Discovery of the first selective, small-molecule GFRα2/3 inhibitors through DNA-encoded library technology.

Studies have shown that disrupting the formation of the ligand-RET-GFRα complex could be an effective way of treating pain and itch. Compared to traditional high-throughput screens, DNA encoded libraries (DELs) have distinguished themselves as a powerful technology for hit identification in recent years. The present work demonstrates the use of DEL technology identifying compound 16 as the first GFRa2/GFRa3 small molecule inhibitor (0.

Discovery of SARxxxx92, a pan-PIM kinase inhibitor, efficacious in a KG1 tumor model.

N-substituted azaindoles were discovered as potent pan-PIM inhibitors. Lead optimization, guided by structure and focused on physico-chemical properties allowed us to solve inherent hERG and permeability liabilities, and provided compound 27, which subsequently impacted KG-1 tumor growth in a mouse model.

Discovery of N-substituted 7-azaindoles as Pan-PIM kinases inhibitors - Lead optimization - Part III.

N-substituted azaindoles were discovered as promising pan-PIM inhibitors. Lead optimization is described en route toward the identification of a clinical candidate. Modulation of physico-chemical properties allowed to solve inherent hERG and permeability liabilities.

Glutaminase is essential for the growth of triple-negative breast cancer cells with a deregulated glutamine metabolism pathway and its suppression synergizes with mTOR inhibition.

Tumor cells display fundamental changes in metabolism and nutrient uptake in order to utilize additional nutrient sources to meet their enhanced bioenergetic requirements. Glutamine (Gln) is one such nutrient that is rapidly taken up by tumor cells to fulfill this increased metabolic demand. A vital step in the catabolism of glutamine is its conversion to glutamate by the mitochondrial enzyme glutaminase (GLS).

Discovery of N-substituted 7-azaindoles as PIM1 kinase inhibitors - Part I.

Novel N-substituted azaindoles have been discovered as PIM1 inhibitors. X-ray structures have played a significant role in orienting the chemistry effort in the initial phase of hit confirmation. Disclosure of an unconventional binding mode for 1 and 2, as demonstrated by X-ray crystallography, is presented and was an important factor in selecting and advancing a lead series.

Discovery of N-substituted 7-azaindoles as Pan-PIM kinase inhibitors - Lead series identification - Part II.

N-Substituted azaindoles have been discovered as pan-PIM kinase inhibitors. Initial SAR, early ADME and PK/PD data of a series of compounds is described and led to the identification of promising pan-PIM inhibitors which validated our interest in the 7-azaindole scaffold and led us to pursue the identification of a clinical candidate.

PIM inhibitors target CD25-positive AML cells through concomitant suppression of STAT5 activation and degradation of MYC oncogene.

Postchemotherapy relapse presents a major unmet medical need in acute myeloid leukemia (AML), where treatment options are limited. CD25 is a leukemic stem cell marker and a conspicuous prognostic marker for overall/relapse-free survival in AML. Rare occurrence of genetic alterations among PIM family members imposes a substantial hurdle in formulating a compelling patient stratification strategy for the clinical development of selective PIM inhibitors in cancer.

Combination of PIM and JAK2 inhibitors synergistically suppresses MPN cell proliferation and overcomes drug resistance.

Inhibitors of JAK2 kinase are emerging as an important treatment modality for myeloproliferative neoplasms (MPN). However, similar to other kinase inhibitors, resistance to JAK2 inhibitors may eventually emerge through a variety of mechanisms. Effective drug combination is one way to enhance therapeutic efficacy and combat resistance against JAK2 inhibitors.

2,4-Diaminopyrimidine MK2 inhibitors. Part II: Structure-based inhibitor optimization.

We describe structure-based optimization of a series of novel 2,4-diaminopyrimidine MK2 inhibitors. Co-crystal structures (see accompanying Letter) demonstrated a unique inhibitor binding mode. Resulting inhibitors had IC(50) values as low as 19nM and moderate selectivity against a kinase panel.

Discovery of thieno[2,3-c]pyridines as potent COT inhibitors.

