Zhu HJ

References (44)

Title : Regulation of human hydrolases and its implications in pharmacokinetics and pharmacodynamics - Jung_2024_Drug.Metab.Dispos__
Author(s) : Jung SM , Zhu HJ
Ref : Drug Metabolism & Disposition: The Biological Fate of Chemicals , : , 2024
Abstract : Hydrolases represent an essential class of enzymes indispensable for the metabolism of various clinically essential medications. Individuals exhibit marked differences in the expression and activation of hydrolases, resulting in significant variability in the pharmacokinetics (PK) and pharmacodynamics (PD) of drugs metabolized by these enzymes. The regulation of hydrolase expression and activity involves both genetic polymorphisms and nongenetic factors. This review examines the current understanding of genetic and nongenetic regulators of six clinically significant hydrolases, including Carboxylesterase 1 (CES1), Carboxylesterase 2 (CES2), Arylacetamide Deacetylase (AADAC), Paraoxonase 1 (PON1), Paraoxonase 3 (PON3), and Cathepsin A (CTSA). We explore genetic variants linked to the expression and activity of the hydrolases and their effects on the PK and PD of their substrate drugs. Regarding nongenetic regulators, we focus on the inhibitors and inducers of these enzymes. Additionally, we examine the developmental expression patterns and gender differences in the hydrolases when pertinent information was available. Many genetic and nongenetic regulators were found to be associated with the expression and activity of the hydrolases and PK and PD. However, hydrolases remain generally understudied compared to other drug-metabolizing enzymes, such as cytochrome P450s. The clinical significance of genetic and nongenetic regulators has not yet been firmly established for the majority of hydrolases. Comprehending the mechanisms that underpin the regulation of these enzymes holds the potential to refine therapeutic regimens, thereby enhancing the efficacy and safety of drugs metabolized by the hydrolases. Significance Statement Hydrolases play a crucial role in the metabolism of numerous clinically important medications. Genetic polymorphisms and nongenetic regulators can affect hydrolases' expression and activity, consequently influencing the exposure and clinical outcomes of hydrolase substrate drugs. A comprehensive understanding of hydrolase regulation can refine therapeutic regimens, ultimately enhancing the efficacy and safety of drugs metabolized by the enzymes.
ESTHER : Jung_2024_Drug.Metab.Dispos__
PubMedSearch : Jung_2024_Drug.Metab.Dispos__
PubMedID: 38777597

Title : Regulation of carboxylesterases and its impact on pharmacokinetics and pharmacodynamics: an up-to-date review - Liu_2024_Expert.Opin.Drug.Metab.Toxicol__1
Author(s) : Liu Y , Li J , Zhu HJ
Ref : Expert Opin Drug Metab Toxicol , :1 , 2024
Abstract : INTRODUCTION: Carboxylesterase 1 (CES1) and carboxylesterase 2 (CES2) are among the most abundant hydrolases in humans, catalyzing the metabolism of numerous clinically important medications, such as methylphenidate and clopidogrel. The large interindividual variability in the expression and activity of CES1 and CES2 affects the pharmacokinetics (PK) and pharmacodynamics (PD) of substrate drugs. AREAS COVERED: This review provides an up-to-date overview of CES expression and activity regulations and examines their impact on the PK and PD of CES substrate drugs. The literature search was conducted on PubMed from inception to January 2024. EXPERT OPINION: Current research revealed modest associations of CES genetic polymorphisms with drug exposure and response. Beyond genomic polymorphisms, transcriptional and posttranslational regulations can also significantly affect CES expression and activity and consequently alter PK and PD. Recent advances in plasma biomarkers of drug-metabolizing enzymes encourage the research of plasma protein and metabolite biomarkers for CES1 and CES2, which could lead to the establishment of precision pharmacotherapy regimens for drugs metabolized by CESs. Moreover, our understanding of tissue-specific expression and substrate selectivity of CES1 and CES2 has shed light on improving the design of CES1- and CES2-activated prodrugs.
ESTHER : Liu_2024_Expert.Opin.Drug.Metab.Toxicol__1
PubMedSearch : Liu_2024_Expert.Opin.Drug.Metab.Toxicol__1
PubMedID: 38706437

