, and beyond can be the future-oriented predictive marker. The optimal patient selection with a proper adjuvant agent in immunotherapy approaches needs to be still revised. Here, we summarize advances in LC immunotherapy approaches with their clinical and preclinical trials considering cancer models and vaccines and the potential of employing immunology to predict immunotherapy effectiveness in cancer patients and address the viewpoints on future directions. We conclude that the field of lung cancer therapeutics can benefit from the use of combination strategies but with comprehension of their limitations and improvements.

Small Tweaks, Major Changes: Post-Translational Modifications That Occur within M2 Macrophages in the Tumor Microenvironment

The majority of proteins are subjected to post-translational modifications (PTMs), regardless of whether they occur in or after biosynthesis of the protein. Capable of altering the physical and chemical properties and functions of proteins, PTMs are thus crucial. By fostering the proliferation, migration, and invasion of cancer cells with which they communicate in the tumor microenvironment (TME), M2 macrophages have emerged as key cellular players in the TME. Furthermore, growing evidence illustrates that PTMs can occur in M2 macrophages as well, possibly participating in molding the multifaceted characteristics and physiological behaviors in the TME. Hence, there is a need to review the PTMs that have been reported to occur within M2 macrophages. Although there are several reviews available regarding the roles of M2 macrophages, the majority of these reviews overlooked PTMs occurring within M2 macrophages. Considering this, in this review, we provide a review focusing on the advancement of PTMs that have been reported to take place within M2 macrophages, mainly in the TME, to better understand the performance of M2 macrophages in the tumor microenvironment. Incidentally, we also briefly cover the advances in developing inhibitors that target PTMs and the application of artificial intelligence (AI) in the prediction and analysis of PTMs at the end of the review.

The interaction of Helicobacter pylori with cancer immunomodulatory stromal cells: New insight into gastric cancer pathogenesis

Gastric cancer is the fourth most common cause of cancer-linked deaths in the world. Gastric tumor cells have biological characteristics such as rapid proliferation, high invasiveness, and drug resistance, which result in recurrence and poor survival. Helicobacter pylori (H. pylori) has been proposed as a first-class carcinogen for gastric cancer according to the 1994 world health organization (WHO) classification. One of the important mechanisms by which H. pylori affects the gastric environment and promotes carcinogenesis is triggering inflammation. H. pylori induces an inflammatory response and a plethora of different signal transduction processes, leading to gastric mucosal disturbance, chronic gastritis, and a multi-step complex pathway that initiates carcinogenesis. It seems undeniable that the interaction between various cell types, including immune cells, gastric epithelium, glands, and stem cells, is vital for the progression and development of carcinogenesis concerning H. pylori. The interactions of H. pylori with surrounding cells play a key role in cancer progression. In this review, we discuss the interplay between H. pylori and tumor-supportive cells, including mesenchymal stem cells (MSCs), cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), and myeloid derived-suppressor cells (MDSCs) in gastric cancer. It is hoped that clarifying the specific mechanisms for 'cross-talk' between H. pylori and these cells will provide promising strategies for developing new treatments.

An Application of Tumor-Associated Macrophages as Immunotherapy Targets: Sialic Acid-Modified EPI-Loaded Liposomes Inhibit Breast Cancer Metastasis

Breast cancer metastasis is an important cause of death in patients with breast cancer and is closely related to circulating tumor cells (CTCs) and the metastatic microenvironment. As the most infiltrating immune cells in the tumor microenvironment (TME), tumor-associated macrophages (TAMs), which highly express sialic acid (SA) receptor (Siglec-1), are closely linked to tumor progression and metastasis. Furthermore, the surface of CTCs also highly expressed receptor (Selectin) for SA. A targeting ligand (SA-CH), composed of SA and cholesterol, was synthesized and modified on the surface of epirubicin (EPI)-loaded liposomes (EPI-SL) as an effective targeting delivery system. Liposomes were evaluated for characteristics, stability, in vitro release, cytotoxicity, cellular uptake, pharmacokinetics, tumor targeting, and pharmacodynamics. In vivo and in vitro experiments showed that EPI-SL enhanced EPI uptake by TAMs. In addition, cellular experiments showed that EPI-SL could also enhance the uptake of EPI by 4T1 cells, resulting in cytotoxicity second only to that of EPI solution. Pharmacodynamic experiments have shown that EPI-SL has optimal tumor inhibition with minimal toxicity, which can be ascribed to the fact that EPI-SL can deliver drugs to tumor based on TAMs and regulate TME through the depletion of TAMs. Our study demonstrated the significant potential of SA-modified liposomes in antitumor metastasis. Schematic diagram of the role of SA-CH modified EPI-loaded liposomes in the model of breast cancer metastasis.

The role of macrophage scavenger receptor 1 (MSR1) in inflammatory disorders and cancer

Macrophage scavenger receptor 1 (MSR1), also named CD204, holds key inflammatory roles in multiple pathophysiologic processes. Present primarily on the surface of various types of macrophage, this receptor variably affects processes such as atherosclerosis, innate and adaptive immunity, lung and liver disease, and more recently, cancer. As highlighted throughout this review, the role of MSR1 is often dichotomous, being either host protective or detrimental to the pathogenesis of disease. We will discuss the role of MSR1 in health and disease with a focus on the molecular mechanisms influencing MSR1 expression, how altered expression affects disease process and macrophage function, the limited cell signalling pathways discovered thus far, the emerging role of MSR1 in tumour associated macrophages as well as the therapeutic potential of targeting MSR1.

The application of the natural killer cells, macrophages and dendritic cells in treating various types of cancer

Innate immune cells such as natural killer (NK) cells, macrophages and dendritic cells (DCs) are involved in the surveillance and clearance of tumor. Intensive research has exposed the mechanisms of recognition and elimination of tumor cells by these immune cells as well as how cancers evade immune response. Hence, harnessing the immune cells has proven to be an effective therapy in treating a variety of cancers. Strategies aimed to harness and augment effector function of these cells for cancer therapy have been the subject of intense researches over the decades. Different immunotherapeutic possibilities are currently being investigated for anti-tumor activity. Pharmacological agents known to influence immune cell migration and function include therapeutic antibodies, modified antibody molecules, toll-like receptor agonists, nucleic acids, chemokine inhibitors, fusion proteins, immunomodulatory drugs, vaccines, adoptive cell transfer and oncolytic virus–based therapy. In this review, we will focus on the preclinical and clinical applications of NK cell, macrophage and DC immunotherapy in cancer treatment.

