Neoplastic "Black Ops": cancer's subversive tactics in overcoming host defenses

Manganese and IL-12 treatment alters the ovarian tumor microenvironment

Metal immunotherapy is a novel adjuvant immunotherapy. Mn2+ can activate STING-a type I IFN response protein-that promotes innate immunity and increases anti-tumor activity by promoting macrophage phagocytosis. IL-12, a cytokine that increases the antigen-presenting ability to promote effector T-cell activation, has potent antitumor activity, albeit with severe adverse effects. In this study, we observed that the combination of Mn2+ and IL-12 has a better antitumor effect and possibly reflects a better safety profile, providing a novel approach and theoretical basis for safe and rapid cancer 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processes between cancer and host immune system, the initially discovered concept of cancer immunosurveillance has been replaced by the current concept of cancer immunoediting consisting of three phases: elimination, equilibrium, and escape.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.

Improving therapeutic resistance: beginning with targeting the tumor microenvironment

Cancer is a serious threat to human health and life. The tumor microenvironment (TME) not only plays a key role in the occurrence, development and metastasis of cancer, but also has a profound impact on treatment resistance. To improve and solve this problem, an increasing number of strategies targeting the TME have been proposed, and great progress has been made in recent years. This article reviews the characteristics and functions of the main matrix components of the TME and the mechanisms by which each component affects drug resistance. Furthermore, this article elaborates on targeting the TME as a strategy to treat acquired drug resistance, reduce tumor metastasis, recurrence, and improve efficacy.

Chitosan-Poly(Acrylic Acid) Nanoparticles Loaded with R848 and MnCl2 Inhibit Melanoma via Regulating Macrophage Polarization and Dendritic Cell Maturation

Purpose

Since immune cells in the tumor microenvironment (TME) can affect the development and progression of tumors, strategies modulating immune cells are considered to have an important therapeutic effect. As a TLR7/8 agonist, R848 effectively activates the innate immune cells to exert an anti-tumor effect. Mn²⁺ has been reported to strongly promote the maturation of antigen-presenting cells (APCs), thereby enhancing the cytotoxicity of CD8⁺ T cells. Thus, we tried to investigate whether chitosan-poly(acrylic acid) nanoparticles (CS-PAA NPs) loaded with R848 and MnCl₂ (R-M@CS-PAA NPs) could exert an anti-tumor effect by regulating the function of immune cells.

Methods

R-M@CS-PAA NPs were prepared, and their basic characteristics, anti-tumor effect, and potential mechanisms were explored both in vitro and in vivo.

Results

R-M@CS-PAA NPs easily released MnCl₂ and R848 at low pH. In B16F10 mouse melanoma model, R-M@CS-PAA NPs exerted the most significant anti-melanoma effect compared with the control group and CS-PAA NPs loaded with R848 or MnCl₂ alone. FITC-labeled R-M@CS-PAA NPs were displayed to be accumulated at the tumor site. R-M@CS-PAA NPs significantly increased the infiltration of M1 macrophages and CD8⁺ T cells but reduced the number of suppressive immune cells in the TME. Moreover, in vitro experiments showed that R-M@CS-PAA NPs polarized macrophages into the M1 phenotype to inhibit the proliferation of B16F10 cells. R-M@CS-PAA NPs also enhanced the killing function of CD8⁺ T cells to B16F10 cells. Of note, R-M@CS-PAA NPs not only promoted the maturation of APCs such as dendritic cells and macrophages by STING and NF-кB pathways, but also enhanced the ability of dendritic cells to present ovalbumin to OT-I CD8⁺ T cells to enhance the cytotoxicity of OT-I CD8⁺ T cells to ovalbumin-expressing B16F10 cells.

Conclusion

These data indicate that the administration of R-M@CS-PAA NPs is an effective therapeutic strategy against melanoma.

