Nitric Oxide Generated by Tumor-Associated Macrophages Is Responsible for Cancer Resistance to Cisplatin and Correlated With Syntaxin 4 and Acid Sphingomyelinase Inhibition

Metabolic interplay: tumor macrophages and regulatory T cells

The tumor microenvironment (TME) contains a complex cellular ecosystem where cancer, stromal, vascular, and immune cells interact. Macrophages and regulatory T cells (Tregs) are critical not only for maintaining immunological homeostasis and tumor growth but also for monitoring the functional states of other immune cells. Emerging evidence reveals that metabolic changes in macrophages and Tregs significantly influence their pro-/antitumor functions through the regulation of signaling cascades and epigenetic reprogramming. Hence, they are increasingly recognized as therapeutic targets in cancer immunotherapy. Specific metabolites in the TME may also affect their pro-/antitumor functions by intervening with the metabolic machinery. We discuss how metabolites influence the immunosuppressive phenotypes of tumor-associated macrophages (TAMs) and Tregs. We then describe how TAMs and Tregs, independently or collaboratively, utilize metabolic mechanisms to suppress the activity of CD8+ T cells. Finally, we highlight promising metabolic interventions that can improve the outcome of current cancer therapies.

The diverse effects of cisplatin on tumor microenvironment: Insights and challenges for the delivery of cisplatin by nanoparticles

Cisplatin is a well-known platinum-based chemotherapy medication that is widely utilized for some malignancies. Despite the direct cytotoxic consequences of cisplatin on tumor cells, studies in the recent decade have revealed that cisplatin can also affect different cells and their secretions in the tumor microenvironment (TME). Cisplatin has complex impacts on the TME, which may contribute to its anti-tumor activity or drug resistance mechanisms. These regulatory effects of cisplatin play a paramount function in tumor growth, invasion, and metastasis. This paper aims to review the diverse impacts of cisplatin and nanoparticles loaded with cisplatin on cancer cells and also non-cancerous cells in TME. The impacts of cisplatin on immune cells, tumor stroma, cancer cells, and also hypoxia will be discussed in the current review. Furthermore, we emphasize the challenges and prospects of using cisplatin in combination with other adjuvants and therapeutic modalities that target TME. We also discuss the potential synergistic effects of cisplatin with immune checkpoint inhibitors (ICIs) and other agents with anticancer potentials such as polyphenols and photosensitizers. Furthermore, the potential of nanoparticles for targeting TME and better delivery of cisplatin into tumors will be discussed.

Tumor-targeted delivery of lnc antisense RNA against RCAS1 by live-attenuated tryptophan-auxotrophic Salmonella inhibited 4T1 breast tumors and metastasis in mice

Emerging chemo- and radiotherapy resistance exacerbated the cancer risk and necessitated novel treatment strategies. Although RNA therapeutics against pro-oncogenic genes are highly effective, tumor-specific delivery remains a barrier to the implementation of this valuable tool. In this study, we report a tryptophan-auxotrophic Salmonella typhimurium strain as an onco-therapeutic delivery system with tumor-targeting ability using 4T1 mice breast-cancer model. The receptor-binding cancer antigen expressed on SiSo cell (RCAS1) is a cancer-specific protein that induces the apoptosis of peripheral lymphocytes and confers tumor immune evasion. We designed a long non-coding antisense-RNA against RCAS1 (asRCAS1) and delivered by Salmonella using a non-antibiotic, auxotrophic-selective, eukaryotic expression plasmid, pJHL204. After in vivo tumor-to-tumor passaging, the JOL2888 (ΔtrpA, ΔtrpE, Δasd + asRCAS1) strain exhibited high sustainability in tumors, but did not last in healthy organs, thereby demonstrating tumor specificity and safety. RCAS1 inhibition in the tumor was confirmed by western blotting and qPCR. In mice, JOL2888 treatment reduced tumor-associated macrophages, improved the T cell population, elicited cell-mediated immunity, and suppressed cancer-promoting genes. Consequently, the JOL2888 treatment significantly decreased the tumor volume by 80%, decreased splenomegaly by 30%, and completely arrested lung metastasis. These findings highlight the intrinsic tumor-targeting ability of tryptophan-auxotrophic Salmonella for delivering onco-therapeutic macromolecules.

Salmonella enterica and outer membrane vesicles are current and future options for cancer treatment

Conventional cancer therapies have many limitations. In the last decade, it has been suggested that bacteria-mediated immunotherapy may circumvent the restrictions of traditional treatments. For example, Salmonella enterica is the most promising bacteria for treating cancer due to its intrinsic abilities, such as killing tumor cells, targeting, penetrating, and proliferating into the tumor. S. enterica has been genetically modified to ensure safety and increase its intrinsic antitumor efficacy. This bacterium has been used as a vector for delivering anticancer agents and as a combination therapy with chemotherapy, radiotherapy, or photothermic. Recent studies have reported the antitumor efficacy of outer membrane vesicles (OMVs) derived from S. enterica. OMVs are considered safer than attenuated bacteria and can stimulate the immune system as they comprise most of the immunogens found on the surface of their parent bacteria. Furthermore, OMVs can also be used as nanocarriers for antitumor agents. This review describes the advances in S. enterica as immunotherapy against cancer and the mechanisms by which Salmonella fights cancer. We also highlight the use of OMVs as immunotherapy and nanocarriers of anticancer agents. OMVs derived from S. enterica are innovative and promising strategies requiring further investigation.

Crosstalk between ferroptosis and macrophages: potential value for targeted treatment in diseases

Ferroptosis is a newly identified form of programmed cell death that is connected to iron-dependent lipid peroxidization. It involves a variety of physiological processes involving iron metabolism, lipid metabolism, oxidative stress, and biosynthesis of nicotinamide adenine dinucleotide phosphate, glutathione, and coenzyme Q10. So far, it has been discovered to contribute to the pathological process of many diseases, such as myocardial infarction, acute kidney injury, atherosclerosis, and so on. Macrophages are innate immune system cells that regulate metabolism, phagocytize pathogens and dead cells, mediate inflammatory reactions, promote tissue repair, etc. Emerging evidence shows strong associations between macrophages and ferroptosis, which can provide us with a deeper comprehension of the pathological process of diseases and new targets for the treatments. In this review, we summarized the crosstalk between macrophages and ferroptosis and anatomized the application of this association in disease treatments, both non-neoplastic and neoplastic diseases. In addition, we have also addressed problems that remain to be investigated, in the hope of inspiring novel therapeutic strategies for diseases.

The Triple Crown: NO, CO, and H2S in cancer cell biology

Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) are three endogenously produced gases with important functions in the vasculature, immune defense, and inflammation. It is increasingly apparent that, far from working in isolation, these three exert many effects by modulating each other's activity. Each gas is produced by three enzymes, which have some tissue specificities and can also be non-enzymatically produced by redox reactions of various substrates. Both NO and CO share similar properties, such as activating soluble guanylate cyclase (sGC) to increase cyclic guanosine monophosphate (cGMP) levels. At the same time, H2S both inhibits phosphodiesterase 5A (PDE5A), an enzyme that metabolizes sGC and exerts redox regulation on sGC. The role of NO, CO, and H2S in the setting of cancer has been quite perplexing, as there is evidence for both tumor-promoting and pro-inflammatory effects and anti-tumor and anti-inflammatory activities. Each gasotransmitter has been found to have dual effects on different aspects of cancer biology, including cancer cell proliferation and apoptosis, invasion and metastasis, angiogenesis, and immunomodulation. These seemingly contradictory actions may relate to each gas having a dual effect dependent on its local flux. In this review, we discuss the major roles of NO, CO, and H2S in the context of cancer, with an effort to highlight the dual nature of each gas in different events occurring during cancer progression.

