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Ji R.,University of Arizona | Chou C.-L.,University of Arizona | Xu W.,University of Arizona | Chen X.-B.,University of Arizona | And 2 more authors.
Molecular Pharmacology

The EP1 prostanoid receptor is one of four subtypes whose cognate physiological ligand is prostaglandin-E2 (PGE2). It is in the family of G-protein-coupled receptors and is known to activate Ca2+ signaling, although relatively little is known about other aspects of E-type prostanoid receptor (EP) 1 receptor signaling. In human embryonic kidney (HEK) cells expressing human EP1 receptors, we now show that PGE2 stimulation of the EP1 receptor up-regulates the expression of hypoxia-inducible factor-1α (HIF-1α), which can be completely blocked by pertussis toxin, indicating coupling to Gi/o. This up-regulation of HIF-1α occurs under normoxic conditions and could be inhibited with wortmannin, Akt inhibitor, and rapamycin, consistent with the activation of a phosphoinositide-3 kinase/Akt/mammalian target of rapamycin (mTOR) signaling pathway, respectively. In contrast to the hypoxia-induced up-regulation of HIF-1α, which involves decreased protein degradation, the up-regulation of HIF-1α by the EP1 receptor was associated with the phosphorylation of ribosomal protein S6 (rpS6), suggesting activation of the ribosomal S6 kinases and increased translation. Stimulation of endogenous EP1 receptors in human HepG2 hepatocellular carcinoma cells recapitulated the normoxic up-regulation of HIF-1α observed in HEK cells, was sensitive to pertussis toxin, and involved the activation of mTOR signaling and phosphorylation of rpS6. In addition, treatment of HepG2 cells with sulprostone, an EP1-selective agonist, up-regulated the mRNA expression of vascular endothelial growth factor-C, a HIF-regulated gene. HIF-1α is known to promote tumor growth and metastasis and is often up-regulated in cancer. Our findings provide a potential mechanism by which increased PGE2 biosynthesis could up-regulate the expression of HIF-1α and promote tumorigenesis. Copyright © 2010 The American Society for Pharmacology and Experimental Therapeutics. Source

Konishi N.,Takeda Pharmaceutical | Hiroe K.,Takeda Pharmaceutical | Kawamura M.,Biological Science Inc.
Journal of Cardiovascular Pharmacology

Endothelial damage triggers platelet adhesion and platelet-associated prothrombinase formation at the point of injury, resulting in the progression of thrombus formation. The present study compared the inhibitory effects of fondaparinux, an indirect factor Xa (FXa) inhibitor, and TAK-442, a direct FXa inhibitor, on platelet-associated prothrombinase activity in the balloon-injured rat artery. TAK-442 and fondaparinux inhibited endogenous FXa activity in platelet-poor human [half-maximal inhibitory concentration (IC 50): 53 nM, TAK-442; 11 nM, fondaparinux] and rat (IC 50: 32 nM, TAK-442; 19 nM, fondaparinux) plasma. TAK-442 inhibited in vitro reconstituted human prothrombinase (system included FXa, calcium, and washed platelets) with an IC 50 value of 51 nM, whereas fondaparinux exhibited only weak inhibition (IC 50: 1700 nM). In a rat model of balloon injury, thrombin activity on the surface of injured vessels increased to 3.2-, 22-, and 5.8-fold the activity on the surface of the intact aorta at 5 minutes, 1 hour, and 24 hours after the injury, respectively. At approximately 1 hour after the injury, TAK-442 blocked platelet-associated thrombin generation on the surface of injured aortas with an IC 50 value of 19 nM, whereas fondaparinux showed no significant inhibition at the highest concentration tested (IC 50: >300 nM). These results suggest a possible limitation of fondaparinux in inhibiting platelet-associated prothrombinase activity and resultant thrombus formation as compared with TAK-442. Copyright © 2011 by Lippincott Williams & Wilkins. Source