Tumor microenvironment components: Allies of cancer progression

Cancer is a disease that affects millions of individuals worldwide and has a great impact on public health. Therefore, the study of tumor biology and an understanding of how the components of the tumor microenvironment behave and interact is extremely important for cancer research. Factors expressed by the components of the tumor microenvironment and induce angiogenesis have important roles in the onset and progression of the tumor. These components are represented by the extracellular matrix, fibroblasts, adipocytes, immune cells, and macrophages, besides endothelial cells, which modulate tumor cells and the tumor microenvironment to favor survival and the progression of cancer. The characteristics and function of the main stromal components and their mechanisms of interaction with the tumor cells that contribute to progression, tumor invasion, and tumor spread will be addressed in this review. Furthermore, reviewing these components is expected to indicate their importance as possible prognostic markers and therapeutic targets.

The Sources of Essential Fatty Acids for Allergic and Cancer Patients; a Connection with Insight into Mammalian Target of Rapamycin: A Narrative Review

Background:

Disturbance in essential fatty acids (EFA) metabolism plays a key role in autoimmune diseases, but EFA supplementation with sources of borage, evening primrose, hemp seed and fish oils was not effective in atopic and cancer diseases, as that seen in the case of multiple sclerosis. It seems that two complexes of the mammalian target of rapamycin (mTOR) signaling, mTORC1 and mTORC2, are congruent with the two bases of the Traditional Iranian Medicine (TIM) therapy, Cold and Hot nature, which are essential for the efficacy of functional oils for controlling immune responses in autoimmune diseases.

Methods:

We searched PubMed database, Web of Science (WOS), Google Scholar, Scopus and selected studies by predefined eligibility criteria. We then assessed their quality and extracted data.

Results:

The oils controlled by Cold or Hot nature may be helpful in maintaining homeostasis and preventing autoimmune diseases. In summary, studies of randomized controlled trials for allergy and cancer patients found no improvement in the signs or response to tests, despite a remarkable change in EFA fractions in the blood by supplementation with sources of borage, evening primrose, hemp seed and fish oils. In contrast, portulaca oleracea oil exhibited protective effects by anti-inflammatory properties via the PI3K/Akt/mTORC2 pathway with a deviation immune response to Th1 to treat atopic diseases and cancer.

Conclusions:

According to the concept of Traditional Iranian Medicine therapy, in contrast to Cold-nature oils, EFA supplementation with the sources of Hot-nature oilsis not suitable for the treatment of atopic and cancerous diseases.

Immune heterogeneity and clinicopathologic characterization of IGFBP2 in 2447 glioma samples

Glioblastoma is an immunosuppressive, deadly brain tumor. IGFBP2, a circulating biomarker for cancer diagnosis and a potential immunotherapeutic target, is attracting more and more attention from oncologists and clinicians. Thus, it is urgent to thoroughly investigate the immune biological process of IGFBP2 to understand tumor immune complexity and provide potential evidence for anti-IGFBP2 therapy. Through authoritative public databases, we enrolled a total of 2447 glioma samples with gene expression profiles. Then, the clinical characteristics and immunosuppressive status of IGFBP2 in the glioma samples were analyzed. Immunohistochemical staining detected the expression of immunosuppressive biomarkers. We found that IGFBP2 expression was upregulated in high-grade glioma and GBM and downregulated in IDH mutant glioma. Increased IGFBP2 accompanied PTEN loss and EGFR amplification. Bioinformatic analysis revealed that IGFBP2 is related to immunological processes. We further selected specific immunologic related gene sets and found IGFBP2 predominated immunosuppressive activities in GBM. Furthermore, we explored the relationship between IGFBP2 and genes that were well-characterized glioma-mediated immunosuppressive molecules to investigate the potential effect of IGFBP2. We discovered that IGFBP2 was correlated with CHI3L1, TNFRSF1A, LGALS1, TIMP1, VEGFA, ANXA1 and LGALS3, which were classic immunosuppressive biomarkers. Higher IGFBP2 expression predicted unfavorable survival for patients with GBM. Our findings implied that IGFBP2 is involved in immunosuppressive activities and is an independent unfavorable prognostic biomarker for patients with GBM. IGFBP2 is a potential immunotherapeutic target for GBM in future clinical trials.