The Importance of M1-and M2-Polarized Macrophages in Glioma and as Potential Treatment Targets

Glioma is the most common and malignant tumor of the central nervous system. Glioblastoma (GBM) is the most aggressive glioma, with a poor prognosis and no effective treatment because of its high invasiveness, metabolic rate, and heterogeneity. The tumor microenvironment (TME) contains many tumor-associated macrophages (TAMs), which play a critical role in tumor proliferation, invasion, metastasis, and angiogenesis and indirectly promote an immunosuppressive microenvironment. TAM is divided into tumor-suppressive M1-like (classic activation of macrophages) and tumor-supportive M2-like (alternatively activated macrophages) polarized cells. TAMs exhibit an M1-like phenotype in the initial stages of tumor progression, and along with the promotion of lysing tumors and the functions of T cells and NK cells, tumor growth is suppressed, and they rapidly transform into M2-like polarized macrophages, which promote tumor progression. In this review, we discuss the mechanism by which M1- and M2-polarized macrophages promote or inhibit the growth of glioblastoma and indicate the future directions for treatment.

Tumor-associated macrophages mediate resistance of EGFR-TKIs in non-small cell lung cancer: mechanisms and prospects

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are the first-line standard treatment for advanced non-small cell lung cancer (NSCLC) with EGFR mutation. However, resistance to EGFR-TKIs is inevitable. Currently, most studies on the mechanism of EGFR-TKIs resistance mainly focus on the spontaneous resistance phenotype of NSCLC cells. Studies have shown that the tumor microenvironment (TME) also mediates EGFR-TKIs resistance in NSCLC. Tumor-associated macrophages (TAMs), one of the central immune cells in the TME of NSCLC, play an essential role in mediating EGFR-TKIs resistance. This study aims to comprehensively review the current mechanisms underlying TAM-mediated resistance to EGFR-TKIs and discuss the potential efficacy of combining EGFR-TKIs with targeted TAMs therapy. Combining EGFR-TKIs with TAMs targeting may improve the prognosis of NSCLC with EGFR mutation to some extent.

Pro-Tumor Activity of Endogenous Nitric Oxide in Anti-Tumor Photodynamic Therapy: Recently Recognized Bystander Effects

Various studies have revealed that several cancer cell types can upregulate inducible nitric oxide synthase (iNOS) and iNOS-derived nitric oxide (NO) after moderate photodynamic treatment (PDT) sensitized by 5-aminolevulinic acid (ALA)-induced protoporphyrin-IX. As will be discussed, the NO signaled cell resistance to photokilling as well as greater growth and migratory aggressiveness of surviving cells. On this basis, it was predicted that diffusible NO from PDT-targeted cells in a tumor might enhance the growth, migration, and invasiveness of non- or poorly PDT-targeted bystander cells. This was tested using a novel approach in which ALA-PDT-targeted cancer cells on a culture dish were initially segregated from non-targeted bystander cells of the same type via impermeable silicone-rimmed rings. Several hours after LED irradiation, the rings were removed, and both cell populations were analyzed in the dark for various responses. After a moderate extent of targeted cell killing (~25%), bystander proliferation and migration were evaluated, and both were found to be significantly enhanced. Enhancement correlated with iNOS/NO upregulation in surviving PDT-targeted cancer cells in the following cell type order: PC3 > MDA-MB-231 > U87 > BLM. If occurring in an actual PDT-challenged tumor, such bystander effects might compromise treatment efficacy by stimulating tumor growth and/or metastatic dissemination. Mitigation of these and other negative NO effects using pharmacologic adjuvants that either inhibit iNOS transcription or enzymatic activity will be discussed.

Decreased melanoma CSF-1 secretion by Cannabigerol treatment reprograms regulatory myeloid cells and reduces tumor progression

During solid tumor progression, the tumor microenvironment (TME) evolves into a highly immunosuppressive milieu. Key players in the immunosuppressive environment are regulatory myeloid cells, including myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs), which are recruited and activated via tumor-secreted cytokines such as colony-stimulating factor 1 (CSF-1). Therefore, the depletion of tumor-secreted cytokines is a leading anticancer strategy. Here, we found that CSF-1 secretion by melanoma cells is decreased following treatment with Cannabis extracts. Cannabigerol (CBG) was identified as the bioactive cannabinoid responsible for the effects. Conditioned media from cells treated with pure CBG or the high-CBG extract reduced the expansion and macrophage transition of the monocytic-MDSC subpopulation. Treated MO-MDSCs also expressed lower levels of iNOS, leading to restored CD8+ T-cell activation. Tumor-bearing mice treated with CBG presented reduced tumor progression, lower TAM frequencies and reduced TAM/M1 ratio. A combination of CBG and αPD-L1 was more effective in reducing tumor progression, enhancing survival and increasing the infiltration of activated cytotoxic T-cells than each treatment separately. We show a novel mechanism for CBG in modulating the TME and enhancing immune checkpoint blockade therapy, underlining its promising therapeutic potential for the treatment of a variety of tumors with elevated CSF-1 expression.

Copper-induced injectable hydrogel with nitric oxide for enhanced immunotherapy by amplifying immunogenic cell death and regulating cancer associated fibroblasts

BACKGROUND

Immunogenic cell death (ICD) induced by different cancer treatments has been widely evaluated to recruit immune cells and trigger the specific antitumor immunity. However, cancer associated fibroblasts (CAFs) can hinder the invasion of immune cells and polarize the recruited monocytes to M2-type macrophages, which greatly restrict the efficacy of immunotherapy (IT).

METHODS

In this study, an injectable hydrogel induced by copper (Cu) has been designed to contain antibody of PD-L1 and nitric oxide (NO) donor. The therapeutic efficacy of hydrogel was studied in 4T1 cells and CAFs in vitro and 4T1 tumor-bearing mice in vivo. The immune effects on cytotoxic T lymphocytes, dendritic cells (DCs) and macrophages were analyzed by flow cytometry. Enzyme-linked immunosorbent assay, immunofluorescence and transcriptome analyses were also performed to evaluate the underlying mechanism.

RESULTS

Due to the absorbance of Cu with the near-infrared laser irradiation, the injectable hydrogel exhibits persistent photothermal effect to kill cancer cells. In addition, the Cu of hydrogel shows the Fenton-like reaction to produce reactive oxygen species as chemodynamic therapy, thereby enhancing cancer treatment and amplifying ICD. More interestingly, we have found that the released NO can significantly increase depletion of CAFs and reduce the proportion of M2-type macrophages in vitro. Furthermore, due to the amplify of ICD, injectable hydrogel can effectively increase the infiltration of immune cells and reverse the immunosuppressive tumor microenvironment (TME) by regulating CAFs to enhance the therapeutic efficacy of anti-PD-L1 in vivo.

CONCLUSIONS

The ion induced self-assembled hydrogel with NO could enhance immunotherapy via amplifying ICD and regulating CAFs. It provides a novel strategy to provoke a robust antitumor immune response for clinical cancer immunotherapy.

Cross-Regulation of the Cellular Redox System, Oxygen, and Sphingolipid Signalling

Redox-active mediators are now appreciated as powerful molecules to regulate cellular dynamics such as viability, proliferation, migration, cell contraction, and relaxation, as well as gene expression under physiological and pathophysiological conditions. These molecules include the various reactive oxygen species (ROS), and the gasotransmitters nitric oxide (NO∙), carbon monoxide (CO), and hydrogen sulfide (H2S). For each of these molecules, direct targets have been identified which transmit the signal from the cellular redox state to a cellular response. Besides these redox mediators, various sphingolipid species have turned out as highly bioactive with strong signalling potential. Recent data suggest that there is a cross-regulation existing between the redox mediators and sphingolipid molecules that have a fundamental impact on a cell’s fate and organ function. This review will summarize the effects of the different redox-active mediators on sphingolipid signalling and metabolism, and the impact of this cross-talk on pathophysiological processes. The relevance of therapeutic approaches will be highlighted.