Title : Cell-Dependent Activation of ProTide Prodrugs and Its Implications in Antiviral Studies - Liu_2023_ACS.Pharmacol.Transl.Sci_6_1340
Author(s) : Liu Y , Sun S , Li J , Wang W , Zhu HJ
Ref : ACS Pharmacol Transl Sci , 6 :1340 , 2023
Abstract : The ProTide prodrug design is a powerful tool to improve cell permeability and enhance the intracellular activation of nucleotide antiviral analogues. Previous in vitro studies showed that the activation of ProTide prodrugs varied in different cell lines. In the present study, we investigated the activation profiles of two antiviral prodrugs tenofovir alafenamide (TAF) and sofosbuvir (SOF) in five cell lines commonly used in antiviral research, namely, Vero E6, Huh-7, Calu-3, A549, and Caco-2. We found that TAF and SOF were activated in a cell-dependent manner with Vero E6 being the least efficient and Huh-7 being the most efficient cell line for activating the prodrugs. We also demonstrated that TAF was activated at a significantly higher rate than SOF. We further analyzed the protein expressions of the activating enzymes carboxylesterase 1, cathepsin A, histidine triad nucleotide-binding protein 1, and the relevant drug transporters P-glycoprotein and organic anion-transporting polypeptides 1B1 and 1B3 in the cell lines using the proteomics data extracted from the literature and proteome database. The results revealed significant differences in the expression patterns of the enzymes and transporters among the cell lines, which might partially contribute to the observed cell-dependent activation of TAF and SOF. These findings highlight the variability of the abundance of activating enzymes and transporters between cell lines and emphasize the importance of selecting appropriate cell lines for assessing the antiviral efficacy of nucleoside/nucleotide prodrugs.
ESTHER : Liu_2023_ACS.Pharmacol.Transl.Sci_6_1340
PubMedSearch : Liu_2023_ACS.Pharmacol.Transl.Sci_6_1340
PubMedID: 37854623

Title : Targeted Absolute Protein Quantification Using SILAC Internal Standard and Full-Length Protein Calibrators (TAQSI) - Wang_2023_Methods.Mol.Biol_2603_269
Author(s) : Wang X , Shi J , Zhu HJ
Ref : Methods Mol Biol , 2603 :269 , 2023
Abstract : Mass spectrometry (MS)-based proteomics has been increasingly used for targeted absolute protein quantifications in both basic and clinical research. There is a great need to overcome some pitfalls of current MS-based targeted absolute protein quantification methods, such as high inter-assay variability and high cost associated with the use of synthesized isotopic peptides/proteins. Here we describe a targeted absolute protein quantification method utilizing SILAC internal standards and unlabeled full-length protein calibrators (TAQSI). The method has proven accurate, precise, reproducible, and cost-effective. Notably, the method is resistant to the variabilities caused by protein extraction and digestion. Moreover, it avoids measurement errors due to nonsynonymous mutations. This versatile method can be used for determining the absolute expressions of numerous proteins in various biological samples. As a proof-of-concept, this method was successfully applied to absolutely quantitate the protein expressions of carboxylesterase 1 (CES1) in human liver tissues.
ESTHER : Wang_2023_Methods.Mol.Biol_2603_269
PubMedSearch : Wang_2023_Methods.Mol.Biol_2603_269
PubMedID: 36370287

Title : Physiologically-based pharmacokinetic modeling to predict methylphenidate exposure affected by interplay among carboxylesterase 1 pharmacogenetics, drug-drug interactions, and sex - Xiao_2022_J.Pharm.Sci__
Author(s) : Xiao J , Shi J , Thompson BR , Smith DE , Zhang T , Zhu HJ
Ref : J Pharm Sci , : , 2022
Abstract : BACKGROUND AND OBJECTIVE: The pharmacokinetics (PK) of methylphenidate (MPH) differ significantly among individuals. Carboxylesterase 1 (CES1) is the primary enzyme metabolizing MPH, and its function is affected by genetic variants, drug-drug interaction (DDI), and sex. The object of this study is to evaluate CES1 pharmacogenetics as related to MPH metabolism using human liver samples and develop a physiologically-based pharmacokinetic (PBPK) modeling approach to investigate the influence of CES1 genotypes and other factors on MPH PK. METHODS: The effect of the CES1 variant G143E (rs71647871) on MPH metabolism was studied utilizing 102 individual human liver S9 (HLS9) fraction samples. PBPK models were developed using the population-based PBPK software PK-Sim(a) by incorporating the HLS9 incubation data. The established models were applied to simulate MPH PK profiles under various clinical scenarios, including different genotypes, drug-alcohol interactions, and the difference between males and females. RESULTSL: The HLS9 incubation study showed that subjects heterozygous for the CES1 variant G143E metabolized MPH at a rate of approximately 50% of that in non-carriers. The developed PBPK models successfully predicted the exposure alteration of MPH from the G143E genetic variant, ethanol-MPH DDI, and sex. Importantly, the study suggests that male G143E carriers who are alcohol consumers are at a higher risk of MPH overexposure. CONCLUSION: PBPK modeling provides a means for better understanding the mechanisms underlying interindividual variability in MPH PK and PD and could be utilized to develop a safer and more effective MPH pharmacotherapy regimen.
ESTHER : Xiao_2022_J.Pharm.Sci__
PubMedSearch : Xiao_2022_J.Pharm.Sci__
PubMedID: 35526575

