Design and biological characterization of a series of dual mechanism ERK1/2 inhibitors with a Triazolopyridinone core.

Oncology clinical development programs have targeted the RAS/RAF/MEK/ERK signaling pathway with small molecule inhibitors for a variety of cancers during the past decades, and most therapies have shown limited or minimal success. Specific BRAF and MEK inhibitors have shown clinical efficacy in patients for the treatment of BRAF-mutant melanoma. However, most cancers have shown treatment resistance after several months of inhibitor usage, and reports indicate resistance is often associated with the reactivation of the MAPK signaling pathway.

Antagonists for Constitutively Active Mutant Estrogen Receptors: Insights into the Roles of Antiestrogen-Core and Side-Chain.

A major risk for patients having estrogen receptor α (ERα)-positive breast cancer is the recurrence of drug-resistant metastases after initial successful treatment with endocrine therapies. Recent studies have implicated a number of activating mutations in the ligand-binding domain of ERα that stabilize the agonist conformation as a prominent mechanism for this acquired resistance. There are several critical gaps in our knowledge regarding the specific pharmacophore requirements of an antagonist that could effectively inhibit all or most of the different mutant ERs.

7TM X-ray structures for class C GPCRs as new drug-discovery tools. 1. mGluR5.

We illustrate, with a focus on mGluR5, how the recently published, first X-ray structures of mGluR 7TM domains, specifically those of mGluR1 and mGluR5 complexed with negative allosteric modulators (NAMs), will begin to influence ligand- (e.g., drug- or sweetener-) discovery efforts involving class C GPCRs.

The role of experimental and computational structural approaches in 7TM drug discovery.

Introduction: Starting with the published X-ray structures of ligand-mediated 7TM proteins in 2007, experimental approaches, led by X-ray structure determinations, and computational approaches, led by docking and molecular dynamics, have converged to elaborate our understanding of this field and demonstrate their effectiveness in drug discovery.

Areas Covered: The authors review the structural information that has emerged for ligand-mediated 7TM proteins, including the class A, B, C, and F receptors, focusing on the 7TM domains for the multi-domain proteins. The authors describe the key regions associated with ligand binding as well as features responsible for function such as activation versus inhibition and biased signaling.

cis-1-Oxo-heterocyclyl-4-amido cyclohexane derivatives as NPY5 receptor antagonists.

The NPY5 receptor binding and pharmacokinetic properties of a novel series of cis-1-oxo-heterocyclyl-4-amido-cyclohexane derivatives are described.

4-(1-Phenyl-1H-pyrazol-4-yl)quinolines as novel, selective and brain penetrant metabotropic glutamate receptor 4 positive allosteric modulators.

4-(1-Phenyl-1H-pyrazol-4-yl)quinoline (1) was identified by screening the Lundbeck compound collection, and characterized as having mGlu4 receptor positive allosteric modulator properties. Compound 1 is selective over other mGlu receptors and a panel of GPCRs, ion channels and enzymes, but has suboptimal lipophilicity and high plasma and brain non-specific binding. In view of the challenges at the hit-to-lead stage previously reported in the development of mGlu4 receptor positive allosteric modulators (PAMs), a thorough structure-mGlu4 PAM activity relationship study was conducted to interrogate the chemical tractability of this chemotype.

Tricyclic thiazolopyrazole derivatives as metabotropic glutamate receptor 4 positive allosteric modulators.

There is an increasing amount of evidence to support that activation of the metabotropic glutamate receptor 4 (mGlu4 receptor), either with an orthosteric agonist or a positive allosteric modulator (PAM), provides impactful interventions in diseases such as Parkinson's disease, anxiety, and pain. mGlu4 PAMs may have several advantages over mGlu4 agonists for a number of reasons. As part of our efforts in identifying therapeutics for central nervous system (CNS) diseases such as Parkinson's disease, we have been focusing on metabotropic glutamate receptors.

Exploration of structure-based drug design opportunities for mGluRs.