Insights into the Safety and Versatility of 4D Printed Intravesical Drug Delivery Systems

This paper focuses on recent advancements in the development of 4D printed drug delivery systems (DDSs) for the intravesical administration of drugs. By coupling the effectiveness of local treatments with major compliance and long-lasting performance, they would represent a promising innovation for the current treatment of bladder pathologies. Being based on a shape-memory pharmaceutical-grade polyvinyl alcohol (PVA), these DDSs are manufactured in a bulky shape, can be programmed to take on a collapsed one suitable for insertion into a catheter and re-expand inside the target organ, following exposure to biological fluids at body temperature, while releasing their content. The biocompatibility of prototypes made of PVAs of different molecular weight, either uncoated or coated with Eudragit®-based formulations, was assessed by excluding relevant in vitro toxicity and inflammatory response using bladder cancer and human monocytic cell lines. Moreover, the feasibility of a novel configuration was preliminarily investigated, targeting the development of prototypes provided with inner reservoirs to be filled with different drug-containing formulations. Samples entailing two cavities, filled during the printing process, were successfully fabricated and showed, in simulated urine at body temperature, potential for controlled release, while maintaining the ability to recover about 70% of their original shape within 3 min.

Targeting tumor-associated macrophages with STING agonism improves the antitumor efficacy of osimertinib in a mouse model of EGFR-mutant lung cancer

Introduction

Despite the impressive clinical response rate of osimertinib, a third-generation EGFR-TKI, as a frontline treatment for patients with EGFR-mutant non-small-cell lung cancer (NSCLC) or as a salvage therapy for patients with T790M mutation, resistance to osimertinib is common in the clinic. The mechanisms underlying osimertinib resistance are heterogenous. While genetic mutations within EGFR or other cancer driver pathways mediated mechanisms are well-documented, the role of tumor cell and tumor immune microenvironment in mediating the response to osimertinib remains elusive.

Methods and results

Here, using a syngeneic mouse model of EGFR-mutant lung cancer, we show that tumor regression elicited by osimertinib requires activation of CD8+ T cells. However, tumor-associated macrophages (TAMs) accumulated in advanced tumors inhibit CD8+ T cell activation and diminish the response to osimertinib. These results are corroborated by analyses of clinical data. Notably, reprogramming TAMs with a systemic STING agonist MSA-2 reinvigorates antitumor immunity and leads to durable tumor regression in mice when combined with osimertinib.

Discussion

Our results reveal a new mechanism of EGFR-TKI resistance and suggest a new therapeutic strategy for the treatment of EGFR-mutant tumors.

Heterogeneity of cGMP signalling in tumour cells and the tumour microenvironment: Challenges and chances for cancer pharmacology and therapeutics

The second messenger cyclic guanosine monophosphate (cGMP) is an important regulator of human (patho-)physiology and has emerged as an attractive drug target. Currently, cGMP-elevating drugs are mainly used to treat cardiovascular diseases, but there is also increasing interest in exploring their potential for cancer prevention and therapy. In this review article, we summarise recent findings in cancer-related cGMP research, with a focus on melanoma, breast cancer, colorectal cancer, prostate cancer, glioma, and ovarian cancer. These studies indicate tremendous heterogeneity of cGMP signalling in tumour tissue. It appears that different tumour and stroma cells, and perhaps different sexes, express different cGMP generators, effectors, and degraders. Therefore, the same cGMP-elevating drug can lead to different outcomes in different tumour settings, ranging from inhibition to promotion of tumourigenesis or therapy resistance. These findings, together with recent evidence that increased cGMP signalling is associated with worse prognosis in several human cancers, challenge the traditional view that cGMP elevation generally has an anti-cancer effect. As cGMP pathways appear to be more stable in the stroma than in tumour cells, we suggest that cGMP-modulating drugs should preferentially target the tumour microenvironment. Indeed, there is evidence that phosphodiesterase 5 inhibitors like sildenafil enhance anti-tumour immunity by acting on immune cells. Moreover, many in vivo results obtained with cGMP-modulating drugs could be explained by effects on the tumour vasculature rather than on the tumour cells themselves. We therefore propose a model that incorporates the NO/cGMP signalling pathway in tumour vessels as a key target for cancer therapy. Deciphering the multifaceted roles of cGMP in cancer is not only a challenge for basic research, but also provides a chance to predict potential adverse effects of cGMP-modulating drugs in cancer patients and to develop novel anti-tumour therapies by precision targeting of the relevant cells and molecular pathways.

Tumor-associated macrophages respond to chemotherapy by detrimental transcriptional reprogramming and suppressing stabilin-1 mediated clearance of EGF

Introduction

Tumor resistance to chemotherapy and metastatic relapse account for more than 90% of cancer specific mortality. Tumor-associated macrophages (TAMs) can process chemotherapeutic agents and impair their action. Little is known about the direct effects of chemotherapy on TAMs.

Methods

The effect of chemotherapeutic platinum agent cisplatin was assessed in the model system of human ex vivo TAMs. Whole-transcriptome sequencing for paired TAMs stimulated and not stimulated by cisplatin was analysed by NGS. Endocytic uptake of EGF was quantified by flow cytometry. Confocal microscopy was used to visualize stabilin-1-mediated internalization and endocytic trafficking of EGF in CHO cells expressing ectopically recombinant stabilin-1 and in stabilin-1+ TAMs. In cohort of patients with breast cancer, the effect of platinum therapy on the transcriptome of TAMs was validated, and differential expression of regulators of endocytosis was identified.

Results

Here we show that chemotherapeutic agent cisplatin can initiate detrimental transcriptional and functional programs in TAMs, without significant impairment of their viability. We focused on the clearance function of TAMs that controls composition of tumor microenvironment. For the first time we demonstrated that TAMs' scavenger receptor stabilin-1 is responsible for the clearance of epidermal growth factor (EGF), a potent stimulator of tumor growth. Cisplatin suppressed both overall and EGF-specific endocytosis in TAMs by bidirectional mode: suppression of positive regulators and stimulation of negative regulators of endocytosis, with strongest effect on synaptotagmin-11 (SYT11), confirmed in patients with breast cancer.

Conclusion

Our data demonstrate that synergistic action of cytostatic agents and innovative immunomodulators is required to overcome cancer therapy resistance.

Shenqi Fuzheng injection reverses M2 macrophage-mediated cisplatin resistance through the PI3K pathway in breast cancer

BACKGROUND

Shenqi Fuzheng injection (SQFZ) combined with chemotherapy can sensitize tumour cells. However, the mechanisms underlying SQFZ's effects remain unknown. In human breast cancer cell lines and M2 macrophages, we showed that SQFZ was a significantly potent agent of sensitization.

METHODS

The human breast cancer cell line, MDA-MB-231/DDP, and the human acute leukaemia mononuclear cell line, THP-1, were used. MDA-MB-231/DDP breast cancer xenografts were established to monitor tumour growth. Resistance-associated proteins were examined by western blotting. Levels of cytokines and chemokines were detected by ELISA. Cell viability was measured using the MTT assay. Apoptosis was detected by flow cytometric analysis.

RESULTS

SQFZ significantly enhanced the capability of cisplatin to reduce tumour mass. SQFZ and cisplatin decreased the expression of CD206 by 1.89-fold and increased that of CD86 by 1.76-fold as compared to cisplatin alone. The levels of PGE2, IL-6, and CCL1 decreased significantly, and the activation of p-PI3K and the expressions of P-gp and ABCG2 were also inhibited by SQFZ in combination with cisplatin treatment in vivo. The survival following cisplatin administration of 60 μM and 120 μM reduced significantly in the presence of SQFZ in MDA-MB-231/DDP and M2 co-cultured cells. IGF-1, a PI3K activator, combined with SQFZ weakened the effects of SQFZ-induced apoptosis from 28.7% to 10.5%. The effects of IGF-1 on increasing the expressions of P-gp, ABCG2, and Bcl-2, and decreasing that of Bax were reversed by SQFZ.

