Adenosine Metabolism: Emerging Concepts for Cancer Therapy

Nanoparticles targeting the adenosine pathway for cancer immunotherapy

Cancer immunotherapy, as an emerging approach to cancer treatment, has tremendous potential for application. Compared to traditional methods such as surgery, chemotherapy, and radiation therapy, it has the ability to restore the patient's immune system, leading to long-term immune memory with less damage to normal tissues. However, immunotherapy has its limitations, including limited therapeutic efficacy, restricted patient populations, and inconsistent treatment responses. Finding effective immunotherapeutic approaches has become a key focus of its clinical application. The adenosine pathway is a recently discovered tumor immune regulatory signaling pathway. It can influence the metabolism and growth of tumor cells by acting through key enzymes in the adenosine pathway, thereby affecting the development of tumors. Therefore, inhibiting the adenosine pathway is an effective cancer immunotherapy. Common adenosine pathway inhibitors include small molecules and antibody proteins, and extensive preclinical trials have demonstrated their effectiveness in inhibiting tumor growth. The short half-life, low bioavailability, and single administration route of adenosine pathway inhibitors limit their clinical application. With the advent of nanotechnology, nano-delivery of adenosine pathway inhibitors has addressed these issues. Compared to traditional drugs, nano-drugs extend the drug's circulation time and improve its distribution within the body. They also offer targeting capabilities and have low toxic side effects, making them very promising for future applications. In this review, we discuss the mechanism of the adenosine pathway in tumor immune suppression, the clinical applications of adenosine pathway inhibitors, and nano-delivery based on adenosine pathway inhibitors. In the final part of this article, we also briefly discuss the technical issues and challenges currently present in nano-delivery of adenosine pathway inhibitors, with the hope of advancing the progress of adenosine inhibitor nano-drugs in clinical treatment.

Tumor derived exosomal ENTPD2 impair CD8+ T cell function in colon cancer through ATP-adenosine metabolism reprogramming

BACKGROUND

Extracellular ATP-AMP-adenosine metabolism plays a pivotal role in modulating tumor immune responses. Previous studies have shown that the conversion of ATP to AMP is primarily catalysed by Ectonucleoside triphosphate diphosphohydrolase 1 (ENTPD1/CD39), a widely studied ATPase, which is expressed in tumor-associated immune cells. However, the function of ATPases derived from tumor cells themselves remains poorly understood. The purpose of this study was to investigate the role of colon cancer cell-derived ATPases in the development and progression of colon cancer.

METHODS

Bioinformatic and tissue microarray analyses were performed to investigate the expression of ATPase family members in colon cancer. An ATP hydrolysis assay, high-performance liquid chromatography (HPLC), and CCK8 and colony formation assays were used to determine the effects of ENTPD2 on the biological functions of colon cancer cells. Flow cytometric and RNA-seq analyses were used to explore the function of CD8+ T cells. Immunoelectron microscopy and western blotting were used to evaluate the expression of ENTPD2 in exosomes. Double-labelling immunofluorescence and western blotting were used to examine the expression of ENTPD2 in serum exosomes and colon cancer tissues.

RESULTS

We found that ENTPD2, rather than the well-known ATPase CD39, is highly expressed in cancer cells and is significantly positively associated with poor patient prognosis in patients with colon cancer. The overexpression of ENTPD2 in cancer cells augmented tumor progression in immunocompetent mice by inhibiting the function of CD8+ T cells. Moreover, ENTPD2 is localized primarily within exosomes. On the one hand, exosomal ENTPD2 reduces extracellular ATP levels, thereby inhibiting P2X7R-mediated NFATc1 nuclear transcription; on the other hand, it facilitates the increased conversion of ATP to adenosine, hence promoting adenosine-A2AR pathway activity. In patients with colon cancer, the serum level of exosomal ENTPD2 is positively associated with advanced TNM stage and high tumor invasion depth. Moreover, the level of ENTPD2 in the serum exosomes of colon cancer patients is positively correlated with the ENTPD2 expression level in paired colon cancer tissues, and the ENTPD2 level in both serum exosomes and tissues is significantly negatively correlated with the ENTPD2 expression level in tumor-infiltrating CD8+ T cells.

CONCLUSION

Our study suggests that exosomal ENTPD2, originated from colon cancer cells, contributes to the immunosuppressive microenvironment by promoting ATP-adenosine metabolism. These findings highlight the importance of exosome-derived hydrolytic enzymes as independent entities in shaping the tumor immune microenvironment.

Verification of In Vitro Anticancer Activity and Bioactive Compounds in Cordyceps Militaris-Infused Sweet Potato Shochu Spirits

Many liqueurs, including spirits infused with botanicals, are crafted not only for their taste and flavor but also for potential medicinal benefits. However, the scientific evidence supporting their medicinal effects remains limited. This study aims to verify in vitro anticancer activity and bioactive compounds in shochu spirits infused with Cordyceps militaris, a Chinese medicine. The results revealed that a bioactive fraction was eluted from the spirit extract with 40% ethanol. The infusion time impacted the inhibitory effect of the spirit extract on the proliferation of colon cancer-derived cell line HCT-116 cells, and a 21-day infusion showed the strongest inhibitory effect. Furthermore, the spirit extract was separated into four fractions, A-D, by high-performance liquid chromatography (HPLC), and Fractions B, C, and D, but not A, exerted the effects of proliferation inhibition and apoptotic induction of HCT-116 cells and HL-60 cells. Furthermore, Fractions B, C, and D were, respectively, identified as adenosine, cordycepin, and N6-(2-hydroxyethyl)-adenosine (HEA) by comprehensive chemical analyses, including proton nuclear magnetic resonance (1H-NMR), Fourier transform infrared spectroscopy (FT-IR), and electrospray ionization mass spectrometry (ESI-MS). To better understand the bioactivity mechanisms of cordycepin and HEA, the agonist and antagonist tests of the A3 adenosine receptor (A3AR) were performed. Cell viability was suppressed by cordycepin, and HEA was restored by the A3AR antagonist MR1523, suggesting that cordycepin and HEA possibly acted as agonists to activate A3ARs to inhibit cell proliferation. Molecular docking simulations revealed that both adenosine and cordycepin bound to the same pocket site of A3ARs, while HEA exhibited a different binding pattern, supporting a possible explanation for the difference in their bioactivity. Taken together, the present study demonstrated that cordycepin and HEA were major bioactive ingredients in Cordyceps militaries-infused sweet potato shochu spirits, which contributed to the in vitro anticancer activity.

The inhibitory effect of adenosine on tumor adaptive immunity and intervention strategies

Adenosine (Ado) is significantly elevated in the tumor microenvironment (TME) compared to normal tissues. It binds to adenosine receptors (AdoRs), suppressing tumor antigen presentation and immune cell activation, thereby inhibiting tumor adaptive immunity. Ado downregulates major histocompatibility complex II (MHC II) and co-stimulatory factors on dendritic cells (DCs) and macrophages, inhibiting antigen presentation. It suppresses anti-tumor cytokine secretion and T cell activation by disrupting T cell receptor (TCR) binding and signal transduction. Ado also inhibits chemokine secretion and KCa3.1 channel activity, impeding effector T cell trafficking and infiltration into the tumor site. Furthermore, Ado diminishes T cell cytotoxicity against tumor cells by promoting immune-suppressive cytokine secretion, upregulating immune checkpoint proteins, and enhancing immune-suppressive cell activity. Reducing Ado production in the TME can significantly enhance anti-tumor immune responses and improve the efficacy of other immunotherapies. Preclinical and clinical development of inhibitors targeting Ado generation or AdoRs is underway. Therefore, this article will summarize and analyze the inhibitory effects and molecular mechanisms of Ado on tumor adaptive immunity, as well as provide an overview of the latest advancements in targeting Ado pathways in anti-tumor immune responses.

Diabetes and the fabkin complex: A dual-edged sword

The Fabkin complex, composed of FABP4, ADK, and NDPKs, emerges as a novel regulator of insulin-producing beta cells, offering promising prospects for diabetes treatment. Our approach, which combines literature review and database analysis, sets the stage for future research. These findings hold significant implications for both diabetes treatment and research, as they present potential therapeutic targets for personalized treatment, leading to enhanced patient outcomes and a deeper comprehension of the disease. The multifaceted role of the Fabkin complex in glucose metabolism, insulin resistance, anti-inflammation, beta cell proliferation, and vascular function underscores its therapeutic potential, reshaping diabetes management and propelling advancements in the field.

The impact of the senescent microenvironment on tumorigenesis: Insights for cancer therapy

The growing global burden of cancer, especially among people aged 60 years and over, has become a key public health issue. This trend suggests the need for a deeper understanding of the various cancer types in order to develop universally effective treatments. A prospective area of research involves elucidating the interplay between the senescent microenvironment and tumor genesis. Currently, most oncology research focuses on adulthood and tends to ignore the potential role of senescent individuals on tumor progression. Senescent cells produce a senescence-associated secretory phenotype (SASP) that has a dual role in the tumor microenvironment (TME). While SASP components can remodel the TME and thus hinder tumor cell proliferation, they can also promote tumorigenesis and progression via pro-inflammatory and pro-proliferative mechanisms. To address this gap, our review seeks to investigate the influence of senescent microenvironment changes on tumor development and their potential implications for cancer therapies.