Functional Crosstalk between PCSK9 Internalization and Pro-Inflammatory Activation in Human Macrophages: Role of Reactive Oxygen Species Release

Atherosclerosis is a cardiovascular disease caused mainly by dyslipidemia and is characterized by the formation of an atheroma plaque and chronic inflammation. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a protease that induces the degradation of the LDL receptor (LDLR), which contributes to increased levels of LDL cholesterol and the progress of atherosclerosis. Given that macrophages are relevant components of the lipidic and inflammatory environment of atherosclerosis, we studied the effects of PCSK9 treatment on human macrophages. Our data show that human macrophages do not express PCSK9 but rapidly incorporate the circulating protein through the LDLR and also activate the pro-inflammatory TLR4 pathway. Both LDLR and TLR4 are internalized after incubation of macrophages with exogenous PCSK9. PCSK9 uptake increases the production of reactive oxygen species and reduces the expression of genes involved in lipid metabolism and cholesterol efflux, while enhancing the production of pro-inflammatory cytokines through a TLR4-dependent mechanism. Under these conditions, the viability of macrophages is compromised, leading to increased cell death. These results provide novel insights into the role of PCSK9 in the crosstalk of lipids and cholesterol metabolism through the LDLR and on the pro-inflammatory activation of macrophages through TLR4 signaling. These pathways are relevant in the outcome of atherosclerosis and highlight the relevance of PCSK9 as a therapeutic target for the treatment of cardiovascular diseases.

Immunotherapy of glioblastoma explants induces interferon-γ responses and spatial immune cell rearrangements in tumor center, but not periphery

A patient-tailored, ex vivo drug response platform for glioblastoma (GBM) would facilitate therapy planning, provide insights into treatment-induced mechanisms in the immune tumor microenvironment (iTME), and enable the discovery of biomarkers of response. We cultured regionally annotated GBM explants in perfusion bioreactors to assess iTME responses to immunotherapy. Explants were treated with anti-CD47, anti-PD-1, or their combination, and analyzed by multiplexed microscopy [CO-Detection by indEXing (CODEX)], enabling the spatially resolved identification of >850,000 single cells, accompanied by explant secretome interrogation. Center and periphery explants differed in their cell type and soluble factor composition, and responses to immunotherapy. A subset of explants displayed increased interferon-γ levels, which correlated with shifts in immune cell composition within specified tissue compartments. Our study demonstrates that ex vivo immunotherapy of GBM explants enables an active antitumoral immune response within the tumor center and provides a framework for multidimensional personalized assessment of tumor response to immunotherapy.

The ‘Danse Macabre’—Neutrophils the Interactive Partner Affecting Oral Cancer Outcomes

Over the past few decades, tremendous advances in the prevention, diagnosis, and treatment of cancer have taken place. However for head and neck cancers, including oral cancer, the overall survival rate is below 50% and they remain the seventh most common malignancy worldwide. These cancers are, commonly, aggressive, genetically complex, and difficult to treat and the delay, which often occurs between early recognition of symptoms and diagnosis, and the start of treatment of these cancers, is associated with poor prognosis. Cancer development and progression occurs in concert with alterations in the surrounding stroma, with the immune system being an essential element in this process. Despite neutrophils having major roles in the pathology of many diseases, they were thought to have little impact on cancer development and progression. Recent studies are now challenging this notion and placing neutrophils as central interactive players with other immune and tumor cells in affecting cancer pathology. This review focuses on how neutrophils and their sub-phenotypes, N1, N2, and myeloid-derived suppressor cells, both directly and indirectly affect the anti-tumor and pro-tumor immune responses. Emphasis is placed on what is currently known about the interaction of neutrophils with myeloid innate immune cells (such as dendritic cells and macrophages), innate lymphoid cells, natural killer cells, and fibroblasts to affect the tumor microenvironment and progression of oral cancer. A better understanding of this dialog will allow for improved therapeutics that concurrently target several components of the tumor microenvironment, increasing the possibility of constructive and positive outcomes for oral cancer patients. For this review, PubMed, Web of Science, and Google Scholar were searched for manuscripts using keywords and combinations thereof of “oral cancer, OSCC, neutrophils, TANs, MDSC, immune cells, head and neck cancer, and tumor microenvironment” with a focus on publications from 2018 to 2021.

Two hydroxyflavanones isolated from Scutellaria baicalensis roots prevent colitis-associated colon cancer in C57BL/6 J mice by inhibiting programmed cell death-1, interleukin 10, and thymocyte selection-associated high mobility group box proteins TOX/TOX2

BACKGROUND

Colorectal cancer was the second leading cause of mortality in 2019 and the number of new colorectal cancer cases was the highest in 2018 and 2019 in Japan.

PURPOSE

The present study investigated the inhibitory effects of 2(S)-2',5,6',7-tetrahydroxyflavanone and 2 (R), 3(R)-2',3,5,6'-7-pentahydroxyflavanone on the incidence and growth of tumors in azoxymethane (AOM) plus dextran sulfate sodium (DSS)-treated mice.

METHODS

The intraperitoneal administration of AOM (10 mg/kg) on day 0 induced colorectal carcinogenesis. Mice were given free and unlimited access to drinking water containing 1.5% (w/v) DSS on days 5 - 8, 30 - 33, and 56 - 57. They were orally administered tetra- and penta-hydroxyflavanones (10 and 30 mg/kg) for 10, 11, and 14 days followed by discontinuation intervals of 20 and 15 days. Cytokine, chemokine, programmed cell death-1 (PD-1), cyclooxygenase (COX)-2, and thymocyte selection-associated high mobility group box protein (TOX)/TOX2 expression levels were measured using their respective ELISA kits and an immunohistochemical analysis.