Stern M.E.,Biological Science Inc.
Investigative ophthalmology & visual science

The purpose of this study was to determine if autoantibodies play a role in the immunopathogenesis of experimental dry eye disease. Dry eye was induced by exposing female C57BL/6 wild-type mice or hen egg lysozyme B-cell receptor transgenic mice to desiccating stress (subcutaneous scopolamine [0.5 mg/0.2 mL] 3 times a day, humidity < 40%, and sustained airflow) for 3 weeks, allowing sufficient time for a humoral immune response. Serum or purified IgG isolated from dry-eye mice or untreated controls was passively transferred to nude recipient mice, which were evaluated for ocular surface inflammation 3 days after transfer. To determine if complement activation contributed to serum-induced dry eye disease, cobra venom factor was used to deplete complement activity. Autoantibodies against kallikrein 13 were identified in serum from dry-eye mice, but were undetectable in untreated controls. Autoantibody-containing serum or purified IgG from dry-eye mice was sufficient to mediate complement-dependent ocular surface inflammation. Serum or purified IgG caused marked inflammatory burden and tissue damage within the ocular surface tissues, including elevated Gr1+ neutrophil infiltration and proinflammatory cytokines/chemokines associated with goblet cell loss. Moreover, complement C3b deposition was found within the ocular surface tissues of mice receiving dry-eye serum, but not in recipients of control serum. Functionally, complement depletion attenuated the ability to transfer dry-eye-specific serum or IgG-mediated disease. These data demonstrate for the first time a complement-dependent pathogenic role of dry-eye-specific autoantibodies, and suggest autoantibody deposition within the ocular surface tissues contributes to the predominantly T-cell-mediated immunopathogenesis of dry eye disease. Source

Chen J.,Biological Science Inc. | Runyan S.A.,Biological Science Inc. | Robinson M.R.,Allergan, Inc.
Clinical Ophthalmology

Introduction: Glaucoma is a multiflactorial disease characterized by progressive optic nerve injury and visual field defects. Elevated intraocular pressure (IOP) is the most widely recognized risk factor for the onset and progression of open-angle glaucoma, and IOP-lowering medications comprise the primary treatment strategy. IOP elevation in glaucoma is associated with diminished or obstructed aqueous humor outflow. Pharmacotherapy reduces IOP by suppressing aqueous inflow and/or increasing aqueous outflow. Purpose: This review focuses on novel non-FDA approved ocular antihypertensive compounds being investigated for IOP reduction in ocular hypertensive and glaucoma patients in active clinical trials within approximately the past 2 years. Methods: The mode of IOP reduction, pharmacology, efficacy, and safety of these new agents were assessed. Relevant drug efficacy and safety trials were identified from searches of various scientific literature databases and clinical trial registries. Compounds with no specified drug class, insufficient background information, reformulations, and fixed-combinations of marketed drugs were not considered. Results: The investigational agents identified comprise those that act on the same targets of established drug classes approved by the FDA (ie, prostaglandin analogs and β-adrenergic blockers) as well as agents belonging to novel drug classes with unique mechanisms of action. Novel targets and compounds evaluated in clinical trials include an action polymerization inhibitor (ie, latrunculin), Rho-associated protein kinase inhibitors, adenosine receptor analogs, an angiotension II type 1 receptor antagonist, cannabinoid receptor agonists, and a serotonin receptor antagonist. Conclusion: The clinical value of novel compounds for the treatment of glaucoma will depend ultimately on demonstrating favorable efficacy and benefit-to-risk ratios relative to currently approved prostaglandin analogs and β-blockers and/or having complementary modes of action. © 2011 Chen et al, publisher and licensee Dove Medical Press Ltd. Source

Wang J.W.,Biological Science Inc. | Woodward D.F.,Biological Science Inc. | Stamer W.D.,Duke University
Investigative Ophthalmology and Visual Science

PURPOSE. The goal of this study was to functionally compare prostaglandin E2 (PGE2)-sensitive receptors in human primary cells involved in conventional outflow. METHODS. The expression profile of prostaglandin (PG) receptors in primary cultures of human trabecular meshwork (TM) and Schlemm's canal (SC) cells were determined by quantitative-PCR. The functional activities of endogenous PGE2-sensitive receptors were evaluated using subtype-selective agonists and antagonists with cell impedance technology. RESULTS. Agonist-sensitive EP1, EP2, and EP4 receptors were present in TM cells, all increasing cell stiffness (or contractility) in a dose-dependent manner. Rank order of efficacy (Emax) for agonists in TM cells were EP1 greater than EP2 greater than EP4 with EC50 1.1 μM, 0.56 μM, and 0.1 μM, respectively, and no functional EP3 receptors were found. Of the four EP receptor subtypes active in SC cells, EP1 and EP3 receptor activation increased cell stiffness, while EP2 and EP4 agonists dose-dependently decreased cell stiffness 47% and 23% with EC50 values of 170 nM and 69 nM, respectively. Consistent with these observations, the Rho kinase inhibitor Y-27632 decreased cell impedance (stiffness) of TM and SC cells (~60%), while Rho GTPase activator thrombin caused cell impedance to increase in both cell types (168%-190%). CONCLUSIONS. Cell impedance positively correlates with cellular stiffness/contractility. Because EP2/4 receptors caused decreased cell stiffness in SC, but not in TM cells, both receptors appear to mediate IOP lowering via changes in SC cell stiffness in the conventional outflow pathway. © 2013 The Association for Research in Vision and Ophthalmology, Inc. Source

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