The metabotropic glutamate receptors (mGluRs) are a subset of the Class C G-Protein Coupled Receptors (GPCRs). Recently, an emerging strategy for drug-discovery efforts targeting mGluRs has been to develop compounds acting at the so-called allosteric site in the 7-transmembrane (7TM) domain, common to all GPCRs, rather than the extracellular (EC) domain containing the orthosteric glutamate-binding site. We examine herein some of the intrinsic relative merits of targeting these two domains.

X-ray structure breakthroughs in the GPCR transmembrane region.

G-protein-coupled receptor (GPCR) proteins [Lundstrom KH, Chiu ML, editors. G protein-coupled receptors in drug discovery. CRC Press; 2006] are the single largest drug target, representing 25-50% of marketed drugs [Overington JP, Al-Lazikani B, Hopkins AL.

Development of an aequorin luminescence calcium assay for high-throughput screening using a plate reader, the LumiLux.

A luminescence assay using a new plate reader, the LumiLux (PerkinElmer, Waltham, MA), has been validated for high-throughput screening (HTS). In this study, we compared the aequorin luminescence-based calcium mobilization assay to the fluorescence-based calcium assay. A cell line stably co-expressing apo-aequorin, a chimeric G-protein, and a G-protein-coupled dopamine receptor was used to screen a collection of 8,106 compounds using the Hamamatsu Photonics (Bridgewater, NJ) FDSS6000 and LumiLux as the plate readers.

Use of the X-ray structure of the beta2-adrenergic receptor for drug discovery. Part 2: Identification of active compounds.

The recently published X-ray structures of the beta(2)-adrenergic receptor are the first examples of ligand-mediated GPCR crystal structures. We have previously performed computational studies that examine the potential viability of these structures for use in drug design, exploiting known ligand activities. Our previous study and a newly reported beta(2)/Timolol X-ray complex provide validation of the computational approaches.

Use of the X-ray structure of the Beta2-adrenergic receptor for drug discovery.

The recently reported X-ray structure of the Beta2-adrenergic receptor, the first reported crystal structure of a ligand-mediated GPCR, is used to explore its utility in computer-aided drug design. Validations were conducted with known beta blockers. This was followed by high-throughput docking studies with proprietary and commercial databases to further validate the X-ray structure's usefulness as a design tool and to explore the potential for discovery of novel chemical classes acting as Beta2 inhibitors.

Homology modeling of the serotonin transporter: insights into the primary escitalopram-binding site.

The serotonin transporter (SERT) is one of the neurotransmitter transporters that plays a critical role in the regulation of endogenous amine concentrations and therefore is an important target for therapeutic agents affecting the central nervous system. The recently published, high resolution X-ray structure of the closely related amino acid transporter, Aquifex aeolicus leucine transporter (LeuT), provides an opportunity to develop a three-dimensional model of the structure of SERT. We present herein a homology model of SERT using LeuT as the template and containing escitalopram as a bound ligand.

1,4-Diazepane-2,5-diones as novel inhibitors of LFA-1.

1,4-Diazepane-2,5-diones (2) are found to be a new class of potent LFA-1 inhibitors. The synthesis, structure, and biological evaluation of these 1,4-diazepine-2,5-diones and related derivatives are described.

Depletion of methionine aminopeptidase 2 does not alter cell response to fumagillin or bengamides.

Inhibition of endothelial cell growth by fumagillin has been assumed to be mediated by inhibition of the molecular target methionine aminopeptidase 2 (MetAp2). New data show that depletion of MetAp2 by siRNA does not inhibit endothelial cell growth. Moreover, MetAp2-depleted endothelial cells remain responsive to inhibition by either fumagillin or a newly identified MetAp2 enzyme inhibitor.

1,4-Diazepane-2-ones as novel inhibitors of LFA-1.

The design, synthesis, and biological evaluation of 1,4-diazepane-2-ones as novel LFA-1 antagonists from a scaffold-based combinatorial library are described. Initial optimization of the library lead has resulted in high-affinity antagonists of the LFA-1/ICAM-1 interaction, such as compounds 18d and 18e with IC(50) values of 110 and 70 nM, respectively.