Adenosine-A2A Receptor Pathway in Cancer Immunotherapy

Photoresponsive Adenosine Derivatives for the Optical Control of Adenosine A2A Receptors in Living Cells

The use of photoresponsive ligands to optically control proteins of interest, known as photopharmacology, is a powerful technique for elucidating cellular function in living cells and animals with a high spatiotemporal resolution. The adenosine A2A receptor (A2AR) is a G protein-coupled receptor that is expressed in various tissues; its dysregulation is implicated in severe diseases such as insomnia and Parkinson's disease. A detailed elucidation of the physiological function of A2AR is, therefore, highly desirable. In the present study, we developed two photoswitchable ligands, photoAd(blue) and photoAd(vio), that target A2AR. Using photoAd(vio), we successfully demonstrated the selective activation of A2AR in living cells by violet-light irradiation with high spatiotemporal resolution.

The potential of nanosystems in disrupting adenosine signaling pathways for tumor immunotherapy

INTRODUCTION

Adenosine (ADO) is a naturally occurring nucleoside primarily synthesized through the hydrolysis of extracellular adenosine triphosphate. Within the tumor microenvironment, ADO levels substantially increase, resulting in suppressed immune responses.

AREAS COVERED

Nanosystems offer a promising approach for precise drug delivery to tumor lesions. In this review, we provide an overview of the current research progress in the development of nanosystems that modulate adenosine signaling for tumor immunotherapy. These nanosystems are designed to target adenosine-hydrolyzing proteins, increase adenosine decomposition, and antagonize adenosine receptors.

EXPERT OPINION

Based on the literature review, adenosine has great potential in tumor immunotherapy, and nano-drug delivery system has great application prospects in targeted cancer therapy in the near future due to its superior characteristics.

The mechanism of PDE7B inhibiting the development of hepatocellular carcinoma through oxidative stress

Background

Liver cancer presents a significant challenge to global health and is currently ranked as the sixth most common form of cancer worldwide. Recent research indicates that phosphodiesterases play a role in various physiological and pathological processes, with a specific focus on their impact on cancer advancement. There is a scarcity of studies investigating the function and mechanisms of phosphodiesterases in the development and progression of hepatocellular carcinoma (HCC).

Methods

Real-time fluorescence quantitative polymerase chain reaction (qRT-PCR) and Western blotting were employed to analyze the expression of PDE7B in hepatocellular carcinoma tissues and cells. The biological role of PDE7B in HCC was investigated by both overexpressing and knocking down PDE7B in liver cancer cell lines. Furthermore, potential target proteins of PDE7B were identified through transcriptome sequencing.

Results

PDE7B is conspicuously reduced in tissues and cells of hepatocellular carcinoma, showing a connection with an unfavorable prognosis. Inhibiting PDE7B boosts the growth, movement, and infiltration of liver cancer cells, while its increased expression has the reverse impact. According to our trials relating to oxidative stress, PDE7B appears to control cell death in liver cancer cells by impacting the production of reactive oxygen species. Therefore, we propose that PDE7B could hinder the initiation and advancement of HCC through an oxidative stress pathway.

Conclusion

The research we conducted reveals that PDE7B, a gene with minimal levels of activity in hepatocellular carcinoma, possesses the capacity to inhibit the proliferation, invasion, and migration of HCC cells. PDE7B can impact the development of hepatocellular carcinoma by adjusting mechanisms related to oxidative stress.

Biomaterials' enhancement of immunotherapy for breast cancer by targeting functional cells in the tumor micro-environment

Immunotherapy for breast cancer is now being considered clinically, and more recently, the number of investigations aimed specifically at nano-biomaterials-assisted immunotherapy for breast cancer treatment is growing. Alterations of the breast cancer micro-environment can play a critical role in anti-tumor immunity and cancer development, progression and metastasis. The improvement and rearrangement of tumor micro-environment (TME) may enhance the permeability of anti-tumor drugs. Therefore, targeting the TME is also an ideal and promising option during the selection of effective nano-biomaterial-based immuno-therapeutic strategies excepted for targeting intrinsic resistant mechanisms of the breast tumor. Although nano-biomaterials designed to specifically release loaded anti-tumor drugs in response to tumor hypoxia and low pH conditions have shown promises and the diversity of the TME components also supports a broad targeting potential for anti-tumor drug designs, yet the applications of nano-biomaterials for targeting immunosuppressive cells/immune cells in the TME for improving the breast cancer treating outcomes, have scarcely been addressed in a scientific review. This review provides a thorough discussion for the application of the different forms of nano-biomaterials, as carrier vehicles for breast cancer immunotherapy, targeting specific types of immune cells in the breast tumor microenvironment. In parallel, the paper provides a critical analysis of current advances/challenges with leading nano-biomaterial-mediated breast cancer immunotherapeutic strategies. The current review is timely and important to the cancer research field and will provide a critical tool for nano-biomaterial design and research groups pushing the clinical translation of new nano-biomaterial-based immuno-strategies targeting breast cancer TME, to further open new avenues for the understanding, prevention, diagnosis and treatment of breast cancer, as well as other cancer types.

Polydeoxyribonucleotide ameliorates IL-1β-induced impairment of chondrogenic differentiation in human bone marrow-derived mesenchymal stem cells

Osteoarthritis (OA) is a degenerative disease of the joints, prevalent worldwide. Polydeoxyribonucleotide (PDRN) is used for treating knee OA. However, the role of PDRN in IL-1β-induced inflammatory responses in human bone marrow-derived mesenchymal stem cells (hBMSCs) remains unknown. Here, we investigated the role of PDRN in IL-1β-induced impairment of chondrogenic differentiation in hBMSCs. hBMSCs treated with PDRN showed a large micromass, enhanced safranin O and alcian blue staining intensity, and increased expression of chondrogenic genes in IL-1β-induced inflammatory responses, in addition to regulation of catabolic and anabolic genes. In addition, PDRN treatment suppressed the expression of inflammatory cytokines and mitigated IL-1β-induced apoptosis in hBMSCs. Mechanistically, PDRN treatment increased the formation of cyclic adenosine monophosphate (cAMP) and upregulated the phosphorylation of cAMP-dependent protein kinase A (PKA)/cAMP response element binding protein (CREB) through the adenosine A2A receptor in hBMSCs and thus blocked the nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) signaling pathway. Thus, IL-1β-induced expression of inflammatory cytokines in hBMSCs was directly reduced by adenosine A2A receptor activation. Based on our results, we suggest that PDRN may be a promising MSC-based therapeutic agent for OA.

Advances in targeting tumor microenvironment for immunotherapy

The tumor microenvironment (TME) provides essential conditions for the occurrence, invasion, and spread of cancer cells. Initial research has uncovered immunosuppressive properties of the TME, which include low oxygen levels (hypoxia), acidic conditions (low pH), increased interstitial pressure, heightened permeability of tumor vasculature, and an inflammatory microenvironment. The presence of various immunosuppressive components leads to immune evasion and affects immunotherapy efficacy. This indicates the potential value of targeting the TME in cancer immunotherapy. Therefore, TME remodeling has become an effective method for enhancing host immune responses against tumors. In this study, we elaborate on the characteristics and composition of the TME and how it weakens immune surveillance and summarize targeted therapeutic strategies for regulating the TME.

