Diagnostic value of adenosine deaminase activity in benign and malignant breast tumors

Fluorogenic target competitors for developing label-free and sensitive folding-unswitching aptamer sensors

BACKGROUND

Aptamers have aroused tremendous applications in sensors, drug deliveries, diagnosis, and therapies. In particular, target-induced global structure switching of aptamers has been widely used to develop selective sensors. However, fluorophore and/or quencher modification, sequence elongation, and nano-interface adsorption are required to design such global structure-switching aptamer sensors (SSAS) in order to signal target binding events. Accordingly, these requirements make SSAS at a high cost and expense of sensors' sensitivity. In this aspect, efforts should be made to overcome these drawbacks of SSAS.

RESULTS

Herein, we tried to develop label-free folding-unswitching aptamer sensors (FUAS) by searching fluorogenic target competitors. Using adenine nucleoside/nucleotide as the proof-of-concept model targets, we screened out berberine (BER) from natural isoquinoline alkaloids (having rings comparable to targets) as the best fluorogenic target competitor. Binding of BER at the conserved nucleotides of intact aptamer foldings turned on this fluorogenic target competitor' fluorescence. Targets then competed with this fluorogenic target competitor over the same conserved nucleotides to cause its release in favor of a resultant fluorescence change. We found that the developed FUAS are much more sensitive than the previously reported SSAS. The FUAS were successfully applied to assays of ATP and adenosine deaminase in serums, and to screening of the adenosine deaminase's inhibitor, verifying the reliability and applicability of this FUAS platform in variant fields.

SIGNIFICANCE

We demonstrate that by designing fluorogenic target competitors, FUAS can be alternatively developed in a label-free manner and with a higher sensitivity than the previously developed SSAS. This work opens a new way to develop high-performance aptamer-based sensors. Furthermore, our developed FUAS should inspire more interest for wide applications incluidng target-triggered drug deliveries when therapeutic fluorogenic target competitors are used.

Prognostic modeling of hepatocellular carcinoma based on T-cell proliferation regulators: a bioinformatics approach

Background

The prognostic value and immune significance of T-cell proliferation regulators (TCRs) in hepatocellular carcinoma (HCC) have not been previously reported. This study aimed to develop a new prognostic model based on TCRs in patients with HCC.

Method

This study used The Cancer Genome Atlas-Liver Hepatocellular Carcinoma (TCGA-LIHC) and International Cancer Genome Consortium-Liver Cancer-Riken, Japan (ICGC-LIRI-JP) datasets along with TCRs. Differentially expressed TCRs (DE-TCRs) were identified by intersecting TCRs and differentially expressed genes between HCC and non-cancerous samples. Prognostic genes were determined using Cox regression analysis and were used to construct a risk model for HCC. Kaplan-Meier survival analysis was performed to assess the difference in survival between high-risk and low-risk groups. Receiver operating characteristic curve was used to assess the validity of risk model, as well as for testing in the ICGC-LIRI-JP dataset. Additionally, independent prognostic factors were identified using multivariate Cox regression analysis and proportional hazards assumption, and they were used to construct a nomogram model. TCGA-LIHC dataset was subjected to tumor microenvironment analysis, drug sensitivity analysis, gene set variation analysis, and immune correlation analysis. The prognostic genes were analyzed using consensus clustering analysis, mutation analysis, copy number variation analysis, gene set enrichment analysis, and molecular prediction analysis.

Results

Among the 18 DE-TCRs, six genes (DCLRE1B, RAN, HOMER1, ADA, CDK1, and IL1RN) could predict the prognosis of HCC. A risk model that can accurately predict HCC prognosis was established based on these genes. An efficient nomogram model was also developed using clinical traits and risk scores. Immune-related analyses revealed that 39 immune checkpoints exhibited differential expression between the high-risk and low-risk groups. The rate of immunotherapy response was low in patients belonging to the high-risk group. Patients with HCC were further divided into cluster 1 and cluster 2 based on prognostic genes. Mutation analysis revealed that HOMER1 and CDK1 harbored missense mutations. DCLRE1B exhibited an increased copy number, whereas RAN exhibited a decreased copy number. The prognostic genes were significantly enriched in tryptophan metabolism pathways.

Conclusions

This bioinformatics analysis identified six TCR genes associated with HCC prognosis that can serve as diagnostic markers and therapeutic targets for HCC.

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.

