Zafirlukast Is a Dual Modulator of Human Soluble Epoxide Hydrolase and Peroxisome Proliferator-Activated Receptor γ

The role of human 5-Lipoxygenase (5-LO) in carcinogenesis - a question of canonical and non-canonical functions

5-Lipoxygenase (5-LO), a fatty acid oxygenase, is the central enzyme in leukotriene (LT) biosynthesis, potent arachidonic acid-derived lipid mediators released by innate immune cells, that control inflammatory and allergic responses. In addition, through interaction with 12- and 15-lipoxgenases, the enzyme is involved in the formation of omega-3 fatty acid-based oxylipins, which are thought to be involved in the resolution of inflammation. The expression of 5-LO is frequently deregulated in solid and liquid tumors, and there is strong evidence that the enzyme plays an important role in carcinogenesis. However, global inhibition of LT formation and signaling has not yet shown the desired success in clinical trials. Curiously, the release of 5-LO-derived lipid mediators from tumor cells is often low, and the exact mechanism by which 5-LO influences tumor cell function is poorly understood. Recent data now show that in addition to releasing oxylipins, 5-LO can also influence gene expression in a lipid mediator-independent manner. These non-canonical functions, including modulation of miRNA processing and transcription factor shuttling, most likely influence cancer cell function and the tumor microenvironment and might explain the low clinical efficacy of pharmacological strategies that previously only targeted oxylipin formation and signaling by 5-LO. This review summarizes the canonical and non-canonical functions of 5-LO with a particular focus on tumorigenesis, highlights unresolved issues, and suggests future research directions.

Knock-out of 5-lipoxygenase in overexpressing tumor cells-consequences on gene expression and cellular function

5-Lipoxygenase (5-LO), the central enzyme in the biosynthesis of leukotrienes, is frequently expressed in human solid malignancies even though the enzyme is not present in the corresponding healthy tissues. There is little knowledge on the consequences of this expression for the tumor cells regarding gene expression and cellular function. We established a knockout (KO) of 5-LO in different cancer cell lines (HCT-116, HT-29, U-2 OS) and studied the consequences on global gene expression using next generation sequencing. Furthermore, cell viability, proliferation, migration and multicellular tumor spheroid (MCTS) formation were studied in these cells. Our results show that 5-LO influences the gene expression and cancer cell function in a cell type-dependent manner. The enzyme affected genes involved in cell adhesion, extracellular matrix formation, G protein signaling and cytoskeleton organization. Furthermore, absence of 5-LO elevated TGFβ₂ expression in HCT-116 cells while MCP-1, fractalkine and platelet-derived growth factor expression was attenuated in U-2 OS cells suggesting that tumor cell-derived 5-LO shapes the tumor microenvironment. In line with the gene expression data, KO of 5-LO had an impact on cell proliferation, motility and MCTS formation. Interestingly, pharmacological inhibition of 5-LO only partly mimicked the KO suggesting that also noncanonical functions are involved.

Montelukast and Acute Coronary Syndrome: The Endowed Drug

Acute coronary syndrome (ACS) is a set of signs and symptoms caused by a reduction of coronary blood flow with subsequent myocardial ischemia. ACS is associated with activation of the leukotriene (LT) pathway with subsequent releases of various LTs, including LTB4, LTC4, and LTD4, which cause inflammatory changes and induction of immunothrombosis. LTs through cysteine leukotriene (CysLT) induce activation of platelets and clotting factors with succeeding coronary thrombosis. CysLT receptor (CysLTR) antagonists such as montelukast (MK) may reduce the risk of the development of ACS and associated complications through suppression of the activation of platelet and clotting factors. Thus, this critical review aimed to elucidate the possible protective role of MK in the management of ACS. The LT pathway is implicated in the pathogenesis of atherosclerosis, cardiac hypertrophy, and heart failure. Inhibition of the LT pathway and CysL1TR by MK might be effective in preventing cardiovascular complications. MK could be an effective novel therapy in the management of ACS through inhibition of pro-inflammatory CysLT1R and modulation of inflammatory signaling pathways. MK can attenuate thrombotic events by inhibiting platelet activation and clotting factors that are activated during the development of ACS. In conclusion, MK could be an effective agent in reducing the severity of ACS and associated complications. Experimental, preclinical, and clinical studies are recommended to confirm the potential therapeutic of MK in the management of ACS.