CAR-T and CAR-NK as cellular cancer immunotherapy for solid tumors

In the past decade, chimeric antigen receptor (CAR)-T cell therapy has emerged as a promising immunotherapeutic approach for combating cancers, demonstrating remarkable efficacy in relapsed/refractory hematological malignancies in both pediatric and adult patients. CAR-natural killer (CAR-NK) cell complements CAR-T cell therapy by offering several distinct advantages. CAR-NK cells do not require HLA compatibility and exhibit low safety concerns. Moreover, CAR-NK cells are conducive to "off-the-shelf" therapeutics, providing significant logistic advantages over CAR-T cells. Both CAR-T and CAR-NK cells have shown consistent and promising results in hematological malignancies. However, their efficacy against solid tumors remains limited due to various obstacles including limited tumor trafficking and infiltration, as well as an immuno-suppressive tumor microenvironment. In this review, we discuss the recent advances and current challenges of CAR-T and CAR-NK cell immunotherapies, with a specific focus on the obstacles to their application in solid tumors. We also analyze in depth the advantages and drawbacks of CAR-NK cells compared to CAR-T cells and highlight CAR-NK CAR optimization. Finally, we explore future perspectives of these adoptive immunotherapies, highlighting the increasing contribution of cutting-edge biotechnological tools in shaping the next generation of cellular immunotherapy.

Combined cancer immunotherapy based on targeting adenosine pathway and PD-1/PDL-1 axis

INTRODUCTION

Cancer immunotherapy has revolutionized the field of oncology, offering new hope to patients with advanced malignancies. Tumor-induced immunosuppression limits the effectiveness of current immunotherapeutic strategies, such as PD-1/PDL-1 checkpoint inhibitors. Adenosine, a purine nucleoside molecule, is crucial to this immunosuppression because it stops T cells from activating and helps regulatory T cells grow. Targeting the adenosine pathway and blocking PD-1/PDL-1 is a potential way to boost the immune system's response to tumors.

AREAS COVERED

This review discusses the current understanding of the adenosine pathway in tumor immunology and the preclinical and clinical data supporting the combination of adenosine pathway inhibitors with PD-1/PDL-1 blockade. We also discuss the challenges and future directions for developing combination immunotherapy targeting the adenosine pathway and the PD-1/PDL-1 axis for cancer treatment.

EXPERT OPINION

The fact that the adenosine signaling pathway controls many immune system processes suggests that it has a wide range of therapeutic uses. Within the next five years, there will be tremendous progress in this area, and the standard of care for treating malignant tumors will have switched from point-to-point therapy to the integration of immunological networks comprised of multiple signaling pathways, like the adenosine axis.

Novel Quinazoline Derivatives as Highly Effective A2A Adenosine Receptor Antagonists

The adenosine A2A receptor (A2AR) has been identified as a therapeutic target for treating neurodegenerative diseases and cancer. In recent years, we have highlighted the 2-aminoquinazoline heterocycle as an promising scaffold for designing new A2AR antagonists, exemplified by 6-bromo-4-(furan-2-yl)quinazolin-2-amine 1 (Ki (hA2AR) = 20 nM). Here, we report the synthesis of new 2-aminoquinazoline derivatives with substitutions at the C6- and C7-positions, and the introduction of aminoalkyl chains containing tertiary amines at the C2-position to enhance antagonist activity and solubility properties. Compound 5m showed a high affinity for hA2AR with a Ki value of 5 nM and demonstrated antagonist activity with an IC50 of 6 µM in a cyclic AMP assay. Introducing aminopentylpiperidine and 4-[(piperidin-1-yl)methyl]aniline substituents maintained the binding affinities (9x, Ki = 21 nM; 10d, Ki = 15 nM) and functional antagonist activities (9x, IC50 = 9 µM; 10d, IC50 = 5 µM) of the synthesized compounds while improving solubility. This study provides insights into the future development of A2AR antagonists for therapeutic applications.

Current Understanding of the Role of Adenosine Receptors in Cancer

Cancer, a complex array of diseases, involves the unbridled proliferation and dissemination of aberrant cells in the body, forming tumors that can infiltrate neighboring tissues and metastasize to distant sites. With over 200 types, each cancer has unique attributes, risks, and treatment avenues. Therapeutic options encompass surgery, chemotherapy, radiation therapy, hormone therapy, immunotherapy, targeted therapy, or a blend of these methods. Yet, these treatments face challenges like late-stage diagnoses, tumor diversity, severe side effects, drug resistance, targeted drug delivery hurdles, and cost barriers. Despite these hurdles, advancements in cancer research, encompassing biology, genetics, and treatment, have enhanced early detection methods, treatment options, and survival rates. Adenosine receptors (ARs), including A1, A2A, A2B, and A3 subtypes, exhibit diverse roles in cancer progression, sometimes promoting or inhibiting tumor growth depending on the receptor subtype, cancer type, and tumor microenvironment. Research on AR ligands has revealed promising anticancer effects in lab studies and animal models, hinting at their potential as cancer therapeutics. Understanding the intricate signaling pathways and interactions of adenosine receptors in cancer is pivotal for crafting targeted therapies that optimize benefits while mitigating drawbacks. This review delves into each adenosine receptor subtype's distinct roles and signaling pathways in cancer, shedding light on their potential as targets for improving cancer treatment outcomes.

Development of Preladenant-Based Radiotracers for Imaging A2AR in Tumors

Activation of the adenosine 2A receptor (A2AR) can lead to tumor immunosuppression, which results in poor prognosis of immunotherapy. The aim of this study was to design novel 18F-labeled probes ([18F]F-PFP2 and [18F]F-PFP4) to visualize A2AR in the tumor. The uptake of radioprobes in A2AR-negative 4T1 breast tumor was lower than that of A2AR-positive B16F10 melanoma at 1 h p.i. (1.22 ± 0.36% ID/g vs 2.80 ± 0.72% ID/g), 2 h p.i. (1.09 ± 0.20% ID/g vs 2.93 ± 0.76% ID/g) and 3 h p.i. (0.89 ± 0.27% ID/g vs 2.73 ± 0.58% ID/g), respectively. B16F10 lung metastasis models were employed to expand the application scenarios, observing significantly higher uptake of [18F]F-PFP2 in metastatic lesions compared to normal lung tissue (5.55 ± 2.18% ID/g vs 1.89 ± 0.65% ID/g, tumor/lung ratio ∼3). It is given that [18F]F-PFP2 might lay the foundation for establishing an A2AR-targeted imaging evaluation system for tumors, which will provide more precise guidance for personalized treatment.

Rosmarinic acid modulates purinergic signaling and induces apoptosis in melanoma cells

Cancer cases have increased worldwide. Cutaneous melanoma (CM), a highly metastatic skin cancer, largely contributes to global statistical cancer death data. Research has shown that rosmarinic acid (RA) is a promising phenolic compound with antineoplastic properties. Thus, we investigated the effects of RA on apoptosis-inducing in melanoma cells, purinergic signaling modulation, and cytokine levels. We treated SK-MEL-28 cells for 24 h with different concentrations of RA and assessed the apoptosis, CD39, CD73, and A2A expression, and cytokine levels. We found RA-induced apoptosis in melanoma cells. Regarding the purinergic system, we verified that RA downregulated the expression of CD73 and A2A, specially at high concentrations of treatment. Additionally, RA increased IL-6, IL-4, IL-10, IFN-γ, and TNF-α levels. Our in vitro results confirm RA's potential to be used to induce melanoma cell apoptosis, having CD73 and A2A as targets when reversion of immune suppression is desired. Further studies in animal models and clinical trials focusing on RA's modulation of purinergic signaling in melanoma are required.

Protective role of the CD73-A2AR axis in cirrhotic cardiomyopathy through negative feedback regulation of the NF-κB pathway

Background

Myocardial inflammation and apoptosis induced by cirrhosis are among the primary mechanisms of cirrhotic cardiomyopathy. CD73, a common extracellular nucleotidase also known as 5'-nucleotidase, is associated with the progression of inflammation and immunity in multiple organs. However, the mechanism by which CD73 contributes to myocardial inflammation and apoptosis in cirrhosis remains unclear.

