Pentostatin: an adenosine deaminase inhibitor for the treatment of hairy cell leukemia

Therapeutic applications of carbohydrate-based compounds: a sweet solution for medical advancement

Carbohydrates, one of the most abundant biomolecules found in nature, have been seen traditionally as a dietary component of foods. Recent findings, however, have unveiled their medicinal potential in the form of carbohydrates-derived drugs. Their remarkable structural diversity, high optical purity, bioavailability, low toxicity and the presence of multiple functional groups have positioned them as a valuable scaffold and an exciting frontier in contemporary therapeutics. At present, more than 170 carbohydrates-based therapeutics have been granted approval by varying regulatory agencies such as United States Food and Drug Administration (FDA), Japan Pharmaceuticals and Medical Devices Agency (PMDA), Chinese National Medical Products Administration (NMPA), and the European Medicines Agency (EMA). This article explores an overview of the fascinating potential and impact of carbohydrate-derived compounds as pharmacological agents and drug delivery vehicles.

Drugs targeting adenosine signaling pathways: A current view

Adenosine is an endogenous nucleoside that regulates many physiological and pathological processes. It is derived from either the intracellular or extracellular dephosphorylation of adenosine triphosphate and interacts with cell-surface G-protein-coupled receptors. Adenosine plays a substantial role in protecting against cell damage in areas of increased tissue metabolism and preventing organ dysfunction in pathological states. Targeting adenosine metabolism and receptor signaling may be an effective therapeutic approach for human diseases, including cardiovascular and central nervous system disorders, rheumatoid arthritis, asthma, renal diseases, and cancer. Several lines of evidence have shown that many drugs exert their beneficial effects by modulating adenosine signaling pathways but this knowledge urgently needs to be summarized, and most importantly, actualized. The present review collects pharmaceuticals and pharmacological or diagnostic tools that target adenosine signaling in their primary or secondary mode of action. We overviewed FDA-approved drugs as well as those currently being studied in clinical trials. Among them are already used in clinic A2A adenosine receptor modulators like istradefylline or regadenoson, but also plenty of anti-platelet, anti-inflammatory, or immunosuppressive, and anti-cancer drugs. On the other hand, we investigated dozens of specific adenosine pathway regulators that are tested in clinical trials to treat human infectious and noninfectious diseases. In conclusion, targeting purinergic signaling represents a great therapeutic challenge. The actual knowledge of the involvement of adenosinergic signaling as part of the mechanism of action of old drugs has open a path not only for drug-repurposing but also for new therapeutic strategies.

Cordycepin (3′-Deoxyadenosine) Suppresses Heat Shock Protein 90 Function and Targets Tumor Growth in an Adenosine Deaminase-Dependent Manner

Alterations in metabolism and energy production are increasingly being recognized as important drivers of neoplasia, raising the possibility that metabolic analogs could disrupt oncogenic pathways. 3′-deoxyadenosine, also known as cordycepin, is an adenosine analog that inhibits the growth of several types of cancer. However, the effects of cordycepin have only been examined in a limited number of tumor types, and its mechanism of action is poorly understood. We found that cordycepin slows the growth and promotes apoptosis in uveal melanoma, as well as a range of other hard-to-treat malignancies, including retinoblastoma, atypical teratoid rhabdoid tumors, and diffuse midline gliomas. Interestingly, these effects were dependent on low adenosine deaminase (ADA) expression or activity. Inhibition of ADA using either siRNA or pharmacologic approaches sensitized tumors with higher ADA to cordycepin in vitro and in vivo, with increased apoptosis, reduced clonogenic capacity, and slower migration of neoplastic cells. Our studies suggest that ADA is both a biomarker predicting response to cordycepin and a target for combination therapy. We also describe a novel mechanism of action for cordycepin: competition with adenosine triphosphate (ATP) in binding to Hsp90, resulting in impaired processing of oncogenic Hsp90 client proteins.

Enhancement of cordycepin production from Cordyceps militaris culture by epigenetic modification

Cordycepin (3'-deoxyadenosine) is a nucleoside analogue and biosynthesised by Cordyceps militaris, an entomopathogenic fungus. In this study, an epigenetic modifier was applied to static liquid cultures to enhance cordycepin production. C. militaris was cultured in a static liquid culture, and valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, was supplemented in order to modifying the epigenetic status. Gene regulatory network was explored to understand the molecular mechanisms underlying cordycepin production. 50 micromolar of VPA enhanced cordycepin production by 41.187% via the upregulation of 5'-nucleotidase, adenylate kinase, phosphorybosyltransferase, Cns1, Cns2, Cnsa3, and Cns4 of C. militaris for at least 2 days after VPA treatment. The maximum production of cordycepin was 2,835.32 ± 34.35 mg/L in 400 mL-working volume. A scaled-up culture was established with a working volume of 10 L, which led to the slight decrease of cordycepin production. This might due to multifactorial effects, for instance limited aeration and an uneven dispersion of nutrients in the culture system. This scaled-up culture was still needed further optimization. The modification of epigenetic status by VPA significantly enhanced cordycepin production by altering key gene regulatory network of C. militaris. The strategy established in this study might be applicable to other microorganism culture in order to improving the production of bioactive compounds. This work aimed to enhance the production of cordycepin by modifying the epigenetic status of C. militaris, in which subsequently altered gene regulatory network of cordycepin biosynthesis pathway. The weekly supplementation of valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, significantly improve cordycepin production over 40%, compared to the untreated control, and the gene regulatory network of C. militaris was also adapted.