Integrating Synthesis, Physicochemical Characterization, and In Silico Studies of Cordycepin-Loaded Bovine Serum Albumin Nanoparticles

Cordycepin gets rapidly metabolized in the body into inactive form due to its structural similarity to adenosine, thus inhibiting its development as a medicinal agent. This study was aimed to improve the solubility and stability of cordycepin, a potential drug with known antiproliferative activity, by encapsulating it in bovine serum albumin: β-cyclodextrin nanoparticles. Cordycepin-loaded nanoparticles (CLNPs) were synthesized using the antisolvent method and characterized thoroughly using various techniques. Our dynamic light scattering measurement showed a particle size and zeta potential of 160 ± 2.75 nm and -20.21 ± 2.1 mV, respectively, for CLNPs. Transmission electron microscopy studies revealed that particles were spherical in morphology. These CLNPs showed sustained release of cordycepin with encapsulation and loading efficiency of 81.62 ± 1.5 and 27.02 ± 2.0%, respectively, based on high-performance liquid chromatography and UV-vis studies. Based on differential scanning calorimetry and zeta potential studies, CLNPs improve cordycepin stability and solubility. Our molecular simulations and binding energy calculation also showed favorable protein interaction between cordycepin, bovine serum albumin, and β-cyclodextrin, further supporting the notion of improved stability. In vitro cytotoxicity, apoptosis, and cellular uptake studies on breast cancer cells showed that the synthesized nanoparticles had greater cytotoxicity as compared to free cordycepin.

The Value of Adenosine Deaminase 2 in the Detection of Tuberculous Pleural Effusion: A Meta-Analysis and Systematic Review

Adenosine deaminase 2 (ADA2) is reported as a novel diagnostic biomarker for tuberculous pleural effusion (TPE) in many studies. This meta-analysis was conducted to systematically evaluate the general diagnostic performance of pleural ADA2 in TPE. After searching for relevant studies that investigated the diagnostic performance of pleural ADA2 in TPE in several databases, we assessed and selected eligible studies to calculate pooled parameters by STATA 16.0 software. A final set of thirteen studies entirely met the inclusion standards and were used to calculate pooled parameters in our meta-analysis. Among them, there were nine English studies and four Chinese studies. The pooled parameters of pleural ADA2 in diagnosing TPE were summarized as follows: sensitivity, 0.91 (95% CI: 0.86-0.95); specificity, 0.93 (95% CI: 0.92-0.95); positive likelihood ratio, 13.9 (95% CI: 10.6-18.3); negative likelihood ratio, 0.09 (95% CI:0.06-0.16); diagnostic odds ratio, 147 (95% CI: 76-284); and the area under the curve, 0.95 (95% CI: 0.93-0.97). Pleural ADA2 is a reliable indicator with excellent accuracy in TPE diagnosis. However, we need to combine pleural ADA2 with diverse examinations to diagnose TPE in clinical practice.

Inhibition of adenosine deaminase activity reverses resistance to the cytotoxic effect of high adenosine levels in cervical cancer cells

Adenosine (ADO) generation in the tumor microenvironment (TME) plays important roles in the promotion of tumor growth, invasion, and metastasis and in suppression of the antitumor immune response. Recently, adenosine deaminase (ADA) activity in the TME has been proposed to be a compensatory mechanism against toxic accumulation of ADO in cancerous tissues. In the present study, the expression and functional activity of ADA in cervical cancer (CeCa) tumor cells were analyzed: C33A (HPV-), CaSki (HPV + ), and HeLa (HPV + ) cells. CeCa tumor cells, as well as activated T lymphocytes (ATLs), which were used as a positive control, showed different ADA contents in the membrane and intracellularly and a strong ability to convert ADO into inosine (INO). Treatment of tumor cells with EHNA, a specific ADA inhibitor, decreased the viability of CeCa tumor cells in a dose-dependent manner. In C33A (EHNA half maximal inhibitory concentration (IC₅₀) = 374 μM), CaSki (EHNA IC₅₀ = 273.6 μM), and HeLa (EHNA IC₅₀ = 252.2 μM) cells, EHNA strongly reversed the resistance of tumor cells to the cytotoxic effect of high concentrations of ADO; 38.82 ± 3.1%, 47.18 ± 4.7%, and 71.63 ± 6.9% of the cells were apoptotic, and 40 ± 4.8%, 52 ± 5.3% and 70 ± 6.8% of the cells had mitochondrial membrane damage, respectively. In ATLs (EHNA IC₅₀ = 391.8 μM) treated with EHNA, 32.4 ± 4.4% were apoptotic, and 32 ± 4.3% had mitochondrial membrane damage. These results suggest that the presence and activity of ADA in CeCa tumor cells can provide protection against the cytotoxic effect of high ADO contents in the TME. Therefore, the inhibition of ADA could be a strategy for the treatment of CeCa.

