cAMP Assay Research Articles

A novel psoralen derivative-MPFC enhances melanogenesis via activation of p38 MAPK and PKA signaling pathways in B16 cells.

As an active compound, psoralen is present in various Chinese herbal medicines and has exhibited significant activity in skin disease treatment. Its derivative 8-methoxypsoralan (8-MOP) is the most commonly used drug to induce repigmentation of vitiligo. In our previous screening assays, 4-methyl-6-phenyl-2H-furo[3,2-g]chromen-2-one(MPFC), a psoralen derivative, was identified as more effective tyrosinase and melanin activator than the positive control 8-MOP in consideration of low doses, as well as low toxicity. The overall purpose of this study was to characterize the melanogenic effect and mechanisms of MPFC in B16 cells. The melanin biosynthesis effects of MPFC were determined by examination of cellular melanin contents, tyrosinase activity assay, cyclic adenosinemonophosphate (cAMP) assay, and western blotting of MPFC-stimulated B16 mouse melanoma cells. Our results showed that MPFC enhanced both melanin synthesis and tyrosinase activity in a concentration-dependent manner as well as significantly activated the expression of melanogenic proteins such as tyrosinase, tyrosinase-related protein-1 and tyrosinase-related protein-2. Western blot analysis showed that MPFC increased the phosphorylation of p38 mitogen-activated protein kinase and cAMP response element-binding protein(CREB) as well as the expression of microphthalmia-associated transcription factor(MITF). Moreover, MPFC stimulated intracellular cAMP levels and induced tyrosinase activity and melanin synthesis were attenuated by H89, a protein kinaseA inhibitor. These results indicated that MPFC-mediated activation of the p38MAPK and the protein kinaseA(PKA) pathway may shed light on a novel approach for an effective therapy for vitiligo.

YH18968, a Novel 1,2,4-Triazolone G-Protein Coupled Receptor 119 Agonist for the Treatment of Type 2 Diabetes Mellitus.

G protein-coupled receptor 119 (GPR119) is expressed in the pancreas and gastrointestinal tract, and its activation promotes insulin secretion in the beta cells of the pancreatic islets as well as the secretion of glucagon-like peptide-1 (GLP-1) in intestinal L cells, consequently improving glucose-stimulated insulin secretion. Due to this dual mechanism of action, the development of small-molecule GPR119 agonists has received significant interest for the treatment of type 2 diabetes. We newly synthesized 1,2,4-triazolone derivatives of GPR119 agonists, which demonstrated excellent outcomes in a cyclic adenosine monophosphate (cAMP) assay. Among the synthesized derivatives, YH18968 showed cAMP=2.8 nM; in GLUTag cell, GLP-1secretion=2.3 fold; in the HIT-T15 cell, and insulin secretion=1.9 fold. Single oral administration of YH18968 improved glucose tolerance and combined treatment with a dipeptidyl peptidase 4 (DPP-4) inhibitor augmented the glucose lowering effect as well as the plasma level of active GLP-1 in normal mice. Single oral administration of YH18968 improved glucose tolerance in a diet induced obese mice model. This effect was maintained after repeated dosing for 4 weeks. The results indicate that YH18968 combined with a DPP-4 inhibitor may be an effective therapeutic candidate for the treatment of type 2 diabetes.

Molecular Mechanisms of Biased and Probe-Dependent Signaling at CXC-Motif Chemokine Receptor CXCR3 Induced by Negative Allosteric Modulators.