Transcriptomic Responses of Cordyceps militaris to Salt Treatment During Cordycepins Production

Cordycepin is a major bioactive compound found in Cordyceps militaris (C. militaris) that exhibits a broad spectrum of biological activities. Hence, it is potentially a bioactive ingredient of pharmaceutical and cosmetic products. However, overexploitation and low productivity of natural C. militaris is a barrier to commercialization, which leads to insufficient supply to meet its existing market demands. In this study, a preliminary study of distinct concentrations of salt treatments toward C. militaris was conducted. Although the growth of C. militaris was inhibited by different salt treatments, the cordycepin production increased significantly accompanied by the increment of salt concentration. Among them, the content of cordycepin in the 7% salt-treated group was five-fold higher than that of the control group. Further transcriptome analysis of samples with four salt concentrations, coupled with Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, several differentially expressed genes (DEGs) were found. Finally, dynamic changes of the expression patterns of four genes involved in the cordycepin biosynthesis pathway were observed by the quantitative real-time PCR. Taken together, our study provides a global transcriptome characterization of the salt treatment adaptation process in C. militaris and facilitates the construction of industrial strains with a high cordycepin production and salt tolerance.

Design, Synthesis, and In Vitro Antiproliferative Activity of Hydantoin and Purine Derivatives with the 4-Acetylphenylpiperazinylalkyl Moiety

Cancer represents one of the most serious health problems and the second leading cause of death around the world. Heterocycles, due to their prevalence in nature as well as their structural and chemical diversity, play an immensely important role in anti-cancer drug discovery. In this paper, a series of hydantoin and purine derivatives containing a 4-acetylphenylpiperazinylalkyl moiety were designed, synthesized, and biologically evaluated for their anticancer activity on selected cancer cell lines (PC3, SW480, SW620). Compound 4, a derivative of 3′,4′-dihydro-2′H-spiro[imidazolidine-4,1′-naphthalene]-2,5-dione, was the most effective against SW480, SW620, and PC3 cancer cell lines. Moreover, 4 has high tumor-targeting selectivity. Based on docking studies, it was concluded that R isomers of 3′,4′-dihydro-2′H-spiro[imidazolidine-4,1′-naphthalene]-2,5-dione could be further studied as promising scaffolds for the development of thymidine phosphorylase inhibitors.

Possible Role of Adenosine in COVID-19 Pathogenesis and Therapeutic Opportunities

The outbreak of the novel coronavirus disease 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome CoronaVirus-2 (SARS-CoV-2) requires urgent clinical interventions. Crucial clinical needs are: 1) prevention of infection and spread of the virus within lung epithelia and between people, 2) attenuation of excessive lung injury in Advanced Respiratory Distress Syndrome, which develops during the end stage of the disease, and 3) prevention of thrombosis associated with SARS-CoV-2 infection. Adenosine and the key adenosine regulators adenosine deaminase (ADA), adenosine kinase (ADK), and equilibrative nucleoside transporter 1 may play a role in COVID-19 pathogenesis. Here, we highlight 1) the non-enzymatic role of ADA by which it might out-compete the virus (SARS-CoV-2) for binding to the CD26 receptor, 2) the enzymatic roles of ADK and ADA to increase adenosine levels and ameliorate Advanced Respiratory Distress Syndrome, and 3) inhibition of adenosine transporters to reduce platelet activation, thrombosis and improve COVID-19 outcomes. Depending on the stage of exposure to and infection by SARS-CoV-2, enhancing adenosine levels by targeting key adenosine regulators such as ADA, ADK and equilibrative nucleoside transporter 1 might find therapeutic use against COVID-19 and warrants further investigation.