Evaluation of hit chemotypes from high throughput screening identified a novel series of 2,4-disubstituted thieno[2,3-c]pyridines as COT kinase inhibitors. Structural modifications exploring SAR at the 2- and 4-positions resulting in inhibitors with improved enzyme potency and cellular activity are disclosed.

Probing the existence of G protein-coupled receptor dimers by positive and negative ligand-dependent cooperative binding.

An increasing amount of ligand binding data on G protein-coupled receptors (GPCRs) is not compatible with the prediction of the simple mass action law. This may be related to the propensity of most GPCRs, if not all, to oligomerize. Indeed, one of the consequences of receptor oligomerization could be a possible cross-talk between the protomers, which in turn could lead to negative or positive cooperative ligand binding.

Discovery and development of a new class of potent, selective, orally active oxytocin receptor antagonists.

We report a novel chemical class of potent oxytocin receptor antagonists showing a high degree of selectivity against the closely related vasopressin receptors (V1a, V1b, V2). An initial compound, 7, was shown to be active in an animal model of preterm labor when administered by the intravenous but not by the oral route. Stepwise SAR investigations around the different structural elements revealed one position, the arenesulfonyl moiety, to be amenable to structural changes.

Introduction of a cis-prolyl mimic in position 7 of the peptide hormone oxytocin does not result in antagonistic activity.

New insights into the structure-activity relationship of the peptide hormone oxytocin are presented. Incorporation of the novel cis-prolyl mimic 2,2-dimethyl-1,3-thiazolidine-4-carboxylic acid (pseudoproline, PsiPro) at position 7 of the hormone yielded the analogue [Cys(Psi(Me,Me)pro)]7oxytocin (1) that showed a 92-95% induction of the cis peptide bond conformation between Cys6 and PsiPro7, as determined by one- and two-dimensional NMR spectra in water and in DMSO-d6. The impact of the dimethyl moiety regarding conformation and bioactivity was investigated by the synthesis of the corresponding dihydro compound, [Cys(Psi(H,H)pro)]7oxytocin (2).

Design of peptide oxytocin antagonists with strikingly higher affinities and selectivities for the human oxytocin receptor than atosiban.

The peptide oxytocin (OT) antagonist atosiban, approved for tocolytic use in Europe (under the tradename Tractocile), represents an important new therapeutic advance for the treatment of premature labor. This paper presents some new peptide OT antagonists which offer promise as superior tocolytics. The solid phase synthesis is reported of four pairs of L and D-2-naphthylalanine (L/D-2Nal) position-2 modified analogs of the following four oxytocin (OT) antagonists: des-9-glycinamide [1-(beta-mercapto-beta,beta-pentamethylene propionic acid), 2-O-methyltyrosine, 4-threonine]ornithine-vasotocin (desGly-NH(2),d(CH(2))(5)[Tyr(Me)(2),Thr(4)]OVT) (A); the Tyr-NH(2) (9) analog of (A), d(CH(2))(5)[Tyr(Me)(2),Thr(4),Tyr-NH(2) (9)]OVT (B); the Eda(9) analog of (A), d(CH(2))(5)[Tyr(Me)(2),Thr(4),Eda(9)]OVT (C); and the retro COCH(2)Ph(4-0H)(10) modified analog of (C), d(CH(2))(5)[Tyr(Me)(2),Thr(4),Eda(9)<-- COCH(2)Ph(4-0H)(10)]OVT (D).

Design of benzophenone-containing photoactivatable linear vasopressin antagonists: pharmacological and photoreactive properties.

We designed and synthesized new photoactivatable linear vasopressin analogues containing benzophenone photophores. All compounds were monitored and purified using RP-HPLC and characterized by mass spectrometry. Affinity and selectivity were determined in CHO cells expressing either human V(1a), V(1b) or V(2) receptor subtypes.

Crosslinking photosensitized by a ruthenium chelate as a tool for labeling and topographical studies of G-protein-coupled receptors.

