Suppression of hypothalamic-pituitary-gonadal function by linzagolix in benign prostatic hyperplasia and polycystic ovary syndrome animal models.

The hypothalamic-pituitary-gonadal (HPG) axis is an important regulatory mechanism involved primarily in the development and regulation of the reproductive systems. The suppression of the HPG axis by gonadotropin-releasing hormone (GnRH) analogues is expected to be effective for the treatment of sex hormone-dependent diseases, such as endometriosis, uterine fibroid, prostate cancer, benign prostatic hyperplasia (BPH) and polycystic ovary syndrome (PCOS). Despite the established involvement of GnRH signalling in these disorders, the therapeutic efficacy of small molecular GnRH antagonists for BPH and PCOS has not been adequately evaluated in non-clinical studies. Therefore, the purpose of the present study was to evaluate the potential of linzagolix, a small molecular GnRH antagonist, as a potential new treatment option for BPH and PCOS. Dogs and rats exhibiting normal prostates and dogs diagnosed with prostatic hyperplasia were used to evaluate the effects of linzagolix in BPH. The effects of linzagolix were also examined in a rat model of PCOS induced by repeated administration of letrozole, an aromatase inhibitor. Linzagolix reduced serum luteinizing hormone and testosterone levels in male rats and normal or BPH model dogs and suppressed prostate weight without testosterone depletion, suggesting the existence of an optimal therapeutic testosterone level for BPH treatment. In a PCOS rat model, linzagolix improved both insulin resistance and ovarian dysfunction. Treatment with linzagolix decreased follicle-stimulating hormone levels, but did not alter serum luteinizing hormone and testosterone levels. These results indicate that linzagolix may provide a new treatment option for GnRH-related disorders, such as BPH and PCOS.

Suppressive effects of linzagolix, a novel non-peptide antagonist of gonadotropin-releasing hormone receptors, in experimental endometriosis model rats.

Endometriosis is an oestrogen-dependent disease in which endometrial-like tissue grows outside the uterus in women of reproductive age. Accordingly, control of oestradiol (E2) levels is an effective treatment for endometriosis. Because gonadotropin-releasing hormone (GnRH) is the main controller of E2 secretion, control of GnRH signalling by GnRH antagonism is an effective strategy for the treatment of sex hormone-dependent diseases such as endometriosis. The purpose of the present study was to evaluate the effects of the potent, orally available and selective GnRH antagonist linzagolix on experimental endometriosis in rats and compare them with those of dienogest, which is used clinically to treat endometriosis. Experimental endometriosis was induced in female rats at the proestrus stage of the oestrous cycle via autotransplantation of endometrial tissue into the renal subcapsular space. Linzagolix significantly decreased cyst volumes compared with the control group at doses of 50 mg/kg or more. Indeed, a suppressive effect of dienogest on cyst volume was observed only at the highest dose evaluated (1 mg/kg). The effective concentration of linzagolix, calculated as the free form of the last-observed drug concentration, was ~1 µmol/L in endometriosis model rats. The present study also reveals that linzagolix exerts a sustained inhibitory effect on E2 secretion, indicating that the suppressive effect on endometriosis cyst volumes could be attributed to its pharmacological suppression of GnRH signalling and serum E2 concentrations. Altogether, our findings indicate that linzagolix may be a useful therapeutic intervention for hormone-dependent diseases including endometriosis.

Pharmacological characterization of linzagolix, a novel, orally active, non-peptide antagonist of gonadotropin-releasing hormone receptors.

Control of gonadotropin-releasing hormone (GnRH) signalling is an effective strategy for the treatment of sex hormone-dependent diseases. GnRH analogues have been widely used for treating these diseases; however, initial stimulation or complete suppression of GnRH signalling by GnRH analogues results in the occurrence of several distinct adverse effects. Accordingly, we aimed to discover small molecule GnRH antagonists with superior pharmacokinetic and pharmacodynamic profiles. Linzagolix is a potent, orally available, and selective GnRH antagonist. Here, we reported the pharmacological characterization of linzagolix in vitro and in vivo. Linzagolix selectively binds to the GnRH receptor and inhibits GnRH-stimulated signalling, in a manner comparable to cetrorelix, a peptide GnRH antagonist. Because the inhibitory effect of the gonad axis is useful for the treatment of gynaecological conditions such as endometriosis and uterine fibroids, we investigated the effect of orally administrated linzagolix on the gonadal axis in ovariectomized and intact cynomolgus monkeys. In ovariectomized monkeys, linzagolix immediately suppressed the serum luteinizing hormone concentration at doses over 1 mg/kg, indicating dose-dependent inhibition that correlated with serum linzagolix concentrations. In intact female monkeys, repeated linzagolix administration suppressed hormone surges and ceased or prolonged menstrual cycles. Furthermore, all animals presenting arrested menstrual cycles following linzagolix treatment showed recovery of hormone secretion and regular menstrual cycles after administration periods ended. Our results demonstrated that linzagolix has potential as a novel agent for reproductive-age women suffering from sex hormone-dependent diseases.

