Extracellular ATP and P2 purinergic signalling in the tumour microenvironment

Modular Engineering of Aptamer-Based Nanobiotechnology for Conditional Control of ATP Sensing

Dynamic changes of intracellular, extracellular, and subcellular adenosine triphosphates (ATPs) have fundamental interdependence with the physio-pathological states of cells. Spatially selective in situ imaging of such ATP dynamics offers valuable mechanistic insights into the related biological activities. Despite significant advances in the design of aptamer sensors for ATP detection, the dearth of methods that enable precise ATP imaging in specific cellular locations remains a challenge in this field. This review focuses on the modular engineering of regulatable sensing technology via the integration of aptamer probe designs with advanced functional nanomaterials, allowing conditional control of ATP sensing and imaging with high spatial precision from subcellular organelles to living animals. Highlighting the recent advances in the design of photo-triggered nanosensors for spatiotemporally controlled ATP imaging, endogenously-triggered ATP sensing in a cell-selective manner, and spatially-controlled nanodevices for ATP imaging in specific organelles and extracellular microenvironments. Emphasis will be put on elucidating the principles of how nanotechnology can be applied to regulate the spatial precision of aptamer-based ATP sensing activities. The authors envision that this perspective provides insights into the engineering of aptamer-based nanobiotechnology for opening new frontiers in precise molecular sensing and other bio-applications.

Targeting the adenosine signaling pathway in macrophages for cancer immunotherapy

One of the ways in which macrophages support tumorigenic growth is by producing adenosine, which acts to dampen antitumor immune responses and is generated by both tumor and immune cells in the tumor microenvironment (TME). Two cell surface expressed molecules, CD73 and CD39, boost catalytic adenosine triphosphate, leading to further increased adenosine synthesis, under hypoxic circumstances in the TME. There are four receptors (A1, A2A, A2B, and A3) expressed on macrophages that allow adenosine to perform its immunomodulatory effect. Researchers have shown that adenosine signaling is a key factor in tumor progression and an attractive therapeutic target for treating cancer. Several antagonistic adenosine-targeting biological therapies that decrease the suppressive action of tumor-associated macrophages have been produced and explored to transform this result from basic research into a therapeutic advantage. Here, we'll review the newest findings from studies of pharmacological compounds that target adenosine receptors, and their potential therapeutic value based on blocking the suppressive action of macrophages in tumors.

Imaging of extracellular and intracellular ATP in pancreatic beta cells reveals correlation between glucose metabolism and purinergic signalling

Adenosine triphosphate (ATP) is a universal energy molecule and yet cells release it and extracellular ATP is an important signalling molecule between cells. Monitoring of ATP levels outside of cells is important for our understanding of physiological and pathophysiological processes in cells/tissues. Here, we focus on pancreatic beta cells (INS-1E) and test the hypothesis that there is an association between intra- and extracellular ATP levels which depends on glucose provision. We imaged real-time changes in extracellular ATP in pancreatic beta cells using two sensors tethered to extracellular aspects of the plasma membrane (eATeam3.10, iATPSnFR1.0). Increase in glucose induced fast micromolar ATP release to the cell surface, depending on glucose concentrations. Chronic pre-treatment with glucose increased the basal ATP signal. In addition, we co-expressed intracellular ATP sensors (ATeam1.30, PercevalHR) in the same cultures and showed that glucose induced fast increases in extracellular and intracellular ATP. Glucose and extracellular ATP stimulated glucose transport monitored by the glucose sensor (FLII12Pglu-700uDelta6). In conclusion, we propose that in beta cells there is a dynamic relation between intra- and extracellular ATP that depends on glucose transport and metabolism and these processes may be tuned by purinergic signalling. Future development of ATP sensors for imaging may aid development of novel approaches to target extracellular ATP in, for example, type 2 diabetes mellitus therapy.

The role of the purinergic ligand-gated ion channel 7 receptor in common digestive system cancers

The incidence of digestive malignancies has increased in recent years, including colorectal cancer (CRC), hepatocellular carcinoma (HCC) and pancreatic cancer. Advanced stages of these cancers are prone to metastasis, which seriously reduce the standard of living of patients and lead to decline in the survival rate of patients. So far there are no good specific drugs to stop this phenomenon. It is very important and urgent to find new biomarkers and therapeutic targets. Purinergic ligand-gated ion channel 7 receptor (P2X7R) is ATP-gated and nonselective ion channel receptor involved in many inflammatory processes and cancer progression. P2X7R is present in many cancer cells and promotes or inhibits cancer development through signal transduction. Studies have presented that P2X7R plays a role in the proliferation and migration of digestive system cancers, such as CRC, HCC and pancreatic cancer. Therefore, P2X7R may serve as a biomarker or therapeutic target for digestive system cancers. This paper describes the structure and function of P2X7R, and mainly reviews the research progress on the role of P2X7R in CRC, HCC and pancreatic cancer.

Current Landscape of Cancer Immunotherapy: Harnessing the Immune Arsenal to Overcome Immune Evasion

Cancer immune evasion represents a leading hallmark of cancer, posing a significant obstacle to the development of successful anticancer therapies. However, the landscape of cancer treatment has significantly evolved, transitioning into the era of immunotherapy from conventional methods such as surgical resection, radiotherapy, chemotherapy, and targeted drug therapy. Immunotherapy has emerged as a pivotal component in cancer treatment, harnessing the body's immune system to combat cancer and offering improved prognostic outcomes for numerous patients. The remarkable success of immunotherapy has spurred significant efforts to enhance the clinical efficacy of existing agents and strategies. Several immunotherapeutic approaches have received approval for targeted cancer treatments, while others are currently in preclinical and clinical trials. This review explores recent progress in unraveling the mechanisms of cancer immune evasion and evaluates the clinical effectiveness of diverse immunotherapy strategies, including cancer vaccines, adoptive cell therapy, and antibody-based treatments. It encompasses both established treatments and those currently under investigation, providing a comprehensive overview of efforts to combat cancer through immunological approaches. Additionally, the article emphasizes the current developments, limitations, and challenges in cancer immunotherapy. Furthermore, by integrating analyses of cancer immunotherapy resistance mechanisms and exploring combination strategies and personalized approaches, it offers valuable insights crucial for the development of novel anticancer immunotherapeutic strategies.

Human P2X7 receptor variants Gly150Arg and Arg276His polymorphisms have differential effects on risk association and cellular functions in pancreatic cancer

BACKGROUND

The purinergic P2X7 receptor (P2X7R) plays an important role in the crosstalk between pancreatic stellate cells (PSCs) and cancer cells, thus promoting progression of pancreatic ductal adenocarcinoma (PDAC). Single nucleotide polymorphisms (SNPs) in the P2X7R have been reported for several cancers, but have not been explored in PDAC.

MATERIALS AND METHODS

Blood samples from PDAC patients and controls were genotyped for 11 non-synonymous SNPs in P2X7R and a risk analysis was performed. Relevant P2X7R-SNP GFP variants were expressed in PSCs and cancer cells and their function was assayed in the following tests. Responses in Ca2+ were studied with Fura-2 and dye uptake with YO-PRO-1. Cell migration was monitored by fluorescence microscopy. Released cytokines were measured with MSD assay.

RESULTS

Risk analysis showed that two SNPs 474G>A and 853G>A (rs28360447, rs7958316), that lead to the Gly150Arg and Arg276His variants, had a significant but opposite risk association with PDAC development, protecting against and predisposing to the disease, respectively. In vitro experiments performed on cancer cells and PSCs expressing the Gly150Arg variant showed reduced intracellular Ca2+ response, fluorescent dye uptake, and cell migration, while the Arg276His variant reduced dye uptake but displayed WT-like Ca2+ responses. As predicted, P2X7R was involved in cytokine release (IL-6, IL-1β, IL-8, TNF-α), but the P2X7R inhibitors displayed varied effects.