RESULTS

The number and area of tumors decreased by 60.6 and 72.9% in mice administered 10 mg/kg tetra- and pentahydroxyflavanones, respectively, with reductions of 95.0 and 87.0% in Ki-67-positive cells, 91.7 and 92.7% in COX-2-postive cells, and 83.1 and 93.8% in TOX/TOX2-positive cells, respectively, in the colon. On the other hand, two tera- and pentahydroxyflavanone had no effect on p53 (a tumor suppressor by cell cycle arrest and apoptosis)-positive cells. The administration of 10 mg/kg tetra- and pentahydroxyflavanones to AOM/DSS-treated mice also resulted in decreases of 59.5 and 42.5% in IL-10 levels and 58.1 and 93.9% in PD-1 levels, respectively, in the colon.

CONCLUSION

The inhibitory effects of tetra- and pentahydroxyflavanones on the growth of colon tumors in AOM/DSS-treated mice appear to be associated with decreases in the colon levels of IL-10 and PD-1 through the down-regulated expression of COX-2 and CD8⁺ T-cell exhaustion by TOX/TOX2 in the tumor microenvironment.

The Single-Cell Level Perspective of the Tumor Microenvironment and Its Remodeling by CAR-T Cells

The tumor microenvironment (TME) is a complex milieu consisting of lymphoid cells, myeloid cells, fibroblasts, and multiple molecules, which play a key role in tumor progression and immunotherapy. TME is characterized by immune-suppressive features, which release anti-inflammatory cytokines such as IL-4 and TGFβ to skew the T cells to a Th2 state as well to polarize tumor-associated macrophages (TAMs) to an anti-inflammatory phenotype to curb the immunotherapy. Considering the heterogeneity of the TME and its role in determining response to chimeric antigen receptor (CAR)-T cells, delineating TME at a single-cell level will provide useful information for cancer treatment. First, we discuss cellular and molecular features that curb the response to CAR-T cells, for example, high expression of immune checkpoint molecules (PD-1, LAG3) and anti-inflammatory cytokines (IL-4, TGFb) that block CAR-T cell function. Then, we summarize how newly invented single-cell technologies such as spatial multi-omics would benefit the understanding of cancer immunotherapy. Finally, we will further describe recent attempts of CAR-T to remodel TME by arming the CAR-T with anti-PD-1 single-chain variants or Th1 triggering cytokines (such as IL-7, IL-12) to remodel TME into a pro-inflammatory state. Herein, we review the single-cell-level signatures of TME and the strategies of CAR-T to remodel TME.

Factors related to the suppression of the antitumour immune response in female dogs with inflammatory mammary carcinoma

Inflammatory mammary carcinoma (IMC), a neoplasia affecting women and female dogs, is considered an aggressive cancer with high metastatic potential and a low survival rate. Studies focused on the tumour microenvironment indicate that the aggressive behaviour of this tumour is primarily correlated with immunological factors as well as inflammation. The objective of this study was to analyse the possible strategies used by the tumour cells to suppress the immune response in female dogs with IMC. Forty-six female dogs were divided into three groups: control (C, n = 10), IMC (n = 14) and mammary carcinoma (MC, n = 22). Clinical-pathological evaluations, survival at follow-up, immunophenotyping of leukocytes in peripheral blood and tumours, and immunohistochemical evaluation of CD4⁺, granzyme B, perforin and FAS-L were performed. Clinical and pathological results showed a higher frequency of the primary form of neoplasia, solid arrays of tumor cells and a lower survival rate in the IMC group (30 days). Morphometric analysis of inflammatory infiltrate revealed more lymphocytes and macrophages in the IMC group. Immunophenotyping analysis of peripheral blood revealed a higher frequency of CD8⁺ T-cells (p = 0.0017), a lower frequency of CD4⁺ T-cells (p <0.0001), and significantly higher mean MHCI and MHCII CD14⁺ fluorescence intensity in the IMC group (p = 0.038 and p = 0.0117, respectively). The immunohistochemical evaluation of tumour sections showed fewer FAS-L-positive inflammatory cells in the IMC group. These results suggest the important contribution of CD8⁺ T-cells, macrophages and FAS-L in the aggressiveness of IMC.

The Give-and-Take Interaction Between the Tumor Microenvironment and Immune Cells Regulating Tumor Progression and Repression

A fundamental concern of the majority of cancer scientists is related to the identification of mechanisms involved in the evolution of neoplastic cells at the cellular and molecular level and how these processes are able to control cancer cells appearance and death. In addition to the genome contribution, such mechanisms involve reciprocal interactions between tumor cells and stromal cells within the tumor microenvironment (TME). Indeed, tumor cells survival and growth rely on dynamic properties controlling pro and anti-tumorigenic processes. The anti-tumorigenic function of the TME is mainly regulated by immune cells such as dendritic cells, natural killer cells, cytotoxic T cells and macrophages and normal fibroblasts. The pro-tumorigenic function is also mediated by other immune cells such as myeloid-derived suppressor cells, M2-tumor-associated macrophages (TAMs) and regulatory T (Treg) cells, as well as carcinoma-associated fibroblasts (CAFs), adipocytes (CAA) and endothelial cells. Several of these cells can show both, pro- and antitumorigenic activity. Here we highlight the importance of the reciprocal interactions between tumor cells and stromal cells in the self-centered behavior of cancer cells and how these complex cellular interactions control tumor progression and repression.

Unveiling the Role of the Tumor Microenvironment in the Treatment of Follicular Lymphoma

Simple Summary

Follicular lymphoma is the most common type of indolent non-Hodgkin lymphoma and is characterized by its heterogeneity and variable course. In addition to tumor cells, the immune microenvironment plays a fundamental role in the pathogenesis of the disease. Despite advances in treatment, responses vary among patients, and outcomes are often unpredictable: a subset of high-risk patients will be refractory to standard treatments or will develop a high-grade histology. In this review, we try to understand the crosstalk between follicular lymphoma B-cells and the tumor microenvironment as well as its impact on prognosis and the risk of transformation. We also highlight recent findings related to novel therapies developed to treat this complex disease, in which genetic mutations and microenvironment cells play a key role.

