Pharmacological profile of MEN91507, a new CysLT(1) receptor antagonist

Classification models and SAR analysis on CysLT1 receptor antagonists using machine learning algorithms

Cysteinyl leukotrienes 1 (CysLT1) receptor is a promising drug target for rhinitis or other allergic diseases. In our study, we built classification models to predict bioactivities of CysLT1 receptor antagonists. We built a dataset with 503 CysLT1 receptor antagonists which were divided into two groups: highly active molecules (IC₅₀ < 1000 nM) and weakly active molecules (IC₅₀ ≥ 1000 nM). The molecules were characterized by several descriptors including CORINA descriptors, MACCS fingerprints, Morgan fingerprint and molecular SMILES. For CORINA descriptors and two types of fingerprints, we used the random forests (RF) and deep neural networks (DNN) to build models. For molecular SMILES, we used recurrent neural networks (RNN) with the self-attention to build models. The accuracies of test sets for all models reached 85%, and the accuracy of the best model (Model 2C) was 93%. In addition, we made structure-activity relationship (SAR) analyses on CysLT1 receptor antagonists, which were based on the output from the random forest models and RNN model. It was found that highly active antagonists usually contained the common substructures such as tetrazoles, indoles and quinolines. These substructures may improve the bioactivity of the CysLT1 receptor antagonists.

Emerging role of cysteinyl LTs in cancer

Cysteinyl leukotrienes (CysLTs) are inflammatory lipid mediators that play a central role in the pathophysiology of several inflammatory diseases. Recently, there has been an increased interest in determining how these lipid mediators orchestrate tumour development and metastasis through promoting a pro-tumour micro-environment. Up-regulation of CysLTs receptors and CysLTs production is found in a number of cancers and has been associated with increased tumorigenesis. Understanding the molecular mechanisms underlying the role of CysLTs and their receptors in cancer progression will help investigate the potential of targeting CysLTs signalling for anti-cancer therapy. This review gives an overview of the biological effects of CysLTs and their receptors, along with current knowledge of their regulation and expression. It also provides a recent update on the molecular mechanisms that have been postulated to explain their role in tumorigenesis and on the potential of anti-CysLTs in the treatment of cancer.

Trapping of a Nonpeptide Ligand by the Extracellular Domains of the Gonadotropin-Releasing Hormone Receptor Results in Insurmountable Antagonism

Drugs that exhibit insurmountable antagonism are proposed to provide improved clinical efficacy through extended receptor blockade. Long-term suppression of the gonadotropin-releasing hormone receptor (GnRHR) is an important therapeutic approach for a number of sex hormone-dependent diseases. In this study, we describe the mechanism and structural components required for insurmountable activity of a GnRHR antagonist. TAK-013 behaves as an insurmountable antagonist at the human receptor (hGnRHR) but as a surmountable antagonist at the macaque receptor (mGnRHR). Mutation of the eight residues that differ between hGnRHR and mGnRHR identified Ser-203 and Leu-300 in extracellular loops (ECL) 2 and 3 of hGnRHR as essential for the insurmountability of TAK-013. Substitution of the corresponding residues in mGnRHR with Ser and Leu (mGnRHR-P203S/V300L) converts TAK-013 to an insurmountable antagonist. In addition, mutation of Met-24 to Leu in the amino terminus of hGnRHR also ablates the insurmountable antagonism of TAK-013. The mechanism of insurmountability of TAK-013 was determined to be governed by its rate of dissociation from the receptor. Although the association rates of TAK-013 to hGnRHR, mGnRHR, and mGnRHR-P203S/V300L do not differ, the dissociation rate half-life correlates closely with the degree of insurmountability observed (169, 9, and 55 min, respectively). Taken together, these data suggest a model of the GnRHR in which ECL2, ECL3, and the amino terminus engage with TAK-013 upon its binding to the transmembrane region of the receptor. These additional interactions form a "trap door" above TAK-013, restricting its dissociation and thus resulting in its insurmountability.

Heterogeneous effect of leucotriene CysLT1receptor antagonists on antigen-induced motor and inflammatory responses in guinea-pig airways

1. The effect of montelukast or MEN91507, selective leucotriene CysLT1 receptor antagonists, on antigen-induced airway inflammation and bronchoconstriction were compared in anaesthetized guinea-pigs. 2. In sensitized animals, ovalbumin (0.3 mg kg(-1), i.v.)-induced microvascular leakage in trachea, intrapulmonary airways, total lung (parenchyma and intrapulmonary airways) and urinary bladder was reduced by MEN91507 (0.01-1 micromol kg(-1), i.v.), whereas montelukast (0.01-1 micromol kg(-1), i.v.) antagonized the effect of the antigen only in the lung and urinary bladder. 3. Ovalbumin (1 mg kg(-1), i.v.)-induced bronchoconstriction was dose dependently antagonized by MEN91507 (10-30 micromol kg(-1), i.v.), whereas the effect of montelukast (0.1-30 micromol kg(-1), i.v.) was marginal (15-30% inhibition). Neither MEN91507 nor montelukast (30 micromol kg(-1), i.v.) affected the bronchoconstrictor response induced by acetylcholine (0.3 micromol kg(-1), i.v.) in sensitized animals. 4. It is concluded that montelukast and MEN91507 display a differential activity against the effect of endogenous leucotrienes, despite the fact that both compounds show a similar antagonist profile against exogenous leucotrienes acting through CysLT1 receptors.

Pharmacological profile of CR3465, a new leukotriene CysLT1 receptor antagonist with broad anti-inflammatory activity

CR3465 (L-Tyrosine, N-[(2-quinolinyl)carbonyl]-O-(7-fluoro-2-quinolinylmethyl) sodium salt) is a potent antagonist of [3H]leukotriene D4 ([3H]LTD4) binding to guinea pig lung preparations, its Ki (4.7+/-0.7 nM) being comparable with that of montelukast (5.6+/-0.6 nM). In tracheal strips from standard or ovalbumin-sensitized guinea pigs, CR3465 caused parallel rightward shifts in the concentration-response curves obtained with either LTD4 or antigen (pA(2), 8.74 and 8.15). Intravenous (i.v.) administration of the agent both antagonized (ED50, 9.9+/-1.9 microg/kg) and reverted LTD4 -induced bronchoconstriction of anesthetized guinea pigs. CR3465 reduced inflammatory infiltrates in the bronchoalveolar lavage fluid after antigen challenge of sensitized animals, and proved also active in inhibiting phosphodiesterase 3 (PDE3) and phosphodiesterase 4 (PDE4) activities exhibited by human platelets and neutrophils (IC50, 2.01+/-0.07 and 4.7+/-0.5 microM). In line with properties shown by phosphodiesterase inhibitors, CR3465 reduced the contractile response of guinea pig airways to histamine and decreased N-formyl-Met-Leu-Phe (fMLP)-induced degranulation of human neutrophils (IC50, 13.8 microM). Oral administration (20 mg/kg) of the compound in rats produced a significant (37%) ex vivo inhibition of tumor necrosis factor-alpha (TNF-alpha) release from lipopolysaccharide-stimulated whole blood. Pharmacokinetic data in the rat demonstrated approximately 100% bioavailability of the agent. We conclude that CR3465 represents a potent leukotriene CysLT1 receptor antagonist with enhanced effects, being also useful for counteracting spasmogenic and inflammatory stimuli other than those elicited by cysteinyl-leukotrienes (Cys-LTs).