CONCLUSION

In conclusion, we provide evidence for the P2X7R SNPs association with PDAC and propose that they could be considered as potential biomarkers.

Emerging potential approaches in alkaline phosphatase (ALP) activatable cancer theranostics

Alkaline phosphatase (ALP) is known as one of the most crucial members of the phosphatase family and encompasses the enormous ability to hydrolyze the phosphate group in various biomolecules; by this, it regulates several events in the pool of biological medium. Owing to its overexpression in various cancer cells, recently, its potential has evolved as a prominent biomarker in cancer research. In this article, we have underlined the recent advances (2019 onwards) of alkaline phosphatase in the arena of emerging cancer theranostics. Herein, we mainly focused on phosphate-locked molecular systems such as peptides, prodrugs, and aggregation-induced emission (AIE)-based molecules. When these theranostics encounter cancer cell-overexpressed ALP, it results in the hydrolysis of the phosphate group, which leads to the release of highly cytotoxic agents along with turn-on fluorophore/pre-existing fluorophore.

Regulatory role of CD39 and CD73 in tumor immunity

CD39 is the rate-limiting enzyme for the molecular signal cascade leading to the generation of ADP and adenosine monophosphate (AMP). In conjunction with CD73, CD39 converts adenosine triphosphate (ATP) to ADP and AMP, which leads to the accumulation of immunosuppressive adenosine in the tumor microenvironment. This review focuses on the role of CD39 and CD73 in immune response and malignant progression, including the expression of CD39 within the tumor microenvironment and its relationship to immune effector cells, and its role in antigen presentation. The role of CD39- and CD73-targeting therapeutics and cancer-directed clinical trials investigating CD39 modulation are also explored.

Enhancing cancer immunotherapy with photodynamic therapy and nanoparticle: making tumor microenvironment hotter to make immunotherapeutic work better

Cancer immunotherapy has made tremendous advancements in treating various malignancies. The biggest hurdle to successful immunotherapy would be the immunosuppressive tumor microenvironment (TME) and low immunogenicity of cancer cells. To make immunotherapy successful, the 'cold' TME must be converted to 'hot' immunostimulatory status to activate residual host immune responses. To this end, the immunosuppressive equilibrium in TME should be broken, and immunogenic cancer cell death ought to be induced to stimulate tumor-killing immune cells appropriately. Photodynamic therapy (PDT) is an efficient way of inducing immunogenic cell death (ICD) of cancer cells and disrupting immune-restrictive tumor tissues. PDT would trigger a chain reaction that would make the TME 'hot' and have ICD-induced tumor antigens presented to immune cells. In principle, the strategic combination of PDT and immunotherapy would synergize to enhance therapeutic outcomes in many intractable tumors. Novel technologies employing nanocarriers were developed to deliver photosensitizers and immunotherapeutic to TME efficiently. New-generation nanomedicines have been developed for PDT immunotherapy in recent years, which will accelerate clinical applications.

The NFATc1/P2X7 receptor relationship in human intervertebral disc cells

A comprehensive understanding of the molecules that play key roles in the physiological and pathological homeostasis of the human intervertebral disc (IVD) remains challenging, as does the development of new therapeutic treatments. We recently found a positive correlation between IVD degeneration (IDD) and P2X7 receptor (P2X7R) expression increases both in the cytoplasm and in the nucleus. Using immunocytochemistry, reverse transcription PCR (RT-PCR), overexpression, and chromatin immunoprecipitation, we found that NFATc1 and hypoxia-inducible factor-1α (HIF-1α) are critical regulators of P2X7R. Both transcription factors are recruited at the promoter of the P2RX7 gene and involved in its positive and negative regulation, respectively. Furthermore, using the proximity ligation assay, we revealed that P2X7R and NFATc1 form a molecular complex and that P2X7R is closely associated with lamin A/C, a major component of the nuclear lamina. Collectively, our study identifies, for the first time, P2X7R and NFATc1 as markers of IVD degeneration and demonstrates that both NFATc1 and lamin A/C are interaction partners of P2X7R.

Epitope Mapping of an Anti-Mouse CD39 Monoclonal Antibody Using PA Scanning and RIEDL Scanning

A cell-surface ectonucleotidase CD39 mediates the conversion of extracellular adenosine triphosphate into immunosuppressive adenosine with another ectonucleotidase CD73. The elevated adenosine in the tumor microenvironment attenuates antitumor immunity, which promotes tumor cell immunologic escape and progression. Anti-CD39 monoclonal antibodies (mAbs), which suppress the enzymatic activity, can be applied to antitumor therapy. Therefore, an understanding of the relationship between the inhibitory activity and epitope of mAbs is important. We previously established an anti-mouse CD39 (anti-mCD39) mAb, C39Mab-1 using the Cell-Based Immunization and Screening method. In this study, we determined the critical epitope of C39Mab-1 using flow cytometry. We performed the PA tag (12 amino acids [aa])-substituted analysis (named PA scanning) and RIEDL tag (5 aa)-substituted analysis (named RIEDL scanning) to determine the critical epitope of C39Mab-1 using flow cytometry. By the combination of PA scanning and RIEDL scanning, we identified the conformational epitope, spanning three segments of 275-279, 282-291, and 306-323 aa of mCD39. These analyses would contribute to the identification of the conformational epitope of membrane proteins.

Purinergic Ca2+ signaling as a novel mechanism of drug tolerance in BRAF mutant melanoma

Drug tolerance is a major cause of relapse after cancer treatment. In spite of intensive efforts1-9, its molecular basis remains poorly understood, hampering actionable intervention. We report a previously unrecognized signaling mechanism supporting drug tolerance in BRAF-mutant melanoma treated with BRAF inhibitors that could be of general relevance to other cancers. Its key features are cell-intrinsic intracellular Ca2+ signaling initiated by P2X7 receptors (purinergic ligand-gated cation channels), and an enhanced ability for these Ca2+ signals to reactivate ERK1/2 in the drug-tolerant state. Extracellular ATP, virtually ubiquitous in living systems, is the ligand that can initiate Ca2+ spikes via P2X7 channels. ATP is abundant in the tumor microenvironment and is released by dying cells, ironically implicating treatment-initiated cancer cell death as a source of trophic stimuli that leads to ERK reactivation and drug tolerance. Such a mechanism immediately offers an explanation of the inevitable relapse after BRAFi treatment in BRAF-mutant melanoma, and points to actionable strategies to overcome it.

Tumor Microenvironment-Induced Drug Depository for Persistent Antitumor Chemotherapy and Immune Activation

Herein, a drug-loading nanosystem that can in situ form drug depository for persistent antitumor chemotherapy and immune regulation is designed and built. The system (DOX@MIL-LOX@AL) is fabricated by packaging alginate on the surface of Doxorubicin (DOX) and lactate oxidase (LOX) loaded MIL-101(Fe)-NH2 nanoparticle, which can easily aggregate in the tumor microenvironment through the cross-linking with intratumoral Ca2+. Benefiting from the tumor retention ability, the fast-formed drug depository will continuously release DOX and Fe ions through the ATP-triggered slow degradation, thus realizing persistent antitumor chemotherapy and immune regulation. Meanwhile, LOX in the non-aggregated nanoparticles is able to convert the lactic acid to H2O2, which will be subsequently decomposed into ·OH by Fe ions to further enhance the DOX-induced immunogenic death effect of tumor cells. Together, with the effective consumption of immunosuppressive lactic acid, long-term chemotherapy, and oxidation therapy, DOX@MIL-LOX@AL can execute high-performance antitumor chemotherapy and immune activation with only one subcutaneous administration.