ELISA based assays to measure adenosine deaminases concentration in serum and saliva for the diagnosis of ADA2 deficiency and cancer

Adenosine deaminases (ADAs) are enzymes of purine metabolism converting adenosine to inosine. There are two types of ADAs in humans ADA1 and ADA2. While both ADA1 and ADA2 share the same substrate, they differ in expression, cellular localization, and catalytic properties. The genetic deficiency of ADA1 results in severe combined immunodeficiency (SCID), while lack in ADA2 (DADA2) results in multiple phenotypes ranging from systemic inflammation to vascular pathology. Clinical studies have shown that the levels of ADAs in biological fluids are altered in pathophysiological conditions, suggesting that ADA activity could be a convenient marker for the diagnosis of immune diseases and cancer. Here, we describe sensitive and straightforward ELISA assays to measure ADA1 and ADA2 concentrations in biological fluids. Analysis of the serum and saliva samples from the healthy controls and DADA2 patients revealed that ADA2 enzyme concentration is significantly lower in patients than in healthy controls. In contrast, the concentration of ADA2 increases in the serum of patients with large granular leukocyte leukemia (LGLL) and patients’ saliva with head and neck cancer. Thus, this simple, non-invasive method allows for distinguishing healthy controls from the affected patient. It can be implemented in screening and diagnosis of DADA2 and follow up the treatment of LGLL and several types of head and neck cancer.

A Metabolism-Related Gene Prognostic Index Bridging Metabolic Signatures and Antitumor Immune Cycling in Head and Neck Squamous Cell Carcinoma

Background

In the era of immunotherapy, predictive or prognostic biomarkers for head and neck squamous cell carcinoma (HNSCC) are urgently needed. Metabolic reprogramming in the tumor microenvironment (TME) is a non-negligible reason for the low therapeutic response to immune checkpoint inhibitor (ICI) therapy. We aimed to construct a metabolism-related gene prognostic index (MRGPI) for HNSCC bridging metabolic characteristics and antitumor immune cycling and identified the immunophenotype, genetic alternations, potential targeted inhibitors, and the benefit of immunotherapy in MRGPI-defined subgroups of HNSCC.

Methods

Based on The Cancer Genome Atlas (TCGA) HNSCC dataset (n = 502), metabolism-related hub genes were identified by the weighted gene co-expression network analysis (WGCNA). Seven genes were identified to construct the MRGPI by using the Cox regression method and validated with an HNSCC dataset (n = 270) from the Gene Expression Omnibus (GEO) database. Afterward, the prognostic value, metabolic activities, genetic alternations, gene set enrichment analysis (GSEA), immunophenotype, Connectivity map (cMAP), and benefit of immunotherapy in MRGPI-defined subgroups were analyzed.

Results

The MRGPI was constructed based on HPRT1, AGPAT4, AMY2B, ACADL, CKM, PLA2G2D, and ADA. Patients in the low-MRGPI group had better overall survival than those in the high-MRGPI group, consistent with the results in the GEO cohort (cutoff value = 1.01). Patients with a low MRGPI score display lower metabolic activities and an active antitumor immunity status and more benefit from immunotherapy. In contrast, a higher MRGPI score was correlated with higher metabolic activities, more TP53 mutation rate, lower antitumor immunity ability, an immunosuppressive TME, and less benefit from immunotherapy.

Conclusion

The MRGPI is a promising indicator to distinguish the prognosis, the metabolic, molecular, and immune phenotype, and the benefit from immunotherapy in HNSCC.

Distinct Roles of Adenosine Deaminase Isoenzymes ADA1 and ADA2: A Pan-Cancer Analysis

Objective

Adenosine deaminase (ADA) plays an important role in immune response, which includes two isoenzymes: ADA1 and ADA2. This study aims to explore the roles of ADA1 and ADA2 in cancers.

Methods

Human Protein Atlas (HPA) and Gene Expression Profiling Interactive Analysis (GEPIA2) databases were used to analyze the mRNA expression of ADA1 and ADA2 in human normal cells and tumor tissues. The enzyme assay was used to detect the ADA1 and ADA2 activities in serum from cancer patients. The Kaplan-Meier (KM) plotter was used to analyze the prognostic value of ADA1 and ADA2. TIMER2.0 was used to explore how ADA1 and ADA2 correlate with immune infiltration and immune checkpoints. cBioPortal database was used to investigate the mutations of ADA1 and ADA2. LinkedOmics was used to screen the ADA1 and ADA2 expression-related genes.