Methods

In this study, a cirrhotic cardiomyopathy model in mice was established by bile duct ligation. Myocardial-specific overexpression of CD73 was achieved by tail vein injection of AAV9 (adeno-associated virus)-cTNT-NT5E-mCherry, and cardiac function in mice was assessed using echocardiography. Myocardial inflammation infiltration and apoptosis were evaluated through pathological observation and ELISA assays. The expression of CD73, A2AR, apoptotic markers, and proteins related to the NF-κB pathway in myocardial tissue were measured.

Results

In the myocardial tissue of the cirrhotic cardiomyopathy mouse model, the expression of CD73 and A2AR increased. Overexpression of CD73 in the myocardium via AAV9 injection and stimulation of A2AR with CGS 21680 inhibited myocardial inflammation and cardiomyocyte apoptosis induced by cirrhosis. Additionally, overexpression of CD73 suppressed the activation of the NF-κB pathway by upregulating the expression of the adenosine receptor A2A.

Conclusion

Our study reveals that the CD73/A2AR signaling axis mitigates myocardial inflammation and apoptosis induced by cirrhosis through negative feedback regulation of the NF-κB pathway.

Structural Modification and Biological Evaluation of 2,8-Disubstituted Adenine and Its Nucleosides as A2A Adenosine Receptor Antagonists: Exploring the Roles of Ribose at Adenosine Receptors

Building on the preceding structural analysis and a structure-activity relationship (SAR) of 8-aryl-2-hexynyl nucleoside hA2AAR antagonist 2a, we strategically inverted C2/C8 substituents and eliminated the ribose moiety. These modifications aimed to mitigate potential steric interactions between ribose and adenosine receptors. The SAR findings indicated that such inversions significantly modulated hA3AR binding affinities depending on the type of ribose, whereas removal of ribose altered the functional efficacy via hA2AAR. Among the synthesized derivatives, 2-aryl-8-hexynyl adenine 4a demonstrated the highest selectivity for hA2AAR (Ki,hA2A = 5.0 ± 0.5 nM, Ki,hA3/Ki,hA2A = 86) and effectively blocked cAMP production and restored IL-2 secretion in PBMCs. Favorable pharmacokinetic properties and a notable enhancement of anticancer effects in combination with an mAb immune checkpoint blockade were observed upon oral administration of 4a. These findings establish 4a as a viable immune-oncology therapeutic candidate.

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.

Clinical and Biologic Correlates of ADORA2A Transcriptomic Expression in Cancer

ADORA2A (adenosine A2a receptor) and ADORA2B propagate immunoregulatory signals, including restricting both innate and adaptive immunity, though recent data also suggest a tumor suppressor effect in certain settings. We evaluated the RNA expression from 514 tumors in a clinical-grade laboratory; 489 patients with advanced/metastatic disease had clinical outcome correlates. Transcript expression was standardized to internal housekeeping genes and ranked (0-100 scale) relative to 735 specimens from 35 different cancer types. Transcript abundance rank values were defined as "low/moderate" (0-74) or "high" (75-100) percentile RNA expression ranks. Overall, 20.8% of tumors had high ADORA2A (≥75 percentile RNA rank). The greatest proportion of high ADORA2A expressors was found in neuroendocrine and breast cancers and sarcomas, whereas the lowest was found in colorectal and ovarian cancers, albeit with patient-to-patient variability. In multivariable logistic regression analysis, there was a significant positive correlation between high ADORA2A RNA expression and a high expression of the immune checkpoint-related molecules PD-1 (p = 0.015), VISTA (p ≤ 0.001), CD38 (p = 0.031), and CD39 (p ≤ 0.001). In 217 immunotherapy-treated patients, high ADORA2A did not correlate significantly with progression-free (p = 0.51) or overall survival (OS) (p = 0.09) from the initiation of the checkpoint blockade. However, high versus not-high ADORA2A transcript expression correlated with longer OS from the time of advanced/metastatic disease (N = 489 patients; (HR 0.69 (95% CI 0.51-0.95) (p = 0.02)). Therefore, high ADORA2A transcript levels may be a favorable prognostic factor, unrelated to immunotherapy. Importantly, ascertaining co-expression patterns of ADORA2A with PD-1 and VISTA in individual tumors as a basis for the precision co-targeting of ADORA2A and these other checkpoint-related molecules warrants investigation in clinical trials.

Safety and pharmacokinetics of imaradenant (AZD4635) in Japanese patients with advanced solid malignancies: a phase I, open-label study

PURPOSE

Imaradenant is a novel potent and selective adenosine A2A receptor antagonist that is hypothesized to reduce immune suppression in the tumor microenvironment. This phase I, open-label, dose-escalation study evaluated the safety, pharmacokinetics, and anti-tumor activity of imaradenant.

METHODS

Japanese patients with advanced solid malignancies received imaradenant 50 mg (n = 3) or 75 mg (n = 7) once daily (QD). The primary objective was safety and tolerability, and the secondary objectives were pharmacokinetics and anti-tumor activity.

RESULTS

The median treatment duration was 2.10 months and 2.14 months for the 50- and 75-mg QD cohorts, respectively. The most common adverse events were nausea, malaise, decreased appetite, and vomiting. Five patients (50%) reported adverse events that were considered causally related to imaradenant; three patients had Grade 2 adverse events of malaise, nausea, and diarrhea. No deaths or serious adverse events occurred. The median times of maximum observed concentrations sampled after a single dose in the 50- and 75-mg QD cohorts were 1.08 h (range, 0.95-1.95) and 2.00 h (range, 0.92-5.52), respectively. There was little accumulation after multiple dosing, with geometric mean accumulation ratios of maximum concentration of 1.3 (50-mg QD) to 1.4 (75-mg QD) and area under the concentration-time curve 0-24 of 1.4 (50-mg QD) to 1.5 (75-mg QD). The best objective response was stable disease (3/10).

CONCLUSION

No new or unexpected safety concerns were identified, and imaradenant had an acceptable safety profile at both 50- and 75-mg QD.

CLINICALTRIALS

gov identifier NCT03980821 (June 10, 2019).

Therapeutic and immunomodulatory potentials of mesenchymal stromal/stem cells and immune checkpoints related molecules

Mesenchymal stromal/stem cells (MSCs) are used in many studies due to their therapeutic potential, including their differentiative ability and immunomodulatory properties. These cells perform their therapeutic functions by using various mechanisms, such as the production of anti-inflammatory cytokines, growth factors, direct cell-to-cell contact, extracellular vesicles (EVs) production, and mitochondrial transfer. However, mechanisms related to immune checkpoints (ICPs) and their effect on the immunomodulatory ability of MSCs are less discussed. The main function of ICPs is to prevent the initiation of unwanted responses and to regulate the immune system responses to maintain the homeostasis of these responses. ICPs are produced by various types of immune system regulatory cells, and defects in their expression and function may be associated with excessive responses that can ultimately lead to autoimmunity. Also, by expressing different types of ICPs and their ligands (ICPLs), tumor cells prevent the formation and durability of immune responses, which leads to tumors' immune escape. ICPs and ICPLs can be produced by MSCs and affect immune cell responses both through their secretion into the microenvironment or direct cell-to-cell interaction. Pre-treatment of MSCs in inflammatory conditions leads to an increase in their therapeutic potential. In addition to the effect that inflammatory environments have on the production of anti-inflammatory cytokines by MSCs, they can increase the expression of various types of ICPLs. In this review, we discuss different types of ICPLs and ICPs expressed by MSCs and their effect on their immunomodulatory and therapeutic potential.