Dysregulation in CD39/CD73 Axis May Trigger the Upsurge of the Immune Suppressive Agent Adenosine in OSA Patients

INTRODUCTION

Although higher incidence of cancer represents a major burden for obstructive sleep apnea (OSA) patients, the molecular pathways driving this association are not completely understood. Interestingly, adenosinergic signaling has emerged as a powerful immune checkpoint driving tumor development and progression.

METHODS

Here, we explored the expression of the adenosinergic ecto-enzymes CD39 and CD73 in T-lymphocytes of OSA patients without any evidence of cancer, as well as their soluble forms in plasma (sCD39 and sCD73), along with adenosine. In addition, we explored the role of intermittent hypoxia (IH) in this context by in vitro models.

RESULTS

Our results showed that CD39 is upregulated while CD73 is downregulated in OSA T-cells' membrane. Moreover, our findings suggest that IH, through HIF-1, mediates the upregulation of both CD39 and CD73; and that CD73 downregulation could be mediated by a higher release of sCD73 by OSA T-lymphocytes. Importantly, we found that both sCD39 and sCD73 are upregulated in OSA plasma, suggesting T-lymphocytes as a potential source for plasmatic sCD73. Finally, our data propose the alterations in CD39/CD73 axis could underlie the upsurge of adenosine levels in the plasma of OSA patients.

CONCLUSION

Our study reveals a hypoxia-mediated alteration of the CD39/CD73 axis in OSA patients, which could trigger ADO upregulation, thus potentially contributing to the immune suppressive environment and ultimately facilitating tumor development and progression. Therefore, our data highlights the need for new longitudinal studies evaluating CD39 and/or CD73 as potential cancer-risk prognostic biomarkers in OSA patients.

Comprehensive insights into potential roles of purinergic P2 receptors on diseases: Signaling pathways involved and potential therapeutics

BACKGROUND

Purinergic P2 receptors, which can be divided into ionotropic P2X receptors and metabotropic P2Y receptors, mediate cellular signal transduction of purine or pyrimidine nucleoside triphosphates and diphosphate. Based on the wide expression of purinergic P2 receptors in tissues and organs, their significance in homeostatic maintenance, metabolism, nociceptive transmission, and other physiological processes is becoming increasingly evident, suggesting that targeting purinergic P2 receptors to regulate biological functions and signal transmission holds significant promise for disease treatment.

AIM OF REVIEW

This review highlights the detailed mechanisms by which purinergic P2 receptors engage in physiological and pathological progress, as well as providing prospective strategies for discovering clinical drug candidates.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The purinergic P2 receptors regulate complex signaling and molecular mechanisms in nervous system, digestive system, immune system and as a result, controlling physical health states and disease progression. There has been a significant rise in research and development focused on purinergic P2 receptors, contributing to an increased number of drug candidates in clinical trials. A few influential pioneers have laid the foundation for advancements in the evaluation, development, and of novel purinergic P2 receptors modulators, including agonists, antagonists, pharmaceutical compositions and combination strategies, despite the different scaffolds of these drug candidates. These advancements hold great potential for improving therapeutic outcomes by specifically targeting purinergic P2 receptors.

Chemoproteomics reveals immunogenic and tumor-associated cell surface substrates of ectokinase CK2α

New epitopes for immune recognition provide the basis of anticancer immunity. Due to the high concentration of extracellular adenosine triphosphate in the tumor microenvironment, we hypothesized that extracellular kinases (ectokinases) could have dysregulated activity and introduce aberrant phosphorylation sites on cell surface proteins. We engineered a cell-tethered version of the extracellular kinase CK2α, demonstrated it was active on cells under tumor-relevant conditions, and profiled its substrate scope using a chemoproteomic workflow. We then demonstrated that mice developed polyreactive antisera in response to syngeneic tumor cells that had been subjected to surface hyperphosphorylation with CK2α. Interestingly, these mice developed B cell and CD4+ T cell responses in response to these antigens but failed to develop a CD8+ T cell response. This work provides a workflow for probing the extracellular phosphoproteome and demonstrates that extracellular phosphoproteins are immunogenic even in a syngeneic system.

Purinergic pathways and their clinical use in the treatment of acute myeloid leukemia

Despite the use of various therapies such as hematopoietic stem cell transplantation and chimeric antigen receptor T cell therapy (CAR-T), the prognosis of patients with acute myeloid leukemia (AML) is still generally poor. However, immunotherapy is currently a hot topic in the treatment of hematological tumors. Extracellular adenosine triphosphate (ATP) can be converted to adenosine diphosphate (ADP) via CD39, and ADP can be converted to adenosine via CD73, which can bind to P1 and P2 receptors to exert immunomodulatory effects. Research on the mechanism of the purinergic signaling pathway can provide a new direction for the treatment of AML, and inhibitors of this signaling pathway have been discovered by several researchers and gradually applied in the clinic. In this paper, the mechanism of the purinergic signaling pathway and its clinical application are described, revealing a new target for the treatment of AML and subsequent improvement in patient prognosis.

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.

ATP-adenosine axis regulation combined with microneedle assisted photoimmunotherapy to boost the immunotherapy efficiency

Immunogenic cell death (ICD) is associated with the release of damage-associated molecular patterns, including ATP, to promote an effective immune cycle against tumors. However, tumors have evolved an effective strategy for degrading extracellular immunostimulatory ATP via the ATP-adenosine axis, allowing the sequential action of the ectonucleotidases CD39 to degrade accumulated immunostimulatory ATP into pleiotropic immunosuppressive adenosine. Here, an ingenious dissolving microneedle patch (DMNs) is designed for the intralesional delivery of CD39 inhibitor (sodium polyoxotungstate, POM-1) and ICD inducer (IR780) co-encapsulated solid lipid nanoparticles (P/I SLNs) for antitumor therapy. Upon insertion into the tumor site, IR780 induces ICD modalities with the release of damage-associated molecular patterns from endogenous tissues, which activates the antitumor immune cycle. Simultaneously, POM-1 promotes the liberation of immunostimulatory ATP and lowers the level of immunosuppressive extracellular adenosine, which supported immune control of tumors via recruiting CD39-expressing immune cells. In vivo antitumor studies prove that this platform can effectively eliminate mice melanoma (tumor growth inhibitory rate of 96.5%) and colorectal adenocarcinoma (tumor growth inhibitory rate of 93.5%). Our results shed light on the immunological aspects of combinatorial phototherapy and ATP-adenosine regulation, which will broaden the scope of synergistic antitumor immunotherapy.

P2X7 receptors: a bibliometric review from 2002 to 2023

For many years, there has been ongoing research on the P2X7 receptor (P2X7R). A comprehensive, systematic, and objective evaluation of the scientific output and status of P2X7R will be instrumental in guiding future research directions. This study aims to present the status and trends of P2X7R research from 2002 to 2023. Publications related to P2X7R were retrieved from the Web of Science Core Collection database. Quantitative analysis and visualization tools were Microsoft Excel, VOSviewer, and CiteSpace software. The analysis content included publication trends, literature co-citation, and keywords. 3282 records were included in total, with the majority of papers published within the last 10 years. Based on literature co-citation and keyword analysis, neuroinflammation, neuropathic pain, gastrointestinal diseases, tumor microenvironment, rheumatoid arthritis, age-related macular degeneration, and P2X7R antagonists were considered to be the hotspots and frontiers of P2X7R research. Researchers will get a more intuitive understanding of the status and trends of P2X7R research from this study.