The purpose was to apply oxidative crosslinking reactions to the study of recognition and signaling mechanisms associated to G-protein-coupled receptors. Using a ruthenium chelate, Ru(bipy)(3)(2+), as photosensitizer and visible light irradiation, in the presence of ammonium persulfate, we performed fast and efficient covalent labeling of the B(2) bradykinin receptor by agonist or antagonist ligands possessing a radio-iodinated phenol moiety. The chemical and topographical specificities of these crosslinking experiments were investigated.

A 13C NMR approach to categorizing potential limitations of alpha,beta-unsaturated carbonyl systems in drug-like molecules.

Compounds that contain an alpha,beta-unsaturated carbonyl moiety are often flagged as potential Michael acceptors. All alpha,beta-unsaturated carbonyl moieties are not equivalent, however, and we sought to better understand this system and its potential implications in drug-like molecules. Measurement of the (13)C NMR shift of the beta-carbon and correlation to in vitro results allowed compounds in our collection to be categorized as potential Michael acceptors, potential substrates for NADPH, or as photoisomerizable.

Heterodimerization of V1a and V2 vasopressin receptors determines the interaction with beta-arrestin and their trafficking patterns.

V1a vasopressin receptor (V1aR) and V2 vasopressin receptor (V2R) present distinct mechanisms of agonist-promoted trafficking. Although both receptors are endocytosed by way of beta-arrestin-dependent processes, beta-arrestin dissociates rapidly from V1aR, allowing its rapid recycling to the plasma membrane while beta-arrestin remains associated with V2R in the endosomes, leading to their intracellular accumulation. Here, we demonstrate that, when coexpressed, the two receptors can be endocytosed as stable heterodimers.

Identification of the binding sites of the SR49059 nonpeptide antagonist into the V1a vasopressin receptor using sulfydryl-reactive ligands and cysteine mutants as chemical sensors.

To identify the binding site of the human V1a vasopressin receptor for the selective nonpeptide antagonist SR49059, we have developed a site-directed irreversible labeling strategy that combines mutagenesis of the receptor and use of sulfydryl-reactive ligands. Based on a three-dimensional model of the antagonist docked into the receptor, hypothetical ligand-receptor interactions were investigated by replacing the residues potentially involved in the binding of the antagonist into cysteines and designing analogues of SR49059 derivatized with isothiocyanate or alpha-chloroacetamide moieties. The F225C, F308C, and K128C mutants of the V1a receptor were expressed in COS-7 or Chinese hamster ovary cells, and their pharmacological properties toward SR49059 and its sulfydryl-reactive analogues were analyzed.

Pharmacology of (2S,4Z)-N-[(2S)-2-hydroxy-2-phenylethyl]-4-(methoxyimino) -1-[(2'-methyl[1,1'-biphenyl]-4-yl)carbonyl]-2-pyrrolidinecarboxamide, a new potent and selective nonpeptide antagonist of the oxytocin receptor.

We have discovered a new, potent, selective, and orally active oxytocin receptor antagonist, (2S,4Z)-N-[(2S)-2-hydroxy-2-phenylethyl]-4-(methoxyimino)-1-[(2'-methyl[1,1'-biphenyl]-4-yl)carbonyl]-2-pyrrolidinecarboxamide (compound 1). We report the biochemical, pharmacological, and pharmacokinetic characterization in vitro and in vivo of this compound. Compound 1 competitively inhibits binding of [3H]oxytocin and the peptide antagonist 125I-ornithine vasotocin analog to human and rat oxytocin receptor expressed in human embryonic kidney 293-EBNA or Chinese hamster ovary cells with nanomolar potency.

Oxytocin and vasopressin V1a and V2 receptors form constitutive homo- and heterodimers during biosynthesis.

G protein-coupled receptor (GPCR) oligomerization is a growing concept that has emerged from several studies suggesting that GPCRs can form both homo- and heterodimers. Using both coimmunoprecipitation and bioluminescence resonance energy transfer (BRET) approaches, we established that the vasopressin V1a, V2, and the oxytocin receptors exist as homo- and hetero-dimers in transfected human embryonic kidney 293T cells. Each receptor protomer had a similar propensity to form homo- and heterodimers, indicating that their relative expression levels may determine the homo-/heterodimer ratio.

