Selectivity of Substrate (Trifluoperazine) and Inhibitor (Amitriptyline, Androsterone, Canrenoic Acid, Hecogenin, Phenylbutazone, Quinidine, Quinine, and Sulfinpyrazone) “Probes” for Human Udp-Glucuronosyltransferases

Uchaipichat, Verawan; Mackenzie, Peter I.; Elliot, David J.; Miners, John O.

doi:10.1124/dmd.105.007369

Cited by 224 publications

(229 citation statements)

References 33 publications

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“…Inhibition studies on individual UGTs demonstrated that androsterone acted as a potent inhibitor of UGT2B7, while phenylbutazone acted as an inhibitor of UGT1A enzymes, which were in agreement with the previous study. 23 Androsterone (100 μM) exhibited potent inhibition against UGT2B7, whereas it showed none or muted inhibition against UGT1As. In the presence of androsterone (100 μM), the remaining activities of UGT2B7, UGT1A1, -1A3, and -1A8 were 12, 58, 84, and 58%, respectively.…”

Section: Chemical Research In Toxicologymentioning

confidence: 99%

“…Androsterone and phenylbutazone have been reported as inhibitors of UGT2B7 and UGT1As, respectively. 23 They were employed in the chemical inhibition study to decipher the roles of individual UGTs in hepatic glucuronidation of DES. In view of the possibility of substrate-dependent inhibition occurring, their inhibitory effects on DES glucuronidation in individual UGTs were tested first in the present study.…”

Section: ■ Experimental Proceduresmentioning

confidence: 99%

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Characterization of UDP-Glucuronosyltransferases Involved in Glucuronidation of Diethylstilbestrol in Human Liver and Intestine

Zhu

Liu

et al. 2012

Chem. Res. Toxicol.

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Diethylstilbestrol (DES), a synthetic estrogen, is famous for its carcinogenic effects. Human exposure to this compound can occur frequently through dietary ingestion and medical treatment. Glucuronidation has been demonstrated to be a predominant metabolic pathway for DES in human. Therefore, glucuronidation metabolism may have a significant impact on its toxicities, and it is essential to clarify this metabolic pathway. Accordingly, this in vitro study is designed to characterize the UGTs involved in DES glucuronidation and, furthermore, to identify the roles of individual isoforms in the reaction in liver and intestine. Human liver microsomes (HLM) displayed much higher potential for DES glucuronidation than human intestinal microsomes (HIM). The intrinsic clearances in HLM and HIM were demonstrated to be 459 and 14 μL/min/mg protein, respectively. Assays with recombinant UGTs demonstrated that UGT1A1, -1A3, -1A8, and -2B7 could catalyze DES glucuronidation, among which UGT2B7 showed the highest affinity. Chemical inhibitors of UGT2B7 and UGT1A1/1A3 both displayed similar inhibition against the reaction in UGT2B7 and HLM. In addition, DES glucuronidation in individual HLM exhibited a large individual variability and strongly correlated to UGT2B7 activity. All evidence indicates that UGT2B7 may act as a major enzyme responsible for DES glucuronidation in human liver. For HIM, both UGT2B7 inhibitor and UGT1A1/1A3/1A8 inhibitor exerted moderate inhibition. It is suggested that although UGT2B7 contributes to DES glucuronidation in intestine, other UGTs may contribute equally. In summary, this study characterizes human UGTs involved in DES glucuronidation in human liver and intestine, which may be helpful for further study about DES-related toxicities. Figure 1), a synthetic nonsteroid estrogen, is famous for its carcinogenicity. Human exposure to this compound can occur directly or indirectly through dietary ingestion and medical treatment. 1−4 DES was once prescribed widely to millions of pregnant women in false hopes of preventing miscarriage and other pregnancy complications in the United States. 1 It is now still accepted as an efficient therapy for the treatment of prostate and breast cancers. 2,3 Aside from its wide clinical applications, DES has found widespread application as a growth promoter in feeding cattle, sheep, and poultry. 4 It was estimated that in 1971 alone as much as 27600 kg of DES was used in livestock feeding in the United States. 5 After widespread and extensive exposures to DES, numerous serious health problems have been encountered. DES was established to cause the rare clear cell adenocarcinoma (CCAC) of the vagina and cervix in "DES daughters" (who are exposed to DES before birth). 6 In addition to CCAC, these daughters were found to suffer from malformations of their genital tracts, which can result in severe pregnancy and fertility problems. 7−9 Just like DES daughters, DES sons were also found to be prone to DES damage in the genitalia. 10 In company with daughters and so...