Title : Identification of regulatory variants of carboxylesterase 1 (CES1): A proof-of-concept study for the application of the Allele-Specific Protein Expression (ASPE) assay in identifying cis-acting regulatory genetic polymorphisms - Her_2022_Proteomics__e2200176
Author(s) : Her L , Shi J , Wang X , He B , Smith L , Jiang H , Zhu HJ
Ref : Proteomics , :e2200176 , 2022
Abstract : It is challenging to study regulatory genetic variants as gene expression is affected by both genetic polymorphisms and non-genetic regulators. The mRNA allele-specific expression (ASE) assay has been increasingly used for the study of cis-acting regulatory variants because cis-acting variants affect gene expression in an allele-specific manner. However, poor correlations between mRNA and protein expressions were observed for many genes, highlighting the importance of studying gene expression regulation at the protein level. In the present study, we conducted a proof-of-concept study to utilize a recently developed allele-specific protein expression (ASPE) assay to identify the cis-acting regulatory variants of CES1 using a large set of human liver samples. The CES1 gene encodes for carboxylesterase 1 (CES1), the most abundant hepatic hydrolase in humans. Two cis-acting regulatory variants were found to be significantly associated with CES1 ASPE, CES1 protein expression, and its catalytic activity on enalapril hydrolysis in human livers. Compared to conventional gene expression-based approaches, ASPE demonstrated an improved statistical power to detect regulatory variants with small effect sizes since allelic protein expression ratios are less prone to the influence of non-genetic regulators (e.g., diseases and inducers). This study suggests that the ASPE approach is a powerful tool for identifying cis-regulatory variants. This article is protected by copyright. All rights reserved.
ESTHER : Her_2022_Proteomics__e2200176
PubMedSearch : Her_2022_Proteomics__e2200176
PubMedID: 36413357
Gene_locus related to this paper: human-CES1

Title : Effect of CES1 genetic variation on enalapril steady-state pharmacokinetics and pharmacodynamics in healthy subjects - Her_2021_Br.J.Clin.Pharmacol__
Author(s) : Her LH , Wang X , Shi J , Choi HJ , Jung SM , Smith LS , Wu AH , Bleske BE , Zhu HJ
Ref : British Journal of Clinical Pharmacology , : , 2021
Abstract : BACKGROUND AND OBJECTIVE: Enalapril is a prodrug and needs to be activated by carboxylesterase 1 (CES1). A previous in vitro study demonstrated the CES1 genetic variant, G143E (rs71647871), significantly impaired enalapril activation. Two previous clinical studies examined the impact of G143E on single-dose enalapril PK (10 mg); however, the results were inconclusive. A prospective, multi-dose, pharmacokinetics, and pharmacodynamics (PK/PD) study was conducted to determine the impact of the CES1 G143E variant on enalapril steady-state PK and PD in healthy volunteers. METHODS: Study participants were stratified to G143E non-carriers (n=15) and G143E carriers (n=6). All the carriers were G143E heterozygotes. Study subjects received enalapril 10 mg daily for seven consecutive days prior to a 72h PK/PD study. Plasma concentrations of enalapril and its active metabolite enalaprilat were quantified by an established LC-MS/MS method. RESULTS: The CES1 G143E carriers had 30.9% lower enalaprilat C(max) (P = 0.03) compared to the non-carriers (38.01 vs. 55.01 ng/mL). The carrier group had 27.5% lower AUC(0-) (P = 0.02) of plasma enalaprilat compared to the non-carriers (374.29 vs. 515.91 ng*hr/mL). The carriers also had a 32.3% lower enalaprilat-to-enalapril AUC(0-) ratio (P = 0.003) relative to the non-carriers. The average maximum reduction of systolic blood pressure in the non-carrier group was approximately 12.4% at the end of the study compared to the baseline (P = 0.001). No statistically significant blood pressure reduction was observed in the G143E carriers. CONCLUSIONS: The CES1 loss-of-function G143E variant significantly impaired enalapril activation and its systolic blood pressure-lowering effect in healthy volunteers.
ESTHER : Her_2021_Br.J.Clin.Pharmacol__
PubMedSearch : Her_2021_Br.J.Clin.Pharmacol__
PubMedID: 33963573