P2X7 Receptor in Dendritic Cells and Macrophages: Implications in Antigen Presentation and T Lymphocyte Activation

The P2X7 receptor, a member of the P2X purinergic receptor family, is a non-selective ion channel. Over the years, it has been associated with various biological functions, from modulating to regulating inflammation. However, its emerging role in antigen presentation has captured the scientific community's attention. This function is essential for the immune system to identify and respond to external threats, such as pathogens and tumor cells, through T lymphocytes. New studies show that the P2X7 receptor is crucial for controlling how antigens are presented and how T cells are activated. These studies focus on antigen-presenting cells, like dendritic cells and macrophages. This review examines how the P2X7 receptor interferes with effective antigen presentation and activates T cells and discusses the fundamental mechanisms that can affect the immune response. Understanding these P2X7-mediated processes in great detail opens up exciting opportunities to create new immunological therapies.

Time-resolved role of P2X4 and P2X7 during CD8+ T cell activation

CD8+ T cells are a crucial part of the adaptive immune system, responsible for combating intracellular pathogens and tumor cells. The initial activation of T cells involves the formation of highly dynamic Ca2+ microdomains. Recently, purinergic signaling was shown to be involved in the formation of the initial Ca2+ microdomains in CD4+ T cells. In this study, the role of purinergic cation channels, particularly P2X4 and P2X7, in CD8+ T cell signaling from initial events to downstream responses was investigated, focusing on various aspects of T cell activation, including Ca2+ microdomains, global Ca2+ responses, NFAT-1 translocation, cytokine expression, and proliferation. While Ca2+ microdomain formation was significantly reduced in the first milliseconds to seconds in CD8+ T cells lacking P2X4 and P2X7 channels, global Ca2+ responses over minutes were comparable between wild-type (WT) and knockout cells. However, the onset velocity was reduced in P2X4-deficient cells, and P2X4, as well as P2X7-deficient cells, exhibited a delayed response to reach a certain level of free cytosolic Ca2+ concentration ([Ca2+]i). NFAT-1 translocation, a crucial transcription factor in T cell activation, was also impaired in CD8+ T cells lacking P2X4 and P2X7. In addition, the expression of IFN-γ, a major pro-inflammatory cytokine produced by activated CD8+ T cells, and Nur77, a negative regulator of T cell activation, was significantly reduced 18h post-stimulation in the knockout cells. In line, the proliferation of T cells after 3 days was also impaired in the absence of P2X4 and P2X7 channels. In summary, the study demonstrates that purinergic signaling through P2X4 and P2X7 enhances initial Ca2+ events during CD8+ T cell activation and plays a crucial role in regulating downstream responses, including NFAT-1 translocation, cytokine expression, and proliferation on multiple timescales. These findings suggest that targeting purinergic signaling pathways may offer potential therapeutic interventions.

Extracellular vesicles as tools and targets in therapy for diseases

Extracellular vesicles (EVs) are nano-sized, membranous structures secreted into the extracellular space. They exhibit diverse sizes, contents, and surface markers and are ubiquitously released from cells under normal and pathological conditions. Human serum is a rich source of these EVs, though their isolation from serum proteins and non-EV lipid particles poses challenges. These vesicles transport various cellular components such as proteins, mRNAs, miRNAs, DNA, and lipids across distances, influencing numerous physiological and pathological events, including those within the tumor microenvironment (TME). Their pivotal roles in cellular communication make EVs promising candidates for therapeutic agents, drug delivery systems, and disease biomarkers. Especially in cancer diagnostics, EV detection can pave the way for early identification and offers potential as diagnostic biomarkers. Moreover, various EV subtypes are emerging as targeted drug delivery tools, highlighting their potential clinical significance. The need for non-invasive biomarkers to monitor biological processes for diagnostic and therapeutic purposes remains unfulfilled. Tapping into the unique composition of EVs could unlock advanced diagnostic and therapeutic avenues in the future. In this review, we discuss in detail the roles of EVs across various conditions, including cancers (encompassing head and neck, lung, gastric, breast, and hepatocellular carcinoma), neurodegenerative disorders, diabetes, viral infections, autoimmune and renal diseases, emphasizing the potential advancements in molecular diagnostics and drug delivery.

Blocking MARCO+ tumor-associated macrophages improves anti-PD-L1 therapy of hepatocellular carcinoma by promoting the activation of STING-IFN type I pathway

The PD-L1/PD-1 axis is a classic immunotherapy target. However, anti-PD-L1/PD-1 therapy alone can not achieve satisfactory results in solid tumors, especially liver cancer. Among the several factors involved in tumor anti-PD-L1/PD-1 treatment resistance, tumor-associated macrophages (TAMs) have attracted attention because of their immunosuppressive ability. TAMs with a macrophage receptor with a collagenous structure (MARCO) are a macrophage subset group with strong immunosuppressive abilities. Clinical specimens and animal experiments revealed a negative correlation between MARCO + TAMs and patient prognosis with liver cancer. Transcriptional data and in vitro and in vivo experiments revealed that MARCO + TAM immunosuppressive ability was related to secretion. MARCO suppressed IFN-β secretion from TAMs, reducing antigen presentation molecule expression, infiltration, and CD8+T cell dysfunction, thus producing an immunosuppressive microenvironment in liver cancer. MARCO can promote dying tumor cell clearance by macrophages, reducing tumor-derived cGAMP and ATP accumulation in the tumor microenvironment and inhibiting sting-IFN-β pathway activation mediated by P2X7R in MARCO+TAMs. Animal experiments revealed that the MARCO and PD-L1 monoclonal antibody combination could significantly inhibit liver cancer growth. Conclusively, targeting MARCO+TAMs can significantly improve anti-PD-L1 resistance in liver cancer, making it a potential novel immune target for liver cancer therapy.

Development of a Sensitive Anti-Mouse CD39 Monoclonal Antibody (C39Mab-1) for Flow Cytometry and Western Blot Analyses

CD39 is involved in adenosine metabolism by converting extracellular ATP to adenosine. As extracellular adenosine plays a critical role in the immune suppression of the tumor microenvironment, the inhibition of CD39 activity by monoclonal antibodies (mAbs) is one of the important strategies for tumor therapy. This study developed specific and sensitive mAbs for mouse CD39 (mCD39) using the Cell-Based Immunization and Screening method. The established anti-mCD39 mAb, C39Mab-1 (rat IgG2a, kappa), reacted with mCD39-overexpressed Chinese hamster ovary-K1 (CHO/mCD39) by flow cytometry. The kinetic analysis using flow cytometry indicated that the dissociation constant of C39Mab-1 for CHO/mCD39 was 7.3 × 10-9 M. Furthermore, C39Mab-1 detected the lysate of CHO/mCD39 by western blot analysis. These results indicated that C39Mab-1 is useful for the detection of mCD39 in many functional studies.

Targeting ENPP1 depletion may be a promising therapeutic strategy for treating oral squamous cell carcinoma via cytotoxic autophagy-related apoptosis

ENPP1 depletion closely related with modulation immunotherapy of several types of cancer. However, the role of ENPP1 correlation with autophagy in oral squamous cell carcinoma (OSCC) pathogenesis remain unknown. In this study, effects of ENPP1 on OSCC cells in vitro were examined by cell proliferation assay, transwell chamber assay, flow cytometry analysis and shRNA technique. Cellular key proteins related to cell autophagy and apoptosis were evaluated by Western blot and immunofluorescent staining. Moreover, functions of ENPP1 on OSCC process were observed in nude mouse model. We reported that overexpression of ENPP1 promote the growth of OSCC cell xenografts in nude mouse model. In contrast, ENPP1 downregulation significantly inhibits OSCC cancer growth and induces apoptosis both in vitro and in vivo, which are preceded by cytotoxic autophagy. ENPP1downregulation induces a robust accumulation of autophagosomes, increases LC3B-II and decreases SQSTM1/p62 in ENPP1-shRNA-treated cells and xenografts. Mechanistic studies show that ENPP1 downregulation increases PRKAA1 phosphorylation leading to ULK1 activation. AMPK-inhibition abrogates ENPP1 downregulation-induced ULK1-activation, LC3B-turnover and SQSTM1/p62-degradation while AMPK-activation potentiates it's effects. Collectively, these data uncover that ENPP1 downregulation induces autophagic cell death in OSCC cancer, which may provide a potential therapeutic target for the treatment of OSCC.