Results

ADA1 was significantly increased in several tumor tissues, including cholangiocarcinoma (CHOL), lymphoid neoplasm diffuse large B-cell lymphoma (DLBC), head and neck squamous cell carcinoma (HNSC), kidney renal clear cell carcinoma (KIRC), ovarian serous cystadenocarcinoma (OV), pancreatic adenocarcinoma (PAAD), thymoma (THYM), and uterine carcinosarcoma (UCS). ADA2 expression was significantly increased in esophageal carcinoma (ESCA), glioblastoma multiforme (GBM), acute myeloid leukemia (LAML), OV, PAAD, skin cutaneous melanoma (SKCM), and stomach adenocarcinoma (STAD). There were no significant changes in serum ADA1 activities in most cancers, while serum ADA2 activities were increased in most cancers. For prognosis, high ADA1 expression was associated with the poor survival in several cancers, including esophageal squamous cell carcinoma (ESCC), HNSC, KIRC, kidney renal papillary cell carcinoma (KIRP), liver hepatocellular carcinoma (LIHC), lung adenocarcinoma (LUAD), and uterine corpus endometrial carcinoma (UCEC). However, high ADA2 expression showed a favorable prognosis in breast invasive carcinoma (BRCA), cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), HNSC, KIRC, KIRP, LUAD, OV, PAAD, sarcoma, and THYM. ADA1 showed a moderate positive correlation with multiple infiltrating immune cells in most cancers. ADA2 was positively correlated with B cells, CD8 T cells, monocytes/macrophages, and dendritic cells (DCs) and was strongly negatively correlated with myeloid-derived suppressor cells. Function analysis showed that ADA1 expression-related genes were mainly enriched in cell division biological progression. However, ADA2-related genes were mainly associated with immune response.

Conclusion

As isoenzymes, ADA1 and ADA2 showed opposite prognostic values and different correlative patterns with immune infiltrating. These data demonstrated the distinct roles of ADA1 and ADA2 in cancer. ADA2 might act as a protective factor in cancer.

Adenosine-Metabolizing Enzymes, Adenosine Kinase and Adenosine Deaminase, in Cancer

The immunosuppressive effect of adenosine in the microenvironment of a tumor is well established. Presently, researchers are developing approaches in immune therapy that target inhibition of adenosine or its signaling such as CD39 or CD73 inhibiting antibodies or adenosine A2A receptor antagonists. However, numerous enzymatic pathways that control ATP-adenosine balance, as well as understudied intracellular adenosine regulation, can prevent successful immunotherapy. This review contains the latest data on two adenosine-lowering enzymes: adenosine kinase (ADK) and adenosine deaminase (ADA). ADK deletes adenosine by its phosphorylation into 5′-adenosine monophosphate. Recent studies have revealed an association between a long nuclear ADK isoform and an increase in global DNA methylation, which explains epigenetic receptor-independent role of adenosine. ADA regulates the level of adenosine by converting it to inosine. The changes in the activity of ADA are detected in patients with various cancer types. The article focuses on the biological significance of these enzymes and their roles in the development of cancer. Perspectives of future studies on these enzymes in therapy for cancer are discussed.

Targeting Adenosine with Adenosine Deaminase 2 to Inhibit Growth of Solid Tumors

Extracellular adenosine in tumors can suppress immune responses and promote tumor growth. Adenosine deaminase 2 (ADA2) converts adenosine into inosine. The role of ADA2 in cancer and whether it can target adenosine for cancer therapy has not been investigated. Here we show that increased ADA2 expression is associated with increased patient survival and enrichment of adaptive immune response pathways in several solid tumor types. Several ADA2 variants were created to improve catalytic efficiency, and PEGylation was used to prolong systemic exposure. In mice, PEGylated ADA2 (PEGADA2) inhibited tumor growth by targeting adenosine in an enzyme activity-dependent manner and thereby modulating immune responses. These findings introduce endogenous ADA2 expression as a prognostic factor and PEGADA2 as a novel immunotherapy for cancer. SIGNIFICANCE: This study identifies ADA2 as a prognostic factor associated with prolonged cancer patient survival and introduces the potential of enzymatic removal of adenosine with engineered ADA2 for cancer immunotherapy.