Abstract

Follicular lymphomas (FL) are neoplasms that resemble normal germinal center (GC) B-cells. Normal GC and neoplastic follicles contain non-neoplastic cells such as T-cells, follicular dendritic cells, cancer associated fibroblasts, and macrophages, which define the tumor microenvironment (TME), which itself is an essential factor in tumor cell survival. The main characteristics of the TME in FL are an increased number of follicular regulatory T-cells (T_reg) and follicular helper T-cells (T_fh), M2-polarization of macrophages, and the development of a nodular network by stromal cells that creates a suitable niche for tumor growth. All of them play important roles in tumor angiogenesis, inhibition of apoptosis, and immune evasion, which are key factors in tumor progression and transformation risk. Based on these findings, novel therapies have been developed to target specific mutations present in the TME cells, restore immune suppression, and modulate TME.

Loss of YTHDF1 in gastric tumors restores sensitivity to antitumor immunity by recruiting mature dendritic cells

Background

Gastric cancer (GC) is one of the most common cancer worldwide. We analyzed the expression of m⁶A regulatory genes in GC cohorts and revealed that YTHDF1 was uniquely upregulated in GC as compared with adjacent normal tissues. In this study, we analyzed the role of YTHDF1 in GC cells and modulation of the tumor immune microenvironment.

Methods

Three GC cohorts (cohort 1, n=101; cohort 2, n=278, and the Cancer Genome Atlas cohort, n=375) were analyzed for YTHDF1 expression. Function of YTHDF1 in GC was determined in GC cell lines. Role of YTHDF1 in antitumor immunity was investigated in allograft models.

Results

YTHDF1 is upregulated in GC compared with adjacent normal tissues, and high YTHDF1 expression was correlated with poor survival of patients with GC at mRNA (p=0.016) and protein levels (p=0.039). Loss of YTHDF1 in human (AGS, BGC823, MKN74) or mouse (YTN16) GC cell lines inhibited cell growth and colony formation in vitro. Strikingly, syngeneic YTN16 tumors with loss of YTHDF1 underwent complete remission in immunocompetent mice, while a lesser effect was found in immunodeficient mice. Consistently, YTHDF1 loss in GC tumors led to recruitment of mature dendritic cells (DCs) with increased MHCII expression and interleukin-12 (IL-12) secretion, which in turn, promoted CD4⁺ and CD8⁺ T cells infiltration with increased interferon-γ (IFN-γ) secretion. Loss of YTHDF1 mediated the overexpression of IFN-γ receptor 1 and JAK/STAT1 signaling pathway in tumor cells, which might contribute to restored sensitivity to antitumor immunity. In addition, pre-emptive exposure of YTN16 tumors with YTHDF1 loss triggered a potent antitumor immune response on rechallenge with wild-type YTN16 cells, implying that YTHDF1 loss induced a lasting systemic antitumor immunity.

Conclusions

YTHDF1 is overexpressed in GC and promotes GC by inducing cell proliferation and repression of DCs-mediated antitumor immune response. YTHDF1 is a promising therapeutic target for GC treatment.

Cancer Immunoediting: Elimination, Equilibrium, and Immune Escape in Solid Tumors

Emphasizing the dynamic processes between cancer and host immune system, the initially discovered concept of cancer immunosurveillance has been replaced by the current concept of cancer immunoediting consisting of three phases: elimination, equilibrium, and escape. Solid tumors composed of both cancer and host stromal cells are an example how the three phases of cancer immunoediting functionally evolve and how tumor shaped by the host immune system gets finally resistant phenotype. The elimination, equilibrium, and escape have been described in this chapter in details, including the role of immune surveillance, cancer dormancy, disruption of the antigen-presenting machinery, tumor-infiltrating immune cells, resistance to apoptosis, as well as the function of tumor stroma, microvesicles, exosomes, and inflammation.

Syngeneic murine glioblastoma models: reactionary immune changes and immunotherapy intervention outcomes

Glioblastoma is the most common primary malignant brain neoplasm with dismal 10-year survival rates of < 1%. Despite promising preliminary results from several novel therapeutic agents, clinical responses have been modest due to several factors, including tumor heterogeneity, immunosuppressive tumor microenvironment, and treatment resistance. Novel immunotherapeutics have been developed to reverse tumor-induced immunosuppression in patients with glioblastomas. In order to recapitulate the tumor microenvironment, reliable in vivo syngeneic murine models are critical for the development of new targeted agents as these models demonstrate rapid tumor induction and reliable tumor growth over multiple generations. Despite the clear advantages of murine models, choosing an appropriate model from an immunological perspective can be difficult and have significant ramifications on the translatability of the results from murine to human trials. Herein, the authors reviewed the 4 most commonly used immunocompetent syngeneic murine glioma models (GL261 [C57BL/6], SB28 [C57BL/6], CT-2A [C57BL/6], and SMA-560 [VM/Dk]) and compared their strengths and weaknesses from an immunological standpoint.

The Characteristics of Tumor Microenvironment in Triple Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a special subtype of breast cancer, accounting for 10-20% of breast cancers with high intrinsic heterogeneity. Its unique immune microenvironment, including high expression of vascular endothelial growth factors, tumor infiltrating lymphocytes (TILs), tumor-associated macrophages (TAMs), and other molecules that promote the growth and migration of tumor cells, has been shown to play a dual role in the occurrence, growth, and metastasis of TNBC. Understanding the TNBC microenvironment is of great significance for the prognosis and treatment of TNBC. In this article, we describe the composition and function of immune cells in the TNBC microenvironment and summarize the major cytokine growth factors and chemokines in the TNBC microenvironment. Finally, we discuss the progress of TNBC, cytokine-induced killer cell therapy, and immune checkpoint therapy.

Therapeutic potential of Scutellaria baicalensis Georgi in lung cancer therapy

BACKGROUND

Globally, lung cancer is the leading cause of cancer associated mortalities. The current conventional chemotherapy remains the preferred treatment option for lung cancer, as surgical resection plays little role in the treatment of over 75% of lung cancer patients. Therefore, there is a need to develop novel potential therapeutic drugs or adjuvants with a high efficiency and safety against lung cancer. Scutellaria baicalensis Georgi, a common Chinese medicinal herb that has been in use for more than 2000 years, has recently been shown to possess significant activities against lung cancer. However, current research progress on pharmacological effects and relevant molecular mechanisms of S. baicalensis in lung cancer therapy have not been systematically summarized.