CONCLUSION

Our findings provide evidence that SQFZ is a potential therapeutic drug for cancer therapy.

Tumor cell-derived asymmetric dimethylarginine regulates macrophage functions and polarization

BACKGROUND

Asymmetric dimethylarginine (ADMA), which is significantly elevated in the plasma of cancer patients, is formed via intracellular recycling of methylated proteins and serves as a precursor for resynthesis of arginine. However, the cause of ADMA elevation in cancers and its impact on the regulation of tumor immunity is not known.

METHODS

Three mouse breast cell lines (normal breast epithelial HC11, breast cancer EMT6 and triple negative breast cancer 4T1) and their equivalent 3D stem cell culture were used to analyze the secretion of ADMA using ELISA and their responses to ADMA. Bone marrow-derived macrophages and/or RAW264.7 cells were used to determine the impact of increased extracellular ADMA on macrophage-tumor interactions. Gene/protein expression was analyzed through RNAseq, qPCR and flow cytometry. Protein functional analyses were conducted via fluorescent imaging (arginine uptake, tumor phagocytosis) and enzymatic assay (arginase activity). Cell viability was measured via MTS assay and/or direct cell counting using Countess III FL system.

RESULTS

For macrophages, ADMA impaired proliferation and phagocytosis of tumor cells, and even caused death in cultures incubated without arginine. ADMA also led to an unusual macrophage phenotype, with increased expression of arginase, cd163 and cd206 but decreased expression of il10 and dectin-1. In contrast to the severely negative impacts on macrophages, ADMA had relatively minor effects on proliferation and survival of mouse normal epithelial HC11 cells, mouse breast cancer EMT6 and 4T1 cells, but there was increased expression of the mesenchymal markers, vimentin and snail2, and decreased expression of the epithelial marker, mucin-1 in EMT6 cells. When tumor cells were co-cultured ex vivo with tumor antigen in vivo-primed splenocytes, the tumor cells secreted more ADMA and there were alterations in the tumor cell arginine metabolic landscape, including increased expression of genes involved in arginine uptake, metabolism and methylation, and decreased expression of a gene that is responsible for arginine demethylation. Additionally, interferon-gamma, a cytokine involved in immune challenge, increased secretion of ADMA in tumor cells, a process attenuated by an autophagy inhibitor.

CONCLUSION

Our results suggest initial immune attack promotes autophagy in tumor cells, which then secrete ADMA to manipulate macrophage polarization favoring tumor tolerance.

Role of nitric oxide in hyper-aggressiveness of tumor cells that survive various anti-cancer therapies

Low level nitric oxide (NO) produced by inducible NO synthase (iNOS) in many malignant tumors is known to play a key role in the survival and proliferation of tumor cells. NO can also induce or augment resistance to anti-tumor treatments such as platinum-based chemotherapy (CT), ionizing radiotherapy (RT), and non-ionizing photodynamic therapy (PDT). In each of these treatments, tumor cells that survive the challenge may exhibit a striking increase in NO-dependent proliferative, migratory, and invasive aggressiveness compared with non-challenged controls. Moreover, NO from cells directly targeted by PDT can often stimulate aggressiveness in non- or poorly targeted bystander cells. Although NO-mediated resistance to many of these therapies is fairly-well recognized by now, the hyper-aggressiveness of surviving cells and bystander counterparts is not. We will focus on these negative aspects in this review, citing examples from the PDT, CT, and RT publications. Increased aggressiveness of cells that escape therapeutic elimination is a concern because it could enhance tumor progression and metastatic dissemination. Pharmacologic approaches for suppressing these negative responses will also be discussed, e.g., administering inhibitors of iNOS activity or iNOS expression as therapeutic adjuvants.

Tumor microenvironment in non-melanoma skin cancer resistance to photodynamic therapy

Non-melanoma skin cancer has recently seen an increase in prevalence, and it is estimated that this grow will continue in the coming years. In this sense, the importance of therapy effectiveness has increased, especially photodynamic therapy. Photodynamic therapy has attracted much attention as a minimally invasive, selective and repeatable approach for skin cancer treatment and prevention. Although its high efficiency, this strategy has also faced problems related to tumor resistance, where the tumor microenvironment has gained a well-deserved role in recent years. Tumor microenvironment denotes a wide variety of elements, such as cancer-associated fibroblasts, immune cells, endothelial cells or the extracellular matrix, where their interaction and the secretion of a wide diversity of cytokines. Therefore, the need of designing new strategies targeting elements of the tumor microenvironment to overcome the observed resistance has become evident. To this end, in this review we focus on the role of cancer-associated fibroblasts and tumor-associated macrophages in the resistance to photodynamic therapy. We are also exploring new approaches consisting in the combination of new and old drugs targeting these cells with photodynamic therapy to enhance treatment outcomes of non-melanoma skin cancer.

Exocytosis Proteins: Typical and Atypical Mechanisms of Action in Skeletal Muscle

Insulin-stimulated glucose uptake in skeletal muscle is of fundamental importance to prevent postprandial hyperglycemia, and long-term deficits in insulin-stimulated glucose uptake underlie insulin resistance and type 2 diabetes. Skeletal muscle is responsible for ~80% of the peripheral glucose uptake from circulation via the insulin-responsive glucose transporter GLUT4. GLUT4 is mainly sequestered in intracellular GLUT4 storage vesicles in the basal state. In response to insulin, the GLUT4 storage vesicles rapidly translocate to the plasma membrane, where they undergo vesicle docking, priming, and fusion via the high-affinity interactions among the soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) exocytosis proteins and their regulators. Numerous studies have elucidated that GLUT4 translocation is defective in insulin resistance and type 2 diabetes. Emerging evidence also links defects in several SNAREs and SNARE regulatory proteins to insulin resistance and type 2 diabetes in rodents and humans. Therefore, we highlight the latest research on the role of SNAREs and their regulatory proteins in insulin-stimulated GLUT4 translocation in skeletal muscle. Subsequently, we discuss the novel emerging role of SNARE proteins as interaction partners in pathways not typically thought to involve SNAREs and how these atypical functions reveal novel therapeutic targets for combating peripheral insulin resistance and diabetes.

Understanding Tricky Cellular and Molecular Interactions in Pancreatic Tumor Microenvironment: New Food for Thought

Pancreatic ductal adenocarcinoma (PDAC) represents 90% of all pancreatic cancer cases and shows a high mortality rate among all solid tumors. PDAC is often associated with poor prognosis, due to the late diagnosis that leads to metastasis development, and limited efficacy of available treatments. The tumor microenvironment (TME) represents a reliable source of novel targets for therapy, and even if many of the biological interactions among stromal, immune, and cancer cells that populate the TME have been studied, much more needs to be clarified. The great limitation in the efficacy of current standard chemoterapy is due to both the dense fibrotic inaccessible TME barrier surrounding cancer cells and the immunological evolution from a tumor-suppressor to an immunosuppressive environment. Nevertheless, combinatorial therapies may prove more effective at overcoming resistance mechanisms and achieving tumor cell killing. To achieve this result, a deeper understanding of the pathological mechanisms driving tumor progression and immune escape is required in order to design rationale-based therapeutic strategies. This review aims to summarize the present knowledge about cellular interactions in the TME, with much attention on immunosuppressive functioning and a specific focus on extracellular matrix (ECM) contribution.

Endothelial nitric oxide synthase (eNOS)-NO signaling axis functions to promote the growth of prostate cancer stem-like cells

BACKGROUND

Accumulating evidence supports that prostate cancer stem-like cells (PCSCs) play significant roles in therapy resistance and metastasis of prostate cancer. Many studies also show that nitric oxide (NO) synthesized by NO synthases can function to promote tumor progression. However, the exact roles of NOSs and NO signaling in the growth regulation of PCSCs and castration-resistant prostate cancer (CRPC) are still not fully understood.