Integrated analysis of purine metabolism assists in predicting prognosis and treatment decisions for patients with lung adenocarcinoma

The incidence of lung cancer, especially lung adenocarcinoma (LUAD), has recently increased. Targeted therapy and immunotherapy combined with conventional treatment have shown surprising benefits in enhancing the LUAD patient's prognosis. For the purpose of guiding treatment planning and the prognosis of LUAD, more research is required. The particular aim of this work was to establish a purine metabolism scoring (PMS) model for the purpose of individually forecasting treatment outcomes and overall survival for patients who have LUAD. Clinical and whole genome data were obtained from the TCGA-LUAD cohort via "UCSC". The 25 driver purine metabolism-related prognostic genes were determined founded on univariate Cox regression. Then PMS was developed through stepwise LASSO Cox regression. Survival analysis indicated that patients who have PMS experienced worse outcomes. We validated the PGM2 effect on lung adenocarcinoma malignancy in in vitro experiments. Univariate as well as multivariate Cox regression suggested that PMS was an independent prognostic indicator for LUAD patients, which was confirmed in subgroup analysis. Functional assay demonstrated that immune response as well as cytotoxicity pathways have a connection with lower PMS, and patients who have low PMS possess an active immune microenvironment. Moreover, the LUAD patients who have low PMS showed greater sensitivity to immunotherapy, targeted therapy, as well as chemotherapy. Knockdown of PGM2 was discovered to decrease the proliferation, invasion, as well as migration of lung adenocarcinoma cells in an in vitro assay. Pertaining to this particular research, we created a PMS model and conducted a thorough analysis of purine metabolism in LUAD in order to determine prognosis and offer recommendations for treatment. This finding offered a fresh concept for the clinical management of LUAD and novel therapy protocols.

Role of STING in the treatment of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is a prevalent form of lung cancer. Patients with advanced NSCLC are currently being treated with various therapies, including traditional radiotherapy, chemotherapy, molecular targeted therapies and immunotherapy. However, a considerable proportion of advance patients who cannot benefit from them. Consequently, it is essential to identify a novel research target that offers an encouraging perspective. The stimulator of interferon genes (STING) has emerged as such a target. At present, it is confirmed that activating STING in NSCLC tumor cells can impede the proliferation and metastasis of dormant tumor cells. This review focuses on the role of STING in NSCLC treatment and the factors influencing its activation. Additionally, it explores the correlation between STING activation and diverse therapy modalities for NSCLC, such as radiotherapy, chemotherapy, molecular targeted therapies and immunotherapy. Furthermore, it proposes the prospect of innovative therapy methods involving nanoparticles, with the aim of using the features of STING to develop more strategies for NSCLC therapy.

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.

Adenosine-modulating synthetic high-density lipoprotein for chemoimmunotherapy of triple-negative breast cancer

Adenosine (ADO) is a common chemotherapy-associated immune checkpoint that hinders anti-tumor immunity-mediated efficacy of chemotherapy. Herein, we created a synthetic high-density lipoprotein (sHDL) by co-assembly of a doxorubicin (DOX)-apolipoprotein A1 mimetic peptide conjugate, PSB-603 (an A2BR inhibitor), phospholipid, and cholesterol oleate with a microfluidic-based method. The obtained DP-sHDL showed a self-promoted drug delivery to cancer cells via remodeling tumor microenvironment. DP-sHDL could trigger the release of ATP from cancer cells and inhibit its conversion into ADO. Consequently, DP-sHDL, while increasing immunogenic cell death, reduced intratumoral ADO levels by 58%. This treatment improved both the density and activity of CD8+ T cells as well as NK cells and relieved the immunosuppressive microenvironment, and led to a substantial inhibition of 4T1 tumor growth, thereby extending the survival of mice. The efficacy of DP-sHDL could be further improved when used in combination with immune checkpoint blockade therapy. We envision that this platform provides a simple yet promising strategy to enhance anti-tumor response of chemotherapy by relieving treatment-associated immunosuppression.

Adenosine in Intestinal Epithelial Barrier Function

At the intestinal front, several lines of defense are in place to resist infection and injury, the mucus layer, gut microbiome and strong epithelial junctions, to name a few. Their collaboration creates a resilient barrier. In intestinal disorders, such as inflammatory bowel disease (IBD), barrier function is compromised, which results in rampant inflammation and tissue injury. In response to the destruction, the intestinal epithelium releases adenosine, a small but powerful nucleoside that functions as an alarm signal. Amidst the chaos of inflammation, adenosine aims to restore order. Within the scope of its effects is the ability to regulate intestinal epithelial barrier integrity. This review aims to define the contributions of adenosine to mucus production, microbiome-dependent barrier protection, tight junction dynamics, chloride secretion and acid-base balance to reinforce its importance in the intestinal epithelial barrier.

Unveiling the mechanisms and challenges of cancer drug resistance

Cancer treatment faces many hurdles and resistance is one among them. Anti-cancer treatment strategies are evolving due to innate and acquired resistance capacity, governed by genetic, epigenetic, proteomic, metabolic, or microenvironmental cues that ultimately enable selected cancer cells to survive and progress under unfavorable conditions. Although the mechanism of drug resistance is being widely studied to generate new target-based drugs with better potency than existing ones. However, due to the broader flexibility in acquired drug resistance, advanced therapeutic options with better efficacy need to be explored. Combination therapy is an alternative with a better success rate though the risk of amplified side effects is commonplace. Moreover, recent groundbreaking precision immune therapy is one of the ways to overcome drug resistance and has revolutionized anticancer therapy to a greater extent with the only limitation of being individual-specific and needs further attention. This review will focus on the challenges and strategies opted by cancer cells to withstand the current therapies at the molecular level and also highlights the emerging therapeutic options -like immunological, and stem cell-based options that may prove to have better potential to challenge the existing problem of therapy resistance. Video Abstract.

Landscape of adenosine pathway and immune checkpoint dual blockade in NSCLC: progress in basic research and clinical application

Lung cancer poses a global threat to human health, while common cancer treatments (chemotherapy and targeted therapies) have limited efficacy. Immunotherapy offers hope of sustained remission for many patients with lung cancer, but a significant proportion of patients fail to respond to treatment owing to immune resistance. There is extensive evidence to suggest the immunosuppressive microenvironment as the cause of this treatment failure. Numerous studies have suggested that the adenosine (ADO) pathway plays an important role in the formation of an immunosuppressive microenvironment and may be a key factor in the development of immune resistance in EGFR-mutant cell lung cancer. Inhibition of this pathway may therefore be a potential target to achieve effective reversal of ADO pathway-mediated immune resistance. Recently, an increasing number of clinical trials have begun to address the broad prospects of using the ADO pathway as an immunotherapeutic strategy. However, few researchers have summarized the theoretical basis and clinical rationale of the ADO pathway and immune checkpoint dual blockade in a systematic and detailed manner, particularly in lung cancer. As such, a timely review of the potential value of the ADO pathway in combination with immunotherapy strategies for lung cancer is warranted. This comprehensive review first describes the role of ADO in the formation of a lung tumor-induced immunosuppressive microenvironment, discusses the key mechanisms of ADO inhibitors in reversing lung immunosuppression, and highlights recent evidence from preclinical and clinical studies of ADO inhibitors combined with immune checkpoint blockers to improve the lung cancer immunosuppressive microenvironment.

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.

Impairment of adenosine signaling disrupts early embryo development: unveiling the underlying mechanisms

Purinergic signaling has been implicated in many biological functions, including development. In this study, we investigate the functions of extracellular adenosine and adenosine receptors using a mouse embryonic stem cell (ESC) line and morula stages isolated from mouse embryos. Feeder-free mouse ESC was investigated in the absence and presence of the leukemia inhibitory factor (LIF), configuring undifferentiated cells and cells undergoing spontaneous differentiation. High alkaline phosphatase (ALPL) and low CD73 levels resulting in low adenosine (eADO) levels were characteristic for pluripotent cells in the presence of the LIF, while LIF deprivation resulted in augmented adenosine levels and reduced pluripotency marker expression, which indicated differentiation. Tracing ESC proliferation by BrdU labeling revealed that the inhibition of ALPL by levamisole resulted in a decrease in proliferation due to less eADO accumulation. Furthermore, caffeine and levamisole treatment, inhibiting adenosine receptor and eADO accumulation, respectively, reduced ESC migration, similar to that observed in the absence of the LIF. Pharmacological approaches of selective adenosine receptor subtype inhibition triggered specific adenosine receptor activities, thus triggering calcium or MAP kinase pathways leading to differentiation. In line with the in vitro data, mouse embryos at the morula stage were sensitive to treatments with A1 and A3 receptor antagonists, leading to the conclusion that A1 receptor and A3 receptor inhibition impairs proliferation and self-renewal and triggers inappropriate differentiation, respectively. The findings herein define the functions of eADO signaling in early development with implications for developmental disorders, in which adenosine receptors or ectonucleotidase dysfunctions are involved, and which could lead to malformations and miscarriages, due to exposure to caffeine.