First-in-human phase 1 of YS110, a monoclonal antibody directed against CD26 in advanced CD26-expressing cancers.

BACKGROUND: YS110 is a humanised IgG1 monoclonal antibody with high affinity to the CD26 antigen. YS110 demonstrated preclinical anti-tumour effects without significant side effects. METHODS: This FIH study was designed to determine the maximal tolerated dose (MTD) and recommended phase 2 dose (RP2D) to assess the tolerance, pharmacokinetics (PK) and pharmacodynamics profiles of YS110 and preliminary efficacy. YS110 were initially administered intravenously once every 2 weeks (Q2W) for three doses and then, based on PK data, once every week (Q1W) for five doses in patients with CD26-expressing solid tumours. RESULTS: Thirty-three patients (22 mesothelioma) received a median of 3 (range 1-30) YS110 infusions across six dose levels (0.1-6 mg kg-1). MTD was not reached and two dose-limiting toxicities (infusion hypersensitivity reactions) led to the institution of a systemic premedication. Low-grade asthenia (30.3%), hypersensitivity (27.3%), nausea (15.2%), flushing (15.2%), chills (12.1%) and pyrexia (12.1%) were reported as ADRs. Pharmacokinetic parameters (AUC and Cmax) increased in proportion with the dose. sCD26/DPPIV assays indicated CD26 modulation. Prolonged stable diseases were observed in 13 out of 26 evaluable patients. CONCLUSIONS: YS110 is well tolerated up to 6 mg kg-1 Q1W, which has been defined as the RP2D, with encouraging prolonged disease stabilisations observed in a number of patients with advanced/refractory mesothelioma.

Identification of Adenine and Benzimidazole Nucleosides as Potent Human Concentrative Nucleoside Transporter 2 Inhibitors: Potential Treatment for Hyperuricemia and Gout.

To test the hypothesis that inhibitors of human concentrative nucleoside transporter 2 (hCNT2) suppress increases in serum urate levels derived from dietary purines, we previously identified adenosine derivative 1 as a potent hCNT2 inhibitor (IC50 = 0.64 µM), but further study was hampered due to its poor solubility. Here we describe the results of subsequent research to identify more soluble and more potent hCNT2 inhibitors, leading to the discovery of the benzimidazole nucleoside 22, which is the most potent hCNT2 inhibitor (IC50 = 0.062 µM) reported to date. Compound 22 significantly suppressed the increase in plasma uric acid levels after oral administration of purine nucleosides in rats. Because compound 22 was poorly absorbed orally in rats (F = 0.51%), its pharmacologic action was mostly limited to the gastrointestinal tract. These findings suggest that inhibition of hCNT2 in the gastrointestinal tract can be a promising approach for the treatment of hyperuricemia.

Hypouricemic effects of novel concentrative nucleoside transporter 2 inhibitors through suppressing intestinal absorption of purine nucleosides.