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Section: Chemical Research In Toxicologymentioning

confidence: 99%

Section: ■ Experimental Proceduresmentioning

confidence: 99%

Characterization of UDP-Glucuronosyltransferases Involved in Glucuronidation of Diethylstilbestrol in Human Liver and Intestine

Zhu

Liu

et al. 2012

Chem. Res. Toxicol.

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“…[15][16][17] Glucuronidation is further influenced by induction, 18,19 phosphorylation, 20 the presence of genetic variants in the UGT coding regions leading to catalytically altered proteins, 21,22 by variants of the promoter regions leading to reduced UGT transcription, 4,13,23 as well as inhibitory effects of therapeutic drugs. Commonly administered drugs with inhibitory potential include amitriptyline, 24 protease inhibitors, 25 ketoconazole, 26 and acyl glucuronide adducts of ketoprofen. 27,28 Therefore, the combination of genetic variants in addition to environmental or therapeutic xenobiotic exposure defines glucuronidation activity and thus the potential risk profile of an individual.…”

mentioning

confidence: 99%

Gilbert's disease and atazanavir: From phenotype to UDP-glucuronosyltransferase haplotype

et al. 2006

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Gilbert's disease leads to intermittent non-hemolytic hyperbilirubinemia by a reduction of hepatic bilirubin glucuronidation associated with the presence of the UDP-glucuronosyltransferase (UGT) 1A1*28 polymorphism. It is considered benign because it does not result in hepatocellular damage. However, pharmacogenetic analyses have linked UGT1A1*28 to drug toxicity and cancer predisposition. The protease inhibitor atazanavir (ATV) is an inhibitor of hepatic UGT activity leading to hyperbilirubinemia in individual patients. Whether this is linked specifically to UGT1A1*28 or to more complex variants influencing glucuronidation is unclear. One hundred and six ATV-treated patients were characterized and genotyped for UGT1A1*28, the UGT1A3 (-66C) and UGT1A7 (-57G) promoter variants, and UGT1A7 129K/131K . ATV treatment increased median bilirubin levels from 10 to 41 mol/L (P ‫؍‬ .001) with hyperbilirubinemia exceeding 43 mol/L in 37%. Hyperbilirubinemia over 43 mol/L was significantly associated not only with UGT1A1*28 but also with UGT1A3-66C, UGT1A7-57G, and UGT1A7 129K/131K , although these variants do not naturally occur in linkage dysequilibrium in blood donors. Homozygous combinations of UGT1A1*28 with the other variants increased from 7.4% (normal bilirubin to 42 mol/L) to 41% to 46.1% (43 to >85 mol/L), and 100% (>85 mol/L). All six patients with hyperbilirubinemia greater than 85 mol/L were homozygous for all four variants identifying a haplotype inherited on a single allele. In conclusion, the genetic variant associated with Gilbert's disease is identified as part of a haplotype of four UGT1A variants spanning three genes at the UGT1A gene locus. This haplotype predisposes to hyperbilirubinemia in ATV treatment and may have an additional role as a pharmacogenomic risk factor for drug therapy. (HEPATOLOGY 2006;44:1324-1332