Methotrexate an Old Drug with New Tricks

Methotrexate (MTX) is the first line drug for the treatment of a number of rheumatic and non-rheumatic disorders. It is currently used as an anchor disease, modifying anti-rheumatic drug in the treatment of rheumatoid arthritis (RA). Despite the development of numerous new targeted therapies, MTX remains the backbone of RA therapy due to its potent efficacy and tolerability. There has been also a growing interest in the use of MTX in the treatment of chronic viral mediated arthritis. Many viruses—including old world alphaviruses, Parvovirus B19, hepatitis B/C virus, and human immunodeficiency virus—have been associated with arthritogenic diseases and reminiscent of RA. MTX may provide benefits although with the potential risk of attenuating patients’ immune surveillance capacities. In this review, we describe the emerging mechanisms of action of MTX as an anti-inflammatory drug and complementing its well-established immunomodulatory activity. The mechanisms involve adenosine signaling modulation, alteration of cytokine networks, generation of reactive oxygen species and HMGB1 alarmin suppression. We also provide a comprehensive understanding of the mechanisms of MTX toxic effects. Lastly, we discussed the efficacy, as well as the safety, of MTX used in the management of viral-related rheumatic syndromes.

Computational and experimental validation of morin as adenosine deaminase inhibitor

Adenosine deaminase (ADA) is one of the major enzymes involved in purin metabolism, it has a significant role in cell growth and differentiation. Over-activity of ADA has been noticed in some pathology, like malignancy and inflammation and makes it an attractive target for the development of drugs for such diseases. In the present study, ADA inhibitory activity of morin, a bioactive flavonoid, was assessed through computational and biophysical methods. The enzyme kinetics data showed that morin is a competitive inhibitor of ADA. Binding energy calculated from ITC analysis was -7.11 kcal/mol. Interaction of morin with ADA was also studied using fluorescence quenching method. Molecular docking studies revealed the structural details of the interaction. Molecular dynamics study in explicit solvent was also conducted to assess the structural stability of protein ligand complex.

Achieving Optimal Outcomes in Chronic Lymphocytic Leukaemia

Chronic lymphocytic leukaemia (CLL) is a disease of late middle age and older. The majority of patients are diagnosed because of a lymphocytosis of at least 5 x 10(9)/L on an incidental blood count. It needs to be distinguished from mantle cell lymphoma and splenic marginal zone lymphoma by lymphocyte markers. The immunophenotype of CLL is sparse surface immunoglobulin, CD5+, CD19+, CD23+, CD79b-, and FMC7-. The disease is staged according to the presence of lymphadenopathy and/or splenomegaly and the features of bone marrow suppression. Most patients have an early stage of disease when diagnosed and perhaps 50% will never progress. This group of patients have a normal life expectancy and do not require treatment beyond reassurance. Progression involves an increasing white cell count, enlarging lymph nodes and spleen, anaemia and thrombocytopenia. Complications of progression include autoimmune haemolytic anaemia and thrombocytopenia, immunodeficiency, and the development of a more aggressive lymphoma. A range of prognostic factors is available to predict progression, but most haematologists rely on close observation of the patient. Intermittent chlorambucil remains the first choice treatment for the majority of patients. Combination chemotherapy offers no advantage. Intravenous fludarabine is probably more effective than chlorambucil, but no trial has yet shown a survival advantage for using it first rather than as a salvage treatment in patients not responding to chlorambucil. It is at least 40 times as expensive as chlorambucil. Cladribine may be as effective as fludarabine, although it has been used less and is even more expensive. Patients who relapse after chlorambucil should be offered retreatment with the same agent and if refractory should be switched to fludarabine, which may also be offered for retreatment on relapse. For patients refractory to both drugs, a variety of options are available. High dose corticosteroids, high dose chlorambucil, CHOP (cyclophosphamide, prednisolone, vincristine and doxorubicin), anti-CD52, anti-CD20 and a range of experimental drugs which are being evaluated in clinical trials. Younger patients should be offered the chance of treatment with curative intent, preferably in the context of a clinical trial. Autologous stem cell transplantation after achieving a remission with fludarabine has relative safety and may produce molecular complete remissions. Only time will tell whether some of these patients are cured but it seems unlikely. Standard allogeneic bone marrow transplant is probably too hazardous for most patients, but non-myeloablative regimens hold out the hope of invoking a graft-versus-leukaemia effect without a high tumour-related mortality. Trials of immunotherapy are exciting options for a few patients in specialised centres.

Acadesine and lipopolysaccharide-evoked pulmonary dysfunction after resuscitation from traumatic shock

BACKGROUND

We have reported that the purine precursor acadesine (AICAR) improved the microcirculation, repleted adenosine triphosphate, and attenuated local and lung neutrophil infiltration after intestinal reperfusion and that it quickly improved systemic hemodynamics after resuscitation from hemorrhagic shock. This study evaluated the therapeutic potential of AICAR after fluid resuscitated trauma.

METHODS

Anesthetized (fentanyl) mongrel pigs were subjected to tissue injury plus hemorrhage and randomized to receive resuscitation fluids comprised of shed blood plus either lactated Ringer's solution (LR) or AICAR (1 or 10 mg/kg bolus + 0.5 mg/kg/min x 30 min). Thereafter either LR or AICAR (1 or 10 mg/kg) was administered at 12-hour intervals for 72 hours. In a smaller series (n = 7) a single bolus (0.5 mg/kg) of the adenosine deaminase inhibitor deoxycoformycin was administered at the time of resuscitation. After 72 hours, and endotoxin challenge (0.5 microgram/kg, lipopolysaccharide [LPS]) was administered.