INTEDE 2.0: the metabolic roadmap of drugs

The metabolic roadmap of drugs (MRD) is a comprehensive atlas for understanding the stepwise and sequential metabolism of certain drug in living organisms. It plays a vital role in lead optimization, personalized medication, and ADMET research. The MRD consists of three main components: (i) the sequential catalyses of drug and its metabolites by different drug-metabolizing enzymes (DMEs), (ii) a comprehensive collection of metabolic reactions along the entire MRD and (iii) a systematic description on efficacy & toxicity for all metabolites of a studied drug. However, there is no database available for describing the comprehensive metabolic roadmaps of drugs. Therefore, in this study, a major update of INTEDE was conducted, which provided the stepwise & sequential metabolic roadmaps for a total of 4701 drugs, and a total of 22 165 metabolic reactions containing 1088 DMEs and 18 882 drug metabolites. Additionally, the INTEDE 2.0 labeled the pharmacological properties (pharmacological activity or toxicity) of metabolites and provided their structural information. Furthermore, 3717 drug metabolism relationships were supplemented (from 7338 to 11 055). All in all, INTEDE 2.0 is highly expected to attract broad interests from related research community and serve as an essential supplement to existing pharmaceutical/biological/chemical databases. INTEDE 2.0 can now be accessible freely without any login requirement at: http://idrblab.org/intede/.

Adenosinergic metabolism pathway: an emerging target for improving outcomes of solid organ transplantation

Extracellular nucleotides are widely recognized as crucial modulators of immune responses in peripheral tissues. Adenosine triphosphate (ATP) and adenosine are key components of extracellular nucleotides, the balance of which contributes to immune homeostasis. Under tissue injury, ATP exerts its pro-inflammatory function, while the adenosinergic pathway rapidly degrades ATP to immunosuppressive adenosine, thus inhibiting excessive and uncontrolled inflammatory responses. Previous reviews have explored the immunoregulatory role of extracellular adenosine in various pathological conditions, especially inflammation and malignancy. However, current knowledge regarding adenosine and adenosinergic metabolism in the context of solid organ transplantation remains fragmented. In this review, we summarize the latest information on adenosine metabolism and the mechanisms by which it suppresses the effector function of immune cells, as well as highlight the protective role of adenosine in all stages of solid organ transplantation, including reducing ischemia reperfusion injury during organ procurement, alleviating rejection, and promoting graft regeneration after transplantation. Finally, we discuss the potential for future clinical translation of adenosinergic pathway in solid organ transplantation.

ENPP1 is an innate immune checkpoint of the anticancer cGAMP-STING pathway in breast cancer

Ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) expression correlates with poor prognosis in many cancers, and we previously discovered that ENPP1 is the dominant hydrolase of extracellular cGAMP: a cancer-cell-produced immunotransmitter that activates the anticancer stimulator of interferon genes (STING) pathway. However, ENPP1 has other catalytic activities and the molecular and cellular mechanisms contributing to its tumorigenic effects remain unclear. Here, using single-cell RNA-seq, we show that ENPP1 in both cancer and normal tissues drives primary breast tumor growth and metastasis by dampening extracellular 2'3'-cyclic-GMP-AMP (cGAMP)-STING-mediated antitumoral immunity. ENPP1 loss-of-function in both cancer cells and normal tissues slowed primary tumor growth and abolished metastasis. Selectively abolishing the cGAMP hydrolysis activity of ENPP1 phenocopied ENPP1 knockout in a STING-dependent manner, demonstrating that restoration of paracrine cGAMP-STING signaling is the dominant anti-cancer mechanism of ENPP1 inhibition. Finally, ENPP1 expression in breast tumors deterministically predicated whether patients would remain free of distant metastasis after pembrolizumab (anti-PD-1) treatment followed by surgery. Altogether, ENPP1 blockade represents a strategy to exploit cancer-produced extracellular cGAMP for controlled local activation of STING and is therefore a promising therapeutic approach against breast cancer.

Ribonucleotide reductase as a therapeutic target for drug repurposing as anthelmintics

Visceral cestodiases, like echinococcoses and cysticercoses, are zoonoses of worldwide distribution and are responsible for public health problems in many countries, especially in underdeveloped regions. Current treatments have low efficiency and there are few drugs currently in use for chemotherapy, making the development of new anthelmintics an urgent matter. The nucleotide salvage pathways are the only ones available for nucleotide synthesis in cestodes and other parasitic helminths, and, here, we used in silico approaches to assess the potential of the enzymes in these pathways as targets for drug repurposing as anthelminthics. First, a genomic survey allowed to identify a repertoire of 28 enzymes of the purine and pyrimidine salvage pathways from the cestode Echinococcus granulosus sensu stricto. Regarding purines, the parasite relies on salvaging free bases rather than salvaging nucleosides. Pyrimidines, on the other hand, can be salvaged from both bases and nucleosides. Druggability of the parasite enzymes was assessed, as well as the availability of commercial inhibitors for them. Druggable enzymes were then ranked according to their potential for drug repurposing and the 17 most promising enzymes were selected for evolutionary analyses. The constructed phylogenetic trees allowed to assess the degree of conservation among ortholog enzymes from parasitic helminths and their mammalian hosts. Positive selection is absent in all assessed flatworm enzymes. A potential target enzyme for drug repurposing, ribonucleotide reductase (RNR), was selected for further assessment. RNR 3D-modelling showed structural similarities between the E. granulosus and the human orthologs suggesting that inhibitors of the human RNR should be effective against the E. granulosus enzyme. In line with that, E. granulosus protoscolices treated in vitro with the inhibitor hydroxyurea had their viability and DNA synthesis reduced. These results are consistent with nucleotide synthesis inhibition and confirm the potential of a nucleotide salvage inhibitors for repurposing as an anthelmintic.

Problems and prospects for finding new pharmacological agents among adenosine receptor agonists, antagonists, or their allosteric modulators for the treatment of cardiovascular diseases

A1-adenosine receptors (A1AR) are widely distributed in the human body and mediate many different effects. They are abundantly present in the cardiovascular system, where they control angiogenesis, vascular tone, heart rate, and conduction. This makes the cardiovascular system A1AR an attractive target for the treatment of cardiovascular diseases (CVD). The review summarizes the literature data on the structure and functioning of A1AR, and analyzes their involvement in the formation of myocardial hypertrophy, ischemia-reperfusion damage, various types of heart rhythm disorders, chronic heart failure, and arterial hypertension. Special attention is paid to the role of some allosteric regulators of A1AR as potential agents for the CVD treatment.

Blockage of EGFR/AKT and mevalonate pathways synergize the antitumor effect of temozolomide by reprogramming energy metabolism in glioblastoma

BACKGROUND

Metabolism reprogramming plays a vital role in glioblastoma (GBM) progression and recurrence by producing enough energy for highly proliferating tumor cells. In addition, metabolic reprogramming is crucial for tumor growth and immune-escape mechanisms. Epidermal growth factor receptor (EGFR) amplification and EGFR-vIII mutation are often detected in GBM cells, contributing to the malignant behavior. This study aimed to investigate the functional role of the EGFR pathway on fatty acid metabolism remodeling and energy generation.

METHODS

Clinical GBM specimens were selected for single-cell RNA sequencing and untargeted metabolomics analysis. A metabolism-associated RTK-fatty acid-gene signature was constructed and verified. MK-2206 and MK-803 were utilized to block the RTK pathway and mevalonate pathway induced abnormal metabolism. Energy metabolism in GBM with activated EGFR pathway was monitored. The antitumor effect of Osimertinib and Atorvastatin assisted by temozolomide (TMZ) was analyzed by an intracranial tumor model in vivo.

RESULTS

GBM with high EGFR expression had characteristics of lipid remodeling and maintaining high cholesterol levels, supported by the single-cell RNA sequencing and metabolomics of clinical GBM samples. Inhibition of the EGFR/AKT and mevalonate pathways could remodel energy metabolism by repressing the tricarboxylic acid cycle and modulating ATP production. Mechanistically, the EGFR/AKT pathway upregulated the expressions of acyl-CoA synthetase short-chain family member 3 (ACSS3), acyl-CoA synthetase long-chain family member 3 (ACSL3), and long-chain fatty acid elongation-related gene ELOVL fatty acid elongase 2 (ELOVL2) in an NF-κB-dependent manner. Moreover, inhibition of the mevalonate pathway reduced the EGFR level on the cell membranes, thereby affecting the signal transduction of the EGFR/AKT pathway. Therefore, targeting the EGFR/AKT and mevalonate pathways enhanced the antitumor effect of TMZ in GBM cells and animal models.