METHODS

The regulatory functions of NOS-NO signaling were evaluated in prostate cancer cells, especially in PCSCs enriched by 3D spheroid culture and CD133/CD44 cell sorting. The molecular mechanisms of NOS-NO signaling in PCSCs growth regulation and tumor metastasis were investigated in PCSCs and mice orthotopic prostate tumor model.

RESULTS

Endothelial NOS (eNOS) exhibited a significant upregulation in high-grade prostate cancer and metastatic CRPC. Xenograft models of CRPC exhibited notable increased eNOS expression and higher intracellular NO levels. PCSCs isolated from various models displayed significant enhanced eNOS-NO signaling. Functional analyses demonstrated that increased eNOS expression could promote in vivo tumorigenicity and metastatic potential of prostate cancer cells. Characterization of eNOS-NO involved downstream pathway which confirmed that enhanced eNOS signaling could promote the growth of PCSCs and antiandrogen-resistant prostate cancer cells via an activated downstream NO-sGC-cGMP-PKG effector signaling pathway. Interestingly, eNOS expression could be co-targeted by nuclear receptor ERRα and transcription factor ERG in prostate cancer cells and PCSCs.

CONCLUSIONS

Enhanced eNOS-NO signaling could function to promote the growth of PCSCs and also the development of metastatic CRPC. Besides eNOS-NO as potential targets, targeting its upstream regulators (ERRα and ERG) of eNOS-NO signaling could also be the therapeutic strategy for the management of advanced prostate cancer, particularly the aggressive cancer carrying with the TMPRSS2:ERG fusion gene.

Upregulation of MTA1 in Colon Cancer Drives A CD8+ T Cell-Rich But Classical Macrophage-Lacking Immunosuppressive Tumor Microenvironment

Background

The MTA1 protein encoded by metastasis-associated protein 1 (MTA1) is a key component of the ATP-dependent nucleosome remodeling and deacetylase (NuRD) complex, which is widely upregulated in cancers. MTA1 extensively affects downstream gene expression by participating in chromatin remodeling. Although it was defined as a metastasis-associated gene in first reports and metastasis is a process prominently affected by the tumor microenvironment, whether it affects the microenvironment has not been investigated. In our study, we elucidated the regulatory effect of MTA1 on tumor-associated macrophages (TAMs) and how this regulation affects the antitumor effect of cytotoxic T lymphocytes (CTLs) in the tumor microenvironment of colorectal cancer.

Methods

We detected the cytokines affected by MTA1 expression via a cytokine antibody array in control HCT116 cells and HCT116 cells overexpressing MTA1. Multiplex IHC staining was conducted on a colorectal cancer tissue array from our cancer cohort. Flow cytometry (FCM) was performed to explore the polarization of macrophages in the coculture system and the antitumor killing effect of CTLs in the coculture system. Bioinformatics analysis was conducted to analyze the Cancer Genome Atlas (TCGA) colorectal cancer cohort and single-cell RNA-seq data to assess the immune infiltration status of the TCGA colorectal cancer cohort and the functions of myeloid cells.

Results

MTA1 upregulation in colorectal cancer was found to drive an immunosuppressive tumor microenvironment. In the tumor microenvironment of MTA1-upregulated colorectal cancer, although CD8⁺ T cells were significantly enriched, macrophages were significantly decreased, which impaired the CTL effect of the CD8⁺ T cells on tumor cells. Moreover, upregulated MTA1 in tumor cells significantly induced infiltrated macrophages into tumor-associated macrophage phenotypes and further weakened the cytotoxic effect of CD8⁺ T cells.

Conclusion

Upregulation of MTA1 in colorectal cancer drives an immunosuppressive tumor microenvironment by decreasing the microphages from the tumor and inducing the residual macrophages into tumor-associated microphage phenotypes to block the activation of the killing CTL, which contributes to cancer progression.

Intratumoral administration of the antisecretory peptide AF16 cures murine gliomas and modulates macrophage functions

Glioblastoma has remained the deadliest primary brain tumor while its current therapy offers only modest survival prolongation. Immunotherapy has failed to record notable benefits in routine glioblastoma treatment. Conventionally, immunotherapy relies on T cells as tumor-killing agents; however, T cells are outnumbered by macrophages in glioblastoma microenvironment. In this study, we explore the effect of AF16, a peptide from the endogenous antisecretory factor protein, on the survival of glioma-bearing mice, the tumor size, and characteristics of the tumor microenvironment with specific focus on macrophages. We elucidate the effect of AF16 on the inflammation-related secretome of human and murine macrophages, as well as human glioblastoma cells. In our results, AF16 alone and in combination with temozolomide leads to cure in immunocompetent mice with orthotopic GL261 gliomas, as well as prolonged survival in immunocompromised mice. We recorded decreased tumor size and changes in infiltration of macrophages and T cells in the murine glioma microenvironment. Human and murine macrophages increased expression of proinflammatory markers in response to AF16 treatment and the same effect was seen in human primary glioblastoma cells. In summary, we present AF16 as an immunomodulatory factor stimulating pro-inflammatory macrophages with a potential to be implemented in glioblastoma treatment protocols.

Proteoglycan Endocan: A multifaceted therapeutic target in Cancer

Endocan is known to be a circulating dermatan sulfate proteoglycan that regulates endothelial cell function. Dysregulation of endocan expression is observed not only in the tumor vasculature but also in cancer cells. Accumulating evidence has revealed that disordered endocan facilitates cancer progression via enhancing cancer cell proliferation, cell mobility, and cancer stemness properties. Recently, various interacting proteins and diverse subcellular localizations of endocan were identified in cancer cells. Herein, we summarize the application of endocan in cancer diagnoses and prognoses using serum and tumor specimens. We further discuss that the aberrant molecular characteristics of endocan may be due to the mislocalization of endocan in cancer cells. Defining the specific cellular roles of endocan will provide a promising diagnostic factor and therapeutic target for cancer patients.

Pseudomonas aeruginosa PcrV Enhances the Nitric Oxide-Mediated Tumoricidal Activity of Tumor-Associated Macrophages via a TLR4/PI3K/AKT/mTOR-Glycolysis-Nitric Oxide Circuit

Tumor-associated macrophages (TAMs), which display a tumor-supportive M2 phenotype, are closely related to tumor growth and metastasis. The reprogramming of TAMs toward a tumoricidal M1 profile has emerged as an attractive strategy for cancer immunotherapy. In this study, we found that the intratumoral injection of PcrV protein, a component of the Pseudomonas aeruginosa type 3 secretion system, suppressed tumor growth and increased apoptosis, inducible nitric oxide synthase (iNOS) expression, and the percentage of M1-polarized TAMs in tumor tissues. Furthermore, the intratumoral injection of PcrV-primed macrophages exerted a similar tumoricidal effect. In vitro analyses revealed that PcrV reeducated TAMs toward an antitumoral M1 phenotype and augmented their nitric oxide (NO)-mediated cytotoxicity against cancer cells. Mechanistically, we found that these effects were dependent on the activation of Toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)-mediated regulation of a PI3K/AKT/mTOR-glycolysis-NO feedback loop via direct interaction with TLR4. Collectively, these results revealed a potential role for PcrV in cancer immunotherapy through the targeting of TAM plasticity.

Macrophage Reprogramming and Cancer Therapeutics: Role of iNOS-Derived NO

Nitric oxide and its production by iNOS is an established mechanism critical to tumor promotion or suppression. Macrophages have important roles in immunity, development, and progression of cancer and have a controversial role in pro- and antitumoral effects. The tumor microenvironment consists of tumor-associated macrophages (TAM), among other cell types that influence the fate of the growing tumor. Depending on the microenvironment and various cues, macrophages polarize into a continuum represented by the M1-like pro-inflammatory phenotype or the anti-inflammatory M2-like phenotype; these two are predominant, while there are subsets and intermediates. Manipulating their plasticity through programming or reprogramming of M2-like to M1-like phenotypes presents the opportunity to maximize tumoricidal defenses. The dual role of iNOS-derived NO also influences TAM activity by repolarization to tumoricidal M1-type phenotype. Regulatory pathways and immunomodulation achieve this through miRNA that may inhibit the immunosuppressive tumor microenvironment. This review summarizes the classical physiology of macrophages and polarization, iNOS activities, and evidence towards TAM reprogramming with current information in glioblastoma and melanoma models, and the immunomodulatory and therapeutic options using iNOS or NO-dependent strategies.