RESULTS

At 1 mg/kg (n = 9), AICAR had no obvious effect versus LR (n = 31). At 10 mg/kg AICAR (n = 11), the fluid required to stabilize hemodynamics after trauma was higher (66 +/- 5 versus 52 +/- 3 ml/kg/hr, p = 0.014), but there were fewer deaths 3 days after trauma versus LR (0 of 11 versus 4 of 31, p = 0.210), fewer deaths within 5 hours after LPS administration (3 of 11 versus 16 of 27, p = 0.074), and a longer survival time after LPS administration (4.5 +/- 0.3 versus 3.9 +/- 0.2 hr, p = 0.054). Deoxycoformycin had similar salutary effects on survival after LPS administration. LPS increased protein permeability of pulmonary capillaries, increased peak inspiratory pressures on constant tidal volume, increased dead space ventilation, and caused progressive arterial desaturation on 0.65 FiO2 (all p < 0.05). This pulmonary dysfunction was associated with a compensatory increase in cardiac output, decrease in systemic vascular resistance, increase in O2 consumption, and rise in plasma cortisol level (all p < 0.05). All these changes were blunted or eliminated with 10 mg/kg AICAR. Hematocrit and systemic pressures were maintained relatively constant after LPS administration with fluid resuscitation, but less was required with AICAR versus LR (40 +/- 8 versus 83 +/- 14 ml/kg/hr, p = 0.023). AICAR caused a concentration-related reduction in CD18 expression on LPS-stimulated neutrophils in vitro, but there was no effect versus LR on circulating leukocyte counts in vivo and no effect of AICAR on LPS-stimulated production of tumor necrosis factor in vitro or in vivo.

CONCLUSIONS

1. AICAR reduced the pulmonary dysfunction associated with posttrauma endotoxemia but had no effect on circulating leukocytes, so its mechanism could be related to an adenosine-mediated improvement in peripheral perfusion or O2 use. 2. AICAR is a generic compound that is safe and apparently efficacious in human beings, so AICAR prophylaxis could be cost-effectively administered to trauma patients.

Purine analogs in the treatment of low-grade lymphomas and chronic lymphocytic leukemias

The purine analogs fludarabine (FAMP), 2-chlorodeoxy-adenosine (2-CDA) and 2-deoxycoformycin (DCF) comprise a novel group of agents with high activity in low-grade lymphoid malignancies. Although all three agents share several mechanisms of action, such as the induction of apoptosis, and toxic effects, such as prolonged immunosuppression, their activity appears to be different in different disorders. While FAMP and possibly also 2-CDA are highly active in chronic lymphocytic leukemia and low-grade follicular lymphomas, 2-CDA and DCF are most effective in hairy cell leukemia. However, prospective comparative evaluations are in progress and their results may ultimately help to define the appropriate indications for and potential side effects of these highly promising new agents.

Aminophylline for methotrexate-induced neurotoxicity

Methotrexate, a mainstay treatment for children with acute lymphoblastic leukaemia, can cause neurotoxicity, with paralysis, seizures, somnolence, anorexia, and headaches. The pathophysiology of this reaction is unknown. It has been suggested that the anti-inflammatory effect of methotrexate in patients with arthritis is due to adenosine release brought on by inhibition of purine synthesis. Since adenosine is a central nervous system depressant, we wondered whether adenosine release in the central nervous system could account for some of the neurotoxicity due to methotrexate, and whether that toxicity could be lessened by displacement of adenosine from its receptor by aminophylline. 6 patients (age 3-16 years) who had methotrexate-induced neurotoxicity unresponsive to standard treatment received 2.5 mg/kg aminophylline. In addition, the concentration of adenosine in the cerebrospinal fluid (CSF) from 11 children completing a 24-h systemic methotrexate protocol was compared with that in 8 newly diagnosed patients and 12 who had not received any treatment for at least a week. 4 of 6 patients with toxic signs and symptoms attributed to methotrexate and unrelieved by steroids, epidural blood patch, promethazine, 5-hydroytryptamine antagonists, paracetamol, and narcotics, had complete resolution of neurotoxicity after or during a 1-h infusion of aminophylline; 2 others had a pronounced improvement but persistent nausea. CSF adenosine concentrations of patients receiving methotrexate, even when there was very slight or no toxicity, were greatly increased compared with control subjects (mean values of 217 and 51 nmol/L, median 175 and 52 nmol/L). Subacute methotrexate neurotoxicity may be mediated by adenosine and relieved by aminophylline.