CONCLUSIONS

Our findings not only uncovered the mechanism of metabolic reprogramming in EGFR-activated GBM but also provided a combinatorial therapeutic strategy for clinical GBM management.

Developmental and foliation changes due to dysregulation of adenosine kinase in the cerebellum

Adenosine kinase (ADK), the major adenosine-metabolizing enzyme, plays a key role in brain development and disease. In humans, mutations in the Adk gene have been linked to developmental delay, stunted growth, and intellectual disability. To better understand the role of ADK in brain development, it is important to dissect the specific roles of the two isoforms of the enzyme expressed in the cytoplasm (ADK-S) and cell nucleus (ADK-L). We, therefore, studied brain development in Adk-tg transgenic mice, which only express ADK-S in the absence of ADK-L throughout development. In the mutant animals, we found a reduction in the overall brain, body size, and weight during fetal and postnatal development. As a major developmental abnormality, we found a profound change in the foliation pattern of the cerebellum. Strikingly, our results indicated aberrant Purkinje cells arborization at P9 and accelerated cell death at P6 and P9. We found defects in cerebellar cell proliferation and migration using a bromodeoxyuridine (BrdU)-based cell proliferation assay at postnatal day 7. Our data demonstrate that dysregulation of ADK expression during brain development profoundly affects brain growth and differentiation.

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.

Expression of ADK-S and ADK-L Isoforms and Their Association with CD39/CD73/A2aR in Colorectal Cancer

The level of mRNA of the long (L) and short (S) isoforms of adenosine kinase (ADK) was analyzed in patients with colorectal cancer (CRC). ADK is required to convert adenosine (ADO) to AMP. It was shown that tumor and normal colon tissues (n=13) do not differ in the level of ADK-S and ADK-L mRNA. At the same time, the level of ADK-S mRNA (tumor: p=0.0214, normal: p=0.005) in the colon tissue was lower than in the blood of CRC patients (n=20), and the level of ADK-L mRNA (tumor: p=0.007, normal: p=0.024), on the contrary, was higher. A negative correlation was found between the level of ADK-S mRNA and the level of A2aR mRNA in both tumor and normal tissues (p=0.018 and p=0.0014, respectively). In the tumor tissue, a positive correlation was shown between ADK-L and CD73 mRNA levels (p=0.017). The obtained data indicate the association ADK with the expression of CD39/CD73/A2aR in CRC patients. In this regard, the effect of recombinant ADK on the expression of CD39 and CD73 ectonucleotidase by T cells in vitro was analyzed. In a culture of peripheral blood mononuclear cells isolated from the blood of 5 healthy donors, ADK did not abolish the inhibitory effect on the expression of CD39 and CD73 by CD8+T cells in the presence of a high concentration of ATP (a source for ADO). Effects on CD39+CD4+, CD73+CD4+T cells and CD39+ Treg cells were also not found.

Anti-inflammatory potency of novel ecto-5'-nucleotidase/CD73 inhibitors in astrocyte culture model of neuroinflammation

Three novel cytosine-derived α,β-methylene diphosphonates designated MRS4598, MRS4552, and MRS4602 were tested in the range of 1 × 10-9 to 1 × 10-3 M for their efficacy and potency in inhibiting membrane-bound ecto-5'-nucleotidase/CD73 activity in primary astrocytes in vitro. The compounds were also tested for their ability to attenuate the reactive astrocyte phenotype induced by proinflammatory cytokines. The main findings are as follows: A) The tested compounds induced concentration-dependent inhibition of CD73 activity, with maximal inhibition achieved at ∼1 × 10-3M; B) All compounds showed high inhibitory potency, as reflected by IC50 values in the submicromolar range; C) All compounds showed high binding capacity, as reflected by Ki values in the low nanomolar range; D) Among the tested compounds, MRS4598 showed the highest inhibitory efficacy and potency, as reflected by IC50 and Ki values of 0.11 μM and 18.2 nM; E) Neither compound affected astrocyte proliferation and cell metabolic activity at concentrations near to IC50; E) MRS4598 was able to inhibit CD73 activity in reactive astrocytes stimulated with TNF-α and to induce concentration-dependent inhibition of CD73 in reactive astrocytes stimulated with IL-1β, with an order of magnitude higher IC50 value; F) MRS4598 was the only compound tested that was able to induce shedding of the CD73 from astrocyte membranes and to enhance astrocyte migration in the scratch wound migration assay, albeit at concentration well above its IC50 value. Given the role of CD73 in neurodegenerative diseases, MRS4598, MRS4552, and MRS4602 are promising pharmacological tools for the treatment of neurodegeneration and neuroinflammation.

ATP protects anti-PD-1/radiation-induced cardiac dysfunction by inhibiting anti-PD-1 exacerbated cardiomyocyte apoptosis, and improving autophagic flux

The synergy between radiotherapy and immunotherapy in treating thoracic cancers presents a potent therapeutic advantage, yet it also carries potential risks. The extent and nature of cumulative cardiac toxicity remain uncertain, prompting the need to discern its mechanisms and devise effective mitigation strategies. Radiation alone or in combination with an anti- Programmed cell death protein1 (PD-1) antibody significantly reduced cardiac function in C57BL/6J mice, and this pathologic effect was aggravated by anti-PD-1 (anti-PD-1 + radiation). To examine the cellular mechanism that causes the detrimental effect of anti-PD-1 upon cardiac function after radiation, AC16 human cardiomyocytes were used to study cardiac apoptosis and cardiac autophagy. Radiation-induced cardiomyocyte apoptosis was significantly promoted by anti-PD-1 treatment, while anti-PD-1 combined radiation administration blocked the cardiac autophagic flux. Adenosine 5'-triphosphate (ATP) (a molecule that promotes lysosomal acidification) not only improved autophagic flux in AC16 human cardiomyocytes, but also attenuated apoptosis induced by radiation and anti-PD-1 treatment. Finally, ATP administration in vivo significantly reduced radiation-induced and anti-PD-1-exacerbated cardiac dysfunction. We demonstrated for the first time that anti-PD-1 can aggravate radiation-induced cardiac dysfunction via promoting cardiomyocyte apoptosis without affecting radiation-arrested autophagic flux. ATP enhanced cardiomyocyte autophagic flux and inhibited apoptosis, improving cardiac function in anti-PD-1/radiation combination-treated animals.

Adenylate kinase immobilized on graphene oxide impairs progression of human lung carcinoma epithelial cells through adenosinergic pathway

Purinergic signaling, the oldest evolutionary transmitter system, has been increasingly studied as a pivotal target for novel anti-cancer therapies. In the present work, the developed nanobiocatalytic system consisting of adenylate kinase immobilized on graphene oxide (AK-GO) was characterized in terms of its physicochemical and biochemical properties. We put special emphasis on the AK-GO influence on purinergic signaling components, that is, ecto-nucleotides concentration and ecto-enzymes expression and activity in human lung carcinoma epithelial (A549) cells. The immobilization-dependent modification of AK kinetic parameters allowed for the removal of ATP excess while maintaining low ATP concentrations, efficient decrease in adenosine concentration, and control of the nucleotide balance in carcinoma cells. The cyto- and hemocompatibility of developed AK-GO nanobiocatalytic system indicates that it can be successfully harnessed for biomedical applications. In A549 cells treated with AK-GO nanobiocatalytic system, the significantly decreased adenosinergic signaling results in reduction of the proliferation and migration capability of cancer cells. This finding is particularly relevant in regard to AK-GO prospective anti-cancer applications.

Increased interleukin-6/C-reactive protein levels are associated with the upregulation of the adenosine pathway and serve as potential markers of therapeutic resistance to immune checkpoint inhibitor-based therapies in non-small cell lung cancer

BACKGROUND

Systemic immune activation, hallmarked by C-reactive protein (CRP) and interleukin-6 (IL-6), can modulate antitumor immune responses. In this study, we evaluated the role of IL-6 and CRP in the stratification of patients with non-small cell lung cancer (NSCLC) treated with immune checkpoint inhibitors (ICIs). We also interrogated the underlying immunosuppressive mechanisms driven by the IL-6/CRP axis.

METHODS

In cohort A (n=308), we estimated the association of baseline CRP with objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) in patients with NSCLC treated with ICIs alone or with chemo-immunotherapy (Chemo-ICI). Baseline tumor bulk RNA sequencing (RNA-seq) of lung adenocarcinomas (LUADs) treated with pembrolizumab (cohort B, n=59) was used to evaluate differential expression of purine metabolism, as well as correlate IL-6 expression with PFS. CODEFACS approach was applied to deconvolve cohort B to characterize the tumor microenvironment by reconstructing the cell-type-specific transcriptome from bulk expression. Using the LUAD cohort from The Cancer Genome Atlas (TCGA) we explored the correlation between IL-6 expression and adenosine gene signatures. In a third cohort (cohort C, n=18), plasma concentrations of CRP, adenosine 2a receptor (A2aR), and IL-6 were measured using ELISA.