18F-Labeled PET Tracers Specific for Adenosine A2A Receptor: Design, Synthesis, and Biological Evaluation

By modifying the structures of targeted A2AR antagonists and tracers, novel compounds 3, 7a, 9, 12c, and BIBD-399 were designed and synthesized. In vitro inhibition experiments demonstrated that 3, 12c, and BIBD-399 have high affinity for A2AR. [18F]3 and [18F]BIBD-399 were successfully synthesized. In terms of biological distribution, the brain uptake of [18F]MNI-444 exhibits greater than that of [18F]3 and [18F]BIBD-399. PET imaging shows that [18F]3 is off-target in the brain, while [18F]BIBD-399 and [18F]MNI-444 can be specifically imaged in regions with high A2AR expression. Differently, [18F]BIBD-399 could quickly reach equilibrium in the targeted region within 10 min after administration, while [18F]MNI-444 shows a slowly increasing trend within 2 h of administration. [18F]BIBD-399 is mainly metabolized by the liver and kidney, and there is no obvious defluorination in vivo. Additional in vitro autoradiography showed that the striatal signals of [18F]BIBD-399 and [18F]MNI-444 were inhibited by the A2AR antagonist SCH442416 but not by the A1R antagonist DPCPX, demonstrating the high A2AR binding specificity of [18F]BIBD-399. Molecular docking further confirms the high affinity of MNI-444 and BIBD-399 for A2AR. Further tMCAo imaging showed that [18F]BIBD-399 can sensitively distinguish between infarcted and noninfarcted sides, a capability not observed with [18F]MNI-444. Given its pharmacokinetic properties and the ability to identify lesion regions, [18F]BIBD-399 has potential advantages in monitoring A2AR changes, meriting further clinical investigation.

Effects of miR-214 on adenosine A2A receptor and carboxymethyl chitosan nanoparticles on the function of keloid fibroblasts and their mechanisms

This work prepared and investigated the impact of carboxymethyl chitosan nanoparticles (MC-NPs) on the proliferative capability of keloid fibroblasts (KFBs) while analyzing the mechanistic roles of miR-214 and adenosine A2A receptor (A2AR) in fibroblasts within hypertrophic scars. MC-NPs were synthesized through ion cross-linking, were characterized using transmission electron microscopy (TEM) and laser particle size scattering. The influence of MC-NPs on the proliferation capacity of KFBs was assessed using the MTT method. Changes in the expression levels of miR-214 and A2AR in KFBs, normal skin fibroblasts (NFBs), hypertrophic scar tissue, and normal skin tissue were analyzed. KFBs were categorized into anti-miR-214, anti-miR-NC, miR-214 mimics, miR-NC, si-A2AR, si-con, anti-miR-214+ si-con, and anti-miR-214+ si-A2AR groups. Bioinformatics target prediction was conducted to explore the interaction between miR-214 and A2AR. Real-time quantitative PCR and immunoblotting (WB) were employed to detect the expression levels of miR-214, A2AR, apoptotic protein Bax, and TGF-β in different cells. Cell counting kit-8 (CCK8) and flow cytometry were employed to assess cell proliferation activity and apoptosis. The results indicated that MC-NPs exhibited spherical particles with an average diameter of 236.47 ± 4.98 nm. The cell OD value in the MC-NPs group was lower than that in KFBs (P < 0.05). The mRNA levels of miR-214 in KFBs and hypertrophic scar tissue were lower than those in NFBs and normal tissue (P < 0.001), while the mRNA and protein levels of A2AR were significantly elevated (P < 0.05). Compared to the control group and anti-miR-NC, the anti-miR-214 group showed significantly increased cell OD values and Bcl-2 protein expression (P < 0.001), decreased levels of apoptotic gene Bax protein, TGF-β gene mRNA, and protein expression (P < 0.001). Continuous complementary binding sites were identified between miR-214 and A2AR. Compared to the control group, the si-A2AR group exhibited a significant decrease in A2AR gene mRNA and protein expression levels (P < 0.001), reduced cell viability (P < 0.001), increased apoptosis rate (P < 0.001), and a significant elevation in TGF-β protein expression (P < 0.001). miR-214 targetedly regulated the expression of A2AR, inducing changes in TGF-β content, promoting the proliferation of keloid fibroblasts, and inhibiting cell apoptosis.

From glioma gloom to immune bloom: unveiling novel immunotherapeutic paradigms-a review

In tumor therapeutics, the transition from conventional cytotoxic drugs to targeted molecular therapies, such as those targeting receptor tyrosine kinases, has been pivotal. Despite this progress, the clinical outcomes have remained modest, with glioblastoma patients' median survival stagnating at less than 15 months. This underscores the urgent need for more specialized treatment strategies. Our review delves into the progression toward immunomodulation in glioma treatment. We dissect critical discoveries in immunotherapy, such as spotlighting the instrumental role of tumor-associated macrophages, which account for approximately half of the immune cells in the glioma microenvironment, and myeloid-derived suppressor cells. The complex interplay between tumor cells and the immune microenvironment has been explored, revealing novel therapeutic targets. The uniqueness of our review is its exhaustive approach, synthesizing current research to elucidate the intricate roles of various molecules and receptors within the glioma microenvironment. This comprehensive synthesis not only maps the current landscape but also provides a blueprint for refining immunotherapy for glioma, signifying a paradigm shift toward leveraging immune mechanisms for improved patient prognosis.

Optical Control of Adenosine A2A Receptor Using Istradefylline Photosensitivity

In recent years, there has been growing interest in the potential therapeutic use of inhibitors of adenosine A2A receptors (A2AR) for the treatment of neurodegenerative diseases and cancer. Nevertheless, the widespread expression of A2AR throughout the body emphasizes the importance of temporally and spatially selective ligands. Photopharmacology is an emerging strategy that utilizes photosensitive ligands to attain high spatiotemporal precision and regulate the function of biomolecules using light. In this study, we combined photochemistry and cellular and in vivo photopharmacology to investigate the light sensitivity of the FDA-approved antagonist istradefylline and its potential use as an A2AR photopharmacological tool. Our findings reveal that istradefylline exhibits rapid trans-to-cis isomerization under near-UV light, and prolonged exposure results in the formation of photocycloaddition products. We demonstrate that exposure to UV light triggers a time-dependent decrease in the antagonistic activity of istradefylline in A2AR-expressing cells and enables real-time optical control of A2AR signaling in living cells and zebrafish. Together, these data demonstrate that istradefylline is a photoinactivatable A2AR antagonist and that this property can be utilized to perform photopharmacological experiments in living cells and animals.

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.

Hypoxia-adenosine axis as therapeutic targets for acute respiratory distress syndrome

The human respiratory and circulatory systems collaborate intricately to ensure oxygen delivery to all cells, which is vital for ATP production and maintaining physiological functions and structures. During limited oxygen availability, hypoxia-inducible factors (HIFs) are stabilized and play a fundamental role in maintaining cellular processes for hypoxia adaptation. First discovered during investigations of erythropoietin production regulation, HIFs influence physiological and pathological processes, including development, inflammation, wound healing, and cancer. HIFs promote extracellular adenosine signaling by enhancing adenosine generation and receptor signaling, representing an endogenous feedback mechanism that curbs excessive inflammation, supports injury resolution, and enhances hypoxia tolerance. This is especially important for conditions that involve tissue hypoxia, such as acute respiratory distress syndrome (ARDS), which globally poses significant health challenges without specific treatment options. Consequently, pharmacological strategies to amplify HIF-mediated adenosine production and receptor signaling are of great importance.

Staphylococcus aureus suppresses the pentose phosphate pathway in human neutrophils via the adenosine receptor A2aR to enhance intracellular survival

IMPORTANCE

Staphylococcus aureus is one of the leading causes of antimicrobial-resistant infections whose success as a pathogen is facilitated by its massive array of immune evasion tactics, including intracellular survival within critical immune cells such as neutrophils, the immune system's first line of defense. In this study, we describe a novel pathway by which intracellular S. aureus can suppress the antimicrobial capabilities of human neutrophils by using the anti-inflammatory adenosine receptor, adora2a (A2aR). We show that signaling through A2aR suppresses the pentose phosphate pathway, a metabolic pathway used to fuel the antimicrobial NADPH oxidase complex that generates reactive oxygen species (ROS). As such, neutrophils show enhanced ROS production and reduced intracellular S. aureus when treated with an A2aR inhibitor. Taken together, we identify A2aR as a potential therapeutic target for combatting intracellular S. aureus infection.