Activity Screening of Fatty Acid Mimetic Drugs Identified Nuclear Receptor Agonists

Fatty acid mimetics (FAM) are bioactive molecules acting through the binding sites of endogenous fatty acid metabolites on enzymes, transporters, and receptors. Due to the special characteristics of these binding sites, FAMs share common chemical features. Pharmacological modulation of fatty acid signaling has therapeutic potential in multiple pathologies, and several FAMs have been developed as drugs. We aimed to elucidate the promiscuity of FAM drugs on lipid-activated transcription factors and tested 64 approved compounds for activation of RAR, PPARs, VDR, LXR, FXR, and RXR. The activity screening revealed nuclear receptor agonism of several FAM drugs and considerable promiscuity of NSAIDs, while other compound classes evolved as selective. These screening results were not anticipated by three well-established target prediction tools, suggesting that FAMs are underrepresented in bioactivity data for model development. The screening dataset may therefore valuably contribute to such tools. Oxaprozin (RXR), tianeptine (PPARδ), mycophenolic acid (RAR), and bortezomib (RAR) exhibited selective agonism on one nuclear receptor and emerged as attractive leads for the selective optimization of side activities. Additionally, their nuclear receptor agonism may contribute relevant and valuable polypharmacology.

Zafirlukast inhibits the growth of lung adenocarcinoma via inhibiting TMEM16A channel activity

Lung cancer has the highest mortality among cancers worldwide due to its high incidence and lack of the effective cures. We have previously demonstrated that the membrane ion channel TMEM16A is a potential drug target for the treatment of lung adenocarcinoma and have identified a pocket of inhibitor binding that provides the basis for screening promising new inhibitors. However, conventional drug discovery strategies are lengthy and costly, and the unpredictable side effects lead to a high failure rate in drug development. Therefore, finding new therapeutic directions for already marketed drugs may be a feasible strategy to obtain safe and effective therapeutic drugs. Here, we screened a library of over 1400 Food and Drug Administration-approved drugs through virtual screening and activity testing. We identified a drug candidate, Zafirlukast (ZAF), clinically approved for the treatment of asthma, that could inhibit the TMEM16A channel in a concentration-dependent manner. Molecular dynamics simulations and site-directed mutagenesis experiments showed that ZAF can bind to S387/N533/R535 in the nonselective inhibitor binding pocket, thereby blocking the channel pore. Furthermore, we demonstrate ZAF can target TMEM16A channel to inhibit the proliferation and migration of lung adenocarcinoma LA795 cells. In vivo experiments showed that ZAF can significantly inhibit lung adenocarcinoma tumor growth in mice. Taken together, we identified ZAF as a novel TMEM16A channel inhibitor with excellent anticancer activity, and as such, it represents a promising candidate for future preclinical and clinical studies.

Structure-Based Design of Dual Partial Peroxisome Proliferator-Activated Receptor γ Agonists/Soluble Epoxide Hydrolase Inhibitors

Polypharmaceutical regimens often impair treatment of patients with metabolic syndrome (MetS), a complex disease cluster, including obesity, hypertension, heart disease, and type II diabetes. Simultaneous targeting of soluble epoxide hydrolase (sEH) and peroxisome proliferator-activated receptor γ (PPARγ) synergistically counteracted MetS in various in vivo models, and dual sEH inhibitors/PPARγ agonists hold great potential to reduce the problems associated with polypharmacy in the context of MetS. However, full activation of PPARγ leads to fluid retention associated with edema and weight gain, while partial PPARγ agonists do not have these drawbacks. In this study, we designed a dual partial PPARγ agonist/sEH inhibitor using a structure-guided approach. Exhaustive structure-activity relationship studies lead to the successful optimization of the designed lead. Crystal structures of one representative compound with both targets revealed potential points for optimization. The optimized compounds exhibited favorable metabolic stability, toxicity, selectivity, and desirable activity in adipocytes and macrophages.