RESULTS

In cohort A, 67.2% of patients had a baseline CRP≥10 mg/L (CRP-H). Patients with CRP-H achieved shorter OS (8.6 vs 14.8 months; p=0.006), shorter PFS (3.3 vs 6.6 months; p=0.013), and lower ORR (24.7% vs 46.3%; p=0.015). After adjusting for relevant clinical variables, CRP-H was confirmed as an independent predictor of increased risk of death (HR 1.51, 95% CI: 1.09 to 2.11) and lower probability of achieving disease response (OR 0.34, 95% CI: 0.13 to 0.89). In cohort B, RNA-seq analysis demonstrated higher IL-6 expression on tumor cells of non-responders, along with a shorter PFS (p<0.05) and enrichment of the purinergic pathway. Within the TCGA LUAD cohort, tumor IL-6 expression strongly correlated with the adenosine signature (R=0.65; p<2.2e-16). Plasma analysis in cohort C demonstrated that CRP-H patients had a greater median baseline level of A2aR (6.0 ng/mL vs 1.3 ng/mL; p=0.01).

CONCLUSIONS

This study demonstrates CRP as a readily available blood-based prognostic biomarker in ICI-treated NSCLC. Additionally, we elucidate a potential link of the CRP/IL-6 axis with the immunosuppressive adenosine signature pathway that could drive inferior outcomes to ICIs in NSCLC and also offer novel therapeutic avenues.

Inhibitory effect of adenosine on adaptive antitumor immunity and intervention strategies

Tumors in which the microenvironment is characterized by lack of immune cell infiltration are referred as "cold tumors" and typically exhibit low responsiveness to immune therapy. Targeting the factors contributing to "cold tumors" formation and converting them into "hot tumors" is a novel strategy for improving the efficacy of immunotherapy. Adenosine, a hydrolysis product of ATP, accumulates with a significantly higher concentration in the tumor microenvironments compared with normal tissue and exerts inhibitory effects on tumor-specific adaptive immunity. Tumor cells, dendritic cells, macrophages, and T cells express abundant adenosine receptors on their surfaces. The binding of adenosine to these receptors initiates downstream signaling pathways that suppress tumor antigen presentation and immune cell activation, consequently dampening adaptive immune responses against tumors. Adenosine down-regulates the expression of major histocompatibility complex Ⅱ and co-stimulatory factors on dendritic cells and macrophages, thereby inhibiting antigen presentation to T cells. Adenosine also inhibits ligand-receptor binding and transmembrane signaling on T cells, concomitantly suppressing the secretion of anti-tumor cytokines and impairing T cell activation. Furthermore, adenosine hinders effector T cell trafficking to tumor sites and infiltration by inhibiting chemokine secretion and KCa3.1 channels. Additionally, adenosine promotes the secretion of immunosuppressive cytokines, increases immune checkpoint protein expression, and enhances the activity of immunosuppressive cells, collectively curbing cytotoxic T cell-mediated tumor cell killing. Given the immunosuppressive role of adenosine in adaptive antitumor immunity, several inhibitors targeting adenosine generation or adenosine receptor blockade are currently in preclinical or clinical development with the aim of enhancing the effectiveness of immunotherapies. This review provides an overview of the inhibitory effects of adenosine on adaptive antitumor immunity, elucidate the molecular mechanisms involved, and summarizes the latest advances in application of adenosine inhibition strategies for antitumor immunotherapy.

Mathematical reconstruction of the metabolic network in an in-vitro multiple myeloma model

It is increasingly apparent that cancer cells, in addition to remodelling their metabolism to survive and proliferate, adapt and manipulate the metabolism of other cells. This property may be a telling sign that pre-clinical tumour metabolism studies exclusively utilising in-vitro mono-culture models could prove to be limited for uncovering novel metabolic targets able to translate into clinical therapies. Although this is increasingly recognised, and work towards addressing the issue is becoming routinary much remains poorly understood. For instance, knowledge regarding the biochemical mechanisms through which cancer cells manipulate non-cancerous cell metabolism, and the subsequent impact on their survival and proliferation remains limited. Additionally, the variations in these processes across different cancer types and progression stages, and their implications for therapy, also remain largely unexplored. This study employs an interdisciplinary approach that leverages the predictive power of mathematical modelling to enrich experimental findings. We develop a functional multicellular in-silico model that facilitates the qualitative and quantitative analysis of the metabolic network spawned by an in-vitro co-culture model of bone marrow mesenchymal stem- and myeloma cell lines. To procure this model, we devised a bespoke human genome constraint-based reconstruction workflow that combines aspects from the legacy mCADRE & Metabotools algorithms, the novel redHuman algorithm, along with 13C-metabolic flux analysis. Our workflow transforms the latest human metabolic network matrix (Recon3D) into two cell-specific models coupled with a metabolic network spanning a shared growth medium. When cross-validating our in-silico model against the in-vitro model, we found that the in-silico model successfully reproduces vital metabolic behaviours of its in-vitro counterpart; results include cell growth predictions, respiration rates, as well as support for observations which suggest cross-shuttling of redox-active metabolites between cells.

Purinergic signalling in cancer therapeutic resistance: From mechanisms to targeting strategies

Purinergic signalling, consisting of extracellular purines and purinergic receptors, modulates cell proliferation, invasion and immunological reaction during cancer progression. Here, we focus on current evidence that suggests the crucial role of purinergic signalling in mediating cancer therapeutic resistance, the major obstacle in cancer treatment. Mechanistically, purinergic signalling can modulate the tumor microenvironment (TME), epithelial-mesenchymal transition (EMT) and anti-tumor immunity, thus affecting drug sensitivity of tumor cells. Currently, some agents attempting to target purinergic signalling either in tumor cells or in tumor-associated immune cells are under preclinical or clinical investigation. Moreover, nano-based delivery technologies significantly improve the efficacy of agents targeting purinergic signalling. In this review article, we summarize the mechanisms of purinergic signalling in promoting cancer therapeutic resistance and discuss the potentials and challenges of targeting purinergic signalling in future cancer treatment.

Heparins are potent inhibitors of ectonucleotide pyrophosphatase/phospho-diesterase-1 (NPP1) - a promising target for the immunotherapy of cancer

Introduction

Heparins, naturally occurring glycosaminoglycans, are widely used for thrombosis prevention. Upon application as anticoagulants in cancer patients, heparins were found to possess additional antitumor activities. Ectonucleotidases have recently been proposed as novel targets for cancer immunotherapy.

Methods and results

In the present study, we discovered that heparin and its derivatives act as potent, selective, allosteric inhibitors of the poorly investigated ectonucleotidase NPP1 (nucleotide pyrophosphatase/phosphodiesterase-1, CD203a). Structure-activity relationships indicated that NPP1 inhibition could be separated from the compounds' antithrombotic effect. Moreover, unfractionated heparin (UFH) and different low molecular weight heparins (LMWHs) inhibited extracellular adenosine production by the NPP1-expressing glioma cell line U87 at therapeutically relevant concentrations. As a consequence, heparins inhibited the ability of U87 cell supernatants to induce CD4+ T cell differentiation into immunosuppressive Treg cells.

Discussion

NPP1 inhibition likely contributes to the anti-cancer effects of heparins, and their specific optimization may lead to improved therapeutics for the immunotherapy of cancer.

Chemobrain: An accelerated aging process linking adenosine A2A receptor signaling in cancer survivors

Chemotherapy has a significant positive impact in cancer treatment outcomes, reducing recurrence and mortality. However, many cancer surviving children and adults suffer from aberrant chemotherapy neurotoxic effects on learning, memory, attention, executive functioning, and processing speed. This chemotherapy-induced cognitive impairment (CICI) is referred to as "chemobrain" or "chemofog". While the underlying mechanisms mediating CICI are still unclear, there is strong evidence that chemotherapy accelerates the biological aging process, manifesting as effects which include telomere shortening, epigenetic dysregulation, oxidative stress, mitochondrial defects, impaired neurogenesis, and neuroinflammation, all of which are known to contribute to increased anxiety and neurocognitive decline. Despite the increased prevalence of CICI, there exists a lack of mechanistic understanding by which chemotherapy detrimentally affects cognition in cancer survivors. Moreover, there are no approved therapeutic interventions for this condition. To address this gap in knowledge, this review attempts to identify how adenosine signaling, particularly through the adenosine A2A receptor, can be an essential tool to attenuate accelerated aging phenotypes. Importantly, the adenosine A2A receptor uniquely stands at the crossroads of cancer treatment and improved cognition, given that it is widely known to control tumor induced immunosuppression in the tumor microenvironment, while also posited to be an essential regulator of cognition in neurodegenerative disease. Consequently, we propose that the adenosine A2A receptor may provide a multifaceted therapeutic strategy to enhance anticancer activity, while combating chemotherapy induced cognitive deficits, both which are essential to provide novel therapeutic interventions against accelerated aging in cancer survivors.