Intercellular crosstalk shapes purinergic metabolism and signaling in cancer cells

CD73-derived adenosine suppresses anti-cancer immunity, and CD73 inhibitors are currently evaluated in several clinical trials. Here, we have assessed enzyme kinetics of all key purinergic ectoenzymes in five cancer cell lines (Hodgkin lymphoma, multiple myeloma, pancreas adenocarcinoma, urinary bladder carcinoma, and glioblastoma) under normoxia and hypoxia. We found that adenosine metabolism varied considerably between individual cancer types. All cell lines investigated exhibited high ecto-adenosine deaminase (ADA) activity, which critically influenced the kinetics of adenosine accumulation. Combining kinetics data with single-cell RNA sequencing data on myeloma and glioblastoma cancerous tissue revealed that purine metabolism is not homogeneously organized, but it differs in a cancer type-specific fashion between malignant cells, stromal cells, and immune cells. Since purine metabolism in cancerous tissue is most likely spatially heterogeneous and differs between the various cell types, diffusion distances in the microenvironment as well as ADA activity may be important variables that influence the level of bioactive adenosine.

The multifaceted role of extracellular ATP in sperm function: From spermatogenesis to fertilization

Extracellular adenosine 5'-triphosphate (ATP) is a vital signaling molecule involved in various physiological processes within the body. In recent years, studies have revealed its significant role in male reproduction, particularly in sperm function. This review explores the multifaceted role of extracellular ATP in sperm function, from spermatogenesis to fertilization. We discuss the impact of extracellular ATP on spermatogenesis, sperm maturation and sperm-egg fusion, highlighting the complex regulatory mechanisms and potential clinical applications in the context of male infertility. By examining the latest research, we emphasize the crucial role of extracellular ATP in sperm function and propose future research directions to further.

Ion channel P2X7 receptor in the progression of cancer

P2X7 receptor (P2X7) is a non-selective and ATP-sensitive ligand-gated cation channel. Studies have confirmed that it is expressed in a variety of cells and correlates with their function, frequently in immune cells and tumor cells. We found increased expression of this receptor in many tumor cells, and it has a role in tumor survival and progression. In immune cells, upregulation of the receptor has a double effect on tumor suppression as well as tumor promotion. This review describes the structure of P2X7 and its role in the tumor microenvironment and presents possible mechanisms of P2X7 in tumor invasion and metastasis. Understanding the potential of P2X7 for tumor treatment, we also present several therapeutic agents targeting P2X7 and their mechanisms of action. In conclusion, the study of P2X7 is an important guideline for the use of clinical tumor therapy and may be able to provide a new idea for tumor treatment, but considering the complexity of the biological effects of P2X7, the drugs should be used with caution in clinical practice.

The potential value of the Purinergic pathway in the prognostic assessment and clinical application of kidney renal clear cell carcinoma

The Purinergic pathway is involved in a variety of important physiological processes in living organisms, and previous studies have shown that aberrant expression of the Purinergic pathway may contribute to the development of a variety of cancers, including kidney renal clear cell carcinoma (KIRC). The aim of this study was to delve into the Purinergic pathway in KIRC and to investigate its potential significance in prognostic assessment and clinical treatment. 33 genes associated with the Purinergic pathway were selected for pan-cancer analysis. Cluster analysis, targeted drug sensitivity analysis and immune cell infiltration analysis were applied to explore the mechanism of Purinergic pathway in KIRC. Using the machine learning process, we found that combining the Lasso+survivalSVM algorithm worked well for predicting survival accuracy in KIRC. We used LASSO regression to pinpoint nine Purinergic genes closely linked to KIRC, using them to create a survival model for KIRC. ROC survival curve was analyzed, and this survival model could effectively predict the survival rate of KIRC patients in the next 5, 7 and 10 years. Further univariate and multivariate Cox regression analyses revealed that age, grading, staging, and risk scores of KIRC patients were significantly associated with their prognostic survival and were identified as independent risk factors for prognosis. The nomogram tool developed through this study can help physicians accurately assess patient prognosis and provide guidance for developing treatment plans. The results of this study may bring new ideas for optimizing the prognostic assessment and therapeutic approaches for KIRC patients.

Impact of Suramin on Key Pathological Features of Sporadic Alzheimer's Disease-Derived Forebrain Neurons

Background

Alzheimer's disease (AD) is characterized by disrupted proteostasis and macroautophagy (hereafter "autophagy"). The pharmacological agent suramin has known autophagy modulation properties with potential efficacy in mitigating AD neuronal pathology.

Objective

In the present work, we investigate the impact of forebrain neuron exposure to suramin on the Akt/mTOR signaling pathway, a major regulator of autophagy, in comparison with rapamycin and chloroquine. We further investigate the effect of suramin on several AD-related biomarkers in sporadic AD (sAD)-derived forebrain neurons.

Methods

Neurons differentiated from ReNcell neural progenitors were used to assess the impact of suramin on the Akt/mTOR signaling pathway relative to the autophagy inducer rapamycin and autophagy inhibitor chloroquine. Mature forebrain neurons were differentiated from induced pluripotent stem cells (iPSCs) sourced from a late-onset sAD patient and treated with 100μM suramin for 72 h, followed by assessments for amyloid-β, phosphorylated tau, oxidative/nitrosative stress, and synaptic puncta density.

Results

Suramin treatment of sAD-derived neurons partially ameliorated the increased p-Tau(S199)/Tau ratio, and fully remediated the increased glutathione to oxidized nitric oxide ratio, observed in untreated sAD-derived neurons relative to healthy controls. These positive results may be due in part to the distinct increases in Akt/mTOR pathway mediator p-p70S6K noted with suramin treatment of both ReNcell-derived and iPSC-derived neurons. Longer term neuronal markers, such as synaptic puncta density, were unaffected by suramin treatment.

Conclusions

These findings provide initial evidence supporting the potential of suramin to reduce the degree of dysregulation in sAD-derived forebrain neurons in part via the modulation of autophagy.

Molecular determinants of immunogenic cell death elicited by radiation therapy

Cancer cells undergoing immunogenic cell death (ICD) can initiate adaptive immune responses against dead cell-associated antigens, provided that (1) said antigens are not perfectly covered by central tolerance (antigenicity), (2) cell death occurs along with the emission of immunostimulatory cytokines and damage-associated molecular patterns (DAMPs) that actively engage immune effector mechanisms (adjuvanticity), and (3) the microenvironment of dying cells is permissive for the initiation of adaptive immunity. Finally, ICD-driven immune responses can only operate and exert cytotoxic effector functions if the microenvironment of target cancer cells enables immune cell infiltration and activity. Multiple forms of radiation, including non-ionizing (ultraviolet) and ionizing radiation, elicit bona fide ICD as they increase both the antigenicity and adjuvanticity of dying cancer cells. Here, we review the molecular determinants of ICD as elicited by radiation as we critically discuss strategies to reinforce the immunogenicity of cancer cells succumbing to clinically available radiation strategies.