Identification of genes associated with gall bladder cell carcinogenesis: Implications in targeted therapy of gall bladder cancer

Gall bladder cancer (GBC) is becoming a very devastating form of hepatobiliary cancer in India. Every year new cases of GBC are quite high in India. Despite recent advanced multimodality treatment options, the survival of GBC patients is very low. If the disease is diagnosed at the advanced stage (with local nodal metastasis or distant metastasis) or surgical resection is inoperable, the prognosis of those patients is very poor. So, perspectives of targeted therapy are being taken. Targeted therapy includes hormone therapy, proteasome inhibitors, signal transduction and apoptosis inhibitors, angiogenesis inhibitors, and immunotherapeutic agents. One such signal transduction inhibitor is the specific short interfering RNA (siRNA) or short hairpin RNA (shRNA). For developing siRNA-mediated therapy shRNA, although several preclinical studies to evaluate the efficacy of these key molecules have been performed using gall bladder cells, many more clinical trials are required. To date, many such genes have been identified. This review will discuss the recently identified genes associated with GBC and those that have implications in its treatment by siRNA or shRNA.

Immune approaches beyond traditional immune checkpoint inhibitors for advanced renal cell carcinoma

Renal cell carcinoma (RCC), especially clear cell RCC, is generally considered an immunotherapy-responsive cancer. Recently, the prognosis for patients with locally advanced and metastatic RCC has significantly improved with the regulatory approvals of anti-PD-1/PD-L1/CTLA-4 immune checkpoint inhibitor (ICI)-based regimens. Yet in most cases, RCC will remain initially unresponsive to treatment or will develop resistance over time. Hence, there remains an unmet need to understand what leads to ICI resistance and to develop novel immune and nonimmune treatments to enhance the response to ICIs. In this review, we highlight recently published studies and the latest clinical studies investigating the next generation of immune approaches to locally advanced and metastatic RCC beyond traditional ICIs. These trials include cytokines, gut microbiota-based therapies, novel immune checkpoint agents, vaccines, and chimeric antigen receptor T cells. These agents are being evaluated as monotherapy or in combination with traditional ICIs and will hopefully provide improved outcomes to patients with RCC soon.

The effect of extracorporeal shock wave on joint capsule fibrosis based on A2AR-Nrf2/HO-1 pathway in a rat extending knee immobilization model

Joint capsule fibrosis, a common complication of joint immobilization, is mainly characterized by abnormal collagen deposition. The present study aimed to investigate the effect of extracorporeal shock wave therapy (ESWT) on reduced collagen deposition in the joint capsule during immobilization-induced joint capsule fibrosis. Additionally, the potential involvement of the adenosine A2A receptor (A2AR)-Neurotrophic factor e2-related factor 2 (Nrf2)/Haem oxygenase-1 (HO-1) pathway was explored. Thirty 3-month-old male Sprague-Dawley rats were randomly assigned to five groups: control (C), immobilization model (IM), natural recovery (NR), ESWT intervention (EI), and ESWT combined with A2AR antagonist SCH 58261 intervention (CI). After the left knee joints of rats in the IM, NR, EI and CI groups were immobilized using a full-extension fixation brace for 4 weeks, the EI and CI groups received ESWT twice a week for 4 weeks. The CI group was also treated with ESWT following intraperitoneal injection of SCH 58261 (0.01 mg/kg) for 4 weeks. The range of motion of the left knee joint was measured, and the protein levels of collagens I and III, A2AR, phosphorylated-protein kinase A/protein kinase A (p-PKA/PKA), p-Nrf2/Nrf2, and HO-1 were analysed by Western blotting. The IM and NR groups showed significantly greater arthrogenic contracture than the C group (P < 0.05). Compared to the NR group, the EI and CI groups exhibited significant improvement in arthrogenic contracture (P < 0.05). Conversely, the EI group showed lower contracture than the CI group (P < 0.05). Similar results were observed for collagen deposition and the protein levels of collagens I and III. The intervention groups (EI and CI groups) showed higher levels of p-Nrf2/Nrf2 and HO-1 than the NR group (P < 0.05). Moreover, the EI group exhibited higher levels of p-PKA/PKA, p-Nrf2/Nrf2, and HO-1 than the CI group (P < 0.05). However, no significant difference was found in the A2AR levels among the five groups (P > 0.05). ESWT may activate A2AR, leading to the phosphorylation of PKA. Subsequently, Nrf2 may be activated, resulting in the upregulation of HO-1, which then reduces collagen deposition and alleviates immobilization-induced joint capsule fibrosis.

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 combined signatures of G protein-coupled receptor family and immune landscape provide a prognostic and therapeutic biomarker in endometrial carcinoma

G protein-coupled receptors (GPRs) are one of the largest surface receptor superfamilies, and many of them play essential roles in biological processes, including immune responses. In this study, we aim to construct a GPR- and tumor immune environment (TME-i)-associated risk signature to predict the prognosis of patients with endometrial carcinoma (EC). The GPR score was generated by applying univariate Cox regression and the Least Absolute Shrinkage and Selection Operator (LASSO) Cox regression in succession. This involved identifying the differentially expressed genes (DEGs) in the Cancer Genome Atlas-Uterine Corpus Endometrioid Carcinoma (TCGA-UCEC) cohort. Simultaneously, the CIBERSORT algorithm was applied to identify the protective immune cells for TME score construction. Subsequently, we combined the GPR and TME scores to establish a GPR-TME classifier for conducting clinical prognosis assessments. Various functional annotation algorithms were used to conduct biological process analysis distinguished by GPR-TME subgroups. Furthermore, weighted correlation network analysis (WGCNA) was applied to depict the tumor somatic mutations landscapes. Finally, we compared the immune-related molecules between GPR-TME subgroups and resorted to the Tumor Immune Dysfunction and Exclusion (TIDE) for immunotherapy response prediction. The mRNA and protein expression of GPR-related gene P2RY14 were, respectively, validated by RT-PCR in clinical samples and HPA database. To conclude, our GPR-TME classifier may aid in predicting the EC patients' prognosis and immunotherapy responses.

Small molecule inhibitors for cancer immunotherapy and associated biomarkers - the current status

Following the success of cancer immunotherapy using large molecules against immune checkpoint inhibitors, the concept of using small molecules to interfere with intracellular negative regulators of anti-tumor immune responses has emerged in recent years. The main targets for small molecule drugs currently include enzymes of negative feedback loops in signaling pathways of immune cells and proteins that promote immunosuppressive signals within the tumor microenvironment. In the adaptive immune system, negative regulators of T cell receptor signaling (MAP4K1, DGKα/ζ, CBL-B, PTPN2, PTPN22, SHP1), co-receptor signaling (CBL-B) and cytokine signaling (PTPN2) have been preclinically validated as promising targets and initial clinical trials with small molecule inhibitors are underway. To enhance innate anti-tumor immune responses, inhibitory immunomodulation of cGAS/STING has been in the focus, and inhibitors of ENPP1 and TREX1 have reached the clinic. In addition, immunosuppressive signals via adenosine can be counteracted by CD39 and CD73 inhibition, while suppression via intratumoral immunosuppressive prostaglandin E can be targeted by EP2/EP4 antagonists. Here, we present the status of the most promising small molecule drug candidates for cancer immunotherapy, all residing relatively early in development, and the potential of relevant biomarkers.

