Brain-Derived Neurotrophic Factor, Neutrophils and Cysteinyl Leukotriene Receptor 1 as Potential Prognostic Biomarkers for Patients with Colon Cancer

The tumor microenvironment has been recognized as a complex network in which immune cells play an important role in cancer progression. We found significantly higher CD66b neutrophil expression in tumor tissue than in matched normal mucosa in the Malmö colon cancer (CC) cohort and poorer survival of stage I-III patients with high CD66b expression. Additionally, mice lacking CysLT1R expression (cysltr1−/−) produce less brain-derived neurotrophic factor (BDNF) compared to WT mice and Montelukast (a CysLT1R antagonist)-treated mice also reduced BDNF expression in a mouse xenograft model with human SW480 CC cells. CD66b and BDNF expression was significantly higher in patient tumor tissues than in the matched normal mucosa. The univariate Cox PH analysis yielded CD66b and BDNF as an independent predictor of overall survival, which was also found in the public TCGA-COAD dataset. We also discovered a strong positive correlation between CD66b, BDNF and CysLT1R expression in the Malmö CC cohort and in the TCGA-COAD dataset. Our data suggest that CD66b/BDNF/CysLT1R expression as a prognostic combined biomarker signature for CC patients.

Urinary leukotrienes and histamine in patients with varying severity of acute dengue

Background Vascular leak is a hallmark of severe dengue, and high leukotriene levels have been observed in dengue mouse models, suggesting a role in disease pathogenesis. We sought to explore their role in acute dengue, by assessing levels of urinary LTE4 and urinary histamine in patients with varying severity of acute dengue. Methods Urinary LTE4, histamine and creatinine were measured by a quantitative ELISA, in healthy individuals (n = 19), patients with dengue fever (DF = 72) and dengue haemorrhagic fever DHF (n = 48). The kinetics of LTE4 and histamine and diurnal variations were assessed in a subset of patients. Results Urinary LTE4 levels were significantly higher (p = 0.004) in patients who proceed to develop DHF when compared to patients with DF during early illness (≤ 4 days) and during the critical phase (p = 0.02), which continued to rise in patients who developed DHF during the course of illness. However, LTE4 is unlikely to be a good biomarker as ROCs gave an AUC value of 0.67 (95% CI 0.57 and 0.76), which was nevertheless significant (p = 0.002). Urinary LTE4 levels did not associate with the degree of viraemia, infecting virus serotype and was not different in those with primary vs secondary dengue. Urinary histamine levels were significantly high in patients with acute dengue although no difference was observed between patients with DF and DHF and again did not associate with the viraemia. Interestingly, LTE4, histamine and the viral loads showed a marked diurnal variation in both patients with DF and DHF. Conclusions Our data suggest that LTE4 could play a role in disease pathogenesis and since there are safe and effective cysteinyl leukotriene receptor blockers, it would be important to assess their efficacy in reducing dengue disease severity.

Phospho-Form Specific Substrates of Protein Kinase B (AKT1)

Protein kinase B (AKT1) is hyper-activated in diverse human tumors. AKT1 is activated by phosphorylation at two key regulatory sites, Thr308 and Ser473. Active AKT1 phosphorylates many, perhaps hundreds, of downstream cellular targets in the cytosol and nucleus. AKT1 is well-known for phosphorylating proteins that regulate cell survival and apoptosis, however, the full catalog of AKT1 substrates remains unknown. Using peptide arrays, we recently discovered that each phosphorylated form of AKT1 (pAKT1S473, pAKT1T308, and ppAKT1S473,T308) has a distinct substrate specificity, and these data were used to predict potential new AKT1 substrates. To test the high-confidence predictions, we synthesized target peptides representing putative AKT1 substrates. Peptides substrates were synthesized by solid phase synthesis and their purity was confirmed by mass spectrometry. Most of the predicted peptides showed phosphate accepting activity similar to or greater than that observed with a peptide derived from a well-established AKT1 substrate, glycogen synthase kinase 3β (GSK-3β). Among the novel substrates, AKT1 was most active with peptides representing PIP3-binding protein Rab11 family-interacting protein 2 and cysteinyl leukotriene receptor 1, indicating their potential role in AKT1-dependent cellular signaling. The ppAKT1S473,T308 enzyme was highly selective for peptides containing a patch of basic residues at −5, −4, −3 and aromatic residues (Phe/Tyr) at +1 positions from the phosphorylation site. The pAKT1S473 variant preferred more acidic peptides, Ser or Pro at +4, and was agnostic to the residue at −5. The data further support our hypothesis that Ser473 phosphorylation plays a key role in modulating AKT1 substrate selectivity.