P2 purinergic receptors regulate the progression of colorectal cancer

More and more studies have revealed that P2 purinergic receptors play a key role in the progression of colorectal cancer (CRC). P2X and P2Y purinergic receptors can be used as promoters and regulators of CRC and play a dual role in the progression of CRC. CRC microenvironment is rich in ATP and its cleavage products (ADP, AMP, Ado), which act as activators of P2X and P2Y purinergic receptors. The activation of P2X and P2Y purinergic receptors regulates the progression of CRC mainly by regulating the function of immune cells and mediating different signal pathways. In this paper, we focus on the specific mechanisms and functional roles of P2X7, P2Y12, and P2Y2 receptors in the growth and progression of CRC. The antagonistic effects of these selective antagonists of P2X purinergic receptors on the growth, invasion, and metastasis of CRC were further discussed. Moreover, different studies have reported that P2X7 receptor can be used as an effective predictor of patients with CRC. All these indicate that P2 purinergic receptors are a key regulator of CRC. Therefore, antagonizing P2 purinergic receptors may be an innovative treatment for CRC.

Lidocaine induces apoptosis in head and neck squamous cell carcinoma through activation of bitter taste receptor T2R14

Head and neck squamous cell carcinomas (HNSCCs) have high mortality and significant treatment-related morbidity. It is vital to discover effective, minimally invasive therapies that improve survival and quality of life. Bitter taste receptors (T2Rs) are expressed in HNSCCs, and T2R activation can induce apoptosis. Lidocaine is a local anesthetic that also activates bitter taste receptor 14 (T2R14). Lidocaine has some anti-cancer effects, but the mechanisms are unclear. Here, we find that lidocaine causes intracellular Ca2+ mobilization through activation of T2R14 in HNSCC cells. T2R14 activation with lidocaine depolarizes mitochondria, inhibits proliferation, and induces apoptosis. Concomitant with mitochondrial Ca2+ influx, ROS production causes T2R14-dependent accumulation of poly-ubiquitinated proteins, suggesting that proteasome inhibition contributes to T2R14-induced apoptosis. Lidocaine may have therapeutic potential in HNSCCs as a topical gel or intratumor injection. In addition, we find that HPV-associated (HPV+) HNSCCs are associated with increased TAS2R14 expression. Lidocaine treatment may benefit these patients, warranting future clinical studies.

ATP ion channel P2X7 receptor as a regulatory molecule in the progression of colorectal cancer

Large amounts of adenosine triphosphate (ATP), a natural P2X7 receptor activator, are released during colorectal carcinogenesis. P2X7 receptor activation regulates the activity of colorectal cancer (CRC) cells by mediating intracellular signal transduction. Importantly, the opening and activation of membrane pores of P2X7 receptor are different, which can play a dual role in promoting or inhibiting the progression of CRC. These can also depend on P2X7 receptor to regulate the activities of immune cells in the microenvironment, play the functions of immune regulation, immune escape and immune monitoring. While the use of P2X7 receptor antagonists (such as BBG, A438079 and A740003) can play a certain inhibitory pharmacological role on the activity of CRC. Therefore, in this paper, the mechanism and immunomodulatory function of P2X7 receptor involved in the progression of CRC were discussed. Moreover, we discussed the effect of antagonizing the activity of P2X7 receptor on the progression of CRC. So P2X7 receptor may be a new pharmacological molecular target for the treatment of CRC.

P2rx1 deficiency alleviates acetaminophen-induced acute liver failure by regulating the STING signaling pathway

AIMS

Purinergic signaling-mediated mitochondria dysfunction and innate immune-mediated inflammation act as triggers during acetaminophen (APAP)-induced liver injury (AILI). However, the underlying mechanisms by which purinoceptor regulates mitochondria function and inflammation response in the progression of AILI remains unclear.

METHODS

First, the hepatic level of purinergic receptor P2X 1 (P2RX1) was identified in the DILI patients and APAP-induced WT mice. P2rx1 knockout (KO) mice (P2rx1-/-) with 300 mg/kg APAP challenge were used for the analysis of the potential role of P2RX1 in the progression of AILI. Administration of DMX, the activator of stimulator of interferon genes (STING), was performed to investigate the effects of the STING-related pathway on APAP-treated P2rx1-/- mice.

RESULTS

The elevated hepatic P2RX1 levels were found in DILI patients and the AILI mice. P2rx1 depletion offered protection against the initial stages of AILI, mainly by inhibiting cell death and promoting inflammation resolution, which was associated with alleviating mitochondria dysfunction. Mechanistically, P2rx1 depletion could inhibit STING-TANK-binding kinase 1 (TBK1)-P65 signaling pathways in vivo. We then showed that DMX-mediated STING activation could greatly aggravate the liver injury of P2rx1-/- mice treated with APAP.

CONCLUSION

Our data confirmed that P2RX1 was inducted during AILI, identified P2RX1 as a novel regulator in mitochondria dysfunction and STING pathways, and suggested a promising therapeutic approach for AILI involving the blockade of P2RX1. 1. It first demonstrated the protective effects of P2rx1 deficiency on acetaminophen-induced liver injury (AILI). 2. P2rx1 knockout alleviates mitochondria function and promotes inflammation resolution after APAP treatment. 3. It first reported the regulation of P2RX1 on the STING signaling pathway in the progress of AILI. 4. P2RX1 blockade is a promising therapeutic strategy for AILI.

A Rat Anti-Mouse CD39 Monoclonal Antibody for Flow Cytometry

By converting extracellular adenosine triphosphate to adenosine, CD39 is involved in adenosine metabolism. The extracellular adenosine plays a critical role in the immune suppression of the tumor microenvironment. Therefore, the inhibition of CD39 activity by monoclonal antibodies (mAbs) is thought to be one of the important strategies for tumor therapy. In this study, we developed novel mAbs for mouse CD39 (mCD39) using the Cell-Based Immunization and Screening (CBIS) method. One of the established anti-mCD39 mAbs, C39Mab-2 (rat IgG2a, lambda), reacted with mCD39-overexpressed Chinese hamster ovary-K1 (CHO/mCD39) and an endogenously mCD39-expressed cell line (SN36) by flow cytometry. The kinetic analysis using flow cytometry indicated that the dissociation constant (KD) values of C39Mab-2 for CHO/mCD39 and SN36 were 5.5 × 10-9 M and 4.9 × 10-9 M, respectively. These results indicated that C39Mab-2 is useful for the detection of mCD39 in flow cytometry.

The role of Pannexin-1 channels, ATP, and purinergic receptors in the pathogenesis of HIV and SARS-CoV-2

Infectious agents such as human immune deficiency virus-1 (HIV) and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) use host proteins to infect, replicate, and induce inflammation within the host. A critical component of these diseases is the axis between pannexin-1 channels, extracellular ATP, and purinergic receptors. Here, we describe the potential therapeutic role of Pannexin-1/purinergic approaches to prevent or reduce the devastating consequences of these pathogens.

Cascaded Antitumor Therapy Excited by Dual Nanozymes Based on Energy Restriction and Photocatalysis

In nanocatalytic medicine, drugs can be transformed into toxic components through highly selective and highly specific catalytic reactions in the tumor microenvironment, avoiding toxic side effects on normal tissues. Due to the coexistence of Ce3+ and Ce4+, CeO2 is endowed with dual nanozyme activities. Herein, CeO2 nanoparticles served as templates to construct a biomimetic nanodrug delivery system (C/CeO2@M) by electrostatic adsorption of carbon quantum dots (CQDs) and coating a homologous tumor cytomembrane. After homologous targeting to tumors, the CQDs emitted 350-600 nm light under 660 nm laser irradiation by upconversion luminescence, which caused a CeO2-mediated photocatalytic reaction to generate reactive oxygen species. The catalase-like activity of CeO2-enabled converting excess H2O2 to O2, which not only alleviated tumor hypoxia and promoted intratumor drug delivery but also provided substrates for subsequent catalytic reactions. Meanwhile, the phosphatase activity of CeO2 could consume adenosine triphosphate (ATP) to block the energy supply for tumor cells, thus limiting cell proliferation and metastasis. The strategy of energy restriction and photocatalysis of dual nanozyme stimulation offers great potentials in enhancing drug penetration and eradicating solid tumors.