Unlocking antitumor immunity with adenosine receptor blockers

Tumors survive by creating a tumor microenvironment (TME) that suppresses antitumor immunity. The TME suppresses the immune system by limiting antigen presentation, inhibiting lymphocyte and natural killer (NK) cell activation, and facilitating T cell exhaustion. Checkpoint inhibitors like anti-PD-1 and anti-CTLA4 are immunostimulatory antibodies, and their blockade extends the survival of some but not all cancer patients. Extracellular adenosine triphosphate (ATP) is abundant in inflamed tumors, and its metabolite, adenosine (ADO), is a driver of immunosuppression mediated by adenosine A2A receptors (A2AR) and adenosine A2B receptors (A2BR) found on tumor-associated lymphoid and myeloid cells. This review will focus on adenosine as a key checkpoint inhibitor-like immunosuppressive player in the TME and how reducing adenosine production or blocking A2AR and A2BR enhances antitumor immunity.

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.

Four Ounces Can Move a Thousand Pounds: The Enormous Value of Nanomaterials in Tumor Immunotherapy

The application of nanomaterials in healthcare has emerged as a promising strategy due to their unique structural diversity, surface properties, and compositional diversity. In particular, nanomaterials have found a significant role in improving drug delivery and inhibiting the growth and metastasis of tumor cells. Moreover, recent studies have highlighted their potential in modulating the tumor microenvironment (TME) and enhancing the activity of immune cells to improve tumor therapy efficacy. Various types of nanomaterials are currently utilized as drug carriers, immunosuppressants, immune activators, immunoassay reagents, and more for tumor immunotherapy. Necessarily, nanomaterials used for tumor immunotherapy can be grouped into two categories: organic and inorganic nanomaterials. Though both have shown the ability to achieve the purpose of tumor immunotherapy, their composition and structural properties result in differences in their mechanisms and modes of action. Organic nanomaterials can be further divided into organic polymers, cell membranes, nanoemulsion-modified, and hydrogel forms. At the same time, inorganic nanomaterials can be broadly classified as nonmetallic and metallic nanomaterials. The current work aims to explore the mechanisms of action of these different types of nanomaterials and their prospects for promoting tumor immunotherapy.

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.

Dipyridamole activates adenosine A2B receptor and AMPK/cAMP signaling and promotes myogenic differentiation of myoblastic C2C12 cells

Introduction: Sarcopenia is defined as a loss of muscle mass and strength. ATP homeostasis is crucial during myogenesis. We determined how the purinergic system modulates myogenesis using dipyridamole (blocks adenosine taken up by the cells) and tenofovir (inhibits ATP release) in a myoblast cell line. Methods: C2C12 cells were differentiated in the presence/absence of tenofovir/dipyridamole, with/without the A2B selective inhibitor PSB-603. Extra-/intracellular nucleotides were examined via HPLC. The expression of muscle differentiation proteins (Pax7, Mif5, MyoD, MyoG, and MHC), PKA/CREB, adenosine receptors (A1, A2A, A2B, and A3), ATP-channel pannexin-1 and the P2X7 receptor was analyzed via WB and RT-PCR. cAMP and AMPK activation was measured. Results: Tenofovir increased intracellular ATP and reduced extracellular adenosine, decreasing Pax7 expression and increasing MHC expression prematurely. Dipyridamole increased intracellular AMP and extracellular adenosine, counteracting the premature myogenesis promoted by tenofovir. All adenosine receptors were expressed during differentiation with dipyridamole, increasing A2B expression. Tenofovir maintained inactive AMPK and decreased cAMP levels, as well as PKAα and pCREB expression, which were recovered with dipyridamole. Discussion: Adenosine and ATP act as mediators in muscle myogenesis. The blockade of ATP release by tenofovir promotes premature myogenesis, with dipyridamole counteracting the premature differentiation promoted by tenofovir via the adenosine A2B receptor and cAMP/AMPK pathways. Therefore, dipyridamole might be of interest as a therapeutic approach in sarcopenia.

The immune checkpoint adenosine 2A receptor is associated with aggressive clinical outcomes and reflects an immunosuppressive tumor microenvironment in human breast cancer

Background

The crosstalk between the immune system and cancer cells has aroused considerable interest over the past decades. To escape immune surveillance cancer cells evolve various strategies orchestrating tumor microenvironment. The discovery of the inhibitory immune checkpoints was a major breakthrough due to their crucial contribution to immune evasion. The A2AR receptor represents one of the most essential pathways within the TME. It is involved in several processes such as hypoxia, tumor progression, and chemoresistance. However, its clinical and immunological significance in human breast cancer remains elusive.

Methods

The mRNA expression and protein analysis were performed by RT-qPCR and immunohistochemistry. The log-rank (Mantel-Cox) test was used to estimate Kaplan-Meier analysis for overall survival. Using large-scale microarray data (METABRIC), digital cytometry was conducted to estimate cell abundance. Analysis was performed using RStudio software (7.8 + 2023.03.0) with EPIC, CIBERSORT, and ImmuneCellAI algorithms. Tumor purity, stromal and immune scores were calculated using the ESTIMATE computational method. Finally, analysis of gene set enrichment (GSEA) and the TISCH2 scRNA-seq database were carried out.

Results

Gene and protein analysis showed that A2AR was overexpressed in breast tumors and was significantly associated with high grade, elevated Ki-67, aggressive molecular and histological subtypes, as well as poor survival. On tumor infiltrating immune cells, A2AR was found to correlate positively with PD-1 and negatively with CTLA-4. On the other hand, our findings disclosed more profuse infiltration of protumoral cells such as M0 and M2 macrophages, Tregs, endothelial and exhausted CD8+ T cells within A2ARhigh tumors. According to the Single-Cell database, A2AR is expressed in malignant, stromal and immune cells. Moreover, it is related to tumor purity, stromal and immune scores. Our results also revealed that CD8+T cells from A2ARhigh patients exhibited an exhausted functional profile. Finally, GSEA analysis highlighted the association of A2AR with biological mechanisms involved in tumor escape and progression.

Conclusion

The present study is the first to elucidate the clinical and immunological relevance of A2AR in breast cancer patients. In light of these findings, A2AR could be deemed a promising therapeutic target to overcome immune evasion prevailing within the TME of breast cancer patients.

Myelosuppression Caused by Nanoparticle Albumin-Bound Paclitaxel in the Northern Chinese Population and the Role of Body Composition

The aim of this study was to examine the relationship between lean body mass (LBM) and the incidence and severity of neutropenia in patients with malignant tumors from Northern China who have received nanoparticle albumin-bound paclitaxel. Twenty-six patients with pathologically confirmed malignant tumors were prospectively included in this study. These 26 patients were divided into Group A (sarcopenia) and Group B (nonsarcopenia). Group A comprised 50% (13/26) of the patients, while Group B comprised the other 50% (13/26). There was no statistically significant difference between both groups in terms of body surface area (P = .052). The incidence of neutropenia in Group A was 76.9% compared to 61.5% in Group B (P = .0673). The incidence of Grade 3 and severe neutropenia was 76.9% versus 61.5% in Groups A and B, respectively (P = .645). These 26 patients were divided into Groups 1 and 2 based on the administered nab-paclitaxel dose per kilogram of LBM, with both groups receiving a body surface area dose of 260 mg/m2 . Group 1 received a nab-paclitaxel dose of 14.19 mg/kg of LBM, whereas Group 2 received 11.37 mg/kg of LBM. In Group 1, the incidence of neutropenia was 71.4%, whereas it was 66.7% in Group 2. Grade 3 or higher neutropenia incidence was 28.6% in Group 1 versus 16.7% in Group 2. Patients with sarcopenia in northern China experienced a higher incidence of severe neutropenia after receiving nab-paclitaxel than patients without sarcopenia. Higher drug dose intensity per unit of LBM may be a contributing factor.