Zafirlukast ameliorates Docetaxel-induced activation of NOD-like receptor protein 3 (NLRP3) inflammasome, mediated by sirtuin1 (SIRT1) in hepatocytes

Docetaxel-associated liver injury has become a serious public health problem, resulting in therapy discontinuation, liver failure, and death. Zafirlukast is a typical leukotriene receptor antagonist used for prophylaxis and chronic treatment of asthma. In this study, we investigate whether treatment with Zafirlukast could alleviate Docetaxel-induced cytotoxicity in hepatocytes. Our results indicate that Zafirlukast mitigated Docetaxel-induced toxicity in LO-2 hepatocytes. Firstly, Zafirlukast reduced the production of 8-hydroxy-2p-deoxyguanosine (8-OHdG) and increased the levels of reduced glutathione (GSH) against Docetaxel. Secondly, Zafirlukast elevated the levels of mitochondrial membrane potential (ΔΨm) and adenosine triphosphate (ATP). Thirdly, Zafirlukast prevented Docetaxel-induced release of lactate dehydrogenase (LDH) and increased cell viability of LO-2 hepatocytes against Docetaxel. We also found that Zafirlukast ameliorated Docetaxel-induced apoptosis by reducing Caspase-3 and Caspase-9 activity. Mechanistically, our results demonstrate that Zafirlukast inhibited the activation of NOD-like receptor protein 3 (NLRP3), mediated by SIRT1. Based on these findings, we conclude that the administration of Zafirlukast might have a protective effect against Docetaxel-induced cytotoxicity in hepatocytes.

Leukotriene receptor antagonist use and cognitive decline in normal cognition, mild cognitive impairment, and Alzheimer's dementia

BACKGROUND

Leukotriene receptor antagonists (LTRAs) alleviate Alzheimer's disease (AD) pathology and improve cognition in animal models; however, clinical evidence is limited. This study aimed to explore the associations between the use of LTRAs (montelukast or zafirlukast) and cognitive performance in people with normal cognition, mild cognitive impairment (MCI), or AD dementia. We hypothesized that LTRA use would be associated with better cognitive performance over time.

METHODS

This longitudinal observational study used data from the National Alzheimer's Coordinating Center. Within groups of participants with normal cognition, MCI, or AD dementia, LTRA users were matched 1:3 to non-users using propensity score matching. Cognitive domains including immediate and delayed memory (Wechsler Memory Scale Revised-Logical Memory IA and IIA), psychomotor processing speed (Digit Symbol Substitution Test), and language (animal naming, vegetable naming, and Boston Naming Test) were compared between users and non-users in mixed-effects linear or Poisson regression models.

RESULTS

In AD dementia, LTRA use was associated with a slower decline in psychomotor processing speed, as measured by the Digit Symbol Substitution Test (Β = 1.466 [0.253, 2.678] symbols/year, n = 442), and language, as measured by animal naming (Β = 0.541 [0.215, 0.866] animals/year, n = 566), vegetable naming (B = 0.309 [0.056, 0.561] vegetables/year, n = 565), and the Boston Naming Test (B = 0.529 [0.005, 1.053] items/year, n = 561). Effect sizes were small but persisted after controlling for a 10% false discovery rate. LTRA use was not associated with changes in memory performance in AD, nor was it associated with changes in cognitive performance in people with normal cognition or MCI. In a post hoc analysis, LTRA use was associated with a slower decline in clinical progression in MCI (B = -0.200 [-0.380, -0.019] points/year, n = 800) and AD dementia (B = -0.321 [-0.597, -0.046] points/year, n = 604) as measured by CDR Sum of Boxes.