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“…Inhibition of 1,25(OH) 2 D 3 monoglucuronide formation was evaluated using hecogenin, a known inhibitor of UGT1A4 [27,28]. Pooled HLM (0.5 mg/mL) or UGT1A4 Supersomes (1 mg/mL) were preincubated with alamethicin at 50 μg of alamethicin/mg of microsomal protein, and different concentrations (0, 5, 20, 50, 100, and 200 μM) of hecogenin for 10 min at room temperature, followed by the addition of 50 mM Tris-HCl (pH 7.4), 10 mM MgCl 2 , 5 mM saccharic acid 1,4-lactone, and 1 μM 1,25(OH) 2 D 3 .…”

Section: Inhibition Of 125(oh) 2 D 3 Monoglucuronide Formationmentioning

confidence: 99%

“…The assay was carried out as described above, except at a substrate concentration of 10 μM. N-glucuronidation rates for trifluoperazine, a known UGT1A4 specific substrate [24,25,26,27] were determined to compare 1,25(OH) 2 D 3 monoglucuronide formation rates with UGT1A4 activity using the same HLM (0.5 mg/mL). The trifluoperazine assay was carried out as described previously [26,28].…”

Section: Inter-liver Differences In 125(oh) 2 D 3 Monoglucuronide Fomentioning

confidence: 99%

Identification of human UDP-glucuronosyltransferases catalyzing hepatic 1α,25-dihydroxyvitamin D3 conjugation

Hashizume¹,

Xu²,

Mohutsky³

et al. 2008

Biochemical Pharmacology

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The biological effects of 1α,25-dihydroxyvitamin D 3 (1,25(OH) 2 D 3 ) are terminated primarily by P450-dependent hydroxylation reactions. However, the hormone is also conjugated in the liver and a metabolite, presumably a glucuronide, undergoes enterohepatic cycling. In this study, the identity of human enzymes capable of catalyzing the 1,25(OH) 2 D 3 glucuronidation reaction was investigated in order to better understand environmental and endogenous factors affecting the disposition and biological effects of vitamin D 3 . Among twelve different UGT isozymes tested, only UGT1A4 ≫ 2B4 and 2B7 supported the reaction. Two different 1,25(OH) 2 D 3 monoglucuronide metabolites were generated by recombinant UGT1A4 and human liver microsomes. The most abundant product was identified by mass spectral and NMR analyses as the 25-O-glucuronide isomer. The formation of 25-O-glucuronide by UGT1A4 Supersomes and human liver microsomes followed simple hyperbolic kinetics, yielding respective K m and V max values of 7.3 and 11.2 μM, and 33.7 ± 1.4 and 32.9 ± 1.9 pmol/min/mg protein. The calculated intrinsic 25-O-glucuronide M1 formation clearance for UGT1A4 was 14-fold higher than the next best isozyme, UGT2B7. There was only limited (4-fold) inter-liver variability in the 25-O-glucuronidation rate, but it was highly correlated with the relative rate of formation of the second, minor metabolite. In addition, formation of both metabolites was inhibited > 80% by the selective UGT1A4 inhibitor, hecogenin. If enterohepatic recycling of 1,25(OH) 2 D 3 represents a significant component of intestinal and systemic 1,25(OH) 2 D 3 disposition, formation of monoglucuronides by hepatic UGT1A4 constitutes an important initial step.

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Selectivity of Substrate (Trifluoperazine) and Inhibitor (Amitriptyline, Androsterone, Canrenoic Acid, Hecogenin, Phenylbutazone, Quinidine, Quinine, and Sulfinpyrazone) “Probes” for Human Udp-Glucuronosyltransferases

Cited by 224 publications

References 33 publications

Characterization of UDP-Glucuronosyltransferases Involved in Glucuronidation of Diethylstilbestrol in Human Liver and Intestine

Characterization of UDP-Glucuronosyltransferases Involved in Glucuronidation of Diethylstilbestrol in Human Liver and Intestine

Gilbert's disease and atazanavir: From phenotype to UDP-glucuronosyltransferase haplotype

Identification of human UDP-glucuronosyltransferases catalyzing hepatic 1α,25-dihydroxyvitamin D3 conjugation

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