PURPOSE

This review aimed at elucidating on the anti-lung cancer mechanisms and antitumor efficacies of S. baicalensis as well as its active ingredients, and providing a valuable reference for further investigation in this field.

METHODS

We used "Scutellaria baicalensis" or the name of the compound in S. baicalensis, in combination with "lung cancer" as key words to systematically search for relevant literature from the Web of Science and PubMed databases. Publications that investigated molecular mechanisms were the only ones selected for analysis. The PRISMA guidelines were followed.

RESULTS

Fifty-four publications met the inclusion criteria for this study. Five anti-lung cancer mechanisms of S. baicalensis and its constituent components are discussed. These mechanisms include apoptosis induction, cell-cycle arrest, suppression of proliferation, blockade of invasion and metastasis, and overcoming drug-resistance. These compounds exhibited high antitumor efficacies and safety against lung cancer xenografts.

CONCLUSION

Studies should aim at elucidating on the anti-cancer mechanisms of S. baicalensis to achieve the ultimate goal of lung cancer therapy.

p53 signaling in cancer progression and therapy

The p53 protein is a transcription factor known as the "guardian of the genome" because of its critical function in preserving genomic integrity. The TP53 gene is mutated in approximately half of all human malignancies, including those of the breast, colon, lung, liver, prostate, bladder, and skin. When DNA damage occurs, the TP53 gene on human chromosome 17 stops the cell cycle. If p53 protein is mutated, the cell cycle is unrestricted and the damaged DNA is replicated, resulting in uncontrolled cell proliferation and cancer tumours. Tumor-associated p53 mutations are usually associated with phenotypes distinct from those caused by the loss of the tumor-suppressing function exerted by wild-type p53protein. Many of these mutant p53 proteins have oncogenic characteristics, and therefore modulate the ability of cancer cells to proliferate, escape apoptosis, invade and metastasize. Because p53 deficiency is so common in human cancer, this protein is an excellent option for cancer treatment. In this review, we will discuss some of the molecular pathways by which mutant p53 proteins might perform their oncogenic activities, as well as prospective treatment methods based on restoring tumor suppressive p53 functions.

RAB42 Promotes Glioma Pathogenesis via the VEGF Signaling Pathway

Angiogenesis plays an important role in tumor initiation and progression of glioma. Seeking for biomarkers associated with angiogenesis is important in enhancing our understanding of glioma biologically and identifying its new drug targets. RNA-sequencing (RNA-seq) data and matched clinical data were downloaded from the CGGA database. A series of filtering analyses were performed to screen for reliable genes: survival, multivariate Cox, ROC curve filtration, and clinical correlation analyses. After immunohistochemical verification, RAB42 was identified as a reliable gene for further single gene analysis. Afterwards, we performed gene set enrichment analysis (GSEA) and co-expression analysis to establish the related molecular mechanisms and signal pathways in glioma. Finally, the gene functions and the mechanisms were investigated in vitro experiments. A total of 23270 mRNA expression and 1018 glioma samples were included in this study. After the three filtering analyses, we selected ten genes for immunohistochemical verification: KLHDC8A, IKIP, HIST1H2BK, HIST1H2BJ, GNG5, FAM114A1, TMEM71, RAB42, CCDC18, and GAS2L3. Immunostaining demonstrated that RAB42 was significantly expressed on the membrane of glioma tissues but not in normal tissues. These results were verified and validated in GEPIA datasets, and the association between RAB42 with clinical features was also evaluated. Analysis of gene functions indicated that RAB42 activated VEGF signaling pathways and the mechanism was associated with natural killer cell mediated cytotoxicity, JAK-STAT signaling pathway and apoptosis pathways by PI3K/AKT in gliomas. Experiments in vitro suggested that the proliferation and invasion of glioma cells might be inhibited after downregulating of RAB42. And the tumorigenesis promotion of RAB42 may relate to the activation of VEGF signaling pathway. Taken together, this study shows that the overexpression of RAB42 is an independent prognostic factor of adverse prognosis. Its pro-oncogenic mechanism may be associated with the activation of VEGF signaling pathways.

Targeting hypoxia and hypoxia-inducible factor-1 in the tumor microenvironment for optimal cancer immunotherapy

The development of new strategies of anticancer immunotherapies has provided promising approaches in the treatment of solid tumors. However, despite the improved survival in responders, most of the patients show incomplete responses with a lack of remarkable clinical improvement. Hypoxia has been identified as a common characteristic of solid tumors contributing to different aspects of tumor progression, including invasion, metastasis, and the creation of the immunosuppressive tumor microenvironment. Hypoxia, through its main mediator, hypoxia-inducible factor-1 (HIF-1) is also associated with the limited efficacy of immunotherapies. Therefore, designing new strategies for immunotherapy implicating therapeutic targeting of HIF-1 molecules may enhance the clinical effectiveness of immunotherapy. Here, we discuss the contribution of hypoxia to the development of the immunosuppressive tumor microenvironment. We will also outline different strategies for targeting hypoxia to provide insight into the therapeutic potential of the application of such strategies to improve the clinical benefit of cancer immunotherapy.

Macrophages in tumor: An inflammatory perspective

Inflammation is a part of carefully co-ordinated healing immune exercise to eliminate injurious stimuli. However, in substantial number of cancer types, it contributes in shaping up of robust tumor microenvironment (TME). Solid TME promotes infiltration of tumor associated macrophages (TAMs) that contributes to cancer promotion. TAMs are functionally heterogeneous and display an extraordinary degree of plasticity, which allow 'Switching' of macrophages into an 'M2', phenotype, linked with immunosuppression, advancement of tumor angiogenesis with metastatic consequences. In contrary to the classical M1 macrophages, these M2 TAMs are high-IL-10, TGF-β secreting-'anti-inflammatory'. In this review, we will discuss the modes of infiltration and switching of TAMs into M2 anti-inflammatory state in the TME to promote immunosuppression and inflammation-driven cancer.