Expression of human vasopressin and oxytocin receptors in Escherichia coli.

In order to produce large amounts of human vasopressin and oxytocin receptors compatible with direct structural biology approaches such as X-ray crystallography, NMR or mass spectrometry, we have expressed these neurohypophysial hormone receptors in Escherichia coli. To facilitate the level of expression, the coding sequence for the V1a vasopressin receptor and the oxytocin receptor were first optimized for bacterial expression. The resulting 'bacterial receptor cDNAs' were then subcloned into pET/T7-driven prokaryotic expression vectors.

Synthesis and characterization of fluorescent antagonists and agonists for human oxytocin and vasopressin V(1)(a) receptors.

The fluoresceinyl (Flu) group has been linked by an amide bond to the side chain amino group at position 8 of (a) two oxytocin (OT) antagonists, to give d(CH(2))(5)[Tyr(Me)(2),Thr(4),Orn(8)(5/6C-Flu),Tyr-NH(2)(9)]VT (Orn(8)(5/6C-Flu)OTA) (1) and desGly-NH(2),d(CH(2))(5)[D- Tyr(2),Thr(4),Orn(8)(5/6C-Flu)]VT (2), and (b) eight Lys(8) and Orn(8) analogues of potent OT agonists, to give d[Lys(8)(5/6C-Flu)]VT (3), d[Thr(4),Lys(8)(5/6C-Flu)]VT (4), [HO(1)][Lys(8)(5/6C-Flu)]VT (5), [HO(1)][Thr(4),Lys(8)(5/6C-Flu)]VT (6), d[Orn(8)(5/6C-Flu)]VT (7), d[Thr(4),Orn(8)(5/6C-Flu)]VT (8), [HO(1)][Orn(8)(5/6C-Flu)]VT (9), and [HO(1)][Thr(4),Orn(8)(5/6C-Flu)]VT (10). The tetramethylrhodamyl (Rhm) group was attached to the precursor peptide of 9 to give [HO(1)][Orn(8)(5/6C-Rhm)]VT (11). All 11 fluorescent peptides were evaluated in human OT and vasopressin V(1a) (vasoconstrictor), V(1b) (pituitary), and V(2) (antidiuretic) receptor binding and functional assays.

Presence of functional oxytocin receptors in cultured human myoblasts.

In the present report, we provide for the first time evidence that functional oxytocin receptors (OTRs) are present in human myoblasts obtained from clonal cultures of postnatal satellite cells. First, binding studies performed with a non selective vasopressin (AVP) and oxytocin (OT) radioligand indicated the presence of a single class of binding sites. Second, OTR mRNA was detected by RT-PCR analysis whereas transcripts for AVP V(1a), V(1b) or V(2) receptors (V(1a)R, V(1b)R and V(2)R respectively) were not detected.

Characterization of (2S,4R)-1-[5-chloro-1-[(2,4-dimethoxyphenyl)sulfonyl]-3-(2-methoxy-phenyl)-2-oxo-2,3-dihydro-1H-indol-3-yl]-4-hydroxy-N,N-dimethyl-2-pyrrolidine carboxamide (SSR149415), a selective and orally active vasopressin V1b receptor antagonist.

(2S,4R)-1-[5-Chloro-1-[(2,4-dimethoxyphenyl)sulfonyl]-3-(2-methoxy-phenyl)-2-oxo-2,3-dihydro-1H-indol-3-yl]-4-hydroxy-N,N-dimethyl-2-pyrrolidine carboxamide (SSR149415), the first selective, nonpeptide vasopressin V1b receptor antagonist yet described, has been characterized in vitro and in vivo. SSR149415 showed competitive nanomolar affinity for animal and human V1b receptors and exhibited much lower affinity for rat and human V1a, V2, and oxytocin receptors. Moreover, this compound did not interact with a large number of other receptors, enzymes, or ion channels.