Macrophage-Derived Adenosine Deaminase 2 Correlates with M2 Macrophage Phenotype in Triple Negative Breast Cancer

Several lines of evidence suggest that altered adenosine deaminase (ADA) activity, especially its ADA2 iso-enzyme, is associated with malignant breast cancer (BC) development. Triple-negative breast cancer (TNBC) is currently the most challenging BC subtype due to its metastatic potential and recurrence. Herein, we analyzed the sources of ADA iso-enzymes in TNBC by investigating the effects of cell-to-cell interactions between TNBC cells, macrophages, lymphocytes, and endothelial cells. We also examined the potential relationship between ADA activity and cancer progression in TNBC patients. In vitro analyses demonstrated that the interactions of immune and endothelial cells with MDA-MB-231 triple negative BC cells modulated their extracellular adenosine metabolism pattern. However, they caused an increase in the ADA1 activity, and did not alter ADA2 activity in cancer cells. In turn, the co-culture of MDA-MB-231 cells with THP-1 monocyte/macrophages, Jurkat cells, and human lung microvascular endothelial cells (HULEC) caused the increase in ADA2 activity on THP-1 cells and ADA1 activity on Jurkat cells and HULEC. Clinical sample analysis revealed that TNBC patients had higher plasma ADA2 activities and lower ADA1/ADA2 ratio at advanced stages of cancer development than in the initial stages, while patients with hormone receptor positive, HER2 negative (HR+HER2-), and triple positive (HR+HER2+) breast cancers at the same stages showed opposite trends. TNBC patients also demonstrated positive associations between plasma ADA2 activity and pro-tumor M2 macrophage markers, as well as between ADA1 activity and endothelial dysfunction or inflammatory parameters. The analysis of TNBC patients, at 6 and 12 months following cancer treatment, did not showed significant changes in plasma ADA activities and macrophage polarization markers, which may be the cause of their therapeutic failure. We conclude that alterations in both ADA iso-enzymes can play a role in breast cancer development and progression by the modulation of extracellular adenosine-dependent pathways. Additionally, the changes in ADA2 activity that may contribute to the differentiation of macrophages into unfavorable pro-tumor M2 phenotype deserve special attention in TNBC.

Cordycepin Nanoencapsulated in Poly(Lactic-Co-Glycolic Acid) Exhibits Better Cytotoxicity and Lower Hemotoxicity Than Free Drug

Purpose

Cordycepin, a natural product isolated from the fungus Cordyceps militaris, is a potential candidate for breast cancer therapy. However, due to its structural similarity with adenosine, cordycepin is rapidly metabolized into an inactive form in the body, hindering its development as a therapeutic agent. In the present study, we have prepared cordycepin as nanoparticles in poly(lactic-co-glycolic acid) (PLGA) and compared their cellular uptake, cytotoxicity and hemolytic potential with free cordycepin.

Materials and Methods

Cordycepin-loaded PLGA nanoparticles (CPNPs) were prepared by the double-emulsion solvent evaporation method. Physico-chemical characterization of the nanoparticles was done by zetasizer, transmission electron microscopy (TEM) and reverse-phase high-pressure liquid chromatography (RP-HPLC) analyses. Cellular uptake and cytotoxicity of CPNPs and free drug were tested in human breast cancer cells (MCF7). Hemolytic potential of both of these forms was evaluated in rat red blood cells (RBCs).

Results

Physico-chemical characterization revealed that CPNPs were spherical in shape, possessed a size range of 179–246 nm, and released the encapsulated drug sustainably over a period of 10 days. CPNPs exhibited a high level of cellular uptake and cytotoxicity than the free drug in MCF-7 cells. While CPNPs were not toxic to rat RBCs even at high concentrations, free cordycepin induced hemolysis of these cells at relatively low concentration.

Conclusion

Our results reveal that delivery as CPNPs could enhance the clinical efficacy of cordycepin substantially.

Identification of potential canine mammary tumour cell biomarkers using proteomic approach: Differences in protein profiles among tumour and normal mammary epithelial cells by two-dimensional electrophoresis-based mass spectrometry

Canine mammary tumours (CMTs) are regarded as invasive with a high rate of recurrent and metastasis in intact female dogs. Tumour diagnosis, therefore, is an important step in predicting and monitoring tumour progression. This study was designed to identify protein expression on CMTs by employing a proteomic approach. The primary cell culture from benign mixed tumour, simple carcinoma, complex carcinoma and normal mammary gland were established, and two-dimensional electrophoresis (2DE) was subsequently performed. The different spots on each sample type were collected for identification using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results indicated that cytokeratin 5 (CK5) and transketolase (TKT) were identified in benign mixed tumour cells and complex carcinoma cells. In contrast, cytokeratin 18 (CK18) and pyruvate kinase PKM were identified in simple carcinoma cells. Moreover, alpha-2-HS-glycoprotein tumour antigen was identified specifically in complex carcinoma cells. In addition, ATP-dependent 6-phosphofructokinase platelet type and elongation factor 2 proteins were observed in benign cells. In conclusion, all expressed proteins in this study have been recognized for acting as their expression that differs from healthy mammary epithelial cells. Expectantly, this study identified the expressed proteins that might be useful in further diagnostic biomarker studies on CMTs.