Tumor-Associated Macrophages as Target for Antitumor Therapy

It is well known that the microenvironment of solid tumors is rich in inflammatory cells that influence tumor growth and development. Macrophages, called tumor-associated macrophages (TAMs), are the most abundant immune cell population present in tumor tissue. Several studies have demonstrated that the density of TAMs is associated with a poor prognosis and positively correlates with tumor growth. Several studies have proved that TAMs may activate and protect tumor stem cells, stimulate their proliferation as well as promote angiogenesis and metastasis. Furthermore, TAMs-derived cytokines and other proteins, such as CCL-17, CCL-22, TGF-β, IL-10, arginase 1, and galectin-3, make a significant contribution to immunosuppression. Since TAMs influence various aspects of cancer progression, there are many attempts to use them as a target for immunotherapy. The numerous studies have shown that the primary tumor growth and the number of metastatic sites can be significantly decreased by decreasing the population of macrophages in tumor tissue, for example, by blocking recruitment of monocytes or eliminating TAMs already present in the tumor tissue. Moreover, there are attempts at reprogramming TAMs into proinflammatory M1 macrophages or neutralizing the protumoral products of TAMs. Another approach uses TAMs for anticancer drug delivery into the tumor environment. In this review, we would like to summarize the clinical and preclinical trials that were focused on macrophages as a target for anticancer therapies.

Effects of microwave ablation on T-cell subsets and cytokines of patients with hepatocellular carcinoma

OBJECTIVES

To investigate the effects of microwave ablation on T-lymphocyte subsets and cytokines in patients with hepatocellular carcinoma.

MATERIAL AND METHODS

Peripheral blood was collected from 45 patients with hepatocellular carcinoma treated by microwave ablation before treatment, one week and one month after treatment. T cells (CD3+, CD4+ and CD8+ cells), CD4+ CD25+ Tregs, and CD16+ CD56+ NK cells were analyzed by flow cytometry. Levels of cytokines (IL-2, IFN-γ, TNF-α, IL-12, IL-4, IL-6, IL-8, and IL-10) were determined by a Luminex 200 analyzer.

RESULTS

Compared with before treatment, CD3+ cells, CD4+ cells and IL-12 increased significantly at one month after the microwave ablation treatment, while IL-4, IL-10 decreased significantly.

CONCLUSIONS

Microwave ablation could relieve the suppression of immune function caused by tumors, promote the deviation of Th2/Th1, and improve immune dysfunction in patients with hepatocellular carcinoma.

Colonization of xenograft tumors by oncolytic vaccinia virus (VACV) results in enhanced tumor killing due to the involvement of myeloid cells

Background

The mechanisms by which vaccinia virus (VACV) interacts with the innate immune components are complex and involve different mechanisms. iNOS-mediated NO production by myeloid cells is one of the central antiviral mechanisms and this study aims to investigate specifically whether iNOS-mediated NO production by myeloid cells, is involved in tumor eradication following the virus treatment.

Methods

Human colon adenocarcinoma (HCT-116) xenograft tumors were infected by VACV. Infiltration of iNOS⁺ myeloid cell population into the tumor, and virus titer was monitored following the treatment. Single-cell suspensions were stained for qualitative and quantitative flow analysis. The effect of different myeloid cell subsets on tumor growth and colonization were investigated by depletion studies. Finally, in vitro culture experiments were carried out to study NO production and tumor cell killing. Student’s t test was used for comparison between groups in all of the experiments.

Results

Infection of human colon adenocarcinoma (HCT-116) xenograft tumors by VACV has led to recruitment of many CD11b⁺ ly6G⁺ myeloid-derived suppressor cells (MDSCs), with enhanced iNOS expression in the tumors, and to an increased intratumoral virus titer between days 7 and 10 post-VACV therapy. In parallel, both single and multiple rounds of iNOS-producing cell depletions caused very rapid tumor growth within the same period after virus injection, indicating that VACV-induced iNOS⁺ MDSCs could be an important antitumor effector component. A continuous blockade of iNOS by its specific inhibitor, L-NIL, showed similar tumor growth enhancement 7–10 days post-infection. Finally, spleen-derived iNOS⁺ MDSCs isolated from virus-injected tumor bearing mice produced higher amounts of NO and effectively killed HCT-116 cells in in vitro transwell experiments.