Hodgkin Lymphoma: A Special Microenvironment

Classical Hodgkin’s lymphoma (cHL) is one of the most particular lymphomas for the few tumor cells surrounded by an inflammatory microenvironment. Reed-Sternberg (RS) and Hodgkin (H) cells reprogram and evade antitumor mechanisms of the normal cells present in the microenvironment. The cells of microenvironment are essential for growth and survival of the RS/H cells and are recruited through the effect of cytokines/chemokines. We summarize recent advances in gene expression profiling (GEP) analysis applied to study microenvironment component in cHL. We also describe the main therapies that target not only the neoplastic cells but also the cellular components of the background.

Macrophages and cancer stem cells: a malevolent alliance

Myeloid cells infiltrating tumors are gaining ever growing attention in the last years because their pro-tumor and immunosuppressive functions are relevant for disease progression and therapeutic responses. The functional ambiguity of tumor-associated macrophages (TAMs), mostly promoting tumor evolution, is a challenging hurdle. This is even more evident in the case of cancer stem cells (CSCs); as active participants in the specialized environment of the cancer stem cell niche, TAMs initiate a reciprocal conversation with CSCs. TAMs contribute to protect CSCs from the hostile environment (exogenous insults, toxic compounds, attacks from the immune cells), and produce several biologically active mediators that modulate crucial developmental pathways that sustain cancer cell stemness. In this review, we have focused our attention on the interaction between TAMs and CSCs; we describe how TAMs impact on CSC biology and, in turn, how CSCs exploit the tissue trophic activity of macrophages to survive and progress. Since CSCs are responsible for therapy resistance and tumor recurrence, they are important therapeutic targets. In view of the recent success in oncology obtained by stimulating the immune system, we discuss some macrophage-targeted therapeutic strategies that may also affect the CSCs and interrupt their malevolent alliance.

Th1 polarization in the tumor microenvironment upregulates the myeloid-derived suppressor-like function of macrophages

Here, we investigated the effect of Th1 polarization in the tumor microenvironment (TME) on tumor-associated macrophage (TAM) maturation and activation. In our immunotherapy mouse model, with a Th1-dominant TME, tumors regressed in all cases, with complete regression in 80% of the cases. Monocyte-derived dendritic cells and activated CD4⁺ and CD8⁺T-cells increased in the tumor-draining lymph node, and correlated with each other in the therapeutic model. However, the cytotoxicity of tumor-infiltrating CD8⁺T-cells was slightly inhibited, whereas the number of T-cells significantly increased. Moreover, the number of TAMs increased; their maturation was inhibited; and nitrotyrosine (NT) production, as well as iNOS and arginase I expression, was increased, suggestive of the myeloid-derived suppressor cell-like immunosuppressive function of TAMs. IFN-γ knockout in the therapeutic model decreased NT production and induced macrophage maturation. Hence, Th1 polarization in the IFN-γ-dominant condition induces T-cell immune responses; however, it also enhances the immunosuppressive activity of TAMs.

Arginase 1-Based Immune Modulatory Vaccines Induce Anticancer Immunity and Synergize with Anti-PD-1 Checkpoint Blockade

Expression of the L-arginine catabolizing enzyme arginase 1 (ARG1) is a central immunosuppressive mechanism mediated by tumor-educated myeloid cells. Increased activity of ARG1 promotes the formation of an immunosuppressive microenvironment and leads to a more aggressive phenotype in many cancers. Intrinsic T-cell immunity against ARG1-derived epitopes in the peripheral blood of cancer patients and healthy subjects has previously been demonstrated. To evaluate the antitumor efficacy of ARG1-derived peptide vaccines as a monotherapy and as a combinational therapy with checkpoint blockade, different in vivo syngeneic mouse tumor models were utilized. To evaluate the antitumor effects, flow cytometry analysis and IHC were performed on tumors, and ELISPOT assays were performed to characterize immune responses. We show that ARG1-targeting therapeutic vaccines were able to activate endogenous antitumor immunity in several in vivo syngeneic mouse tumor models and to modulate the cell composition of the tumor microenvironment without causing any associated side effects or systemic toxicity. ARG1-targeting vaccines in combination with anti-PD-1 also resulted in increased T-cell infiltration, decreased ARG1 expression, reduced suppressive function of tumor-educated myeloid cells, and a shift in the M1/M2 ratio of tumor-infiltrating macrophages. These results indicated that the induced shift toward a more proinflammatory microenvironment by ARG1-targeting immunotherapy favors effective tumor control when combined with anti-PD-1 checkpoint blockade. Our data illustrate the ability of ARG1-based immune modulatory vaccination to elicit antigen-specific immunosurveillance and imply the feasibility of this novel immunotherapeutic approach for clinical translation.

The implications of nitric oxide metabolism in the treatment of glial tumors

Glial tumors are the most common intracranial malignancies. Unfortunately, despite such a high prevalence, patients' prognosis is usually poor. It is related to the high invasiveness, tendency to relapse and the resistance of tumors to traditional methods of treatment. An important link in the aspect of these issues may be nitric oxide (NO) metabolism. It is a very complex mechanism with multidirectional effects on the neoplastic process. Depending on the concentration axis, it can both exert pro-tumor action as well as contribute to the inhibition of tumorigenesis. The latest observations show that the control of its metabolism can be very helpful in the development of new methods of treating gliomas, as well as in increasing the effectiveness of the agents currently used. The influence of nitric oxide and nitric oxide synthase (NOS) activity on glioma stem cells seem to be of particular importance. The use of specific inhibitors may allow the reduction of tumor growth and its tendency to relapse. Another important feature of GSCs is their conditioning of glioma resistance to traditional forms of treatment. Recent studies have shown that modulation of NO metabolism can suppress this effect, preventing the induction of radio and chemoresistance. Moreover, nitric oxide is involved in the regulation of a number of immune mechanisms. Adequate modulation of its metabolism may contribute to the induction of an anti-tumor response in the patients' immune system.

The prognosis of cancer patients undergoing liposomal doxorubicin-based chemotherapy: A systematic review and meta-analysis

BACKGROUND

It is well known that liposome-based delivery of cytotoxic chemotherapeutics has been proposed as a putative strategy to enhance drug tolerability and efficacy compared to the conventional chemotherapy. However, its potential effect on improving prognosis remains largely unknown. The current meta-analysis is to explore the prognosis of cancer patients undergoing liposomal doxorubicin-based chemotherapy.