CONCLUSIONS

The use of LTRAs was associated with preserved function in non-amnestic cognitive domains in AD dementia. The role of leukotrienes and their receptors in cognitive decline warrants further investigation and the leukotriene pathway may represent a target for AD treatment.

Role of leukotriene pathway and montelukast in pulmonary and extrapulmonary manifestations of Covid-19: The enigmatic entity

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2), the responsible agent for the coronavirus disease 2019 (Covid-19), has its entry point through interaction with angiotensin converting enzyme 2 (ACE2) receptors, highly expressed in lung type II alveolar cells and other tissues, like heart, pancreas, brain, and vascular endothelium. This review aimed to elucidate the potential role of leukotrienes (LTs) in the pathogenesis and clinical presentation of SARS-CoV-2 infection, and to reveal the critical role of LT pathway receptor antagonists and inhibitors in Covid-19 management. A literature search was done in PubMed, Scopus, Web of Science and Google Scholar databases to find the potential role of montelukast and other LT inhibitors in the management of pulmonary and extra-pulmonary manifestations triggered by SARS-CoV-2. Data obtained so far underline that pulmonary and extra-pulmonary manifestations in Covid-19 are attributed to a direct effect of SARS-CoV-2 in expressed ACE2 receptors or indirectly through NF-κB dependent induction of a cytokine storm. Montelukast can ameliorate extra-pulmonary manifestations in Covid-19 either directly through blocking of Cys-LTRs in different organs or indirectly through inhibition of the NF-κB signaling pathway.

Zafirlukast promotes mitochondrial respiration by stimulating mitochondrial biogenesis in human bronchial epithelial cells

Lung diseases, including asthma, pose a serious global health issue. Loss of mitochondrial function and decreased mitochondrial biogenesis play pivotal roles in the initiation and progression of chronic lung diseases. Thus, maintaining mitochondrial function and homeostasis is an important treatment goal. Zafirlukast is a CysLTR1 antagonist that is widely used as an adjuvant treatment for asthma. In the present study, we investigated the effects of zafirlukast in vitro using human bronchial epithelial cells (BECs). We performed measurements of oxygen consumption and bioenergetics and found that zafirlukast increased mitochondrial respiration and biogenesis in human BECs as evidenced by increased mitochondrial mass and mtDNA/nDNA. Through real-time PCR and western blot analysis, we found that zafirlukast significantly increased the expression of PGC-1α, NRF1, and TFAM at both the mRNA and protein levels. Finally, we determined that these effects are mediated through CREB signaling and that inhibition of CREB with its specific inhibitor H89 abolished the effects of zafirlukast described above. Thus, zafirlukast might have potential in enhancing mitochondrial function by promoting mitochondrial biogenesis in human bronchial epithelial cells through upregulating the expression of PGC-1α and activating the CREB pathway.

Targeting sterol alpha-14 demethylase of Leishmania donovani to fight against leishmaniasis

Leishmaniasis is a neglected tropical disease caused by the protozoan parasite Leishmania. It is endemic in more than 89 different countries worldwide. Sterol alpha-14 demethylase (LdSDM), a sterol biosynthetic pathway enzyme in Leishmania donovani, plays an essential role in parasite survival and proliferation. Here, we used a drug repurposing approach to virtually screen the library of the Food and Drug Administration (FDA)-approved drugs against LdSDM to identify the potential lead-drug against leishmaniasis. Zafirlukast and avodart showed the best binding with LdSDM. Zafirlukast was tested for in vitro antileishmanial assay, but no significant effect on L. donovani promastigotes was observed even at higher concentrations. On the other hand, avodart profoundly inhibited parasite growth at relatively lower concentrations. Further, avodart showed a significant decrease in the number of intra-macrophagic amastigotes. Avodart-induced reactive oxygen species (ROS) in the parasites in a dose-dependent manner. ROS induced by avodart led to the induction of apoptosis-like cell death in the parasites as observed through annexin V/PI staining. Here, for the first time, we reported the antileishmanial activity and its possible mechanism of action of FDA-approved drug, avodart, establishing a nice example of the drug-repurposing approach. Our study suggested the possible use of avodart as an effective antileishmanial agent after further detailed validations.

