In Vitro Metabolic Characterization, Phenotyping, and Kinetic Studies of 9cUAB30, a Retinoid X Receptor-Specific Retinoid

Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama, United States
Drug Metabolism and Disposition (Impact Factor: 3.25). 08/2007; 35(7):1157-64. DOI: 10.1124/dmd.106.013938
Source: PubMed


The present study was conducted to compare the in vitro phase I and phase II metabolic profiles of (2E,4E,6Z,8E)-8-(3',4'-dihydro-1'(2'H)-naphthalen-1'-ylidene)-3,7-dimethyl-2,4,6-octatrienoic acid (9cUAB30) in human, rat, and dog microsomes and to characterize and identify the associated metabolic kinetics and specific isozymes from human liver microsomes (HLM) responsible for metabolism, respectively. Data from these experiments revealed that nine (M1-M9) phase I metabolites along with a single glucuronide conjugate were observed across the species investigated. With the exception of glucuronidation, no evidence of metabolism was detected for phase II enzymes (data not shown). Significant differences between species with regard to metabolic profile, stability, and gender were noted. For the eight phase I metabolites detected in HLM, the specific isozymes responsible for the biotransformations were CYP2C8, CYP2C9, and CYP2C19, with minor contributions from CYP1A2 and CYP2B6. For the glucuronide conjugate, UGT1A9 was the major catalyzing enzyme, with a minor contribution from UGT1A3. Kinetic analysis of eight of the detected metabolites indicated that four seemed to follow classical hyperbolic kinetics, whereas the remaining four showed evidence of either autoactivation or substrate inhibition.

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    • "We recently examined a series of RXR agonists employing gene expression arrays (Vedell et al. 2013). The agonists examined were Targretin (TRG) (the only clinically employed RXR agonist) (Farol and Hymes 2004; Rigas and Dragnev 2005; Gniadecki et al. 2007; Lansigan and Foss 2010) and two RXR-selective agonists, UAB30 and 4-Me-UAB30, (Muccio et al. 1998; Atigadda et al. 2003; Grubbs et al. 2006; Gorman et al. 2007; Kolesar et al. 2010). Recently the 3D structures of RXR homodimers were determined containing either TRG or UAB30 and a coactivator peptide (Boerma et al. 2014). "
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    ABSTRACT: The ability of the retinoid X receptors (RXRs) specific agonists (targretin [TRG] and UAB30) to alter rat liver gene and protein expression was determined using Affymetrix Exon arrays and high-performance liquid chromatography – tandem mass spectrometry (LC-MS/MS). TRG profoundly increases triglycerides levels while UAB30 does not. The expression patterns of transcripts or proteins from rat liver treated with TRG or UAB-30 were different from controls and each other. There were six times more gene transcripts identified than proteins. Differentially expressed RNAs or proteins were mapped into known gene ontology (GO) categories and GeneGo Metacore (KEGG) pathway maps. The GO categories which were highly overrepresented with differentially expressed RNAs (P < 10−16) were also overrepresented at the protein level. This high concordance of GO Terms was achieved despite the fact that typically ≤1/3 of the elements identified by gene expression were identified by proteomics. Within these GO categories, the magnitude of alterations induced by RXR agonists at the transcript and protein levels were correlated. When GO categories with moderate overrepresentation (10−5 < P < 10−9) were examined, there was greater discordance between the transcript and protein data. Examination of KEGG pathway maps with highly significant changes at both the protein and the RNA levels showed that the individual proteins/genes altered were often the same and changes were of similar magnitude; while KEGG pathways showed limited statistical significance and exhibited minimal overlap. Finally, metabolomics analysis of liver and serum identified altered expression of metabolites related to fatty acid oxidation and bile acid metabolism that were consistent with transcript/protein changes. We observed significant concordance between genomics and proteomics implying either can identify pathways modulated and can indirectly predict resulting physiologic effects.
    Full-text · Article · Dec 2014
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    • "Enzyme kinetic parameters for S002-333 (or enantiomers) in this study were predicted in terms of K m (mM) and relative V max as a peak area ratio of metabolite versus internal standard due to unavailability of metabolite standards (Gorman et al., 2007). The kinetic studies were performed using HLM and cDNA-expressed CYP2C9, 2C19 and 3A4. "
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