Co-inhibition of adenosine 2b receptor and programmed death-ligand 1 promotes the recruitment and cytotoxicity of natural killer cells in oral squamous cell carcinoma

Adenosine promotes anti-tumor immune responses by modulating the functions of T-cells and natural killer (NK) cells in the tumor microenvironment; however, the role of adenosine receptors in the progression of oral squamous cell carcinoma (OSCC) and its effects on immune checkpoint therapy remain unclear. In this study, we obtained the tumor tissues from 80 OSCC patients admitted at the Shandong University Qilu Hospital between February 2014 and December 2016. Thereafter, we detected the expression of adenosine 2b receptor (A2BR) and programmed death-ligand 1 (PD-L1) using immunohistochemical staining and analyzed the association between their expression in different regions of the tumor tissues, such as tumor nest, border, and paracancer stroma. To determine the role of A2BR in PD-L1 expression, CAL-27 (an OSCC cell line) was treated with BAY60-6583 (an A2BR agonist), and PD-L1 expression was determined using western blot and flow cytometry. Furthermore, CAL-27 was treated with a nuclear transcription factor-kappa B (NF-κ B) inhibitor, PDTC, to determine whether A2BR regulates PD-L1 expression via the NF-κ B signaling pathway. Additionally, a transwell assay was performed to verify the effect of A2BR and PD-L1 on NK cell recruitment. The results of our study demonstrated that A2BR and PD-L1 are co-expressed in OSCC. Moreover, treatment with BAY60-6583 induced PD-L1 expression in the CAL-27 cells, which was partially reduced in cells pretreated with PDTC, suggesting that A2BR agonists induce PD-L1 expression via the induction of the NF-κ B signaling pathway. Furthermore, high A2BR expression in OSCC was associated with lower infiltration of NK cells. Additionally, our results demonstrated that treatment with MRS-1706 (an A2BR inverse agonist) and/or CD274 (a PD-L1-neutralizing antibody) promoted NK cell recruitment and cytotoxicity against OSCC cells. Altogether, our findings highlight the synergistic effect of co-inhibition of A2BR and PD-L1 in the treatment of OSCC via the modulation of NK cell recruitment and cytotoxicity.

EGFR alterations in glioblastoma play a role in antitumor immunity regulation

The epidermal growth factor receptor (EGFR) is the most frequently altered gene in glioblastoma (GBM), which plays an important role in tumor development and anti-tumor immune response. While current molecular targeted therapies against the EGFR signaling pathway and its downstream key molecules have not demonstrated favorable clinical outcomes in GBM. Whereas tumor immunotherapies, especially immune checkpoint inhibitors, have shown durable antitumor responses in many cancers. However, the clinical efficacy is limited in patients carrying EGFR alterations, indicating that EGFR signaling may involve tumor immune response. Recent studies reveal that EGFR alterations not only promote GBM cell proliferation but also influence immune components in the tumor microenvironment (TME), leading to the recruitment of immunosuppressive cells (e.g., M2-like TAMs, MDSCs, and Tregs), and inhibition of T and NK cell activation. Moreover, EGFR alterations upregulate the expression of immunosuppressive molecules or cytokines (such as PD-L1, CD73, TGF-β). This review explores the role of EGFR alterations in establishing an immunosuppressive TME and hopes to provide a theoretical basis for combining targeted EGFR inhibitors with immunotherapy for GBM.

Novel therapies for metastatic prostate cancer

INTRODUCTION

Patients with metastatic prostate cancer, especially in the castrate-resistant setting, have a poor prognosis. Many agents have been approved for metastatic prostate cancer, such as androgen receptor pathway inhibitors, taxane-based chemotherapy, radiopharmaceuticals, and immunotherapy. However, prostate cancer remains the leading cause of cancer deaths in nonsmoking men. Fortunately, many more novel agents are under investigation.

AREAS COVERED

We provide an overview of the broad group of novel therapies for metastatic prostate cancer, with an emphasis on active and recruiting clinical trials that have been recently published and/or presented at national or international meetings.

EXPERT OPINION

The future for patients with metastatic prostate cancer is promising, with further development of novel therapies such as radiopharmaceuticals. Based on a growing understanding of prostate cancer biology, novel agents are being designed to overcome resistance to approved therapies. There are many trials using novel agents either as monotherapy or in combination with already approved agents with potential to further improve outcomes for men with advanced prostate cancer.

Dynamic polarization of tumor-associated macrophages and their interaction with intratumoral T cells in an inflamed tumor microenvironment: from mechanistic insights to therapeutic opportunities

Immunotherapy has brought a paradigm shift in the treatment of tumors in recent decades. However, a significant proportion of patients remain unresponsive, largely due to the immunosuppressive tumor microenvironment (TME). Tumor-associated macrophages (TAMs) play crucial roles in shaping the TME by exhibiting dual identities as both mediators and responders of inflammation. TAMs closely interact with intratumoral T cells, regulating their infiltration, activation, expansion, effector function, and exhaustion through multiple secretory and surface factors. Nevertheless, the heterogeneous and plastic nature of TAMs renders the targeting of any of these factors alone inadequate and poses significant challenges for mechanistic studies and clinical translation of corresponding therapies. In this review, we present a comprehensive summary of the mechanisms by which TAMs dynamically polarize to influence intratumoral T cells, with a focus on their interaction with other TME cells and metabolic competition. For each mechanism, we also discuss relevant therapeutic opportunities, including non-specific and targeted approaches in combination with checkpoint inhibitors and cellular therapies. Our ultimate goal is to develop macrophage-centered therapies that can fine-tune tumor inflammation and empower immunotherapy.

Characterization of serotonin-5-HTR1E signaling pathways and its role in cell survival

5-Hydroxytryptamine receptor 1E (5-HTR1E) is reported to activate cyclic AMP (cAMP) and extracellular-signal related kinases (ERK) pathways via its ligands and binding partners, but the detailed mechanism underlying the serotonin-induced 5-HTR1E signaling is still not known. In the present study, we determined the cellular regulators of ERK and cAMP signaling pathways in response to serotonin-induced 5-HTR1E activation in 5-HTR1E overexpressing HEK293 cells. We found that Pertussis Toxin (PTX) treatment completely reversed the effect of serotonin-5-HTR1E mediated signaling on cAMP and ERK pathways, confirming the involvement of a Gαi-linked cascade. We also observed that Gβγ and Gq were not associated with 5-HTR1E activation, while blocking protein kinase A (PKA) inhibited ERK signaling only, and had no effect on cAMP. Additionally, serotonin-stimulated ERK1/2 phosphorylation was similar in 5-HTR1E overexpressing, β-arrestin-deficient HEK293 cells and is solely dependent on G protein signaling. siRNA mediated gene knockdown studies in SH-SY5Y cells revealed that the inhibition of 5-HTR1E reduced the expression of cMyc, Cyclin D1, Cyclin E and BCL2 genes which are related to cell cycle regulation and survival. MTT assays showed that 5-HTR1E knockdown in SHSY-5Y and U118 cells inhibited cell survival significantly. In addition to the signaling mechanism, we also performed RNA-seq analysis in 5-HTR1E overexpressing HEK293 cells and found that 5-HTR1E can regulate the expression of Receptor activity modifying protein 1 (RAMP1), Nuclear receptor 1 (NR4A1) and other Cyclin genes. These findings indicate that serotonin interaction with 5-HTR1E receptor simultaneously activates cAMP and ERK pathway in HEK293 cells and its expression is important for cell survival.

Role of adenosine A2a receptor in cancers and autoimmune diseases

Adenosine receptors are P1 class of purinergic receptors that belong to G protein-coupled receptors. There are 4 subtypes of adenosine receptors, namely A1, A2A, A2B, and A3. A2AR has a high affinity for the ligand adenosine. Under pathological conditions or external stimuli, ATP is sequentially hydrolyzed to adenosine by CD39 and CD73. The combination of adenosine and A2AR can increase the concentration of cAMP and activate a series of downstream signaling pathways, and further playing the role of immunosuppression and promotion of tumor invasion. A2AR is expressed to some extent on various immune cells, where it is abnormally expressed on immune cells in cancers and autoimmune diseases. A2AR expression also correlates with disease progression. Inhibitors and agonists of A2AR may be potential new strategies for treatment of cancers and autoimmune diseases. We herein briefly reviewed the expression and distribution of A2AR, adenosine/A2AR signaling pathway, expression, and potential as a therapeutic target.