Exploring CD39 and CD73 Expression as Potential Biomarkers in Prostate Cancer

Prostate cancer (PC) is the most diagnosed tumor in males and ranks as the second leading cause of male mortality in the western world. The CD39 and CD73 enzymes play a crucial role in cancer regulation by degrading nucleotides and forming nucleosides. This study aimed to investigate the expression of the CD39 and CD73 enzymes as potential therapeutic targets for PC. The initial part of this study retrospectively analyzed tissue samples from 23 PC patients. Using the TissueFAXSTM cytometry platform, we found significantly higher levels of CD39-labeling its intensity compared to CD73. Additionally, we observed a correlation between the Gleason score and the intensity of CD39 expression. In the prospective arm, blood samples were collected from 25 patients at the time of diagnosis and after six months of treatment to determine the expression of CD39 and CD73 in the serum extracellular vesicles (EVs) and to analyze nucleotide hydrolysis. Notably, the expression of CD39 in the EVs was significantly increased compared to the CD73 and/or combined CD39/CD73 expression levels at initial collection. Furthermore, our results demonstrated positive correlations between ADP hydrolysis and the transurethral resection and Gleason score. Understanding the role of ectonucleotidases is crucial for identifying new biomarkers in PC.

A collagen-immobilized nanodevice for in situ ratiometric imaging of cancer biomarkers in the tumor microenvironment

Monitoring the spatiotemporal dynamics of cancer biomarkers within the tumor microenvironment (TME) is critical to understanding their roles in tumorigenesis. Here, we reported a multifunctional fusion protein (collagen-binding domain and duck circovirus tag fused to mCherry, CBD-mCherry-DCV) capable of binding collagen with high affinity and covalently binding specific nucleic acids with exceptional efficiency. We then constructed a chimeric protein-nucleic acid nanodevice (CPNN) using CBD-mCherry-DCV and an aptamer-based sensing module to enable spatially controlled ratiometric imaging of cancer biomarkers in the TME. The collagen-anchoring module CBD-mCherry-DCV allowed specific immobilization of CPNN on 3D multicellular tumor spheroids, enabling the sensing module to achieve "off-on" fluorescence imaging of cancer biomarkers upon specific target recognition by an aptamer. Taking advantage of the constant fluorescence signal of mCherry and the activatable fluorescence response of Cy5 to specific cancer biomarkers, the detection sensitivity and reliability of CPNN were improved by self-calibrating the signal intensity. Specifically, CPNN enabled ratiometric fluorescence imaging of varying concentrations of exogenous PDGF-BB and ATP in tumor spheroids with a high signal-to-background ratio. Furthermore, it allowed the visual monitoring of endogenous PDGF-BB and ATP released from cells. Overall, this study demonstrates the potential of the nanodevice as a versatile approach for the visualization and imaging of cancer biomarkers in the TME.

Adenosine in cancer immunotherapy: Taking off on a new plane

As a new pillar of cancer therapy, tumor immunotherapy has brought irreplaceable durable responses in tumors. Considering its low response rate, additional immune regulatory mechanisms will be critical for the development of next-generation immune therapeutics. As a key regulatory mechanism, adenosine (ADO) protects tissues from excessive immune responses, but as a metabolite highly concentrated in tumor microenvironments, extracellular adenosine acts on adenosine receptors (mainly A2A receptors) expressed on MDSCs, Tregs, NK cells, effector T cells, DCs, and macrophages to promote tumor cell escape from immune surveillance by inhibiting the immune response. Amounting preclinical studies have demonstrated the adenosine pathway as a novel checkpoint for immunotherapy. Large number of adenosine pathway targeting clinical trials are now underway, including antibodies against CD39 and CD73 as well as A2A receptor inhibitors. There has been evidence of antitumor efficacy of these inhibitors in early clinical trials among a variety of tumors such as breast cancer, prostate cancer, non-small cell lung cancer, etc. As more clinical trial results are published, the combination of blockade of this pathway with immune checkpoint inhibitors, targeted drugs, traditional chemotherapy medications, radiotherapy and endocrine therapy will provide cancer patients with better clinical outcomes. We would elaborate on the role of CD39-CD73-A2AR pathway in the contribution of tumor microenvironment and the targeting of the adenosinergic pathway for cancer therapy in the review.

Tumor Microenvironment-Responsive Hydrogel for Direct Extracellular ATP Imaging-Guided Surgical Resection with Clear Boundaries

Most solid tumors are clinically treated using surgical resection, and the presence of residual tumor tissues at the surgical margins often determines tumor survival and recurrence. Herein, a hydrogel (Apt-HEX/Cp-BHQ1 Gel, termed AHB Gel) is developed for fluorescence-guided surgical resection. AHB Gel is constructed by tethering a polyacrylamide hydrogel and ATP-responsive aptamers together. It exhibits strong fluorescence under high ATP concentrations corresponding to the TME (100-500 µm) but shows little fluorescence at low ATP concentrations (10-100 nm) such as those in normal tissues. AHB Gel can rapidly (within 3 min) emit fluorescence after exposure to ATP, and the fluorescence signal only occurs at sites exposed to high ATP, resulting in a clear boundary between the ATP-high and ATP-low regions. In vivo, AHB Gel exhibits specific tumor-targeting capacity with no fluorescence response in normal tissue, providing clear tumor boundaries. In addition, AHB Gel has good storage stability, which is conducive to its future clinical application. In summary, AHB Gel is a novel tumor microenvironment-targeted DNA-hybrid hydrogel for ATP-based fluorescence imaging. It can enable the precise imaging of tumor tissues, showing promising application in fluorescence-guided surgeries in the future.

ATP promotes resident CD34+ cell migration mainly through P2Y2-Stim1-ERK/p38 pathway

Extracellular adenosine triphosphate (ATP) is one of the most abundant biochemical constitutes within the stem cell microenvironment and is postulated to play critical roles in cell migration. However, it is unclear whether ATP regulates the cell migration of CD34+ vascular wall-resident stem/progenitor cells (VW-SCs) and participates in angiogenesis. Therefore, the biological mechanisms of cell migration mediated by ATP was determined by in vivo subcutaneous matrigel plug assay, ex vivo aortic ring assay, in vitro transwell migration assay, and other molecular methods. In the present study, ATP dose-dependently promoted CD34+ VW-SCs migration, which was more obviously attenuated by inhibiting or knocking down P2Y2 than P2Y6. Furthermore, it was confirmed that ATP potently promoted the migration of resident CD34+ cells from cultured aortic artery rings and differentiation into endothelial cells in matrigel plugs by using inducible lineage tracing Cd34-CreERT2; R26-tdTomato mice, whereas P2Y2 and P2Y6 blocker greatly inhibited the effect of ATP. In addition, ATP enhanced the protein expression of stromal interaction molecule 1 (STIM1) on cell membrane, blocking the calcium release-activated calcium (CRAC) channel with shSTIM1 or BTP2 apparently inhibited ATP-evoked intracellular Ca2+ elevation and channel opening, thereby suppressing ATP-driven cell migration. Moreover, extracellular signal-regulated protein kinase (ERK) inhibitor PD98059 and p38 inhibitor SB203580 remarkably inhibited ERK and p38 phosphorylation, cytoskeleton rearrangement, and subsequent cell migration. Unexpectedly, it was found that knocking down STIM1 greatly inhibited ATP-triggered ERK/p38 activation. Taken together, it was suggested that P2Y2 signaled through the CRAC channel mediated Ca2+ influx and ERK/p38 pathway to reorganize the cytoskeleton and promoted the migration of CD34+ VW-SCs.NEW & NOTEWORTHY In this study, we observed that the purinergic receptor P2Y2 is critical in the regulation of vascular wall-resident CD34+ cells' migration. ATP could activate STIM1-mediated extracellular Ca2+ entry by triggering STIM1 translocation to the plasma membrane, and knockdown of STIM1 prevented ERK/p38 activation-mediated cytoskeleton rearrangement and cell migration.