Human adenosine deaminase 2 deficiency: A multi-faceted inborn error of immunity

Human adenosine deaminase 1 deficiency was described in the 1970s to cause severe combined immunodeficiency. The residual adenosine deaminase activity in these patients was attributed to adenosine deaminase 2. Human adenosine deaminase type 2 deficiency (DADA2), due to biallelic deleterious mutations in the ADA2 gene, is the first described monogenic type of small- and medium-size vessel vasculitis. The phenotype of DADA2 also includes lymphoproliferation, cytopenia, and variable degrees of immunodeficiency. The physiological role of ADA2 is still enigmatic hence the pathophysiology of the condition is unclear. Preliminary data showed that in the absence of ADA2, macrophage differentiation is skewed to a pro-inflammatory M1 subset, which is detrimental for endothelial integrity. The inflammatory phenotype responds well to anti-TNF therapy with etanercept and that is the first-line treatment for prevention of severe vascular events including strokes. The classic immunosuppressive drugs are not successful in controlling the disease activity. However, hematopoietic stem cell transplantation (HSCT) has been shown to be a definitive cure in DADA2 patients who present with a severe cytopenia. HSCT can also cure the vascular phenotype and is the treatment modality for patients' refractory to anti-cytokine therapies. In this review, we describe what is currently known about the molecular mechanisms of DADA2. Further research on the pathophysiology of this multifaceted condition is needed to fine-tune and steer future therapeutic strategies.

Adenosine deaminase inhibition

Adenosine deaminase is a critical enzyme in purine metabolism that regulates intra and extracellular adenosine concentrations by converting it to inosine. Adenosine is an important purine that regulates numerous physiological functions by interacting with its receptors. Adenosine and consequently adenosine deaminase can have pro or anti-inflammatory effects on tissues depending on how much time has passed from the start of the injury. In addition, an increase in adenosine deaminase activity has been reported for various diseases and the significant effect of deaminase inhibition on the clinical course of different diseases has been reported. However, the use of inhibitors is limited to only a few medical indications. Data on the increase of adenosine deaminase activity in different diseases and the impact of its inhibition in various cases have been collected and are discussed in this review. Overall, the evidence shows that many studies have been done to introduce inhibitors, however, in vivo studies have been much less than in vitro, and often have not been expanded for clinical use.

CD73: an emerging checkpoint for cancer immunotherapy

CD73 is a novel immune checkpoint associated with adenosine metabolism that promotes tumor progression by suppressing antitumor immune response and promoting angiogenesis. The inhibition of CD73, in combination with immune checkpoint blockade, targeted therapy or conventional therapy, improves antitumor effects in numerous preclinical mouse models of cancer. Emerging evidence suggests that the combination of anti-CD73 and immune checkpoint blockade has promising clinical activity in patients with advanced solid tumors. In this review, we will discuss the specific role of CD73 on both tumor cells and nontumor cells in regulating tumor immunity and tumorigenesis and provide an update on the current view of the antitumor activity of targeting CD73 by mAb or small molecule selective inhibitors in preclinical and clinical settings.

Prognostic value of serum liver enzymes in oral and oropharynx squamous cell carcinomas

BACKGROUND

Serum liver enzymes, which catalyze relevant catabolic pathways, have been indicated to be diagnostic and prognostic tools for several malignant tumors. The correlation between serum liver enzymes levels and survival in patients with oral and oropharynx squamous cell carcinomas (OSCC) is still absent. Here, we conducted a study focusing on predictive value of serum liver enzymes in terms of prognosis in the patients.

METHODS

A retrospective study including 134 OSCC patients from years 2009 to 2014 was performed to investigate the association between levels of pre-treatment serum liver enzymes, various clinical parameters and prognostic outcomes, which are overall survival (OS) and disease-free survival (DFS). Log-rank tests with Kaplan-Meier method were used to detect potential prognostic biomarkers. Multivariate analyses by Cox proportional hazards model were used to identify significant predictors of prognosis.

RESULTS

Serum adenosine deaminase (ADA) level was associated with patients' OS and DFS by univariate analyses (P = 0.006 and P = 0.024, respectively). Multivariate analyses showed that higher serum ADA (>17.2 U/L) (P = 0.019) as well as positive lymph node status (P = 0.035) independently predicted worse OS of patients with OSCC. In addition, older age (≥60 years) (P = 0.043) and positive lymph node status (P = 0.027) were independently prognostic parameters for poorer DFS.

CONCLUSIONS

Pre-operative serum ADA levels may serve as a reliable independent prognostic predictor for OS in OSCC patients.