METHODS

A detailed review of English and Chinese literature was conducted up to March 21, 2020. We evaluate its possible correlations using hazard ratios (HRs) with 95% confidence intervals (CIs). The pooled data were calculated by STATA software and Review Manager 5.3 software.

RESULTS

Consequently, 26 studies including 7943 patients were satisfied in current analysis. There were no significant differences between liposomal and conventional chemotherapy in OS (HR = 0.98, 95%CI: 0.93-1.04, P = .544) and PFS (HR = 1.00, 95%CI: 0.92-1.10, P = .945). Likewise, subgroup-analysis regarding country, cancer type, and sample sizes also showed the similar results of the 2 paired groups.

CONCLUSION

Taken together, our finding has demonstrated that there was no association of undergoing liposomal doxorubicin-based chemotherapy with cancer prognosis. However, detailed and further studies are needed to confirm our conclusion.

Pan-Cancer Analysis of Immune Complement Signature C3/C5/C3AR1/C5AR1 in Association with Tumor Immune Evasion and Therapy Resistance

Despite the advances in our understanding of the genetic and immunological basis of cancer, cancer remains a major public health burden with an ever-increasing incidence rate globally. Nevertheless, increasing evidence suggests that the components of the complement system could regulate the tumor microenvironment (TME) to promote cancer progression, recurrence, and metastasis. In the present study, we used an integrative multi-omics analysis of clinical data to explore the relationships between the expression levels of and genetic and epigenetic alterations in C3, C5, C3AR1, and C5AR1 and tumor immune evasion, therapy response, and patient prognosis in various cancer types. We found that the complements C3, C5, C3AR1, and C5AR1 have deregulated expression in human malignancies and are associated with activation of immune-related oncogenic processes and poor prognosis of cancer patients. Furthermore, we found that the increased expression levels of C3, C5, C3AR1, and C5AR1 were primarily predicted by copy number variation and gene methylation and were associated with dysfunctional T-cell phenotypes. Single nucleotide variation in the gene signature co-occurred with multiple oncogenic mutations and is associated with the progression of onco-immune-related diseases. Further correlation analysis revealed that C3, C5, C3AR1, and C5AR1 were associated with tumor immune evasion via dysfunctional T-cell phenotypes with a lesser contribution of T-cell exclusion. Lastly, we also demonstrated that the expression levels of C3, C5, C3AR1, and C5AR1 were associated with context-dependent chemotherapy, lymphocyte-mediated tumor killing, and immunotherapy outcomes in different cancer types. In conclusion, the complement components C3, C5, C3AR1, and C5AR1 serve as attractive targets for strategizing cancer immunotherapy and response follow-up.

Macrophage polarization synergizes with oxaliplatin in lung cancer immunotherapy via enhanced tumor cell phagocytosis

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LLC cells pretreated with OXA were more prone to be phagocytized by M1 than M2 macrophages.

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M2 repolarized to M1 by R848 in vitro showed enhanced phagocytic ability to OXA-treated LLC cells.

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Macrophage polarization from pro-tumor M2 to anti-tumor M1 synergizes with OXA.

Calreticulin (CALR) exposure is required for most immunogenic cell death (ICD) in the anti-tumor immunity induced by chemotherapeutic agents. The present study aimed to explore the anti-tumor efficacy of the combined administration of oxaliplatin (OXA) and R848 (an agent for macrophage polarization) in lung cancer cells. Flow cytometry and immunostaining assays were performed to evaluate CALR exposure induced by OXA in the murine Lewis lung carcinoma (LLC) cells. The phagocytosis of macrophages was determined using flow cytometry and western blotting assays. The anti-tumor efficacy of the OXA and R848 combination was evaluated using flow cytometry and western blotting in vitro and in vivo. OXA induced CALR exposure on the surface of LLC cells after low dose and short duration of treatment (20 μM OXA for 24 h). LLC cells pretreated with OXA were more prone to be phagocytized by M1 than M2 macrophages. M2 macrophages repolarized to M1 by R848 in vitro showed enhanced phagocytic ability to OXA-treated LLC cells. Finally, combined administration of OXA and R848 exhibited a synergistic anti-tumor effect than single agent applied in vitro and in vivo. Macrophage polarization from pro-tumor M2 to anti-tumor M1 synergizes with OXA in lung cancer immunotherapy via enhanced tumor cell phagocytosis.

The Trinity of Matrix Metalloproteinases, Inflammation, and Cancer: A Literature Review of Recent Updates

The critical link between cancer and inflammation has been known for many years. This complex network was further complexed by revealing the association of the matrix metalloproteinase family members with inflammatory cytokines, which were previously known to be responsible for the development of metastasis. This article summarizes the current studies which evaluate the relationship between cancer and inflammatory microenvironment as well as the roles of MMPs on invasion and metastasis together.

Monocyte Infiltration and Differentiation in 3D Multicellular Spheroid Cancer Models

Tumor-associated macrophages often correlate with tumor progression, and therapies targeting immune cells in tumors have emerged as promising treatments. To select effective therapies, we established an in vitro 3D multicellular spheroid model including cancer cells, fibroblasts, and monocytes. We analyzed monocyte infiltration and differentiation in spheroids generated from fibroblasts and either of the cancer cell lines MCF-7, HT-29, PANC-1, or MIA PaCa-2. Monocytes rapidly infiltrated spheroids and differentiated into mature macrophages with diverse phenotypes in a cancer cell line-dependent manner. MIA PaCa-2 spheroids polarized infiltrating monocytes to M2-like macrophages with high CD206 and CD14 expression, whereas monocytes polarized by MCF-7 spheroids displayed an M1-like phenotype. Monocytes in HT-29 and PANC-1 primarily obtained an M2-like phenotype but also showed upregulation of M1 markers. Analysis of the secretion of 43 soluble factors demonstrated that the cytokine profile between spheroid cultures differed considerably depending on the cancer cell line. Secretion of most of the cytokines increased upon the addition of monocytes resulting in a more inflammatory and pro-tumorigenic environment. These multicellular spheroids can be used to recapitulate the tumor microenvironment and the phenotype of tumor-associated macrophages in vitro and provide more realistic 3D cancer models allowing the in vitro screening of immunotherapeutic compounds.