Our recent explorations of allosteric modulators with improved properties resulted in the identification of two biased negative allosteric modulators, BD103 (N-1-{[3-(4-ethoxyphenyl)-4-oxo-3,4-dihydropyrido[2,3-d]pyrimi-din2yl]ethyl}-4-(4-fluorobutoxy)-N-[(1-methylpiperidin-4-yl)methyl}]butanamide) and BD064 (5-[(N-{1-[3-(4-ethoxyphenyl)-4-oxo-3,4-dihydropyrido[2,3-d]pyrimidin-2-yl]ethyl-2-[4-fluoro-3-(trifluoromethyl)phenyl]acetamido)methyl]-2-fluorophenyl}boronic acid), that exhibited probe-dependent inhibition of CXC-motif chemokine receptor CXCR3 signaling. With the intention to elucidate the structural mechanisms underlying their selectivity and probe dependence, we used site-directed mutagenesis combined with homology modeling and docking to identify amino acids of CXCR3 that contribute to modulator binding, signaling, and transmission of cooperativity. With the use of allosteric radioligand RAMX3 ([3H]N-{1-[3-(4-ethoxyphenyl)-4-oxo-3,4-dihydropyrido[2,3-d]pyrimidin-2-yl]ethyl}-2-[4-fluoro-3-(trifluoromethyl)phenyl]-N-[(1-methylpiperidin-4-yl)methyl]acetamide), we identified that F1313.32 and Y3087.43 contribute specifically to the binding pocket of BD064, whereas D1864.60 solely participates in the stabilization of binding conformation of BD103. The influence of mutations on the ability of negative allosteric modulators to inhibit chemokine-mediated activation (CXCL11 and CXCL10) was assessed with the bioluminescence resonance energy transfer-based cAMP and β-arrestin recruitment assay. Obtained data revealed complex molecular mechanisms governing biased and probe-dependent signaling at CXCR3. In particular, F1313.32, S3047.39, and Y3087.43 emerged as key residues for the compounds to modulate the chemokine response. Notably, D1864.60, W2686.48, and S3047.39 turned out to play a role in signal pathway selectivity of CXCL10, as mutations of these residues led to a G protein-active but β-arrestin-inactive conformation. These diverse effects of mutations suggest the existence of ligand- and pathway-specific receptor conformations and give new insights in the sophisticated signaling machinery between allosteric ligands, chemokines, and their receptors, which can provide a powerful platform for the development of new allosteric drugs with improved pharmacological properties.

Structural basis for the interaction of diapause hormone with its receptor in the silkworm, Bombyx mori.

Diapause hormone (DH) is a 24-aa amidated neuropeptide that elicits the embryonic diapause of the silkworm, Bombyx mori ( Bommo), via sensitive and selective interaction with its receptor, Bommo DH receptor ( Bommo-DHR). Previous studies of the structure-activity relationship of Bommo-DH were all based on an in vivo diapause-induction bioassay, which has provided little information on the structure of Bommo-DHR or its iteration with DH. Here, to unveil the interaction of Bommo-DH with its receptor, N-terminally truncated analogs and alanine-scanning mutants of Bommo-DH were chemically synthesized and functionally evaluated by using a Cy5.5-labeled Bommo-DH competitive binding assay and Bommo-DHR-based functional assays, including cAMP assay and Ca2+ mobilization assay. Our study demonstrates that the C-terminal residues of Arg23 and Leu24 of Bommo-DH are essential for the binding and activation of Bommo-DHR, and that Trp19 and Phe20 also contribute to the functional activity of Bommo-DH. In contrast, when Gly21 or Pro22 were replaced with alanine, both mutants exhibited binding and signaling activities that were indistinguishable from the wild-type peptide. Furthermore, our homology modeling and molecular dynamics simulations, together with experimental validations, have identified the residues of Glu89, Phe172, Phe194, and Tyr299 in Bommo-DHR that are critically involved in the interaction with Bommo-DH. These results may deepen our understanding of the interactions of class-A GPCRs with their peptidic ligands, particularly those between pheromone biosynthesis-activating neuropeptide/DH family neuropeptides and their cognate receptors.-Shen, Z., Jiang, X., Yan, L., Chen, Y., Wang, W., Shi, Y., Shi, L., Liu, D., Zhou, N. Structural basis for the interaction of diapause hormone with its receptor in the silkworm, Bombyx mori.

Characterization of the properties of four opioid analgesics approved in Japan with cells stably expressing μORs using the CellKey™ and GloSensor™ cAMP assay systems

Characterization of the properties of four opioid analgesics approved in Japan with cells stably expressing μORs using the CellKey™ and GloSensor™ cAMP assay systems

Abstract B130: Differentiated pharmacology of the imipridone ONC201: the first selective DRD2/3 antagonist in clinical oncology