Conclusions

We initially hypothesized that NO could be one of the factors that limits active spreading of the virus in the cancerous tissue. In contrast to our initial hypothesis, we observed that PMN-MDSCs were the main producer of NO through iNOS and NO provided a beneficial antitumor effect, The results strongly support an important novel role for VACV infection in the tumor microenvironment. VACV convert tumor-promoting MDSCs into tumor-killing cells by inducing higher NO production.

Nuclear FAK controls chemokine transcription, Tregs, and evasion of anti-tumor immunity

Focal adhesion kinase (FAK) promotes anti-tumor immune evasion. Specifically, the kinase activity of nuclear-targeted FAK in squamous cell carcinoma (SCC) cells drives exhaustion of CD8(+) T cells and recruitment of regulatory T cells (Tregs) in the tumor microenvironment by regulating chemokine/cytokine and ligand-receptor networks, including via transcription of Ccl5, which is crucial. These changes inhibit antigen-primed cytotoxic CD8(+) T cell activity, permitting growth of FAK-expressing tumors. Mechanistically, nuclear FAK is associated with chromatin and exists in complex with transcription factors and their upstream regulators that control Ccl5 expression. Furthermore, FAK's immuno-modulatory nuclear activities may be specific to cancerous squamous epithelial cells, as normal keratinocytes do not have nuclear FAK. Finally, we show that a small-molecule FAK kinase inhibitor, VS-4718, which is currently in clinical development, also drives depletion of Tregs and promotes a CD8(+) T cell-mediated anti-tumor response. Therefore, FAK inhibitors may trigger immune-mediated tumor regression, providing previously unrecognized therapeutic opportunities.

Improving Prospects for Targeting RAS

RAS mutations are among the most common oncogenic drivers in human cancers, affecting nearly a third of all solid tumors and around a fifth of common myeloid malignancies, but they have evaded therapeutic interventions, despite being the focus of intense research over the last three decades. Recent discoveries lend new understanding about the structure, function, and signaling of RAS and have opened new avenues for development of much needed new therapies. We discuss the various approaches under investigation to target mutant RAS proteins. The recent development of direct RAS inhibitors specific to KRAS G12C mutations represents a landmark discovery that promises to change the perception about RAS's druggability. Multiple clinical trials targeting synthetically lethal partners and/or downstream signaling partners of RAS are underway. Novel inhibitors targeting various arms of RAS processing and signaling have yielded encouraging results in the laboratory, but refinement of the drug-like properties of these molecules is required before they will be ready for the clinic.

Galectin-3 Binding Protein Secreted by Breast Cancer Cells Inhibits Monocyte-Derived Fibrocyte Differentiation

To metastasize, tumor cells often need to migrate through a layer of collagen-containing scar tissue which encapsulates the tumor. A key component of scar tissue and fibrosing diseases is the monocyte-derived fibrocyte, a collagen-secreting profibrotic cell. To test the hypothesis that invasive tumor cells may block the formation of the fibrous sheath, we determined whether tumor cells secrete factors that inhibit monocyte-derived fibrocyte differentiation. We found that the human metastatic breast cancer cell line MDA-MB-231 secretes activity that inhibits human monocyte-derived fibrocyte differentiation, whereas less aggressive breast cancer cell lines secrete less of this activity. Purification indicated that Galectin-3 binding protein (LGALS3BP) is the active factor. Recombinant LGALS3BP inhibits monocyte-derived fibrocyte differentiation, and immunodepletion of LGALS3BP from MDA-MB 231 conditioned media removes the monocyte-derived fibrocyte differentiation-inhibiting activity. LGALS3BP inhibits the differentiation of monocyte-derived fibrocytes from wild-type mouse spleen cells, but not from SIGN-R1(-/-) mouse spleen cells, suggesting that CD209/SIGN-R1 is required for the LGALS3BP effect. Galectin-3 and galectin-1, binding partners of LGALS3BP, potentiate monocyte-derived fibrocyte differentiation. In breast cancer biopsies, increased levels of tumor cell-associated LGALS3BP were observed in regions of the tumor that were invading the surrounding stroma. These findings suggest LGALS3BP and galectin-3 as new targets to treat metastatic cancer and fibrosing diseases.