Pressure-Dependent Elevation of Vasoactive Intestinal Peptide Level in Chicken Choroid

PURPOSE

Autonomic control is important in maintaining ocular integrity. As recent data suggested that intrinsic choroidal neurons (ICN), an intrinsic choroidal autonomic control, may regulate choroidal thickening via release of the vasodilative vasoactive intestinal peptide (VIP), it was the aim of the study to investigate the level of choroidal VIP (VIP_chor) in the presence of an increased atmospheric pressure in a chicken model.

METHODS

Chicken choroidal whole mounts were exposed to ambient pressure (n = 20) and 40 mm Hg (n = 20) in a PC-controlled, open chamber system for 24 and 72 h, respectively. The VIP concentration was analyzed by ELISA, and the total protein concentration was measured by the BCA assay. Statistical analysis was done using an unpaired two-tailed t-test.

RESULTS

The pressurization systems enabled choroidal whole mount pressurization (40 mm Hg) with humidifying, pressure, temperature, and gas exchange. Overall, the VIP_chor level concentration was significantly increased at 40 mmHg compared to the ambient pressure (30.09 ± 7.18 pg vs. 20.69 ± 3.24 pg; p < 0.0001). Subgroup analysis yielded a significantly increased VIP_chor level at 40 mmHg compared to the ambient pressure after 24 h (28.42 ± 6.03 pg vs. 20.76 ± 4.06 pg; p = 0.005) and 72 h (31.77 ± 7.82 pg vs. 20.61 ± 2.12 pg; p = 0.002), respectively. The VIP_chor elevation at 40 mm Hg ranged between 1.37- (24 h) and 1.54-fold (72 h) compared to the ambient pressure. No difference was observed between the VIP_chor level at 24 h and 72 h (p > 0.05).

CONCLUSIONS

The increase of the total choroidal VIP level, representing the intracellular VIP content, in the presence of an increased ambient pressure argues for a retention of VIP within the neurons, decreasing both vasodilatation and, consequently, choroid thickness. This finding might be a passive or even active function of ICN in the regulation of choroidal thickness, ocular integrity and IOP.

CD39/CD73/A2AR pathway and cancer immunotherapy

Cancer development is closely associated with immunosuppressive tumor microenvironment (TME) that attenuates antitumor immune responses and promotes tumor cell immunologic escape. The sequential conversion of extracellular ATP into adenosine by two important cell-surface ectonucleosidases CD39 and CD73 play critical roles in reshaping an immunosuppressive TME. The accumulated extracellular adenosine mediates its regulatory functions by binding to one of four adenosine receptors (A1R, A2AR, A2BR and A3R). The A2AR elicits its profound immunosuppressive function via regulating cAMP signaling. The increasing evidence suggests that CD39, CD73 and A2AR could be used as novel therapeutic targets for manipulating the antitumor immunity. In recent years, monoclonal antibodies or small molecule inhibitors targeting the CD39/CD73/A2AR pathway have been investigated in clinical trials as single agents or in combination with anti-PD-1/PD-L1 therapies. In this review, we provide an updated summary about the pathophysiological function of the adenosinergic pathway in cancer development, metastasis and drug resistance. The targeting of one or more components of the adenosinergic pathway for cancer therapy and circumvention of immunotherapy resistance are also discussed. Emerging biomarkers that may be used to guide the selection of CD39/CD73/A2AR-targeting treatment strategies for individual cancer patients is also deliberated.

Non-carcinogenic/non-nephrotoxic aristolochic acid IVa exhibited anti-inflammatory activities in mice

Aristolochic acid (AA)-containing herbs have been prescribed for thousands of years as anti-inflammatory drugs, despite the active pharmaceutical ingredients remaining unclear. However, exposure to AAI and AAII has been proven to be a significant risk factor for severe nephropathy and carcinogenicity. AAIVa, an analogue abundant in AA-containing herbs, showed neither carcinogenicity nor nephrotoxicity in our study and other reports, implying that the pharmacological effects of AAIVa on inflammation are worth studying. Herein, we employed RAW 264.7 cells, the ear edema mouse model, and the lipopolysaccharide (LPS)-induced systematic inflammation model in TNF-IRES-Luc mice (tracking TNFα luciferase activities in real-time) to evaluate the anti-inframammary effect of AAIVa. Our results showed that AAIVa could decrease pro-inflammatory cytokines (TNFα and IL-6) production in LPS-stimulated RAW 264.7 cells, indicating its anti-inflammatory effects in vitro. Furthermore, the application of AAIVa (400 and 600 μg/ear) could significantly inhibit phorbol 12-myristate 13-acetate-induced ear edema, suggesting its topical anti-inflammatory activity in vivo. Moreover, LPS-stimulated TNF-IRES-Luc mice were used to investigate the onset and duration of AAIVa on systematic inflammation. A single dosage of AAIVa (100 mg/kg, i.g.) could suppress LPS-triggered inflammation, by decreasing luciferase activities of TNFα at 3 h in TNF-IRES-Luc mice. In addition, the online pharmacological databases predicted that AAIVa might target the regulation of T cell activation-related protein (ADA, ADORA2A, ERBB2) to exhibit anti-inflammatory effect. In conclusion, we demonstrated that AAIVa had anti-inflammatory effect for the first time; our findings are constructive for further studies on pharmacological mechanism of AAIVa.

Inhibition of CD73 expression or A2AR blockade reduces MRP1 expression and increases the sensitivity of cervical cancer cells to cisplatin

Recently, a link between the biological activity of CD73 in solid tumors and multidrug resistance protein (MRP) has been proposed. Cisplatin (CP) is the most widely used anticancer agent to treat advanced and recurrent cervical cancer (CC). However, multidrug resistance protein-1 (MRP1) is overexpressed in approximately 85% of these tumors and has been strongly associated with cisplatin resistance (CPR). In this study, we examine the involvement of CD73 and the interaction of adenosine (ADO) with its receptors (ARs) in MRP1 expression in CC cells. We found that ADO positively modulates MRP1 expression in CC cells in a dose-dependent manner. The inhibition of CD73 expression with a CD73-targeted siRNA and A2AR blockade with the selective antagonist ZM241385 significantly decreased MRP1 expression and the extrusive capacity of CC cells, making them significantly more sensitive to CP treatment than cancer cells treated with MK-751, a specific MRP1 inhibitor. These results suggest CD73 inhibition or blocking ADO signaling through A2AR could be strategies to reverse CPR in patients with advanced or recurrent CC, which is characterized by very low response rates to CP (10%-20%).

Evolving roles of CD38 metabolism in solid tumour microenvironment

Given that plenty of clinical findings and reviews have already explained in detail on the progression of CD38 in multiple myeloma and haematological system tumours, here we no longer give unnecessary discussion on the above progression. Though therapeutic antibodies have been regarded as a greatest breakthrough in multiple myeloma immunotherapies due to the durable anti-tumour responses in the clinic, but the role of CD38 in the immunologic regulation and evasion of non-hematopoietic solid tumours are just initiated and controversial. Therefore, we will focus on the bio-function of CD38 enzymatic substrates or metabolites in the variety of non-hematopoietic malignancies and the potential therapeutic value of targeting the CD38-NAD+ or CD38-cADPR/ADPR signal axis. Though limited, we review some ongoing researches and clinical trials on therapeutic approaches in solid tumour as well.