Prognostic Implication of Plasma Metabolites in Gastric Cancer

Gastric cancer (GC) typically carries a poor prognosis as it is often diagnosed at a late stage. Altered metabolism has been found to impact cancer outcomes and affect patients' quality of life, and the role of metabolites in gastric cancer prognosis has not been sufficiently understood. We aimed to establish a prognostic prediction model for GC patients based on a metabolism-associated signature and identify the unique role of metabolites in the prognosis of GC. Thus, we conducted untargeted metabolomics to detect the plasma metabolites of 218 patients with gastric adenocarcinoma and explored the metabolites related to the survival of patients with gastric cancer. Firstly, we divided patients into two groups based on the cutoff value of the abundance of each of the 60 metabolites and compared the differences using Kaplan-Meier (K-M) survival analysis. As a result, 23 metabolites associated with gastric cancer survival were identified. To establish a risk score model, we performed LASSO regression and Cox regression analysis on the 60 metabolites and identified 8 metabolites as an independent prognostic factor. Furthermore, a nomogram incorporating clinical parameters and the metabolic signature was constructed to help individualize outcome predictions. The results of the ROC curve and nomogram plot showed good predictive performance of metabolic risk features. Finally, we performed pathway analysis on the 24 metabolites identified in the two parts, and the results indicated that purine metabolism and arachidonic acid metabolism play important roles in gastric cancer prognosis. Our study highlights the important role of metabolites in the progression of gastric cancer and newly identified metabolites could be potential biomarkers or therapeutic targets for gastric cancer patients.

pH-sensitive tumor-tropism hybrid membrane-coated nanoparticles for reprogramming the tumor microenvironment and boosting the antitumor immunity

Metabolic dysregulation contributes not only to cancer development but also to a tumor immune microenvironment (TIME), which poses great challenges to chemo- and immunotherapy. Targeting metabolic reprogramming has recently emerged as a promising strategy for cancer treatment, but the lethality against solid tumors appears to be fairly restricted, partially due to the poor solubility of small molecule drugs. Herein, we construct a versatile biomimetic nanoplatform (referred to as HM-BPT) employing pH-sensitive tumor-tropism hybrid membrane-coated Manganese oxide (MnO2) nanoparticles for the delivery of BPTES, a glutamine metabolism inhibitor. Basically, hybrid membranes consisting of mesenchymal stem cell membranes (MSCm) and pH-sensitive liposomes (pSL) enable the biomimetic nanoplatform to target TME and escape from endo/lysosomes after endocytosis. The results reveal that HM-BPT treatment leads to remarkable tumor inhibition, cytotoxic T lymphocyte (CTL) infiltration, as well as M1 phenotype repolarization and stimulator of IFN genes (STING) pathway activation in macrophages in a 4T1 xenograft model. Furthermore, glutathione (GSH) depletion and oxygen (O2) supply synergistically ameliorate the immunosuppressive status of the TME, boosting potent antitumor immune responses. Overall, our study explores an integrated therapeutic platform for TME reprogramming and immune activation, offering tremendous promise for cancer combination therapy. STATEMENT OF SIGNIFICANCE: Metabolic abnormalities and the tumor immune microenvironment (TIME) lead to hyporesponsiveness to conventional therapies, ultimately resulting in refractory malignancies. In the current work, a biomimetic nanoplatform (HM-BPT) was developed for TME metabolic reprogramming in favor of immunotherapy. Particularly, hybrid membrane camouflage endowed the nanoplatform with TME targeting, endo/lysosomal escape, and sensitive release properties. The impact of hybrid membrane fusion ratio on cellular uptake and cell viability was explored, yielding beneficial references for the future development of bioactive nanomaterials. Intravenous administration of HM-BPT substantially relieved tumor burden and restored innate and acquired immune activation in 4T1 xenograft models. In conclusion, the created HM-BPT system has the potential to be a promising nanoplatform for combining cancer therapies.

Aberrant adenosine signaling in patients with focal cortical dysplasia

Focal cortical dysplasia (FCD), a common malformation of cortical development, is frequently associated with pharmacoresistant epilepsy in both children and adults. Adenosine is an inhibitory modulator of brain activity and a prospective anti-seizure agent with potential for clinical translation. Our previous results demonstrated that the major adenosine-metabolizing enzyme adenosine kinase (ADK) was upregulated in balloon cells (BCs) within FCD type IIB lesions, suggesting that dysfunction of the adenosine system is implicated in the pathophysiology of FCD. In our current study, we therefore performed a comprehensive analysis of adenosine signaling in surgically resected cortical specimens from patients with FCD type I and type II via immunohistochemistry and immunoblot analysis. Adenosine enzyme signaling was assessed by quantifying the levels of the key enzymes of adenosine metabolism, i.e., ADK, adenosine deaminase (ADA), and ecto-5'-nucleotidase (CD73). Adenosine receptor signaling was assessed by quantifying the levels of adenosine A2A receptor (A2AR) and putative downstream mediators of adenosine, namely, glutamate transporter-1 (GLT-1) and mammalian target of rapamycin (mTOR). Within lesions in FCD specimens, we found that the adenosine-metabolizing enzymes ADK and ADA, as well as the adenosine-producing enzyme CD73, were upregulated. We also observed an increase in A2AR density, as well as a decrease in GLT-1 levels and an increase in mTOR levels, in FCD specimens compared with control tissue. These results suggest that dysregulation of the adenosine system is a common pathologic feature of both FCD type I and type II. The adenosine system might therefore be a therapeutic target for the treatment of epilepsy associated with FCD.

Unraveling the Mechanisms of Ch-SeNP Cytotoxicity against Cancer Cells: Insights from Targeted and Untargeted Metabolomics

Although chitosan-stabilized selenium nanoparticles (Ch-SeNPs) have emerged as a promising chemical form of selenium for anticancer purposes, gathering more profound knowledge related to molecular dysfunctions contributes significantly to the promotion of their evolution as a chemotherapeutic drug. In this sense, metabolites are the end products in the flow of gene expression and, thus, the most sensitive to changes in the physiological state of a biological system. Therefore, metabolomics provides a functional readout of the biochemical activity and cell state. In the present study, we evaluated alterations in the metabolomes of HepG2 cells after the exposure to Ch-SeNPs to elucidate the biomolecular mechanisms involved in their therapeutic effect. A targeted metabolomic approach was conducted to evaluate the levels of four of the main energy-related metabolites (adenosine triphosphate (ATP); adenosine diphosphate (ADP); nicotinamide adenine dinucleotide (NAD+); and 1,4-dihydronicotinamide adenine dinucleotide (NADH)), revealing alterations as a result of exposure to Ch-SeNPs related to a shortage in the energy supply system in the cell. In addition, an untargeted metabolomic experiment was performed, which allowed for the study of alterations in the global metabolic profile as a consequence of Ch-SeNP exposure. The results indicate that the TCA cycle and glycolytic pathways were impaired, while alternative pathways such as glutaminolysis and cysteine metabolism were upregulated. Additionally, increased fructose levels suggested the induction of hypoxia-like conditions. These findings highlight the potential of Ch-SeNPs to disrupt cancer cell metabolism and provide insights into the mechanisms underlying their antitumor effects.

A2b and A3 adenosine receptors may act as promotive and prognostic factors in oral squamous cell carcinoma

This study aimed to examine the expression and potential effects of adenosine receptors in oral squamous cell carcinoma (OSCC). Data on mRNA expression of adenosine receptors in OSCC samples were collected from The Cancer Genome Atlas database. Adenosine-regulated signaling pathways and biological processes were investigated via immune cell infiltration analysis, bioinformatics analysis, and immunohistochemistry. Overexpression of A2bR and A3R was significantly correlated with the prognosis of OSCC (P < 0.05). A3R expression in OSCC patients was significantly and positively correlated with the infiltration of six types of immune cells: B cells, CD4+ T cells, CD8+ T cells, neutrophils, macrophages, and myeloid dendritic cells. A2bR expression weakly and negatively correlated with B-cell infiltration only. The expression of A2bR in OSCC was positively correlated with E-cadherin and PCNA, while the expression of A3R was positively correlated with that of cleaved caspase-3. Within the limitations of the study it seems that the overexpression of A2bR and A3R results in the poor prognosis of OSCC, suggesting that A2bR promotes cell proliferation in OSCC, while A3R may be involved in OSCC progression by regulating tumor cell apoptosis and immune microenvironment.