A Population of Tumor-Infiltrating CD4+ T Cells Co-Expressing CD38 and CD39 Is Associated with Checkpoint Inhibitor Resistance

PURPOSE

We previously showed that elevated frequencies of peripheral blood CD3+CD4+CD127-GARP-CD38+CD39+ T cells were associated with checkpoint immunotherapy resistance in patients with metastatic melanoma. In the present study, we sought to further investigate this population of ectoenzyme-expressing T cells (Teee).

EXPERIMENTAL DESIGN

Teee derived from the peripheral blood of patients with metastatic melanoma were evaluated by bulk RNA-sequencing (RNA-seq) and flow cytometry. The presence of Teee in the tumor microenvironment was assessed using publically available single-cell RNA-seq datasets of melanoma, lung, and bladder cancers along with multispectral immunofluorescent imaging of melanoma patient formalin-fixed, paraffin-embedded specimens. Suppressive function of Teee was determined by an in vitro autologous suppression assay.

RESULTS

Teee had phenotypes associated with proliferation, apoptosis, exhaustion, and high expression of inhibitory molecules. Cells with a Teee gene signature were present in tumors of patients with melanoma, lung, and bladder cancers. CD4+ T cells co-expressing CD38 and CD39 in the tumor microenvironment were preferentially associated with Ki67- CD8+ T cells. Co-culture of patient Teee with autologous T cells resulted in decreased proliferation of target T cells. High baseline intratumoral frequencies of Teee were associated with checkpoint immunotherapy resistance and poor overall survival in patients with metastatic melanoma.

CONCLUSIONS

These results demonstrate that a novel population of CD4+ T cells co-expressing CD38 and CD39 is found both in the peripheral blood and tumor of patients with melanoma and is associated with checkpoint immunotherapy resistance.

The Immune Regulatory Role of Adenosine in the Tumor Microenvironment

Adenosine, an immunosuppressive metabolite, is produced by adenosine triphosphate (ATP) released from dying or stressed cells and is found at high levels in the tumor microenvironment of most solid tumors. It mediates pro-tumor activities by inducing tumor cell proliferation, migration or invasion, tumor tissue angiogenesis, and chemoresistance. In addition, adenosine plays an important role in regulating anti-tumor immune responses and facilitating tumor immune escape. Adenosine receptors are broadly expressed by tumor-infiltrated immune cells, including suppressive tumor-associated macrophages and CD4+ regulatory T cells, as well as effector CD4+ T cells and CD8+ cytotoxic T lymphocytes. Therefore, adenosine is indispensable in down-regulating anti-tumor immune responses in the tumor microenvironment and contributes to tumor progression. This review describes the current progress on the role of adenosine/adenosine receptor pathway in regulating the tumor-infiltrating immune cells that contribute to tumor immune evasion and aims to provide insights into adenosine-targeted tumor immunotherapy.

RNA Interference against ATP as a Gene Therapy Approach for Prostate Cancer

Chemotherapeutic agents targeting energy metabolism have not achieved satisfactory results in different types of tumors. Herein, we developed an RNA interference (RNAi) method against adenosine triphosphate (ATP) by constructing an interfering plasmid-expressing ATP-binding RNA aptamer, which notably inhibited the growth of prostate cancer cells through diminishing the availability of cytoplasmic ATP and impairing the homeostasis of energy metabolism, and both glycolysis and oxidative phosphorylation were suppressed after RNAi treatment. Further identifying the mechanism underlying the effects of ATP aptamer, we surprisingly found that it markedly reduced the activity of membrane ionic channels and membrane potential which led to the dysfunction of mitochondria, such as the decrease of mitochondrial number, reduction in the respiration rate, and decline of mitochondrial membrane potential and ATP production. Meanwhile, the shortage of ATP impeded the formation of lamellipodia that are essential for the movement of cells, consequently resulting in a significant reduction of cell migration. Both the downregulation of the phosphorylation of AMP-activated protein kinase (AMPK) and endoplasmic reticulum kinase (ERK) and diminishing of lamellipodium formation led to cell apoptosis as well as the inhibition of angiogenesis and invasion. In conclusion, as the first RNAi modality targeting the blocking of ATP consumption, the present method can disturb the respiratory chain and ATP pool, which provides a novel regime for tumor therapies..

Purine and purinergic receptors in health and disease

Purines and purinergic receptors are widely distributed throughout the human body. Purine molecules within cells play crucial roles in regulating energy metabolism and other cellular processes, while extracellular purines transmit signals through specific purinergic receptors. The ubiquitous purinergic signaling maintains normal neural excitability, digestion and absorption, respiratory movement, and other complex physiological activities, and participates in cell proliferation, differentiation, migration, and death. Pathological dysregulation of purinergic signaling can result in the development of various diseases, including neurodegeneration, inflammatory reactions, and malignant tumors. The dysregulation or dysfunction of purines and purinergic receptors has been demonstrated to be closely associated with tumor progression. Compared with other subtypes of purinergic receptors, the P2X7 receptor (P2X7R) exhibits distinct characteristics (i.e., a low affinity for ATP, dual functionality upon activation, the mediation of ion channels, and nonselective pores formation) and is considered a promising target for antitumor therapy, particularly in patients with poor response to immunotherapy This review summarizes the physiological and pathological significance of purinergic signaling and purinergic receptors, analyzes their complex relationship with tumors, and proposes potential antitumor immunotherapy strategies from tumor P2X7R inhibition, tumor P2X7R overactivation, and host P2X7R activation. This review provides a reference for clinical immunotherapy and mechanism investigation.

Programming Injectable DNA Hydrogels Yields Tumor Microenvironment-Activatable and Immune-Instructive Depots for Augmented Chemo-Immunotherapy

Injectable hydrogels have attracted increasing attention for promoting systemic antitumor immune response through the co-delivery of chemotherapeutics and immunomodulators. However, the biosafety and bioactivity of conventional hydrogel depots are often impaired by insufficient possibilities for post-gelling injection and means for biofunction integration. Here, an unprecedented injectable stimuli-responsive immunomodulatory depot through programming a super-soft DNA hydrogel adjuvant is reported. This hydrogel system encoded with adenosine triphosphate aptamers can be intratumorally injected in a gel formulation and then undergoes significant molecular conformation change to stimulate the distinct release kinetics of co-encapsulated therapeutics. In this scenario, doxorubicin is first released to induce immunogenic cell death that intimately works together with the polymerized cytosine-phosphate-guanine oligodeoxynucleotide (CpG ODN) in gel scaffold for effectively recruiting and activating dendritic cells. The polymerized CpG ODN not only enhances tumor immunogenicity but minimizes free CpG-induced splenomegaly. Furthermore, the subsequently released anti-programmed cell death protein ligand 1 (aPDL1) blocks the corresponding immune inhibitory checkpoint molecule on tumor cells to sensitize antitumor T-cell immunity. This work thus contributes to the first proof-of-concept demonstration of a programmable super-soft DNA hydrogel system that perfectly matches the synergistic therapeutic modalities based on chemotherapeutic toxicity, in situ vaccination, and immune checkpoint blockade.