Abstract Background: ONC201, founding member of the imipridone class of compounds, has demonstrated biologic activity and exceptional safety in advanced cancer patients. In this study, we identified and characterized a previously unknown binding target of ONC201. Methods: Binding targets for ONC201 were predicted by BANDIT–a machine learning-based drug target identification platform that uses clinical, genomics, chemical, and structural datasets for small molecules with validated binding targets. GPCR antagonism was evaluated using beta-arrestin recruitment and cAMP reporter assays in Chinese hamster ovary cells. KB values were determined with Schild analyses and DRD2 binding was confirmed with radio-labeled ligand competition assays. Shotgun mutagenesis across 350 amino acids of DRD2 was performed and dopamine-induced calcium flux assays were conducted in HEK-293T cells. Results: BANDIT predicted that ONC201 would bind with high selectivity to the G-protein coupled receptors (GPCRs) dopamine receptor D2(DRD2) and D3 (DRD3). DRD2 is overexpressed in glioblastoma, controls prosurvival signaling pathways, and its antagonism causes proapoptotic and antiproliferative effects in malignant cells. β-arrestin recruitment and cAMP assays determined that ONC201 selectively antagonizes DRD2 and DRD3. Consistent with BANDIT predictions and in contrast to other DRD2 antagonist antipsychotics, ONC201 did not antagonize other dopamine receptors or other closely related GPCRs. Schild analyses and radiolabeled ligand competition assays revealed DRD2 affinities that were consistent with those identified for ONC201 anticancer activity. In accordance with superior selectivity, ONC201 exhibited a wider therapeutic window compared to other antipsychotics. In support of the hypothesis that selectively targeting the Gi-coupled D2-like receptors yields superior anticancer efficacy, combined inhibition of DRD2 and DRD1, a Gs-coupled D1-like receptor, was found to be inferior to DRD2 inhibition alone. ONC201 exhibited a very slow association rate for DRD2 relative to antipsychotics, whereas the dissociation rate was similar to atypical antipsychotics that are better tolerated. Shotgun mutagenesis of DRD2 identified 8 residues that are critical for ONC201-mediated antagonism of dopamine-induced calcium flux via DRD2. Some of the residues were specific to DRD2 and DRD3, suggesting a potential role of these residues in conferring ONC201 selectivity. Consistent with competitive inhibition, several mutated residues were within the orthosteric binding site (OBS); however, two distal residues were identified outside of the OBS. The latter suggesting a secondary binding pocket and concurrent noncompetitive antagonism of DRD2. Conclusion: The receptor pharmacology of ONC201, the first selective DRD2/3 antagonist in clinical oncology, may underpin its unique selectivity, safety, and anticancer activity that has been observed in clinical trials. Citation Format: Neel S. Madhukar, Varun Vijay Prabhu, Lakshmi Anantharaman, Chidananda Sulli, Edgar Davidson, Sean Deacon, Joseph Rucker, Neil Charter, Benjamin Doranz, Wolfgang Oster, Olivier Elemento, R. Benjamin Free, David Sibley, Joshua E. Allen. Differentiated pharmacology of the imipridone ONC201: the first selective DRD2/3 antagonist in clinical oncology [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B130.

Evaluation of in silico approach for prediction of presence of opioid peptides in wheat

Opioid like morphine and codeine are used for the management of pain, but are associated with serious side-effects limiting their use. Wheat gluten proteins were assessed for the presence of opioid peptides on the basis of tyrosine and proline within their sequence. Eleven peptides were identified and occurrence of predicted sequences or their structural motifs were analysed using BIOPEP database and ranked using PeptideRanker. Based on higher peptide ranking, three sequences YPG, YYPG and YIPP were selected for determination of opioid activity by cAMP assay against µ and κ opioid receptors. Three peptides inhibited the production of cAMP to varied degree with EC50 values of YPG, YYPG and YIPP were 5.3 mM, 1.5 mM and 2.9 mM for µ-opioid receptor, and 1.9 mM, 1.2 mM and 3.2 mM for κ-opioid receptor, respectively. The study showed that in silico approach can be used for the prediction of opioid peptides from gluten.

A bi-functional IL-6-HaloTag® as a tool to measure the cell-surface expression of recombinant odorant receptors and to facilitate their activity quantification.