Acid Sphingomyelinase Controls Early Phases of Skeletal Muscle Regeneration by Shaping the Macrophage Phenotype

Skeletal muscle regeneration is a complex process involving crosstalk between immune cells and myogenic precursor cells, i.e., satellite cells. In this scenario, macrophage recruitment in damaged muscles is a mandatory step for tissue repair since pro-inflammatory M1 macrophages promote the activation of satellite cells, stimulating their proliferation and then, after switching into anti-inflammatory M2 macrophages, they prompt satellite cells' differentiation into myotubes and resolve inflammation. Here, we show that acid sphingomyelinase (ASMase), a key enzyme in sphingolipid metabolism, is activated after skeletal muscle injury induced in vivo by the injection of cardiotoxin. ASMase ablation shortens the early phases of skeletal muscle regeneration without affecting satellite cell behavior. Of interest, ASMase regulates the balance between M1 and M2 macrophages in the injured muscles so that the absence of the enzyme reduces inflammation. The analysis of macrophage populations indicates that these events depend on the altered polarization of M1 macrophages towards an M2 phenotype. Our results unravel a novel role of ASMase in regulating immune response during muscle regeneration/repair and suggest ASMase as a supplemental therapeutic target in conditions of redundant inflammation that impairs muscle recovery.

Regulation of T Cells in Cancer by Nitric Oxide

The T cell-mediated immune response is primarily involved in the fight against infectious diseases and cancer and its underlying mechanisms are complex. The anti-tumor T cell response is regulated by various T cell subsets and other cells and tissues in the tumor microenvironment (TME). Various mechanisms are involved in the regulation of these various effector cells. One mechanism is the iNOS/.NO that has been reported to be intimately involved in the regulation and differentiation of the various cells that regulate the anti-tumor CD8 T cells. Both endogenous and exogenous .NO are implicated in this regulation. Importantly, the exposure of T cells to .NO had different effects on the immune response, depending on the .NO concentration and time of exposure. For instance, iNOS in T cells regulates activation-induced cell death and inhibits Treg induction. Effector CD8 T cells exposed to .NO result in the upregulation of death receptors and enhance their anti-tumor cytotoxic activity. .NO-Tregs suppress CD4 Th17 cells and their differentiation. Myeloid-derived suppressor cells (MDSCs) expressing iNOS inhibit T cell functions via .NO and inhibit anti-tumor CD8 T cells. Therefore, both .NO donors and .NO inhibitors are potential therapeutics tailored to specific target cells that regulate the T cell effector anti-tumor response.

Bringing Macrophages to the Frontline against Cancer: Current Immunotherapies Targeting Macrophages

Macrophages are found in all tissues and display outstanding functional diversity. From embryo to birth and throughout adult life, they play critical roles in development, homeostasis, tissue repair, immunity, and, importantly, in the control of cancer growth. In this review, we will briefly detail the multi-functional, protumoral, and antitumoral roles of macrophages in the tumor microenvironment. Our objective is to focus on the ever-growing therapeutic opportunities, with promising preclinical and clinical results developed in recent years, to modulate the contribution of macrophages in oncologic diseases. While the majority of cancer immunotherapies target T cells, we believe that macrophages have a promising therapeutic potential as tumoricidal effectors and in mobilizing their surroundings towards antitumor immunity to efficiently limit cancer progression.

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 role of extracellular matrix in tumour angiogenesis: the throne has NOx servants

The extracellular matrix (ECM) dynamics in tumour tissue are deregulated compared to the ECM in healthy tissue along with disorganized architecture and irregular behaviour of the residing cells. Nitric oxide (NO) as a pleiotropic molecule exerts different effects on the components of the ECM driving or inhibiting augmented angiogenesis and tumour progression and tumour cell proliferation and metastasis. These effects rely on the concentration of NO within the tumour tissue, the nature of the surrounding microenvironment and the sensitivity of resident cells to NO. In this review article, we summarize the recent findings on the correlation between the levels of NO and the ECM components towards the modulation of tumour angiogenesis in different types of cancers. These are discussed principally in the context of how NO modulates the expression of ECM proteins resulting in either the promotion or inhibition of tumour growth via tumour angiogenesis. Furthermore, the regulatory effects of individual ECM components on the expression of the NO synthase enzymes and NO production were reviewed. These findings support the current efforts for developing effective therapeutics for cancers.

MDSC in Mice and Men: Mechanisms of Immunosuppression in Cancer

Myeloid-derived suppressor cells (MDSCs) expand during pathological conditions in both humans and mice and their presence is linked to poor clinical outcomes for cancer patients. Studying MDSC immunosuppression is restricted by MDSCs’ rarity, short lifespan, heterogeneity, poor viability after freezing and the lack of MDSC-specific markers. In this review, we will compare identification and isolation strategies for human and murine MDSCs. We will also assess what direct and indirect immunosuppressive mechanisms have been attributed to MDSCs. While some immunosuppressive mechanisms are well-documented in mice, e.g., generation of ROS, direct evidence is still lacking in humans. In future, bulk or single-cell genomics could elucidate which phenotypic and functional phenotypes MDSCs adopt in particular microenvironments and help to identify potential targets for therapy.

Inhibition of the NRF2/KEAP1 Axis: A Promising Therapeutic Strategy to Alter Redox Balance of Cancer Cells

Significance: The nuclear factor erythroid 2-related factor 2/Kelch-like ECH-associated protein 1 (NRF2/KEAP1) pathway is a crucial and highly conserved defensive system that is required to maintain or restore the intracellular homeostasis in response to oxidative, electrophilic, and other types of stress conditions. The tight control of NRF2 function is maintained by a complex network of biological interactions between positive and negative regulators that ultimately ensure context-specific activation, culminating in the NRF2-driven transcription of cytoprotective genes. Recent Advances: Recent studies indicate that deregulated NRF2 activation is a frequent event in malignant tumors, wherein it is associated with metabolic reprogramming, increased antioxidant capacity, chemoresistance, and poor clinical outcome. On the other hand, the growing interest in the modulation of the cancer cells' redox balance identified NRF2 as an ideal therapeutic target. Critical Issues: For this reason, many efforts have been made to identify potent and selective NRF2 inhibitors that might be used as single agents or adjuvants of anticancer drugs with redox disrupting properties. Despite the lack of specific NRF2 inhibitors still represents a major clinical hurdle, the researchers have exploited alternative strategies to disrupt NRF2 signaling at different levels of its biological activation. Future Directions: Given its dualistic role in tumor initiation and progression, the identification of the appropriate biological context of NRF2 activation and the specific clinicopathological features of patients cohorts wherein its inactivation is expected to have clinical benefits, will represent a major goal in the field of cancer research. In this review, we will briefly describe the structure and function of the NRF2/ KEAP1 system and some of the most promising NRF2 inhibitors, with a particular emphasis on natural compounds and drug repurposing. Antioxid. Redox Signal. 34, 1428-1483.

Targeting Immunometabolism in Glioblastoma

We have only recently begun to understand how cancer metabolism affects antitumor responses and immunotherapy outcomes. Certain immunometabolic targets have been actively pursued in other tumor types, however, glioblastoma research has been slow to exploit the therapeutic vulnerabilities of immunometabolism. In this review, we highlight the pathways that are most relevant to glioblastoma and focus on how these immunometabolic pathways influence tumor growth and immune suppression. We discuss hypoxia, glycolysis, tryptophan metabolism, arginine metabolism, 2-Hydroxyglutarate (2HG) metabolism, adenosine metabolism, and altered phospholipid metabolism, in order to provide an analysis and overview of the field of glioblastoma immunometabolism.