A novel adenosine signalling-based prognostic signature in gastric cancer and its association with cancer immune features and immunotherapy response

Reliable prognostic signatures that can reflect the intrinsic characteristics of gastric cancer (GC) are still rare. Here, we developed an adenosine-based prognostic signature and explored its association with the tumour immune in GC patients, aiming at confirming the prognostic value of adenosine-related genes and guiding the GC risk stratification and immunotherapeutic response prediction. We collected adenosine pathway-related genes from STRING websites and manual searching. We enrolled the The Cancer Genome Atlas cohort and four gene expression omnibus cohorts of GC for generating and validating the adenosine pathway-based signature using the Cox regression method. Gene expression in the signature was verified using polymerase chain reaction. We also performed gene set enrichment analysis, immune infiltration assessment and immunotherapy response prediction based on this signature. Our study resulted in a six-gene adenosine signature (GNAS, CXCR4, PPP1R1B, ADCY6, NT5E and NOS3) for risk stratification of GC prognosis, with the highest area under the receiver operating characteristic curve up to 0.767 for predicting 10-year overall survival (OS). In the training cohort, patients with signature-defined high risk had significantly poorer OS than those with low risk (p < .001). Multivariate analysis identified the signature as an independent prognostic factor (hazard ratio 2.863, 95% confidence interval [1.871-4.381], p < .001). These findings were confirmed in four independent cohorts. Expression detection showed that all signature genes were upregulated in both GC tissues and cell lines. Further analysis revealed that the signature-defined high-risk patients were characterised by immunosuppressive states and associated with a poor immunotherapy response. In conclusion, the adenosine pathway-based signature represents a promising risk stratification tool for GC in guiding individualised prognostication and immunotherapy.

Inhibitors of the CD73-adenosinergic checkpoint as promising combinatory agents for conventional and advanced cancer immunotherapy

The cell surface enzyme CD73 is increasingly appreciated as a pivotal non-redundant immune checkpoint (IC) in addition to PD-1/PD-L1 and CTLA-4. CD73 produces extracellular adenosine (eADO), which not only inhibits antitumor T cell activity via the adenosine receptor (AR) A_2AR, but also enhances the immune inhibitory function of cancer-associated fibroblasts and myeloid cells via A_2BR. Preclinical studies show that inhibition of the CD73-adenosinergic pathway in experimental models of many solid tumors either as a monotherapy or, more effectively, in combination with PD-1/PD-L1 or CTLA-4 IC blockades, improves antitumor immunity and tumor control. Consequently, approximately 50 ongoing phase I/II clinical trials targeting the CD73-adenosinergic IC are currently listed on https://clinicaltrials.gov. Most of the listed trials employ CD73 inhibitors or anti-CD73 antibodies alone, in combination with A_2AR antagonists, and/or with PD-1/PD-L1 blockade. Recent evidence suggests that the distribution of CD73, A_2AR and A_2BR in tumor microenvironments (TME) is heterogeneous, and this distribution affects CD73-adenosinergic IC function. The new insights have implications for the optimally effective, carefully tailored approaches to therapeutic targeting of this essential IC. In the mini-review, we briefly discuss the cellular and molecular mechanisms of CD73/eADO-mediated immunosuppression during tumor progression and therapy in the spatial context of the TME. We include preclinical data regarding therapeutic CD73-eADO blockade in tumor models as well as available clinical data from completed trials that targeted CD73-adenosinergic IC with or without PD-1/PD-L1 inhibitors and discuss factors that are potentially important for optimal therapeutic outcomes in cancer patients.

A2AR antagonist treatment for multiple sclerosis: Current progress and future prospects

Emerging evidence suggests that both selective and non-selective Adenosine A2A receptor (A2AR) antagonists could effectively protect mice from experimental autoimmune encephalomyelitis (EAE), which is the most commonly used animal model for multiple sclerosis (MS) research. Meanwhile, the recent FDA approval of Nourianz® (istradefylline) in 2019 as an add-on treatment to levodopa in Parkinson's disease (PD) with "OFF" episodes, along with its proven clinical safety, has prompted us to explore the potential of A2AR antagonists in treating multiple sclerosis (MS) through clinical trials. However, despite promising findings in experimental autoimmune encephalomyelitis (EAE), the complex and contradictory role of A2AR signaling in EAE pathology has raised concerns about the feasibility of using A2AR antagonists as a therapeutic approach for MS. This review addresses the potential effect of A2AR antagonists on EAE/MS in both the peripheral immune system (PIS) and the central nervous system (CNS). In brief, A2AR antagonists had a moderate effect on the proliferation and inflammatory response, while exhibiting a potent anti-inflammatory effect in the CNS through their impact on microglia, astrocytes, and the endothelial cells/epithelium of the blood-brain barrier. Consequently, A2AR signaling remains an essential immunomodulator in EAE/MS, suggesting that A2AR antagonists hold promise as a drug class for treating MS.

ENPP1 is an innate immune checkpoint of the anticancer cGAMP-STING pathway

ENPP1 expression correlates with poor prognosis in many cancers, and we previously discovered that ENPP1 is the dominant hydrolase of extracellular cGAMP: a cancer-cell-produced immunotransmitter that activates the anticancer STING pathway. However, ENPP1 has other catalytic activities and the molecular and cellular mechanisms contributing to its tumorigenic effects remain unclear. Here, using single cell RNA-seq (scRNA-seq), we show that ENPP1 overexpression drives primary breast tumor growth and metastasis by synergistically dampening extracellular cGAMP-STING mediated antitumoral immunity and activating immunosuppressive extracellular adenosine (eADO) signaling. In addition to cancer cells, stromal and immune cells in the tumor microenvironment (TME) also express ENPP1 that restrains their response to tumor-derived cGAMP. Enpp1 loss-of-function in both cancer cells and normal tissues slowed primary tumor initiation and growth and prevented metastasis in an extracellular cGAMP- and STING-dependent manner. Selectively abolishing the cGAMP hydrolysis activity of ENPP1 phenocopied total ENPP1 knockout, demonstrating that restoration of paracrine cGAMP-STING signaling is the dominant anti-cancer mechanism of ENPP1 inhibition. Strikingly, we find that breast cancer patients with low ENPP1 expression have significantly higher immune infiltration and improved response to therapeutics impacting cancer immunity upstream or downstream of the cGAMP-STING pathway, like PARP inhibitors and anti-PD1. Altogether, selective inhibition of ENPP1's cGAMP hydrolase activity alleviates an innate immune checkpoint to boost cancer immunity and is therefore a promising therapeutic approach against breast cancer that may synergize with other cancer immunotherapies.

Cell metabolism-based optimization strategy of CAR-T cell function in cancer therapy

Adoptive cell therapy (ACT) using chimeric antigen receptor (CAR)-modified T cells has revolutionized the field of immune-oncology, showing remarkable efficacy against hematological malignancies. However, its success in solid tumors is limited by factors such as easy recurrence and poor efficacy. The effector function and persistence of CAR-T cells are critical to the success of therapy and are modulated by metabolic and nutrient-sensing mechanisms. Moreover, the immunosuppressive tumor microenvironment (TME), characterized by acidity, hypoxia, nutrient depletion, and metabolite accumulation caused by the high metabolic demands of tumor cells, can lead to T cell "exhaustion" and compromise the efficacy of CAR-T cells. In this review, we outline the metabolic characteristics of T cells at different stages of differentiation and summarize how these metabolic programs may be disrupted in the TME. We also discuss potential metabolic approaches to improve the efficacy and persistence of CAR-T cells, providing a new strategy for the clinical application of CAR-T cell therapy.

Metabolic crosstalk between stromal and malignant cells in the bone marrow niche

Bone marrow is the primary site of blood cell production in adults and serves as the source of osteoblasts and osteoclasts that maintain bone homeostasis. The medullary microenvironment is also involved in malignancy, providing a fertile soil for the growth of blood cancers or solid tumors metastasizing to bone. The cellular composition of the bone marrow is highly complex, consisting of hematopoietic stem and progenitor cells, maturing blood cells, skeletal stem cells, osteoblasts, mesenchymal stromal cells, adipocytes, endothelial cells, lymphatic endothelial cells, perivascular cells, and nerve cells. Intercellular communication at different levels is essential to ensure proper skeletal and hematopoietic tissue function, but it is altered when malignant cells colonize the bone marrow niche. While communication often involves soluble factors such as cytokines, chemokines, and growth factors, as well as their respective cell-surface receptors, cells can also communicate by exchanging metabolic information. In this review, we discuss the importance of metabolic crosstalk between different cells in the bone marrow microenvironment, particularly concerning the malignant setting.

Development of Optical-Based Molecularly Imprinted Nanosensors for Adenosine Detection

Adenosine nucleoside is an important molecule in human physiology. The levels of adenosine nucleoside in urine and plasma are directly or indirectly related to diseases such as neurodegenerative diseases and cancer. In the present study, adenosine-imprinted and non-imprinted poly(2-hydroxyethyl methacrylate-methacrylic acid) (poly(HEMA-MAA)) surface plasmon resonance (SPR) nanosensors were prepared for the determination of adenosine nucleoside. First, MAA/adenosine pre-polymerization complexes were prepared at different molar ratios using adenosine as a template molecule and methacrylic acid (MAA) as a monomer, and SPR nanosensor surfaces were optimized by determining the highest imprinting factor of the chip surfaces. The surfaces of adenosine-imprinted and non-imprinted SPR nanosensors were characterized by using atomic force microscopy, ellipsometry, and contact angle measurements. Kinetic analyses were made with different concentrations in the range of 0.5-400.0 nM for the detection range with a pH 7.4 phosphate buffer solution. The limit of detection in adenosine aqueous solutions, artificial plasma, and artificial urine was determined to be 0.018, 0.015, and 0.013 nM, respectively. In the selectivity analysis of the developed nanosensors, the selectivity of adenosine SPR nanosensors in solutions at different concentrations was determined by using guanosine and cytidine nucleosides. The relative selectivity coefficients of adenosine-imprinted SPR nanosensors for adenosine/cytidine and adenosine/guanosine are 3.836 and 3.427, respectively. Since adenosine-imprinted SPR nanosensors are intended to be used in medical analysis and research, adenosine analysis has also been studied in artificial urine and artificial plasma samples.