The functional cell surface expression of recombinant odorant receptors typically has been investigated by expressing N-terminally extended, “tagged” receptors in test cell systems, using antibody-based immunocytochemistry or flow cytometry, and by measuring odorant/receptor-induced cAMP signaling, mostly by an odorant/receptor-induced and cAMP signaling-dependent transcriptional activation of a luciferase-based luminescence assay. In the present protocol, we explain a method to measure the cell-surface expression and signaling of recombinant odorant receptors carrying a bi-functional, N-terminal ‘IL-6-HaloTag®’. IL-6, being a secreted cytokine, facilitates functional cell surface expression of recombinant HaloTag®-odorant receptors, and the HaloTag® protein serves as a highly specific acceptor for cell-impermeant or cell-permeant, fluorophore-coupled ligands, which enable the quantification of odorant receptor expression by antibody-independent, chemical live-cell staining and flow cytometry. Here, we describe how to measure the cell surface expression of recombinant IL-6-HaloTag®-odorant receptors in HEK-293 cells or NxG 108CC15 cells, by live-cell staining and flow cytometry, and how to measure an odorant-induced activation of these receptors by the fast, real-time, luminescence-based GloSensor® cAMP assay.

Synthesis of Photoswitchable Δ9-Tetrahydrocannabinol Derivatives Enables Optical Control of Cannabinoid Receptor 1 Signaling.

The cannabinoid receptor 1 (CB1) is an inhibitory G protein-coupled receptor abundantly expressed in the central nervous system. It has rich pharmacology and largely accounts for the recreational use of cannabis. We describe efficient asymmetric syntheses of four photoswitchable Δ9-tetrahydrocannabinol derivatives (azo-THCs) from a central building block 3-Br-THC. Using electrophysiology and a FRET-based cAMP assay, two compounds are identified as potent CB1 agonists that change their effect upon illumination. As such, azo-THCs enable CB1-mediated optical control of inwardly rectifying potassium channels, as well as adenylyl cyclase.

Hyaluronate – parathyroid hormone peptide conjugate for transdermal treatment of osteoporosis

Human parathyroid hormone 1–34 fragment (PTH1–34) has been used as a FDA-approved therapeutics to treat osteoporosis by daily subcutaneous injection. In this work, we successfully developed PTH1–34 conjugated hyaluronic acid (HA) for the transdermal treatment of osteoporosis with improved patient compliance. HA-PTH1–34 conjugate was synthesized by the coupling reaction between aldehyde group introduced to HA and amine group of PTH1–34. After characterization by gel permeation chromatography (GPC) and ELISA, the biological effect of HA-PTH1–34 conjugate on the proliferation of human osteoblast cells was confirmed by in vitro calcium colorimetric assay and cAMP assay. Two-photon microscopy clearly visualized the effective skin penetration of FITC modified HA-PTH1–34 conjugate. The transdermally delivered HA-PTH1–34 conjugates elevated the blood calcium concentration for more than 2 days, reflecting the feasibility for the treatment of osteoporosis.

A novel homozygous mutation in the FSHR gene is causative for primary ovarian insufficiency

To identify the potential FSHR mutation in a Chinese woman with primary ovarian insufficiency (POI). Genetic and functional studies. University-based reproductive medicine center. A POI patient, her family members, and another 192 control women with regular menstruation. Ovarian biopsy was performed in the patient. Sanger sequencing was carried out for the patient, her sister, and parents. The novel variant identified was further confirmed with the use of control subjects. Sanger sequencing and genotype analysis to identify the potential variant of the FSHR gene; hematoxylin and eosin staining of the ovarian section to observe the follicular development; Western blotting and immunofluorescence to detect FSH receptor (FSHR) expression; and cyclic adenosine monophosphate (cAMP) assay to monitor FSH-induced signaling. Histologic examination of the ovaries in the patient revealed follicular development up to the early antral stage. Mutational screening and genotype analysis of the FSHR gene identified a novel homozygous mutation c.175C>T (p.R59X) in exon 2, which was inherited in the autosomal recessive mode from her heterozygous parents but was absent in her sister and the 192 control women. Functional studies demonstrated that invitro the nonsense mutation caused the loss of full-length FSHR expression and that p.R59X mutant showed no response to FSH stimulation in the cAMP level. The mutation p.R59X in FSHR is causative for POI by means of arresting folliculogenesis.