Adenosine deaminase inhibition suppresses progression of 4T1 murine breast cancer by adenosine receptor-dependent mechanisms

The activity of a cell-surface ecto-adenosine deaminase (eADA) is markedly increased in the endothelial activation and vascular inflammation leading to decreased adenosine concentration and alterations in adenosine signalling. Depending on the specific pathway activated, extracellular purines mediate host cell response or regulate growth and cytotoxicity on tumour cells. The aim of this study was to test the effects of adenosine deaminase inhibition by 2'deoxycoformycin (dCF) on the breast cancer development. dCF treatment decreased a tumour growth and a final tumour mass in female BALB/c mice injected orthotopically with 4T1 cancer cells. dCF also counteracted cancer-induced endothelial dysfunction in orthotopic and intravenous 4T1 mouse breast cancer models. In turn, this low dCF dose had a minor effect on immune stimulation exerted by 4T1 cell implantation. In vitro studies revealed that dCF suppressed migration and invasion of 4T1 cells via A2a and A3 adenosine receptor activation as well as 4T1 cell adhesion and transmigration through the endothelial cell layer via A2a receptor stimulation. Similar effects of dCF were observed in human breast cancer cells. Moreover, dCF improved a barrier function of endothelial cells decreasing its permeability. This study highlights beneficial effects of adenosine deaminase inhibition on breast cancer development. The inhibition of adenosine deaminase activity by dCF reduced tumour size that was closely related to the decreased aggressiveness of tumour cells by adenosine receptor-dependent mechanisms and endothelial protection.

Adenosinergic signaling as a target for natural killer cell immunotherapy

Purinergic signaling through adenosine plays a key role in immune regulation. Hypoxia-driven accumulation of extracellular adenosine results in the generation of an immunosuppressive niche that fuels tumor development. Such immunometabolic modulation has shown to be a promising therapeutic target through blockade of adenosine receptors which mediate adenosine's immunosuppressive function, or cancer-associated ectonucleotidases CD39 and CD73 that catalyze the synthesis of adenosine. Adenosinergic signaling heavily implicates natural killer cells through both direct and indirect effects on their cytolytic activity, expression of cytotoxic granules, interferon-γ, and activating receptors. Continuing work has uncovered multiple checkpoints linked to adenosine within the purinergic signaling cascade as contributing to immune evasion from NK cell effector function. Here, we discuss these checkpoints and the recent body of work that focuses on adenosinergic signaling as a target for natural killer cell of cancer.

Adenosine Deaminase Activity in Chronic Lymphocytic Leukemia and Healthy Subjects

BACKGROUND

B cell chronic lymphocytic leukemia is one of the most frequent hematologic malignancies in the world. Cellular surface CD markers and serum Beta-2-microglobulin may be used as a prognostic tool in CLL patients.

OBJECTIVES

In the present study we introduce serum adenosine deaminase as a diagnostic marker in CLL.

MATERIALS AND METHODS

Blood samples were collected from B-CLL and healthy subjects. White blood cell, red blood cell and platelet count and blood Erythrocyte sedimentation rate was recorded and serum Beta-2-microglobulin, Lactate dehydrogenase and total ADA enzyme activity were determined.

RESULTS

Serum ADA activity was significantly higher in patients group than that of controls. ADA had a significant and direct correlation with B2M, WBC, LDH and ESR. However, there was not any relation between ADA and the stages of disease. Diagnostic cut-off, sensitivity and specificity of the serum ADA test were 27.97 U/L, 91% and 94%, respectively.

CONCLUSIONS

A higher ADA activity in patients group and its correlation with CLL markers were seen in our study. High diagnostic value of serum ADA in our study suggests that it might be considered as a useful screening tool among the other markers in CLL.

Purinergic signalling and cancer

Receptors for extracellular nucleotides are widely expressed by mammalian cells. They mediate a large array of responses ranging from growth stimulation to apoptosis, from chemotaxis to cell differentiation and from nociception to cytokine release, as well as neurotransmission. Pharma industry is involved in the development and clinical testing of drugs selectively targeting the different P1 nucleoside and P2 nucleotide receptor subtypes. As described in detail in the present review, P2 receptors are expressed by all tumours, in some cases to a very high level. Activation or inhibition of selected P2 receptor subtypes brings about cancer cell death or growth inhibition. The field has been largely neglected by current research in oncology, yet the evidence presented in this review, most of which is based on in vitro studies, although with a limited amount from in vivo experiments and human studies, warrants further efforts to explore the therapeutic potential of purinoceptor targeting in cancer.