Hypoxia-inducible factor orchestrates adenosine metabolism to promote liver cancer development

Hypoxia-induced adenosine creates an immunosuppressive tumor microenvironment (TME) and dampens the efficacy of immune checkpoint inhibitors (ICIs). We found that hypoxia-inducible factor 1 (HIF-1) orchestrates adenosine efflux through two steps in hepatocellular carcinoma (HCC). First, HIF-1 activates transcriptional repressor MXI1, which inhibits adenosine kinase (ADK), resulting in the failure of adenosine phosphorylation to adenosine monophosphate. This leads to adenosine accumulation in hypoxic cancer cells. Second, HIF-1 transcriptionally activates equilibrative nucleoside transporter 4, pumping adenosine into the interstitial space of HCC, elevating extracellular adenosine levels. Multiple in vitro assays demonstrated the immunosuppressive role of adenosine on T cells and myeloid cells. Knockout of ADK in vivo skewed intratumoral immune cells to protumorigenic and promoted tumor progression. Therapeutically, combination treatment of adenosine receptor antagonists and anti-PD-1 prolonged survival of HCC-bearing mice. We illustrated the dual role of hypoxia in establishing an adenosine-mediated immunosuppressive TME and offered a potential therapeutic approach that synergizes with ICIs in HCC.

The resurgence of the Adora2b receptor as an immunotherapeutic target in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a dense desmoplastic stroma that impedes drug delivery, reduces parenchymal blood flow, and suppresses the anti-tumor immune response. The extracellular matrix and abundance of stromal cells result in severe hypoxia within the tumor microenvironment (TME), and emerging publications evaluating PDAC tumorigenesis have shown the adenosine signaling pathway promotes an immunosuppressive TME and contributes to the overall low survival rate. Hypoxia increases many elements of the adenosine signaling pathway, resulting in higher adenosine levels in the TME, further contributing to immune suppression. Extracellular adenosine signals through 4 adenosine receptors (Adora1, Adora2a, Adora2b, Adora3). Of the 4 receptors, Adora2b has the lowest affinity for adenosine and thus, has important consequences when stimulated by adenosine binding in the hypoxic TME. We and others have shown that Adora2b is present in normal pancreas tissue, and in injured or diseased pancreatic tissue, Adora2b levels are significantly elevated. The Adora2b receptor is present on many immune cells, including macrophages, dendritic cells, natural killer cells, natural killer T cells, γδ T cells, B cells, T cells, CD4+ T cells, and CD8+ T cells. In these immune cell types, adenosine signaling through Adora2b can reduce the adaptive anti-tumor response, augmenting immune suppression, or may contribute to transformation and changes in fibrosis, perineural invasion, or the vasculature by binding the Adora2b receptor on neoplastic epithelial cells, cancer-associated fibroblasts, blood vessels, lymphatic vessels, and nerves. In this review, we discuss the mechanistic consequences of Adora2b activation on cell types in the tumor microenvironment. As the cell-autonomous role of adenosine signaling through Adora2b has not been comprehensively studied in pancreatic cancer cells, we will also discuss published data from other malignancies to infer emerging therapeutic considerations for targeting the Adora2b adenosine receptor to reduce the proliferative, invasive, and metastatic potential of PDAC cells.

A2AR as a Prognostic Marker and a Potential Immunotherapy Target in Human Glioma

Gliomas are considered one of the most malignant tumors in the body. The immune system has the ability to control the initiation and development of tumors, including gliomas. Thus, immune cells find themselves controlled by various molecular pathways, inhibiting their activation, such as the immunosuppressive adenosine 2A receptor (A2AR). Our objective was to establish the expression profile and role of A2AR at the transcriptomic level, using real-time RT-PCR in Moroccan glioma patients, in addition to TCGA and CGGA cohorts. The real-time RT-PCR results in Moroccan patients showed that high expression of this gene was associated with poor survival in males. Our study on the CGGA cohort corroborated these results. In addition, there was a positive association of A2AR with T-cell exhaustion genes. A2AR also correlated strongly with genes that are primarily enriched in focal adhesion and extracellular matrix interactions, inducing epithelial mesenchymal transition, angiogenesis, and glioma growth. However, in the TCGA cohort, the A2AR showed results that were different from the two previously examined cohorts. In fact, this gene was instead linked to a good prognosis in patients with the astrocytoma histological type. The correlation and enrichment results reinforced the prognostic role of A2AR in this TCGA cohort, in which its high expression was shown to be related to lymphocyte differentiation and a successful cytolytic response, suggesting a more efficient anti-tumor immune response. Correlations and differential analyses based on A2AR gene expression, to understand the cause of the association of this gene with two different prognoses (CGGA males and TCGA Astrocytoma), showed that the overexpression of A2AR in Chinese male patients could be associated with the overexpression of extracellular adenosine, which binds to A2AR to induce immunosuppression and consequently a poor prognosis. However, in the second group (TCGA astrocytomas), the overexpression of the gene could be associated with an adenosine deficiency, and therefore this receptor does not undergo activation. The absence of A2AR activation in these patients may have protected them from immunosuppression, which could reflect the good prognosis. A2AR can be considered a promising therapeutic target in male CGGA and Moroccan patients with gliomas.

Relationship between the Gene Expression of Adenosine Kinase Isoforms and the Expression of CD39 and CD73 Ectonucleotidases in Colorectal Cancer

Tumor cells have the capacity to create an adenosine-rich immunosuppressive environment, which can interfere with antitumor immunotherapy. Approaches are currently being developed with a view to suppressing the production of adenosine or its signals. Such approaches include the use of antibodies to inhibit CD39, CD73, and adenosine-receptor antagonists. However, the abundance of enzymatic pathways that control the ATP-adenosine balance, as well as the still poorly understood intracellular adenosine regulation, makes the hoped-for success unlikely. In the present study, the enzyme adenosine kinase (ADK) needed to convert adenosine to adenosine monophosphate, thereby regulating its levels, was investigated. To do so, peripheral blood samples from patients with colorectal cancer (CRC) (n = 31) were collected with blood samples from healthy donors (n = 17) used as controls. ADK gene expression levels and those of its long (ADK-L) and short (ADK-S) isoforms were measured. The relationship between the levels of ADK gene expression and that of CD39, CD73, and A2aR genes was analyzed. It turned out that in the group of CRC patients (stages III-IV), the level of ADK-L mRNA was lower (p < 0.0011) when compared to that of the control. For the first time, an average correlation was found between the level of expression of CD39 and ADK-S (r = -0.468 at p = 0.043) and between CD73 and ADK-L (r = 0.518 at p = 0.0232) in CRC patients. Flow cytometry was used to assess the content of CD39/CD73-expressing CD8+, CD4+ and Treg lymphocytes, as well as their relationship with the level of ADK gene expression in CRC patients. But no significant correlations were found.

Astrocyte-neuron circuits in epilepsy

The epilepsies are a diverse spectrum of disease states characterized by spontaneous seizures and associated comorbidities. Neuron-focused perspectives have yielded an array of widely used anti-seizure medications and are able to explain some, but not all, of the imbalance of excitation and inhibition which manifests itself as spontaneous seizures. Furthermore, the rate of pharmacoresistant epilepsy remains high despite the regular approval of novel anti-seizure medications. Gaining a more complete understanding of the processes that turn a healthy brain into an epileptic brain (epileptogenesis) as well as the processes which generate individual seizures (ictogenesis) may necessitate broadening our focus to other cell types. As will be detailed in this review, astrocytes augment neuronal activity at the level of individual neurons in the form of gliotransmission and the tripartite synapse. Under normal conditions, astrocytes are essential to the maintenance of blood-brain barrier integrity and remediation of inflammation and oxidative stress, but in epilepsy these functions are impaired. Epilepsy results in disruptions in the way astrocytes relate to each other by gap junctions which has important implications for ion and water homeostasis. In their activated state, astrocytes contribute to imbalances in neuronal excitability due to their decreased capacity to take up and metabolize glutamate and an increased capacity to metabolize adenosine. Furthermore, due to their increased adenosine metabolism, activated astrocytes may contribute to DNA hypermethylation and other epigenetic changes that underly epileptogenesis. Lastly, we will explore the potential explanatory power of these changes in astrocyte function in detail in the specific context of the comorbid occurrence of epilepsy and Alzheimer's disease and the disruption in sleep-wake regulation associated with both conditions.