Distribution of the inositol 1,4,5-trisphosphate receptor, P400, in adult rat brain

The distribution of the inositol 1,4,5-trisphosphate receptor protein, P400, was investigated in adult rat brain by immunocytochemistry with the monoclonal antibody 4C11 raised against mouse cerebellar inositol 1,4,5- trisphosphate receptor protein. Immunoreactive neuronal cell bodies were detected in the cerebral cortex, the claustrum, the endopiriform nucleus, the corpus callosum, the anterior olfactory nuclei, the olfactory tubercle, the nucleus accumbens, the lateral septum, the bed nucleus of the stria terminalis, the hippocampal formation, the dentate gyrus, the caudate- putamen, the fundus striatum, the amygdaloid complex, the thalamus, the caudolateral part of the hypothalamus, the supramammillary nuclei, the substantia nigra, the pedunculopontine tegmental nucleus, the ventrotegmental area, the Purkinje cells in the cerebellum, the dorsal cochlear nucleus, the subnucleus oralis and caudalis of trigeminal nerve, and the dorsal horn of the spinal cord. Immunoreactive fibres were found in the medial forebrain bundle, the globus pallidus, the stria terminalis, the pyramidal tract, the spinal tract of trigeminal nerve, and the ventral horn of spinal cord. Nerve fibres forming a dense plexus ending in terminal-like boutons were detected in relation to nonimmunoreactive neurons of the dentate, interpositus, and fastigial nuclei of the cerebellum and around neurons of the vestibular nuclei. This receptor protein binds a specific second messenger, inositol 1,4,5-trisphosphate, which produces a mobilization of intracellular Ca2+ and a modulation of transmitter release.Peer Reviewe

Discovery of ONO-7300243 from a Novel Class of Lysophosphatidic Acid Receptor 1 Antagonists: From Hit to Lead

Lysophosphatidic acid (LPA) evokes various physiological responses through a series of G protein-coupled receptors known as LPA_1–6. A high throughput screen against LPA₁ gave compound <b>7a</b> as a hit. The subsequent optimization of <b>7a</b> led to <b>ONO-7300243</b> (<b>17a</b>) as a novel, potent LPA₁ antagonist, which showed good efficacy <i>in vivo</i>. The oral dosing of <b>17a</b> at 30 mg/kg led to reduced intraurethral pressure in rats. Notably, this compound was equal in potency to the α₁ adrenoceptor antagonist tamsulosin, which is used in clinical practice to treat dysuria with benign prostatic hyperplasia (BPH). In contrast to tamsulosin, compound <b>17a</b> had no impact on the mean blood pressure at this dose. These results suggest that LPA₁ antagonists could be used to treat BPH without affecting the blood pressure. Herein, we report the hit-to-lead optimization of a unique series of LPA₁ antagonists and their <i>in vivo</i> efficacy

A Novel Highly Potent Autotaxin/ENPP2 Inhibitor Produces Prolonged Decreases in Plasma Lysophosphatidic Acid Formation <i>In Vivo</i> and Regulates Urethral Tension

<div><p>Autotaxin, also known as ectonucleotide pyrophosphatase/phosphodiesterase 2 (ENPP2), is a secreted enzyme that has lysophospholipase D activity, which converts lysophosphatidylcholine to bioactive lysophosphatidic acid. Lysophosphatidic acid activates at least six G-protein coupled recpetors, which promote cell proliferation, survival, migration and muscle contraction. These physiological effects become dysfunctional in the pathology of cancer, fibrosis, and pain. To date, several autotaxin/ENPP2 inhibitors have been reported; however, none were able to completely and continuously inhibit autotaxin/ENPP2 <i>in vivo</i>. In this study, we report the discovery of a highly potent autotaxin/ENPP2 inhibitor, ONO-8430506, which decreased plasma lysophosphatidic acid formation.</p><p>The IC₅₀ values of ONO-8540506 for lysophospholipase D activity were 6.4–19 nM for recombinant autotaxin/ENPP2 proteins and 4.7–11.6 nM for plasma from various animal species. Plasma lysophosphatidic acid formation during 1-h incubation was almost completely inhibited by the addition of >300 nM of the compound to human plasma. In addition, when administered orally to rats at a dose of 30 mg/kg, the compound demonstrated good pharmacokinetics in rats and persistently inhibited plasma lysophosphatidic acid formation even at 24 h after administration.</p><p>Smooth muscle contraction is a known to be promoted by lysophosphatidic acid. In this study, we showed that dosing rats with ONO-8430506 decreased intraurethral pressure accompanied by urethral relaxation. These findings demonstrate the potential of this autotaxin/ENPP2 inhibitor for the treatment of various diseases caused by lysophosphatidic acid, including urethral obstructive disease such as benign prostatic hyperplasia.</p></div

mTOR Inhibitors Control the Growth of EGFR Mutant Lung Cancer Even after Acquiring Resistance by HGF

<div><p>Resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), gefitinib and erlotinib, is a critical problem in the treatment of <i>EGFR</i> mutant lung cancer. Several mechanisms, including bypass signaling by hepatocyte growth factor (HGF)-triggered Met activation, are implicated as mediators of resistance. The mammalian target of rapamycin (mTOR), is a downstream conduit of EGFR and MET signaling, and is thus considered a therapeutically attractive target in the treatment of various types of cancers. The purpose of this study was to examine whether 2 clinically approved mTOR inhibitors, temsirolimus and everolimus, overcome HGF-dependent resistance to EGFR-TKIs in <i>EGFR</i> mutant lung cancer cells. Both temsirolimus and everolimus inhibited the phosphorylation of p70S6K and 4E-BP1, which are downstream targets of the mTOR pathway, and reduced the viability of <i>EGFR</i> mutant lung cancer cells, PC-9, and HCC827, even in the presence of HGF <i>in vitro</i>. In a xenograft model, temsirolimus suppressed the growth of PC-9 cells overexpressing the <i>HGF</i>-gene; this was associated with suppression of the mTOR signaling pathway and tumor angiogenesis. In contrast, erlotinib did not suppress this signaling pathway or tumor growth. Multiple mechanisms, including the inhibition of vascular endothelial growth factor production by tumor cells and suppression of endothelial cell viability, contribute to the anti-angiogenic effect of temsirolimus. These findings indicate that mTOR inhibitors may be useful for controlling HGF-triggered EGFR-TKI resistance in <i>EGFR</i> mutant lung cancer, and they provide the rationale for clinical trials of mTOR inhibitors in patients stratified by <i>EGFR</i> mutation and HGF expression status.</p></div