We have developed concentrative nucleoside transporter 2 (CNT2) inhibitors as a novel pharmacological approach for improving hyperuricemia by inhibiting intestinal absorption of purines. Dietary purine nucleosides are absorbed in the small intestines by CNTs expressed in the apical membrane. In humans, the absorbed purine nucleosides are rapidly degraded to their final end product, uric acid, by xanthine oxidase. Based on the expression profile of human CNTs in digestive tract tissues, we established a working hypothesis that mainly CNT2 contributes to the intestinal absorption of purine nucleosides. In order to confirm this possibility, we developed CNT2 inhibitors and found that (2R,3R,4S,5R)-2-(6-amino-8-{[3'-(3-aminopropoxy)-biphenyl-4-ylmethyl]-amino}-9H-purin-9-yl)-5-hydroxymethyl-tetrahydrofuran-3,4-diol (KGO-2142) and 1-[3-(5-{[1-((2R,3R,4S,5R)-3,4-dihydroxy-5-hydroxymethyl-tetrahydrofuran-2-yl)-1H-benzimidazol-2-ylamino]-methyl}-2-ethoxyphenoxy)-propyl]-piperidine-4-carboxylic acid amide (KGO-2173) were inhibitory. These CNT2 inhibitors had potent inhibitory activity against inosine uptake via human CNT2, but they did not potently interfere with nucleoside uptake via human CNT1, CNT3 or equilibrative nucleoside transporters (ENTs) in vitro. After oral administration of KGO-2173 along with [(14)C]-inosine, KGO-2173 significantly decreased the urinary excretion of radioactivity at 6 and 24h in rats. Since dietary purine nucleosides are not utilized in the body and are excreted into the urine rapidly, this decrease in radioactivity in the urine represented the inhibitory activity of KGO-2173 toward the absorption of [(14)C]-inosine in the small intestines. KGO-2142 almost completely inhibited dietary RNA-induced hyperuricemia and the increase in urinary excretion of uric acid in cebus monkeys. These novel CNT2 inhibitors, KGO-2142 and KGO-2173, could be useful therapeutic options for the treatment of hyperuricemia.

The Delta intracellular domain mediates TGF-beta/Activin signaling through binding to Smads and has an important bi-directional function in the Notch-Delta signaling pathway.

Delta is a major transmembrane ligand for Notch receptor that mediates numerous cell fate decisions. The Notch signaling pathway has long been thought to be mono-directional, because ligands for Notch were generally believed to be unable to transmit signals into the cells expressing them. However, we showed here that Notch also supplies signals to neighboring mouse neural stem cells (NSCs). To investigate the Notch-Delta signaling pathway in a bi-directional manner, we analyzed functional roles of the intracellular domain of mouse Delta like protein 1 (Dll1IC). In developing mouse NSCs, Dll1IC, which is released from cell membrane by proteolysis, is present in the nucleus. Furthermore, we screened for transcription factors that bind to Dll1IC and demonstrated that Dll1IC binds specifically to transcription factors involved in TGF-beta/Activin signaling--Smad2, Smad3 and Smad4--and enhances Smad-dependent transcription. In addition, the results of the present study indicated that over-expression of Dll1IC in embryonic carcinoma P19 cells induced neurons, and this induction was blocked by SB431542, which is a specific inhibitor of TGF-beta/Activin signaling. These observations strongly suggested that Dll1IC mediates TGF-beta/Activin signaling through binding to Smads and plays an important role for bi-directional Notch-Delta signaling pathway.

Localization of a long-chain acyl-CoA hydrolase in spermatogenic cells in mice.

Brain acyl-CoA hydrolase (BACH) hydrolyzes long-chain acyl-CoAs to free fatty acids and CoA-SH. BACH is highly distributed in brain and is localized in neurons, but not glial cells. This suggests that BACH plays a specific role in neurons. BACH is also detected in testis, although the expression profile of BACH is unknown in testis. In this study, developmental changes and cellular distribution of BACH were examined in mouse testis. Before postnatal day (P) 10, BACH was detected at very low levels by Western blotting. Then, BACH content rapidly increased from P14 and reached maximum levels at P21, remaining high until at least P70. The increase in BACH content corresponded to the appearance of pachytene spermatocytes, which was confirmed by immunohistochemistry. BACH was also detectable in spermatids, but not in spermatogonia, mature spermatozoa. These results suggest that BACH is expressed in a cell-specific manner and plays a role in spermatogenesis.

Expression of acyl-CoA hydrolase in the developing mouse brain.

Brain acyl-CoA hydrolase (BACH) is a cytosolic enzyme responsible for the brain long-chain acyl-CoA thioesterase activity, that is the highest in the body. BACH was detected in the mouse brain as early as embryonic day (E) 11.5 by immunoblotting. The level of the major isoform (43-kDa) was low until E12.5, but promptly elevated to a peak 7 days after birth. Thereafter, it declined somewhat and reached a steady-state level in adulthood. These changes in BACH expression were approximately reflected in the palmitoyl-CoA hydrolyzing activity in the developing mouse brain, and the time course was quite similar to that of microtubule-associated protein 2 (MAP2) expression. In immunohistochemistry of E14.5 embryo brains, cells expressing BACH almost coincided with the cells committed to the neuronal lineage, which expressed MAP2 but not nestin. These results indicate that BACH expression is induced during embryogenesis in association with neuronal differentiation, and persists after terminal differentiation into neurons in postnatal stages, resulting in the constitutive high expression of BACH in the adult brain in a neuron-specific manner.

