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Organ - specific expression profiles of rat treated with targretin, 9-cis retinoic acid, and 4-hydroxyphenylretinamide

ABSTRACT: A rexinoid, targretin (TRG) and two retinoids, 9-cis retinoic acid (9cRA) and 4-hydroxyphenylretinamide (4HPR) were examined for their effects on gene expression in rat mammary gland, liver, and lung tissues. The chemopreventive effects of these agents have largely been attributed to their ability to interact with retinoic acid receptors (RAR) and/or retinoid X-receptors (RXR). TRG interacts with the RXR receptors. 9cRA interacts with both the RAR and RXR receptors, while 4HPR has a moderate affinity primarily for RAR gamma. Based on previously performed mammary chemoprevention studies, TRG (150mg/Kg diet), 9cRA (100 mg/Kg diet), and 4HPR (792 mg/Kg diet), were administrated to rats continually in their diet for 7 days. Tissue - and agent - specific expression differences were determined by comparing tissues from treated rats with those form rats administered a control diet. There were significantly more changes seen associated with TRG than 9cRA or 4HPR. Only a limited number of expression changes were found with 4HPR treatment. For each organ, TRG and 9cRA treated tissues clustered closely together, whereas 4HPR treated tissues clustered with the tissues from the control diet group. In contrast to 9cRA treatment, TRG treatment altered genes that involved fatty acid metabolism and modulation of various cytochromes P450 in the liver clearly demonstrating the very disparate nature of these two retinoids. These expression signatures could provide useful pharmacodynamic biomarkers for retinoids’ treatment and chemoprevention. Keywords: parallel sample

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE3952 | GEO | 2005/12/31

SECONDARY ACCESSION(S): PRJNA94205

REPOSITORIES: GEO

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Project description:A rexinoid, targretin (TRG) and two retinoids, 9-cis retinoic acid (9cRA) and 4-hydroxyphenylretinamide (4HPR) were examined for their effects on gene expression in rat mammary gland, liver, and lung tissues. The chemopreventive effects of these agents have largely been attributed to their ability to interact with retinoic acid receptors (RAR) and/or retinoid X-receptors (RXR). TRG interacts with the RXR receptors. 9cRA interacts with both the RAR and RXR receptors, while 4HPR has a moderate affinity primarily for RAR gamma. Based on previously performed mammary chemoprevention studies, TRG (150mg/Kg diet), 9cRA (100 mg/Kg diet), and 4HPR (792 mg/Kg diet), were administrated to rats continually in their diet for 7 days. Tissue - and agent - specific expression differences were determined by comparing tissues from treated rats with those form rats administered a control diet. There were significantly more changes seen associated with TRG than 9cRA or 4HPR. Only a limited number of expression changes were found with 4HPR treatment. For each organ, TRG and 9cRA treated tissues clustered closely together, whereas 4HPR treated tissues clustered with the tissues from the control diet group. In contrast to 9cRA treatment, TRG treatment altered genes that involved fatty acid metabolism and modulation of various cytochromes P450 in the liver clearly demonstrating the very disparate nature of these two retinoids. These expression signatures could provide useful pharmacodynamic biomarkers for retinoidsâ treatment and chemoprevention. Experiment Overall Design: Agent : The 3 agents were obtained from NCI Chemical Repository (Bethesda, MD), Targretin, 9-cis retinoic acid, and 4-hydroxyphenylretinamide. Experiment Overall Design: Rat :Female Sprague-Dawley rats were used (Harlan Sprague-Dawley, Inc. Indianapolis, IN) Experiment Overall Design: Treatment: Starting at 100 days of age, the rats received treatment of TRG (60 mg/kg BW, gavage), 9cRA (100 mg/kg diet), or 4HPR (782 mg/kg diet) for 7 days. At the end of the 7-day treatment, normal mammary gland, liver and lung tissues were collected.

Project description:Haffez2017 - RAR interaction with synthetic analogues This model is described in the article: The molecular basis of the interactions between synthetic retinoic acid analogues and the retinoic acid receptors Hesham Haffez, David R. Chisholm, Roy Valentine, Ehmke Pohl, Christopher Redfern and Andrew Whiting MedChemComm Abstract: All-trans-retinoic acid (ATRA) and its synthetic analogues EC23 and EC19 direct cellular differentiation by interacting as ligands for the retinoic acid receptor (RARÎ±, Î² and Î³) family of nuclear receptor proteins. To date, a number of crystal structures of natural and synthetic ligands complexed to their target proteins have been solved, providing molecular level snap-shots of ligand binding. However, a deeper understanding of receptor and ligand flexibility and conformational freedom is required to develop stable and effective ATRA analogues for clinical use. Therefore, we have used molecular modelling techniques to define RAR interactions with ATRA and two synthetic analogues, EC19 and EC23, and compared their predicted biochemical activities to experimental measurements of relative ligand affinity and recruitment of coactivator proteins. A comprehensive molecular docking approach that explored the conformational space of the ligands indicated that ATRA is able to bind the three RAR proteins in a number of conformations with one extended structure being favoured. In contrast the biologically-distinct isomer, 9-cis-retinoic acid (9CRA), showed significantly less conformational flexibility in the RAR binding pockets. These findings were used to inform docking studies of the synthetic retinoids EC23 and EC19, and their respective methyl esters. EC23 was found to be an excellent mimic for ATRA, and occupied similar binding modes to ATRA in all three target RAR proteins. In comparison, EC19 exhibited an alternative binding mode which reduces the strength of key polar interactions in RARÎ±/Î³ but is well-suited to the larger RARÎ² binding pocket. In contrast, docking of the corresponding esters revealed the loss of key polar interactions which may explain the much reduced biological activity. Our computational results were complemented using an in vitro binding assay based on FRET measurements, which showed that EC23 was a strongly binding, pan-agonist of the RARs, while EC19 exhibited specificity for RARÎ², as predicted by the docking studies. These findings can account for the distinct behaviour of EC23 and EC19 in cellular differentiation assays, and additionally, the methods described herein can be further applied to the understanding of the molecular basis for the selectivity of different retinoids to RARÎ±, Î² and Î³. This model is hosted on BioModels Database and identified by: BIOMD0000000629. To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

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Organ - specific expression profiles of rat treated with targretin, 9-cis retinoic acid, and 4-hydroxyphenylretinamide

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