Personalizing immunotherapy: Balancing predictability and precision

Despite great expectations and research efforts, anticancer immunotherapy has not yet become a definitive cure. Perhaps, this is because past reductionist approaches were too simplistic for the patient-specific complex system of co-evolving tumor cells and host immunity. Recent efforts based on a systems-based approach promise improved clinical outcomes engendered by a dynamic modification of personalized therapeutic regimens.

Non-Inflammasome Forming NLRs in Inflammation and Tumorigenesis

Aberrant inflammation is an enabling characteristic of tumorigenesis. Thus, signaling cascades that alter inflammatory activation and resolution are of specific relevance to disease pathogenesis. Pattern recognition receptors (PRRs) are essential mediators of the host immune response and have emerged as critical elements affecting multiple facets of tumor pathobiology. The nucleotide-binding domain and leucine-rich repeat containing (NLR) proteins are intracellular PRRs that sense microbial and non-microbial products. Members of the NLR family can be divided into functional sub-groups based on their ability to either positively or negatively regulate the host immune response. Recent studies have identified a novel sub-group of non-inflammasome forming NLRs that negatively regulate diverse biological pathways associated with both inflammation and tumorigenesis. Understanding the mechanisms underlying the function of these unique NLRs will assist in the rationale design of future therapeutic strategies targeting a wide spectrum of inflammatory diseases and cancer. Here, we will discuss recent findings associated with this novel NLR sub-group and mechanisms by which these PRRs may function to alter cancer pathogenesis.

Origin and pharmacological modulation of tumor-associated regulatory dendritic cells

Protumorigenic activity of immune regulatory cells has been proven to play a major role in precluding immunosurveillance and limiting the efficacy of anticancer therapies. Although several approaches have been offered to deplete myeloid-derived suppressor cells (MDSC) and regulatory T cells, there are no data on how to control suppressive dendritic cell (DC) accumulation or function in the tumor environment. Although immunosuppressive function of DC in cancer was implicated to immature and plasmacytoid DC, details of how conventional DC (cDC) develop immunosuppressive properties remain less understood. Here, we show that the development of lung cancer in mice was associated with fast accumulation of regulatory DC (regDC) prior to the appearance of MDSC. Using the in vitro and in vivo approaches, we demonstrated that (i)both cDC and MDSC could be polarized into protumor regDC in the lung cancer environment; (ii) cDC → regDC polarization was mediated by the small Rho GTPase signaling, which could be controlled by noncytotoxic doses of paclitaxel; and (iii) prevention of regDC appearance increased the antitumor potential of DC vaccine in lung cancer. These findings not only bring new players to the family of myeloid regulatory cells and provide new targets for cancer therapy, but offer novel insights into the immunomodulatory capacity of chemotherapeutic agents used in low, noncytotoxic doses.

Tumor-induced perturbations of cytokines and immune cell networks

Until recently, the intrinsically high level of cross-talk between immune cells, the complexity of immune cell development, and the pleiotropic nature of cytokine signaling have hampered progress in understanding the mechanisms of immunosuppression by which tumor cells circumvent native and adaptive immune responses. One technology that has helped to shed light on this complex signaling network is the cytokine antibody array, which facilitates simultaneous screening of dozens to hundreds of secreted signal proteins in complex biological samples. The combined applications of traditional methods of molecular and cell biology with the high-content, high-throughput screening capabilities of cytokine antibody arrays and other multiplexed immunoassays have revealed a complex mechanism that involves multiple cytokine signals contributed not just by tumor cells but by stromal cells and a wide spectrum of immune cell types. This review will summarize the interactions among cancerous and immune cell types, as well as the key cytokine signals that are required for tumors to survive immunoediting in a dormant state or to grow and spread by escaping it. Additionally, it will present examples of how probing secreted cell-cell signal networks in the tumor microenvironment (TME) with cytokine screens have contributed to our current understanding of these processes and discuss the implications of this understanding to antitumor therapies.