EXTH-43. DIFFERENTIATED PHARMACOLOGY OF THE IMIPRIDONE ONC201, THE FIRST SELECTIVE DRD2/3 ANTAGONIST IN CLINICAL NEURO-ONCOLOGY

ONC201, founding member of the imipridone class of compounds, has demonstrated evidence of tumor shrinkage along with exceptional safety in recurrent glioblastoma patients. In this study, we identified and characterized a previously unknown binding target of ONC201. BANDIT – a machine learning-based drug target identification platform – predicted that ONC201 would bind with high selectivity to the G-protein coupled receptors (GPCRs) dopamine receptor D2(DRD2) and D3 (DRD3). DRD2 is overexpressed in glioblastoma, controls pro-survival mechanisms, and its antagonism causes pro-apoptotic effects in malignant cells. PathHunter® β-arrestin and cAMP assays determined that ONC201 selectively antagonizes DRD2 and DRD3. Consistent with BANDIT and in contrast to DRD2 blocking antipsychotics, ONC201 did not antagonize other dopamine receptors or other closely related GPCRs with identified endogenous ligands. Schild analyses and radioligand competition assays revealed DRD2 affinities that were consistent with those identified for ONC201 anticancer activity. In accordance with superior selectivity, ONC201 exhibited a wider therapeutic window compared to other antipsychotics. In support of the hypothesis that selectively targeting D2-like receptors yields superior anti-cancer efficacy, combined DRD2/DRD1 inhibition was found to be inferior to DRD2 inhibition alone. ONC201 exhibited a very slow association rate for DRD2 relative to antipsychotics, whereas the dissociation rate was similar to atypical antipsychotics that are better tolerated clinically. Shotgun mutagenesis across 350 amino acids of DRD2 identified 8 residues critical for ONC201-mediated antagonism of DRD2-induced calcium flux. Several residues were not conserved among other dopamine receptors, suggesting a potential role in conferring ONC201 selectivity. Consistent with competitive inhibition, several mutated residues were within the orthosteric binding site (OBS), however, two distal residues were identified outside of the OBS suggesting a secondary binding pocket. In summary, receptor pharmacology of ONC201, the first selective DRD2/3 antagonist in clinical neuro-oncology, may explain its unique selectivity, safety, and anti-cancer activity in clinical trials.

Standard Curves Are Necessary to Determine Pharmacological Properties for Ligands in Functional Assays Using Competition Binding Technologies.

Homogeneous functional assays that utilize competition binding technology are widely used for determining pharmacological properties such as intrinsic activity and potency. One example is time-resolved fluorescence resonance energy transfer (TR-FRET) 3',5'-cyclic adenosine monophosphate (cAMP) assays, where labeled cAMP (tracer) and a labeled anti-cAMP antibody bind together to produce a TR-FRET signal when the two constituents are proximal to each other. This signal is disrupted when unlabeled and cellularly generated cAMP competes with the tracer cAMP for binding to the labeled antibody. It is important that the resulting assay signal, usually expressed as a TR-FRET ratio, be transformed to cAMP concentration using a cAMP standard curve. However, examples are still generated in the literature wherein investigators have used the ratiometric signal (not transformed using a standard curve) to determine values for intrinsic activity and potency of ligands. Untransformed raw data often produce reasonable looking sigmoidal concentration response curves, perhaps tempting investigators to use the raw data instead of the transformed data for applying pharmacological models. In this article, we describe the correct procedure for determining the potency and intrinsic activity of ligands that result in changes in cAMP levels using a lysate dilution assay of GLP-1 (7-36)-mediated TR-FRET cAMP accumulation and simulated data. We also highlight how the inappropriate use of raw signal data can dramatically affect interpretation of intrinsic activity and potency of ligands, and how this can adversely affect drug discovery programs. These findings apply not only to cAMP functional assays but also to other functional cellular signaling assays that utilize competition binding technologies.

Rac1 plays a role in CXCL12 but not CCL3-induced chemotaxis and Rac1 GEF inhibitor NSC23766 has off target effects on CXCR4

