ABSTRACT
Herein, we describe the preparation of liposomes with folate-targeting properties for the encapsulation of anti-sarcosine antibodies (antisarAbs@LIP) and sarcosine (sar@LIP). The competitive inhibitory effects of exogenously added folic acid supported the role of folate targeting in liposome internalization. We examined the effects of repeated administration on mice PC-3 xenografts. Sar@LIP treatment significantly increased tumor volume and weight compared to controls treated with empty liposomes. Moreover, antisarAbs@LIP administration exhibited a mild antitumor effect. We also identified differences in gene expression patterns post-treatment. Furthermore, Sar@LIP treatment resulted in decreased amounts of tumor zinc ions and total metallothioneins. Examination of the spatial distribution across the tumor sections revealed a sarcosine-related decline of the MT1X isoform within the marginal regions but an elevation after antisarAbs@LIP administration. Our exploratory results demonstrate the importance of sarcosine as an oncometabolite in PCa. Moreover, we have shown that sarcosine can be a potential target for anticancer strategies in management of PCa.
Subject(s)
Antibodies, Monoclonal/administration & dosage , Folic Acid/metabolism , Liposomes , Prostatic Neoplasms/metabolism , Prostatic Neoplasms/pathology , Sarcosine/antagonists & inhibitors , Animals , Cell Line, Tumor , Disease Models, Animal , Dose-Response Relationship, Drug , Humans , Liposomes/chemistry , Liposomes/ultrastructure , Male , Metallothionein/metabolism , Mice , Models, Biological , Phosphatidylethanolamines , Prostatic Neoplasms/drug therapy , Sarcosine/chemistry , Tumor Burden/drug effects , Xenograft Model Antitumor Assays , Zinc/metabolismABSTRACT
Several studies have shown that glycine transporter 1 (GlyT1) inhibitors have anxiolytic actions. There are two types of glycine receptor: the strychnine-sensitive glycine receptor (GlyA) and the strychnine-insensitive glycine receptor (GlyB); however, which receptor is the main contributor to the anxiolytic actions of GlyT1 inhibitors is yet to be determined. Here, we clarified which glycine receptor is the main contributor to the anxiolytic effects of GlyT1 inhibitors by using maternal separation-induced ultrasonic vocalization (USV) by rat pups as an index of anxiety. We confirmed that administration of the benzodiazepine diazepam or the selective serotonin reuptake inhibitor escitaloplam, which are both clinically proven anxiolytics, or the GlyT1 inhibitor SSR504734 (2-chloro-N-[(S)-phenyl[(2S)-piperidin-2-yl] methyl]-3-trifluoromethyl benzamide), decreases USV in rat pups. In addition, we showed that another GlyT1 inhibitor, ALX5407 ((R)-N-[3-(4'-fluorophenyl)-3(4'-phenylphenoxy)propyl]sarcosine) also decreases USV in rat pups. SSR504734- or ALX5407-induced decreases in USV were dose-dependently reversed by administration of the GlyA antagonist strychnine, whereas the diazepam- or escitalopram-induced decreases in USV were not. Furthermore, GlyT1-induced decreases in USV were not reversed by administration of the GlyB antagonist L-687,414. Together, these results suggest that GlyA activation is the main contributor to the anxiolytic actions of GlyT1 inhibitors and that the anxiolytic actions of diazepam and escitalopram cannot be attributed to GlyA activation. Our findings provide new insights into the importance of the activation of GlyA in the anxiolytic effects of GlyT1 inhibitors.
Subject(s)
Anti-Anxiety Agents/therapeutic use , Anxiety, Separation/drug therapy , Glycine Plasma Membrane Transport Proteins/antagonists & inhibitors , Maternal Deprivation , Membrane Transport Modulators/therapeutic use , Receptors, Glycine/agonists , Vocalization, Animal/drug effects , Animals , Animals, Newborn , Anti-Anxiety Agents/administration & dosage , Anti-Anxiety Agents/adverse effects , Anti-Anxiety Agents/chemistry , Anxiety, Separation/etiology , Benzamides/administration & dosage , Benzamides/adverse effects , Benzamides/antagonists & inhibitors , Benzamides/therapeutic use , Body Temperature/drug effects , Dose-Response Relationship, Drug , Drug Interactions , Glycine Plasma Membrane Transport Proteins/metabolism , Membrane Transport Modulators/administration & dosage , Membrane Transport Modulators/adverse effects , Membrane Transport Modulators/chemistry , Molecular Targeted Therapy , Piperidines/administration & dosage , Piperidines/adverse effects , Piperidines/antagonists & inhibitors , Piperidines/therapeutic use , Pyrrolidinones/therapeutic use , Rats, Sprague-Dawley , Receptors, Glycine/antagonists & inhibitors , Receptors, Glycine/metabolism , Sarcosine/administration & dosage , Sarcosine/adverse effects , Sarcosine/analogs & derivatives , Sarcosine/antagonists & inhibitors , Sarcosine/therapeutic use , Strychnine/pharmacology , UltrasonicsABSTRACT
Choline is abundant in association with eukaryotes and plays roles in osmoprotection, thermoprotection, and membrane biosynthesis in many bacteria. Aerobic catabolism of choline is widespread among soil proteobacteria, particularly those associated with eukaryotes. Catabolism of choline as a carbon, nitrogen, and/or energy source may play important roles in association with eukaryotes, including pathogenesis, symbioses, and nutrient cycling. We sought to generate choline analogues to study bacterial choline catabolism in vitro and in situ. Here we report the characterization of a choline analogue, propargylcholine, which inhibits choline catabolism at the level of Dgc enzyme-catalyzed dimethylglycine demethylation in Pseudomonas aeruginosa. We used genetic analyses and 13C nuclear magnetic resonance to demonstrate that propargylcholine is catabolized to its inhibitory form, propargylmethylglycine. Chemically synthesized propargylmethylglycine was also an inhibitor of growth on choline. Bioinformatic analysis suggests that there are genes encoding DgcA homologues in a variety of proteobacteria. We examined the broader utility of propargylcholine and propargylmethylglycine by assessing growth of other members of the proteobacteria that are known to grow on choline and possess putative DgcA homologues. Propargylcholine showed utility as a growth inhibitor in P. aeruginosa but did not inhibit growth in other proteobacteria tested. In contrast, propargylmethylglycine was able to inhibit choline-dependent growth in all tested proteobacteria, including Pseudomonas mendocina, Pseudomonas fluorescens, Pseudomonas putida, Burkholderia cepacia, Burkholderia ambifaria, and Sinorhizobium meliloti. We predict that chemical inhibitors of choline catabolism will be useful for studying this pathway in clinical and environmental isolates and could be a useful tool to study proteobacterial choline catabolism in situ.