Dacomitinib improves chemosensitivity of cisplatin-resistant human ovarian cancer cells

Drug resistance hinders effectiveness of human ovarian cancer (OC) therapies, such as cisplatin or paclitaxel therapy. Although dacomitinib, a novel anticancer agent is used against multiple types of cancers, such as non-small cell lung cancer, head and neck cancer, few studies report its effectiveness in drug-resistant human OC cells. In the present study, would healing, microplate spectrophotometer analysis, flow cytometry analysis, western blotting and Gene Expression Omnibus (GEO) analysis were used to detect the synergistic effect of dacomitinib and cisplatin in human OC SKOV-3 or OV-4 cells. Co-administration of dacomitinib and cisplatin significantly reduced viability and promoted cell apoptosis of drug resistant OC cells. In addition, dacomitinib increased Cadherin 1 (CDH1) levels and decreased P-glycoprotein (P-GP) levels in cisplatin-resistant OC cells. In addition, GEO analysis demonstrated that dacomitinib inhibited the epidermal growth factor receptor (EGFR) signaling pathway. In summary, dacomitinib improves chemosensitivity of cisplatin in human OC by regulating CDH1 and P-GP protein levels and inhibiting the EGFR signaling pathway.

The Role of Tumor-Stroma Interactions in Drug Resistance Within Tumor Microenvironment

Cancer cells resistance to various therapies remains to be a key challenge nowadays. For a long time, scientists focused on tumor cells themselves for the mechanisms of acquired drug resistance. However, recent evidence showed that tumor microenvironment (TME) is essential for regulating immune escape, drug resistance, progression and metastasis of malignant cells. Reciprocal interactions between cancer cells and non-malignant cells within this milieu often reshape the TME and promote drug resistance. Therefore, advanced knowledge about these sophisticated interactions is significant for the design of effective therapeutic approaches. In this review, we highlight cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), myeloid-derived suppressor cells (MDSCs), T-regulatory lymphocytes (Tregs), mesenchymal stem cells (MSCs), cancer-associated adipocytes (CAAs), and tumor endothelial cells (TECs) existing in TME, as well as their multiple cross-talk with tumor cells, which eventually endows tumor cells with therapeutic resistance.

Syntaxin 4 Mediates NF-κB Signaling and Chemokine Ligand Expression via Specific Interaction With IκBβ

Enrichment of human islets with syntaxin 4 (STX4) improves functional β-cell mass through a nuclear factor-κB (NF-κB)-dependent mechanism. However, the detailed mechanisms underlying the protective effect of STX4 are unknown. For determination of the signaling events linking STX4 enrichment and downregulation of NF-κB activity, STX4 was overexpressed in human islets, EndoC-βH1 and INS-1 832/13 cells in culture, and the cells were challenged with the proinflammatory cytokines interleukin-1β, tumor necrosis factor-α, and interferon-γ individually and in combination. STX4 expression suppressed cytokine-induced proteasomal degradation of IκBβ but not IκBα. Inhibition of IKKβ prevented IκBβ degradation, suggesting that IKKβ phosphorylates IκBβ. Moreover, the IKKβ inhibitor, as well as a proteosomal degradation inhibitor, prevented the loss of STX4 caused by cytokines. This suggests that STX4 may be phosphorylated by IKKβ in response to cytokines, targeting STX4 for proteosomal degradation. Expression of a stabilized form of STX4 further protected IκBβ from proteasomal degradation, and like wild-type STX4, stabilized STX4 coimmunoprecipitated with IκBβ and the p50-NF-κB. This work proposes a novel pathway wherein STX4 regulates cytokine-induced NF-κB signaling in β-cells via associating with and preventing IκBβ degradation, suppressing chemokine expression, and protecting islet β-cells from cytokine-mediated dysfunction and demise.

Conventional and Unconventional Mechanisms by which Exocytosis Proteins Oversee β-cell Function and Protection

Type 2 diabetes (T2D) is one of the prominent causes of morbidity and mortality in the United States and beyond, reaching global pandemic proportions. One hallmark of T2D is dysfunctional glucose-stimulated insulin secretion from the pancreatic β-cell. Insulin is secreted via the recruitment of insulin secretory granules to the plasma membrane, where the soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) and SNARE regulators work together to dock the secretory granules and release insulin into the circulation. SNARE proteins and their regulators include the Syntaxins, SNAPs, Sec1/Munc18, VAMPs, and double C2-domain proteins. Recent studies using genomics, proteomics, and biochemical approaches have linked deficiencies of exocytosis proteins with the onset and progression of T2D. Promising results are also emerging wherein restoration or enhancement of certain exocytosis proteins to β-cells improves whole-body glucose homeostasis, enhances β-cell function, and surprisingly, protection of β-cell mass. Intriguingly, overexpression and knockout studies have revealed novel functions of certain exocytosis proteins, like Syntaxin 4, suggesting that exocytosis proteins can impact a variety of pathways, including inflammatory signaling and aging. In this review, we present the conventional and unconventional functions of β-cell exocytosis proteins in normal physiology and T2D and describe how these insights might improve clinical care for T2D.

Dynamic Changes of Urine Proteome in Rat Models Inoculated with Two Different Hepatoma Cell Lines

Urine can accumulate systemic changes with no mechanism to be stable, which may reflect early changes associated with physiological or pathophysiological processes. To explore the potential value of the urine proteome, two rat models were established by intrahepatic injection of two different hepatoma cell lines, CBRH-7919 and RH-35. Urine samples were collected and analyzed. Compared with controls, the two models exhibited different numbers and types of differentially expressed urinary proteins despite having similar histological results. The results were compared with the urine proteome of a Walker 256 (W-256) liver tumor model. The differentially expressed urinary protein patterns in the three models were different. These findings demonstrate that changes in the urine proteomes of the two models can be detected at early stages and that the patterns of differentially expressed urinary proteins can differ even when the histological results are similar. Urinary proteins have potential utility for distinguishing among different tumor cells grown in the same organ.

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

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

Nitric Oxide in Macrophage Immunometabolism: Hiding in Plain Sight

Nitric Oxide (NO) is a soluble endogenous gas with various biological functions like signaling, and working as an effector molecule or metabolic regulator. In response to inflammatory signals, immune myeloid cells, like macrophages, increase production of cytokines and NO, which is important for pathogen killing. Under these proinflammatory circumstances, called “M1”, macrophages undergo a series of metabolic changes including rewiring of their tricarboxylic acid (TCA) cycle. Here, we review findings indicating that NO, through its interaction with heme and non-heme metal containing proteins, together with components of the electron transport chain, functions not only as a regulator of cell respiration, but also a modulator of intracellular cell metabolism. Moreover, diverse effects of NO and NO-derived reactive nitrogen species (RNS) involve precise interactions with different targets depending on concentration, temporal, and spatial restrictions. Although the role of NO in macrophage reprogramming has been in evidence for some time, current models have largely minimized its importance. It has, therefore, been hiding in plain sight. A review of the chemical properties of NO, past biochemical studies, and recent publications, necessitates that mechanisms of macrophage TCA reprogramming during stimulation must be re-imagined and re-interpreted as mechanistic results of NO exposure. The revised model of metabolic rewiring we describe here incorporates many early findings regarding NO biochemistry and brings NO out of hiding and to the forefront of macrophages immunometabolism.