Adenosine induces cell cycle arrest and apoptosis via cyclinD1/Cdk4 and Bcl-2/Bax pathways in human ovarian cancer cell line OVCAR-3

Adenosine is a regulatory molecule with widespread physiological effects in almost every cells and acts as a potent regulator of cell growth. Adenosine has been shown to inhibit cell growth and induce apoptosis in the several cancer cells via caspase activation and Bcl-2/Bax pathway. The present study was designed to understand the mechanism underlying adenosine-induced apoptosis in the OVCAR-3 human ovarian cancer cells. MTT viability, BrdU and cell counting assays were used to study the cell proliferation effect of adenosine in presence of adenosine deaminase inhibitor and the nucleoside transporter inhibitor. Cell cycle analysis, propidium iodide and annexin V staining, caspase-3 activity assay, cyclinD1, Cdk4, Bcl-2 and Bax protein expressions were assessed to detect apoptosis. Adenosine significantly inhibited cell proliferation in a concentration-dependent manner in OVCAR-3 cell line. Adenosine induced cell cycle arrest in G0/G1 phase via Cdk4/cyclinD1-mediated pathway. Adenosine induced apoptosis, which was determined by Annexin V-FITC staining and increased sub-G1 population. Moreover, down-regulation of Bcl-2 protein expression, up-regulation of Bax protein expression and activation of caspase-3 were observed in response to adenosine treatment. The results of this study suggest that extracellular adenosine induced G1 cell cycle arrest and apoptosis in ovarian cancer cells via cyclinD1/ Cdk4 and Bcl-2/Bax pathways and caspase-3 activation. These data might suggest that adenosine could be used as an agent for the treatment of ovarian cancer.

Evaluation of PDE5 and PDE9 expression in benign and malignant breast tumors

BACKGROUND AND AIMS

Phosphodiesterases 5 and 9 (PDE5, PDE9) are enzymes responsible for regulating second messenger signaling by hydrolyzing 3',5' cyclic guanosine monophosphate (cGMP). PDE isoforms are deregulated in some types of human cancer. The present study was carried out to evaluate the expression of phosphodiesterase isoenzymes, PDE5 and PDE9, in benign and malignant breast tumors.

METHODS

The expression levels of PDE5 and PDE9 were assayed in malignant and benign breast tumors and corresponding normal breast tissues using quantitative real-time RT-PCR. Moreover, the correlation between PDE5, PDE9 relative expression and clinicopathological characteristics were analyzed.

RESULTS

The relative expressions of PDE5 and PDE9 in malignant tumors were significantly higher than those of respective normal breast tissues and benign tumors (5.5-fold, p <0.001 and 6-fold, p <0.001, respectively). Furthermore, a significant positive correlation was found between PDE5 and PDE9 overexpression and tumor grade, stage, and lymph node involvement. However, a negative correlation was observed with age.

CONCLUSIONS

Based on the present results, it is concluded that assessment of PDE5 and PDE9 expression may be useful in the differential diagnosis of benign and malignant breast disease and successful treatment of breast cancer. To the best of our knowledge, this is the first study to show that PDE5 and PDE9 expression levels are higher in malignant breast tumors than those of normal and benign breast tissue.

Role of the purinergic system in patients with cervical intraepithelial neoplasia and uterine cancer

INTRODUCTION

Cervical cancer remains the second leading cause of death among women. Intraepithelial neoplasias and uterine invasive cancer are frequently associated with disturbances in coagulation and changes in the concentrations of adenine nucleotides. This work intended to analyze changes in extracellular adenine nucleotide hydrolysis and blood platelet aggregation in patients diagnosed for cervical intraepithelial neoplasia in different stages as well as uterine invasive cancer.

PATIENTS AND METHODS

NTPDase, E-NPP, 5'-nucleotidase, total ADA and its isoforms (ADA1 and ADA2), as well as the platelet aggregation from patients with different stages of cervical intraepithelial neoplasia (NICs I, NIC II, NIC III) and uterine invasive cancer were verified.

RESULTS

Neither ATP hydrolysis nor E-NPP activity was changed by the neoplasia stage. On the other hand, ADP and AMP hydrolysis as well as ADA activity were enhanced in NIC I group. AMP hydrolysis was also increased in the cancer group. ADA 1 was the ADA isoform found in platelets from both control and patient groups.

CONCLUSION

Our results showed for the first time that NTPDase, 5'-nucleotidase, E-NPP and ADA are not sensible regarding the grade of neoplasia development, since no significant difference was found between the groups studied. Only ADP hydrolysis and ADA activity showed a significant enhancement in NIC I group related to the other stages possibly as a result of the beginning of the neoplasic transformation. This increase could be reflecting a body's reaction against the probable high adenosine levels. We propose for the first time that the ADA isoform present in platelets is ADA 1.