Human brain acyl-CoA hydrolase isoforms encoded by a single gene.

Acyl-CoA hydrolases are a group of enzymes that catalyze the hydrolysis of acyl-CoA thioesters to free fatty acids and CoA-SH. The human brain acyl-CoA hydrolase (BACH) gene comprises 13 exons, generating several isoforms through the alternative use of exons. Four first exons (1a-1d) can be used, and three patterns of splicing occur at exon X located between exons 7 and 8 that contains an internal 3(')-splice acceptor site and creates premature stop codons. When examined with green fluorescent protein-fusion constructs expressed in Neuro-2a cells, the nuclear localization signal encoded by exon 9 was functional by itself, whereas the whole structure was cytosolic, suggesting nuclear translocation of the enzyme. This was consistent with dual staining of the cytosol and nucleus in certain neurons by immunohistochemistry using anti-BACH antibody. The mitochondrial targeting signals encoded by exons 1b and 1c were also functional and directed mitochondrial localization of BACH isoforms with the signals. Although BACH mRNA containing the sequence derived from exon 1a, but not exon X, was exclusively expressed in human brain, these results suggest that the human BACH gene can express long-chain acyl-CoA hydrolase activity in multiple intracellular compartments by generating BACH isoforms with differential localization signals to affect various cellular functions that involve acyl-CoAs.

Immunohistochemical localization of acyl-CoA hydrolase/thioesterase multigene family members to rat epithelia.

Acyl-CoA hydrolases cleave acyl-CoA thioesters to free fatty acids and coenzyme A. The potency of these enzymes may serve to modulate cellular levels of acyl-CoAs to affect various cellular functions, including lipid metabolism. In this study, we investigated the tissue distribution of this multigene family of enzymes, focusing on cytosolic (CTE-I) and mitochondrial acyl-CoA thioesterases (MTE-I) in adult rats, using an anti-CTE-I antibody which recognizes both the isoforms. Western blotting detected them mainly in organs closely related to fatty acid oxidation, of which kidney contained the highest levels of both enzymes. Immunohistochemistry localized the enzymes primarily in the proximal tubules, where a large energy demand is expected and fatty acids represent a major fuel, correlating well with the intrarenal distribution of peroxisomal beta-oxidation. In situ hybridization suggested colocalization of CTE-I and MTE-I in the kidney. The immunoreactivity was also found in various epithelial tissues in the body, including Harderian gland and sebaceous gland. These results demonstrated the distribution of CTE-I and MTE-I in a wide variety of rat tissues, primarily characterized by an epithelial localization, being consistent with their involvement in fatty acid metabolism.

Characterization of mouse homolog of brain acyl-CoA hydrolase: molecular cloning and neuronal localization.

Acyl-CoA hydrolase could provide a mechanism via its potency to modulate cellular concentrations of acyl-CoAs for the regulation of various cellular events including fatty acid metabolism and gene expression. However, only limited evidence of this is available. To better understand the physiological role of this enzyme, we characterized a mouse brain acyl-CoA hydrolase, mBACH. The cloned cDNA for mBACH encoded a 338-amino-acid polypeptide with >95% identity to the human and rat homologs, indicating that the BACH gene is highly conserved among species. This was supported by the similarity in genomic organization of the BACH gene between humans and mice. Bacterially expressed mBACH was highly active against long-chain acyl-CoAs with a relatively broad specificity for chain length. While palmitoyl-CoA hydrolase activity was widely distributed in mouse tissues, it was marked in the brain, consistent with mBACH being almost exclusively distributed in this tissue, where >80% of the enzyme activity was explained by mBACH present in the cytosol. Immunohistochemistry demonstrated a neuronal localization of mBACH in both the central and peripheral nervous systems. In neurons, mBACH was distributed throughout the cell body and neurites. Although four isoforms except mBACH itself, that may be generated by the alternative use of exons of a single mBACH gene, were cloned, their mRNA levels in the brain were estimated to be negligible. However, a 50-kDa polypeptide besides the major one of 43-kDa seemed to be translated from the mBACH mRNA with differential in-frame ATG triplets used as the initiation codon. These findings will contribute to the functional analysis of the BACH gene using mice including genetic studies.