Midkine rewires the melanoma microenvironment toward a tolerogenic and immune-resistant state

An open question in aggressive cancers such as melanoma is how malignant cells can shift the immune system to pro-tumorigenic functions. Here we identify midkine (MDK) as a melanoma-secreted driver of an inflamed, but immune evasive, microenvironment that defines poor patient prognosis and resistance to immune checkpoint blockade. Mechanistically, MDK was found to control the transcriptome of melanoma cells, allowing for coordinated activation of nuclear factor-κB and downregulation of interferon-associated pathways. The resulting MDK-modulated secretome educated macrophages towards tolerant phenotypes that promoted CD8⁺ T cell dysfunction. In contrast, genetic targeting of MDK sensitized melanoma cells to anti-PD-1/anti-PD-L1 treatment. Emphasizing the translational relevance of these findings, the expression profile of MDK-depleted tumors was enriched in key indicators of a good response to immune checkpoint blockers in independent patient cohorts. Together, these data reveal that MDK acts as an internal modulator of autocrine and paracrine signals that maintain immune suppression in aggressive melanomas.

Sphingolipid Metabolism in Glioblastoma and Metastatic Brain Tumors: A Review of Sphingomyelinases and Sphingosine-1-Phosphate

Glioblastoma (GBM) is a primary malignant brain tumor with a dismal prognosis, partially due to our inability to completely remove and kill all GBM cells. Rapid tumor recurrence contributes to a median survival of only 15 months with the current standard of care which includes maximal surgical resection, radiation, and temozolomide (TMZ), a blood-brain barrier (BBB) penetrant chemotherapy. Radiation and TMZ cause sphingomyelinases (SMase) to hydrolyze sphingomyelins to generate ceramides, which induce apoptosis. However, cells can evade apoptosis by converting ceramides to sphingosine-1-phosphate (S1P). S1P has been implicated in a wide range of cancers including GBM. Upregulation of S1P has been linked to the proliferation and invasion of GBM and other cancers that display a propensity for brain metastasis. To mediate their biological effects, SMases and S1P modulate signaling via phospholipase C (PLC) and phospholipase D (PLD). In addition, both SMase and S1P may alter the integrity of the BBB leading to infiltration of tumor-promoting immune populations. SMase activity has been associated with tumor evasion of the immune system, while S1P creates a gradient for trafficking of innate and adaptive immune cells. This review will explore the role of sphingolipid metabolism and pharmacological interventions in GBM and metastatic brain tumors with a focus on SMase and S1P.

Macrophage‑derived exosomes attenuate the susceptibility of oral squamous cell carcinoma cells to chemotherapeutic drugs through the AKT/GSK‑3β pathway

Although chemotherapy is initially effective in debulking tumor mass in a number of different types of malignancy, tumor cells gradually acquire chemoresistance and frequently progress to advanced clinical stage. Accumulating evidence has indicated that the tumor sensitivity to several chemotherapeutic drugs is regulated by tumor stromal cells including macrophages. However, the role of macrophages in the efficacy of chemotherapeutics on oral squamous cell carcinoma (OSCC) cells is poorly understood. In the present study, the effects of macrophage-secreted exosomes on the sensitivity of OSCC cells towards chemotherapeutic agents were examined. Specifically, the effects of exosomes derived from THP-1 cells and primary human macrophages (PHM) were assessed on the chemosensitivity of OSC-4 cells treated with 5-fluorouracil (5-FU) and cis-diamminedichloroplatinum (CDDP). The THP-1- and PHM-derived exosomes promoted dose-dependent proliferation, decreased the proliferative inhibitory effects of 5-FU and CDDP and decreased apoptosis in OSC-4 cells through activation of the AKT/glycogen synthase kinase-3β signaling pathway. LY294002, a PI3K inhibitor, and MK-2206, an AKT inhibitor, were both able to suppress the observed decrease in sensitivity to chemotherapeutic agents induced by exosomes. Overall, the data from the present study suggested that the macrophage-derived exosomes may decrease the sensitivity to chemotherapeutic agents in OSCC cells. Thus, targeting the interaction between OSCC cells and macrophage-derived exosomes may be considered as a therapeutic approach to improve the chemosensitivity of the tumor microenvironment in oral cancer.

"Re-educating" Tumor Associated Macrophages as a Novel Immunotherapy Strategy for Neuroblastoma

Neuroblastoma is the most common extracranial pediatric tumor and often presents with metastatic disease, and patients with high-risk neuroblastoma have survival rates of ~50%. Neuroblastoma tumorigenesis is associated with the infiltration of various types of immune cells, including myeloid derived suppressor cells, tumor associated macrophages (TAMs), and regulatory T cells, which foster tumor growth and harbor immunosuppressive functions. In particular, TAMs predict poor clinical outcomes in neuroblastoma, and among these immune cells, TAMs with an M2 phenotype comprise an immune cell population that promotes tumor metastasis, contributes to immunosuppression, and leads to failure of radiation or checkpoint inhibitor therapy. This review article summarizes the role of macrophages in tumor angiogenesis, metastasis, and immunosuppression in neuroblastoma and discusses the recent advances in "macrophage-targeting strategies" in neuroblastoma with a focus on three aspects: (1) inhibition of macrophage recruitment, (2) targeting macrophage survival, and (3) reprogramming of macrophages into an immunostimulatory phenotype.

Tumor associated macrophages and 'NO'

Nitric oxide (NO) and its pro and anti-tumor activities are dual roles that continue to be debated in cancer biology. The cell situations in the tumor and within the tumor microenvironment also have roles involving NO. In early tumorigenic events, macrophages in the tumor microenvironment promote tumor cell death, and later are reprogramed to support the growth of tumor, through regulatory events involving NO and several stimulatory signals. These two opposing and active phenotypes of tumor associated macrophages known as the M1 or anti-tumorigenic state and M2 or pro-tumorigenic state show differences in metabolic pathways such as glycolysis and arginine utilization, signaling pathways and cytokine induction including iNOS expression, therefore contributing to their function. Polarization of M2 to M1 macrophages, inhibition of M2 state, or reprogramming via NO in combination with other signals may determine or alter tumor kinetics. These strategies and an overview are presented.

Cellular backpacks for macrophage immunotherapy

Adoptive cell transfers have emerged as a disruptive approach to treat disease in a manner that is more specific than using small-molecule drugs; however, unlike traditional drugs, cells are living entities that can alter their function in response to environmental cues. In the present study, we report an engineered particle referred to as a "backpack" that can robustly adhere to macrophage surfaces and regulate cellular phenotypes in vivo. Backpacks evade phagocytosis for several days and release cytokines to continuously guide the polarization of macrophages toward antitumor phenotypes. We demonstrate that these antitumor phenotypes are durable, even in the strongly immunosuppressive environment of a murine breast cancer model. Conserved phenotypes led to reduced metastatic burdens and slowed tumor growths compared with those of mice treated with an equal dose of macrophages with free cytokine. Overall, these studies highlight a new pathway to control and maintain phenotypes of adoptive cellular immunotherapies.

Curcumin circumvent lactate-induced chemoresistance in hepatic cancer cells through modulation of hydroxycarboxylic acid receptor-1

Curcumin has been demonstrated to affect the chemoresistance in cancer cells of various origins. However, its ability to modulate lactate-induced chemoresistance remains unclear. The Present investigation demonstrates that curcumin inhibits the survival of HepG2 and HuT78 cells and can modulate chemo-susceptibility of HepG2 cells. Experimental simulation of simultaneous and pre-treatment suggest cooperatively between curcumin and anticancer drugs as well as the modulation of molecular regulators. Inhibition of glucose consumption, lactate production, extracellular acidity and augmented level of Nitric oxide were observed. DAPI staining revealed hyper condensation of chromatin in curcumin-treated HepG2 cells. Curcumin also diminished the lactate-induced chemoresistance against doxorubicin in hepatic cancer cells along with down regulation of lactate receptor (hydroxycarboxylic acid receptor-1; HCAR-1/GPR81). Alteration of the extracellular milieu along with inhibited expression of genes (hif-1α, ldh-a, mct-1, mdr-1 and stat-3) and proteins (HIF-1α and HCAR-1) are indicated to be involved in curcumin-induced reversal of chemoresistance in HepG2 cells. Findings of present investigation contribute to knowledge of curcumin mediated chemosensitization and its mechanism.