Biological effects and mechanisms of matrine and other constituents of Sophora flavescens in colorectal cancer

The plant Sophora flavescens Ait. has been used in the clinical management of colorectal cancer (CRC). Its constituent compounds, notably the alkaloids matrine, oxymatrine, and sophoridine, have received considerable research attention in experimental models of CRC in vivo and in vitro. This review found that extracts of S. flavescens and/or its constituent compounds have been reported to inhibit CRC cell proliferation by inducing cell-cycle arrest at the G1 phase, inducing apoptosis via the intrinsic pathway, interfering in cancer metabolism, inhibiting metastasis and angiogenesis, regulating senescence and telomeres, regulating the tumour microenvironment and down-regulating cancer-related inflammation. In addition, matrine and oxymatrine reversed multi-drug resistance and enhanced the effects of chemotherapies. These anti-cancer effects were associated with regulation of several cellular signalling pathways including: MAPK/ERK, PI3K/AKT/mTOR, p38MAPK, NF-κB, Hippo/LATS2, TGF-β/Smad, JAK/STAT3, RhoA/ROC, and Wnt/ β-catenin pathways. These multiple actions in CRC suggest the alkaloids of S. flavescens may be therapeutic candidates for CRC management. Nevertheless, there remains considerable scope for future research into its flavonoid constituents, the effects of combinations of compounds, and the interaction between these compounds and anti-cancer drugs. In addition, more research is needed to investigate likely drug ligand-receptor interactions for each of the bioactive compounds.

Trabectedin (Yondelis®) as a Therapeutic Option in Gynecological Cancers: A Focus on its Mechanisms of Action, Clinical Activity and Genomic Predictors of Drug Response

The use of predictive biomarkers provides potential individualized cancer therapeutic options to prevent therapy failure as well as serious toxicities. Several recent studies showed that predictive and prognostic biomarkers are a notable personalized strategy to improve patients' care in several cancers. Trabectedin (Yondelis®) is a cytotoxic agent, derived from a marine organism, harbouring a significant antitumor activity against several cancers such as soft tissue sarcoma, ovarian, and breast cancers. Recently and with the advent of molecular genetic testing, BRCA mutational status was found as an important predictor of response to this anticancer drug, especially in gynecological cancers. The aim of this updated review is to discuss the mechanisms of action of trabectedin against the wellknown cancer hallmarks described until today. The current advances were also examined related to genomic biomarkers that can be used in the future to predict the efficacy of this potent anticancer natural molecule in various gynecological cancers.

Tumor-Associated Macrophages: Combination of Therapies, the Approach to Improve Cancer Treatment

Macrophages are one of the most important cells of the innate immune system and are known for their ability to engulf and digest foreign substances, including cellular debris and tumor cells. They can convert into tumor-associated macrophages (TAMs) when mature macrophages are recruited into the tumor microenvironment. Their role in cancer progression, metastasis, and therapy failure is of special note. The aim of this review is to understand how the presence of TAMs are both advantageous and disadvantageous in the immune system.

Macrophage Polarization States in the Tumor Microenvironment

The M1/M2 macrophage paradigm plays a key role in tumor progression. M1 macrophages are historically regarded as anti-tumor, while M2-polarized macrophages, commonly deemed tumor-associated macrophages (TAMs), are contributors to many pro-tumorigenic outcomes in cancer through angiogenic and lymphangiogenic regulation, immune suppression, hypoxia induction, tumor cell proliferation, and metastasis. The tumor microenvironment (TME) can influence macrophage recruitment and polarization, giving way to these pro-tumorigenic outcomes. Investigating TME-induced macrophage polarization is critical for further understanding of TAM-related pro-tumor outcomes and potential development of new therapeutic approaches. This review explores the current understanding of TME-induced macrophage polarization and the role of M2-polarized macrophages in promoting tumor progression.

Perspectives on Hypoxia Signaling in Tumor Stroma

Hypoxia is a well-known characteristic of solid tumors that contributes to tumor progression and metastasis. Oxygen deprivation due to high demand of proliferating cancer cells and standard of care therapies induce hypoxia. Hypoxia signaling, mainly mediated by the hypoxia-inducible transcription factor (HIF) family, results in tumor cell migration, proliferation, metabolic changes, and resistance to therapy. Additionally, the hypoxic tumor microenvironment impacts multiple cellular and non-cellular compartments in the tumor stroma, including disordered tumor vasculature, homeostasis of ECM. Hypoxia also has a multifaceted and often contradictory influence on immune cell function, which contributes to an immunosuppressive environment. Here, we review the important function of HIF in tumor stromal components and summarize current clinical trials targeting hypoxia. We provide an overview of hypoxia signaling in tumor stroma that might help address some of the challenges associated with hypoxia-targeted therapies.

M2 tumor-associated macrophages play important role in predicting response to neoadjuvant chemotherapy in triple-negative breast carcinoma

PURPOSE

Two types of macrophages are present in tumor microenvironment. M1 macrophages exhibit potent anti-tumor properties, while M2 macrophages play the pro-tumoral roles. The presence of M2 macrophages is associated with worsened overall survival in triple-negative breast carcinoma (TNBC) patients. However, the relationship between M2 macrophages and response to neoadjuvant chemotherapy (NAC) is unknown.

METHODS

M2 macrophages were investigated on biopsy whole sections from 66 TNBCs treated with NAC by CD163 together with other immune checkpoint markers (PD1, PD-L1 and CD8) using a multi-color immunohistochemical multiplex assay.

RESULTS

Incomplete response was significantly associated with older age, lower PD-L1 expression (tumor and stroma), lower levels of CD8-positive TILs in stroma, but higher level of CD163-positive macrophages, with the level of CD163-positive M2 macrophages in peritumoral area as the strongest factor.

CONCLUSIONS

Our data have demonstrated that the level of CD163-positive M2 macrophages was significantly higher in TNBC patients with incomplete response than patients with complete response, suggesting M2 macrophages' important role in predicting TNBC patients' response to NAC.