Cell migration towards a chemotactic stimulus relies on the re-arrangement of the cytoskeleton, which is triggered by activation of small G proteins RhoA, Rac1 and Cdc42, and leads to formation of lamellopodia and actin polymerisation amongst other effects. Here we show that Rac1 is important for CXCR4 induced chemotaxis but not for CCR1/CCR5 induced chemotaxis. For CXCL12-induced migration via CXCR4, breast cancer MCF-7 cells are reliant on Rac1, similarly to THP-1 monocytes and Jurkat T-cells. For CCL3-induced migration via CCR1 and/or CCR5, Rac1 signalling does not regulate cell migration in either suspension or adherent cells. We have confirmed the involvement of Rac1 with the use of a specific Rac1 blocking peptide. We also used a Rac1 inhibitor EHT 1864 and a Rac1-GEF inhibitor NSC23766 to probe the importance of Rac1 in chemotaxis. Both inhibitors did not block CCL3-induced chemotaxis, but they were able to block CXCL12-induced chemotaxis. This confirms that Rac1 activation is not essential for CCL3-induced migration, however NSC23766 might have secondary effects on CXCR4. This small molecule exhibits agonistic features in internalisation and cAMP assays, whereas it acts as an antagonist for CXCR4 in migration and calcium release assays. Our findings strongly suggest that Rac1 activation is not necessary for CCL3 signalling, and reveal that NSC23766 could be a novel CXCR4 receptor ligand.

In search of a small molecule agonist of the relaxin receptor RXFP1 for the treatment of liver fibrosis

The peptide hormone human relaxin-2 (H2-RLX) has emerged as a potential therapy for cardiovascular and fibrotic diseases, but its short in vivo half-life is an obstacle to long-term administration. The discovery of ML290 demonstrated that it is possible to identify small molecule agonists of the cognate G-protein coupled receptor for H2-RLX (relaxin family peptide receptor-1 (RXFP1)). In our efforts to generate a new medicine for liver fibrosis, we sought to identify improved small molecule functional mimetics of H2-RLX with selective, full agonist or positive allosteric modulator activity against RXFP1. First, we confirmed expression of RXFP1 in human diseased liver. We developed a robust cellular cAMP reporter assay of RXFP1 signaling in HEK293 cells transiently expressing RXFP1. A high-throughput screen did not identify further specific agonists or positive allosteric modulators of RXFP1, affirming the low druggability of this receptor. As an alternative approach, we generated novel ML290 analogues and tested their activity in the HEK293-RXFP1 cAMP assay and the human hepatic cell line LX-2. Differences in activity of compounds on cAMP activation compared with changes in expression of fibrotic markers indicate the need to better understand cell- and tissue-specific signaling mechanisms and their disease-relevant phenotypes in order to enable drug discovery.

The type VI adenylyl cyclase protects cardiomyocytes from \u03b2-adrenergic stress by a PKA/STAT3-dependent pathway

BackgroundThe type VI adenylyl cyclase (AC6) is a main contributor of cAMP production in the heart. The amino acid (aa) sequence of AC6 is highly homologous to that of another major cardiac adenylyl cyclase, AC5, except for its N-terminus (AC6-N, aa 1–86). Activation of AC6, rather than AC5, produces cardioprotective effects against heart failure, while the underlying mechanism remains to be unveiled. Using an AC6-null (AC6−/−) mouse and a knockin mouse with AC6-N deletion (AC6 ΔN/ΔN), we aimed to investigate the cardioprotective mechanism of AC6 in the heart.MethodsWestern blot analysis and immunofluorescence staining were performed to determine the intracellular distribution of AC6, AC6-ΔN (a truncated AC6 lacking the first 86 amino acids), and STAT3 activation. Activities of AC6 and AC6-ΔN in the heart were assessed by cAMP assay. Apoptosis of cardiomyocytes were evaluated by the TUNEL assay and a propidium iodine-based survival assay. Fibrosis was examined by collagen staining.ResultsImmunofluorescence staining revealed that cardiac AC6 was mainly anchored on the sarcolemmal membranes, while AC6-ΔN was redistributed to the sarcoplasmic reticulum. AC6ΔN/ΔN and AC6−/− mice had more apoptotic myocytes and cardiac remodeling than WT mice in experimental models of isoproterenol (ISO)-induced myocardial injury. Adult cardiomyocytes isolated from AC6ΔN/ΔN or AC6−/− mice survived poorly after exposure to ISO, which produced no effect on WT cardiomyocytes under the condition tested. Importantly, ISO treatment induced cardiac STAT3 phosphorylation/activation in WT mice, but not in AC6ΔN/ΔN and AC6−/− mice. Pharmacological blockage of PKA-, Src-, or STAT3- pathway markedly reduced the survival of WT myocytes in the presence of ISO, but did not affect those of AC6ΔN/ΔN and AC6−/− myocytes, suggesting an important role of AC6 in mediating cardioprotective action through the activation of PKA-Src-STAT3-signaling.ConclusionsCollectively, AC6-N controls the anchorage of cardiac AC6 on the sarcolemmal membrane, which enables the coupling of AC6 with the pro-survival PKA-STAT3 pathway. Our findings may facilitate the development of novel therapies for heart failure.