Zafirlukast is a broad-spectrum thiol isomerase inhibitor that inhibits thrombosis without altering bleeding times

BACKGROUND AND PURPOSE

Multiple members of the thiol isomerase (TI) family of enzymes are present in and released by platelets. Inhibition of these enzymes results in diminished platelet responses, aggregation, adhesion and thrombus formation. Recently, the therapeutic potential of TI inhibition has been recognised and drug-development technologies were used to identify selective small molecule inhibitors. To date, few pan-TI inhibitors have been characterised and the most studied, bacitracin, is known to be nephrotoxic, which prohibits its systemic therapeutic usage.

EXPERIMENTAL APPROACH

We therefore sought to identify novel broad-spectrum inhibitors of these enzymes and test their effects in vivo. A total of 3,641 compounds were screened for inhibitory effects on the redox activity of ERp5, protein disulphide isomerase (PDI), ERp57, ERp72 and thioredoxin in an insulin turbidity assay. Of the lead compounds identified, zafirlukast was selected for further investigation.

KEY RESULTS

When applied to platelets, zafirlukast diminished platelet responses in vitro. Zafirlukast was antithrombotic in murine models of thrombosis but did not impair responses in a model of haemostasis. Since TIs are known to modulate adhesion receptor function, we explored the effects of zafirlukast on cell migration. This was inhibited independently of cysteinyl LT receptor expression and was associated with modulation of cell-surface free thiol levels consistent with alterations in redox activity on the cell surface.

CONCLUSION AND IMPLICATIONS

We identify zafirlukast to be a novel, potent, broad-spectrum TI inhibitor, with wide-ranging effects on platelet function, thrombosis and integrin-mediated cell migration. Zafirlukast is antithrombotic but does not cause bleeding.

Pan-SMARCA/PB1 Bromodomain Inhibitors and Their Role in Regulating Adipogenesis

Accessibility of the human genome is modulated by the ATP-driven SWI/SNF chromatin remodeling multiprotein complexes BAF (BRG1/BRM-associated factor) and PBAF (polybromo-associated BAF factor), which involves reading of acetylated histone tails by the bromodomain-containing proteins SMARCA2 (BRM), SMARCA4 (BRG1), and polybromo-1. Dysregulation of chromatin remodeling leads to aberrant cell proliferation and differentiation. Here, we have characterized a set of potent and cell-active bromodomain inhibitors with pan-selectivity for canonical family VIII bromodomains. Targeted SWI/SNF bromodomain inhibition blocked the expression of key genes during adipogenesis, including the transcription factors PPARγ and C/EBPα, and impaired the differentiation of 3T3-L1 murine fibroblasts into adipocytes. Our data highlight the role of SWI/SNF bromodomains in adipogenesis and provide a framework for the development of SWI/SNF bromodomain inhibitors for indirect targeting of key transcription factors regulating cell differentiation.

Epoxy Fatty Acids Are Promising Targets for Treatment of Pain, Cardiovascular Disease and Other Indications Characterized by Mitochondrial Dysfunction, Endoplasmic Stress and Inflammation