The invisible arm of immunity in common cancer chemoprevention agents

Immunoprevention refers to a strategy of preventing pathogen-associated and spontaneous cancers through the use of vaccines, antibodies, and immune modulators. Immune modulators function by enhancing the endogenous ability of the immune system to monitor for malignancy, so-called "immunosurveillance." There is growing evidence that many of the most promising cancer chemoprevention agents including aspirin, COX-2 inhibitors, aromatase inhibitors, and bisphosphonates mediate their effects, in part, by enhancing immunosurveillance and reversing the immune evasive mechanisms that premalignant lesions use. In the following review, we introduce critical components of the human immune surveillance system-dendritic cells, T cells, and immune suppressive cells-and discuss the emerging data suggesting that common chemoprevention agents may modulate the function of these immunologic cells.

Growth inhibition of different human colorectal cancer xenografts after a single intravenous injection of oncolytic vaccinia virus GLV-1h68

Background

Despite availability of efficient treatment regimens for early stage colorectal cancer, treatment regimens for late stage colorectal cancer are generally not effective and thus need improvement. Oncolytic virotherapy using replication-competent vaccinia virus (VACV) strains is a promising new strategy for therapy of a variety of human cancers.

Methods

Oncolytic efficacy of replication-competent vaccinia virus GLV-1h68 was analyzed in both, cell cultures and subcutaneous xenograft tumor models.

Results

In this study we demonstrated for the first time that the replication-competent recombinant VACV GLV-1h68 efficiently infected, replicated in, and subsequently lysed various human colorectal cancer lines (Colo 205, HCT-15, HCT-116, HT-29, and SW-620) derived from patients at all four stages of disease. Additionally, in tumor xenograft models in athymic nude mice, a single injection of intravenously administered GLV-1h68 significantly inhibited tumor growth of two different human colorectal cell line tumors (Duke’s type A-stage HCT-116 and Duke’s type C-stage SW-620), significantly improving survival compared to untreated mice. Expression of the viral marker gene ruc-gfp allowed for real-time analysis of the virus infection in cell cultures and in mice. GLV-1h68 treatment was well-tolerated in all animals and viral replication was confined to the tumor. GLV-1h68 treatment elicited a significant up-regulation of murine immune-related antigens like IFN-γ, IP-10, MCP-1, MCP-3, MCP-5, RANTES and TNF-γ and a greater infiltration of macrophages and NK cells in tumors as compared to untreated controls.

Conclusion

The anti-tumor activity observed against colorectal cancer cells in these studies was a result of direct viral oncolysis by GLV-1h68 and inflammation-mediated innate immune responses. The therapeutic effects occurred in tumors regardless of the stage of disease from which the cells were derived. Thus, the recombinant vaccinia virus GLV-1h68 has the potential to treat colorectal cancers independently of the stage of progression.

Covert operations: cancer's many subversive tactics in overcoming host defenses

In an effort to use the patient's T cells to fight his or her own cancer, we inadvertently discovered a distinctive form of tumor-induced immune suppression. T cells from tumor-bearing patients are often defective in signaling. They lack the zeta chain of the T-cell receptor and the src kinases crucial for its downstream effects including lck. They truncate the carboxy terminal of the p50 NF-kappaB transcription factor. At the population level, CD4 T cells are polarized toward the Th2 subtype and inhibitory Tregs expand. These T cells can recover after several days of culture outside of the tumor-bearing host environment. The effect is mediated by one or more factors made by the tumor given that the same T-cell defects occur in mice with tumors implanted in hollow fibers that never directly contact cells of the host. Several promising strategies may overcome these immunosuppressive effects.