Screening of Prospective Plant Compounds as H1R and CL1R Inhibitors and Its Antiallergic Efficacy through Molecular Docking Approach

Allergens have the ability to enter the body and cause illness. Leukotriene is the widespread allergen which could stimulate mast cells to discharge histamine which causes allergy symptoms. An effective strategy for treating leukotriene-induced allergy is to find the inhibitors of leukotriene or histamine activity from phytochemicals. For this purpose, a library of 8,500 phytochemicals was generated using MOE software. The structures of histamine-1 receptor and cysteinyl leukotriene receptor-1 were predicted by the homology modeling method through the SWISS model. The phytochemicals were docked with predicted structures of histamine-1 and cysteinyl leukotriene receptor-1 in MOE software to determine the binding affinity of the phytochemicals against the targets. Moreover, chemoinformatics properties and ADMET of phytochemicals were assessed to find the drug likeness behavior of compounds. Compound ID 10054216 has the lowest S -score value for H-1 receptor that is -18.9186 kcal/mol which is lower than the value of standard -15.167 kcal/mol. The other compounds 393471, 71448939, 10722577, and 442614 also showed good S -score values than the standard. Moreover, compound ID 11843082 has the lowest S -score value for CL1R that is -15.481 kcal/mol which is lower than the value of standard -12.453 kcal/mol. The other compounds 72284, 5282102, 66559251, and 102506430 also showed good S -score values than the standard. In this research article, we performed molecular docking to find the best inhibitors against H1R and CL1R and their antiallergic efficacy. This in silico knowledge will be helpful in near future for the design of novel, safe, and less costing H-1 receptor and CL1R inhibitors with the aim to improve human life quality.

Possible Therapeutic Potential of Cysteinyl Leukotriene Receptor Antagonist Montelukast in Treatment of SARS-CoV-2-Induced COVID-19

<b><i>Background:</i></b> The coronavirus disease-19 (COVID-19) pandemic is a serious devastating disease and has posed a global health emergency. So far, there is not any specific therapy approved till date to control the clinical symptoms of the disease. Remdesivir has been approved by the FDA as an emergency clinical therapy. But it may not be effective alone to control the disease as it can only control the viral replication in the host. <b><i>Summary:</i></b> This article summarizes the possible therapeutic potential and benefits of using montelukast, a cysteinyl leukotriene 1 (CysLT₁) receptor antagonist, to control COVID-19 pathophysiology. Montelukast has shown anti-inflammatory effects, reduced cytokine production, improvement in post-infection cough production and other lung complications. <b><i>Key Messages:</i></b> Recent reports clearly indicate a distinct role of CysLT-regulated cytokines and immunological signaling in COVID-19. Thus, montelukast may have a clinical potential to control lung pathology during COVID-19.

Direct evidence that the GPCR CysLTR2 mutant causative of uveal melanoma is constitutively active with highly biased signaling

Uveal melanoma is the most common eye cancer in adults and is clinically and genetically distinct from skin cutaneous melanoma. In a subset of cases, the oncogenic driver is an activating mutation in CYSLTR2, the gene encoding the G protein-coupled receptor (GPCR) cysteinyl-leukotriene receptor 2. The mutant CYSLTR2 encodes for CysLTR2-L129Q receptor, with the substitution of Leu to Gln at position 129 (3.43). The ability of CysLTR2-L129Q to cause malignant transformation has been hypothesized to result from constitutive activity, but how the receptor could escape desensitization is unknown. Here we characterize the functional properties of CysLTR2-L129Q. We show that CysLTR2-L129Q is a constitutively active mutant that strongly drives Gq/11 signaling pathways. However, CysLTR2-L129Q only poorly recruits β-arrestin. Using a modified Slack-Hall operational model, we quantified the constitutive activity for both pathways and conclude that CysLTR2-L129Q displays profound signaling bias for Gq/11 signaling pathways while escaping β-arrestin-mediated downregulation. CYSLTR2 is the first known example of a GPCR driver oncogene that encodes a highly biased constitutively active mutant receptor. These results provide new insights into the mechanism of CysLTR2-L129Q oncoprotein signaling and suggest CYSLTR2 as a promising potential therapeutic target in uveal melanoma.

Cysteinyl leukotriene receptor 1 modulates autophagic activity in retinal pigment epithelial cells

The retinal pigment epithelium (RPE), which is among the tissues in the body that are exposed to the highest levels of phagocytosis and oxidative stress, is dependent on autophagy function. Impaired autophagy and continuous cellular stress are associated with various disorders, such as dry age-related macular degeneration (AMD), a disease for which effective therapies are lacking. Cysteinyl leukotriene receptor (CysLTR) 1 is a potential modulator of autophagy; thus, the aim of this study was to investigate the role of CysLTR1 in autophagy regulation in the RPE cell line ARPE-19. The polarized ARPE-19 monolayer exhibited expression of CysLTR1, which was colocalized with β-tubulin III. In ARPE-19 cells, autophagic activity was rhythmically regulated and was increased upon CysLTR1 inhibition by Zafirlukast (ZK) treatment. H2O2 affected the proautophagic regulatory effect of ZK treatment depending on whether it was applied simultaneously with or prior to ZK treatment. Furthermore, mRNA levels of genes related to the leukotriene system, autophagy and the unfolded protein response were positively correlated. As CysLTR1 is involved in autophagy regulation under basal and oxidative stress conditions, a dysfunctional leukotriene system could negatively affect RPE functions. Therefore, CysLTR1 is a potential target for new treatment approaches for neurodegenerative disorders, such as AMD.