Bioactive lipid mediators resulting from the metabolism of polyunsaturated fatty acids (PUFA) are controlled by many pathways that regulate the levels of these mediators and maintain homeostasis to prevent disease. PUFA metabolism is driven primarily through three pathways. Two pathways, the cyclooxygenase (COX) and lipoxygenase (LO) enzymatic pathways, form metabolites that are mostly inflammatory, while the third route of metabolism results from the oxidation by the cytochrome P450 enzymes to form hydroxylated PUFA and epoxide metabolites. These epoxygenated fatty acids (EpFA) demonstrate largely anti-inflammatory and beneficial properties, in contrast to the other metabolites formed from the degradation of PUFA. Dysregulation of these systems often leads to chronic disease. Pharmaceutical targets of disease focus on preventing the formation of inflammatory metabolites from the COX and LO pathways, while maintaining the EpFA and increasing their concentration in the body is seen as beneficial to treating and preventing disease. The soluble epoxide hydrolase (sEH) is the major route of metabolism of EpFA. Inhibiting its activity increases concentrations of beneficial EpFA, and often disease states correlate to mutations in the sEH enzyme that increase its activity and decrease the concentrations of EpFA in the body. Recent approaches to increasing EpFA include synthetic mimics that replicate biological activity of EpFA while preventing their metabolism, while other approaches focus on developing small molecule inhibitors to the sEH. Increasing EpFA concentrations in the body has demonstrated multiple beneficial effects in treating many diseases, including inflammatory and painful conditions, cardiovascular disease, neurological and disease of the central nervous system. Demonstration of efficacy in so many disease states can be explained by the fundamental mechanism that EpFA have of maintaining healthy microvasculature and preventing mitochondrial and endoplasmic reticulum stress. While there are no FDA approved methods that target the sEH or other enzymes responsible for metabolizing EpFA, current clinical efforts to test for efficacy by increasing EpFA that include inhibiting the sEH or administration of EpFA mimics that block metabolism are in progress.

Zafirlukast protects blood-brain barrier integrity from ischemic brain injury

Stroke has been considered the second leading cause of death worldwide, and ischemic stroke accounts for the vast majority of stroke cases. Some of the main features of ischemic stroke are increased brain permeability, ischemia/reperfusion injury, oxidative stress, and acute inflammation. Antagonism of cysLT1R has been shown to provide cardiovascular and neural benefits. In the present study, we investigated the effects of the cysLT1R antagonist zafirlukast both in vivo and in vitro using a middle cerebral artery occlusion (MCAO) mouse model and human brain microvascular endothelial cells (HBMVECs). In vivo, we found that zafirlukast pretreatment could reduce MCAO-induced increased brain permeability by rescuing the expression levels of the tight junction proteins occludin and ZO-1. In vitro, we found that zafirlukast could suppress the increase in endothelial monolayer permeability induced by OGD/R via rescue of occludin and ZO-1 expression; additionally, we found that zafirlukast prevented OGD/R-induced degradation of the extracellular matrix via inhibition of MMP-2 and MMP-9 expression. Finally, we found that zafirlukast could also inhibit OGD/R-induced activation of the critical proinflammatory regulator NF-κB by preventing phosphorylation and nuclear translocation of p65 protein. Together, our findings demonstrate a promising role for zafirlukast in preventing damage induced by ischemic stroke and reperfusion injury.

Asthma pharmacotherapy: an update on leukotriene treatments

Introduction: Asthma is a chronic inflammatory disease of the airways with a large heterogeneity of clinical phenotypes. There has been increasing interest regarding the role of cysteinyl leukotriene (LT) and leukotriene receptor antagonists (LTRA) in asthma treatment.Areas covered: This review summarized the data (published in PubMed during 1984-2019) regarding LTRA treatment in asthma and LTs-related airway inflammation mechanisms. Involvement of LTs C₄/D₄/E₄ has been demonstrated in the several aspects of airway inflammation and remodeling. Novel pathways related to LTE₄, the most potent mediator, and its respective receptors have recently been studied. Antagonists against cysteinyl leukotriene receptor (CysLTR) type 1, including montelukast, pranlukast and zafirlukast, have been widely prescribed in clinical practices; however, some clinical trials have shown insignificant responses to LTRAs in adult asthmatics, while some phenotypes of adult asthma showed more favorable responses to LTRAs including aspirin-exacerbated respiratory disease, elderly asthma, asthma associated with smoking, obesity and allergic rhinitis.Expert opinion: Further investigations are needed to understand the role of LTs in airway inflammation and remodeling of the asthmatic airways. There is a lack of biomarkers to predict responsiveness to LTRA, especially in adult asthmatics. Besides CysLTR1 antagonists, targets aiming other LT pathways should be considered.