Discovery of Novel Proline-Based Neuropeptide FF Receptor Antagonists.

The neuropeptide FF (NPFF) system has been implicated in a number of physiological processes including modulating the pharmacological activity of opioid analgesics and several other classes of drugs of abuse. In this study, we report the discovery of a novel proline scaffold with antagonistic activity at the NPFF receptors through a high throughput screening campaign using a functional calcium mobilization assay. Focused structure-activity relationship studies on the initial hit 1 have resulted in several analogs with calcium mobilization potencies in the submicromolar range and modest selectivity for the NPFF1 receptor. Affinities and potencies of these compounds were confirmed in radioligand binding and functional cAMP assays. Two compounds, 16 and 33, had good solubility and blood-brain barrier permeability that fall within the range of CNS permeant candidates without the liability of being a P-glycoprotein substrate. Finally, both compounds reversed fentanyl-induced hyperalgesia in rats when administered intraperitoneally. Together, these results point to the potential of these proline analogs as promising NPFF receptor antagonists.

Abstract 1683: A novel adenosine A2A receptor antagonist optimized for high potency in adenosine-rich tumor microenvironment boosts antitumor immunity

Abstract High levels of extracellular adenosine in the tumor microenvironment are known to play a significant role in tumor immune evasion and promote tumor growth and metastasis. We defined the receptor(s) required for mediating the effect of adenosine on immune cells within the tumor microenvionment and report the characterization of a novel Immuno-Oncology-dedicated adenosine receptor 2A antagonist that functions in the high adenosine concentration found in tumors. We first explored the expression of the four adenosine receptors in primary human immune cells. A2A receptor was the main adenosine receptor expressed by CD4 and CD8 T lymphocytes and monocytes, and the only one in mature monocyte-derived dendritic cells and NK cells. A2B receptor was poorly detected in T cells and monocytes, while A1 and A3 receptors were never detected. Given these expression patterns, we further studied A2A functions in primary human T lymphocytes and monocytes. Selective A2A agonists such as CGS-21680 strongly suppressed cytokine production by activated primary human T lymphocytes, thus highlighting that A2A is the main effector receptor of the sensing of adenosine in tumors. We further confirmed the elevated extracellular adenosine level in the tumor microenvironment in several mouse and human tumors. High adenosine levels correlated with strong tumoral expression of CD73, the enzyme that converts AMP to adenosine. Interestingly, we showed that A2A receptor antagonists designed for Parkinson’s disease dramatically lost potency in a high adenosine environment ; our data indicated that a 30-fold dose increase may be required for full target inhibition within tumors. Therefore we developed a novel and potent A2A blocker with sub-nanomolar Ki and IC50 in a cAMP assay and a more than 100-fold selectivity over other adenosine receptors. Our lead compound kept a high potency in an adenosine-rich environment and restored cytokine production even in the presence of high concentrations of A2A agonists. iTeos inhibitor also efficiently reversed AMP-mediated T cell suppression. Furthermore, our compound rescued A2A receptor agonist-induced decrease of TNFα production by primary human monocytes, and was able to potently increase CD8 T cell cytotoxicity in a cytotoxicity assay with CD8 T cells as effectors and cancer cells as targets. These results suggest that iTeos new generation of A2A receptor antagonist, designed to keep a high potency in the adenosine-rich tumor microenvironment, may offer a new therapeutic opportunity in Immuno-Oncology. Citation Format: Erica Houthuys, Margreet Brouwer, Florence Nyawouame, Romain Pirson, Reece Marillier, Theo Deregnaucourt, Joao Marchante, Jakub Swiercz, Charlotte Moulin, Vanesa Bol, Gregory Driessens, Michel Detheux, Christophe Quéva, Stefano Crosignani, Bruno Gomes. A novel adenosine A2A receptor antagonist optimized for high potency in adenosine-rich tumor microenvironment boosts antitumor immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1683. doi:10.1158/1538-7445.AM2017-1683

Abstract 5223: Differentiated receptor pharmacology of imipridone ONC201: The first DRD2 antagonist in clinical development for oncology

Abstract ONC201 is the founding member of the imipridone class of compounds which selectively target G protein-coupled receptors (GPCRs). ONC201, currently in clinical trials, possesses an exceptional safety profile combined with anti-cancer effects that are driven by activation of the integrated stress response and inhibition of Ras signaling. In this study, we identified and characterized the previously unknown binding target of ONC201. Following its phenotypic discovery, a series of experiments indicated that ONC201 does not directly interact with many known cancer drug targets. BANDIT - a machine learning based drug target identification platform - predicted that ONC201 selectively antagonizes the GPCR dopamine receptor D2 (DRD2). DRD2 is overexpressed in many cancers, controls various pro-survival mechanisms including Ras signaling and stress pathways, and its antagonism causes anti-proliferative and pro-apoptotic effects in malignant cells. PathHunter® β-Arrestin and cAMP assays determined that ONC201 selectively antagonizes DRD2 and DRD3. Antipsychotics antagonize multiple dopamine receptor family members that belong to either the D1-like or D2-like subfamilies that cause opposing downstream effects. Consistent with BANDIT, in contrast to antipsychotics, ONC201 did not antagonize other dopamine receptors or other GPCRs with known ligands. Schild analysis and radioligand competition assays revealed a DRD2 affinity of ~3uM, consistent with ONC201 anticancer activity. In accordance with superior selectivity of ONC201 among the GPCR superfamily, ONC201 exhibited a wide therapeutic window in tumor versus normal cell viability assays compared to antipsychotics. In support of the hypothesis that selectively targeting D2-like receptors yields superior anti-cancer efficacy, combined DRD2/DRD1 inhibition with tool compounds was inferior to DRD2 inhibition alone. Further characterization revealed that ONC201 had a very slow association rate for DRD2 relative to antipsychotics, whereas the dissociation rate was similar to atypical antipsychotics that are well tolerated. Shotgun mutagenesis alanine scan mapping across 350 amino acids of DRD2 identified 8 residues critical for ONC201-mediated antagonism of dopamine-induced calcium flux. Several of these residues were not conserved among the dopamine receptor family and the residue with the largest effect is not conserved in any other family member, suggesting the basis of ONC201 specificity. Consistent with competitive inhibition, several residues were within the orthosteric binding site, however, two allosteric residues were also identified. In summary, ONC201 is the first DRD2 antagonist under clinical development for oncology and its differentiated receptor pharmacology explains its unique selectivity, anti-cancer activity, and safety that has been observed in clinical trials. Citation Format: Neel Madhukar, Varun Vijay Prabhu, Lakshmi Anantharaman, Chidananda Sulli, Edgar Davidson, Sean Deacon, Rohinton Tarapore, Joseph Rucker, Neil Charter, Banjamin Doranz, Wolfgang Oster, Olivier Elemento, Joshua Allen. Differentiated receptor pharmacology of imipridone ONC201: The first DRD2 antagonist in clinical development for oncology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5223. doi:10.1158/1538-7445.AM2017-5223

Synthesis and evaluation of (E)-2-(5-phenylpent-2-en-4-ynamido)cyclohex-1-ene-1-carboxylate derivatives as HCA2 receptor agonists

Novel series of compounds consisting of 2-amidocyclohex-1-ene carboxylate and phenyl parts which are connected by enyne (compounds 2a–f), but-1-yne (compounds 4a–j), and phenylethylene (compounds 5a–f) linkers as HCA2 full agonists were designed and their functional activity using cAMP assay and binding affinity using radioligand (3H-niacin) binding assay were evaluated. In general, compounds of all three series exhibit similar HCA2 binding and activation profile. However, the activity is strongly dependent on the substituent at the aromatic part of the structure. Among the structures evaluated, the highest affinity and potency in all series were exhibited by compounds containing 4-hydroxy and/or 2-chloro or 2-fluoro substituents. The most active compounds in the enyne and but-1-yne series in the cAMP assay are 2-fluoro,4-hydroxy and 2-chloro,4-hydroxy phenyl derivatives 2f, 4f, and 4g showing potency similar to the previously described 4-hydroxy-biphenyl analogue 5c.