Title : Plasma carboxylesterase 1 predicts methylphenidate exposure: a proof-of-concept study using plasma protein biomarker for hepatic drug metabolism - Shi_2021_Clin.Pharmacol.Ther__
Author(s) : Shi J , Xiao J , Wang X , Jung SM , Bleske BE , Markowitz JS , Patrick KS , Zhu HJ
Ref : Clinical Pharmacology & Therapeutics , : , 2021
Abstract : Hepatic drug-metabolizing enzymes (DMEs) play critical roles in determining the pharmacokinetics and pharmacodynamics of numerous therapeutic agents. As such, noninvasive biomarkers capable of predicting DME expression in the liver have the potential to be used to personalize pharmacotherapy and improve drug treatment outcomes. In the present study, we quantified carboxylesterase 1 (CES1) protein concentrations in plasma samples collected during a methylphenidate (MPH) PK study. CES1 is a prominent hepatic enzyme responsible for the metabolism of many medications containing small ester moieties, including MPH. The results revealed a significant inverse correlation between plasma CES1 protein concentrations and the area under the concentration-time curves (AUCs) of plasma d-MPH (p = 0.014, r = -0.617). In addition, when plasma CES1 protein levels were normalized to the plasma concentrations of 24 liver-enriched proteins to account for potential interindividual differences in hepatic protein release rate, the correlation was further improved (p = 0.003, r = -0.703), suggesting that plasma CES1 protein could explain approximately 50% of the variability in d-MPH AUCs in the study participants. A physiologically based pharmacokinetic (PBPK) modeling simulation revealed that the CES1-based individualized dosing strategy might significantly reduce d-MPH exposure variability in pediatric patients relative to conventional fixed dosing trial and error regimens. This proof-of-concept study indicates that the plasma protein of a hepatic DME may serve as a biomarker for predicting its metabolic function and the pharmacokinetics of its substrate drugs.
ESTHER : Shi_2021_Clin.Pharmacol.Ther__
PubMedSearch : Shi_2021_Clin.Pharmacol.Ther__
PubMedID: 34743324

Title : Activation of Tenofovir Alafenamide and Sofosbuvir in the Human Lung and Its Implications in the Development of Nucleoside\/Nucleotide Prodrugs for Treating SARS-CoV-2 Pulmonary Infection - Li_2021_Pharmaceutics_13_
Author(s) : Li J , Liu S , Shi J , Zhu HJ
Ref : Pharmaceutics , 13 : , 2021
Abstract : ProTide technology is a powerful tool for the design of nucleoside/nucleotide analog prodrugs. ProTide prodrug design improves cell permeability and enhances intracellular activation. The hydrolysis of the ester bond of a ProTide is a determinant of the intracellular activation efficiency and final antiviral efficacy of the prodrug. The hydrolysis is dictated by the catalytic activity and abundance of activating enzymes. The antiviral agents tenofovir alafenamide (TAF) and sofosbuvir (SBV) are typical ProTides. Both TAF and SBV have also been proposed to treat patients with COVID-19. However, the mechanisms underlying the activation of the two prodrugs in the lung remain inconclusive. In the present study, we profiled the catalytic activity of serine hydrolases in human lung S9 fractions using an activity-based protein profiling assay. We evaluated the hydrolysis of TAF and SBV using human lung and liver S9 fractions and purified enzymes. The results showed that CatA and CES1 were involved in the hydrolysis of the two prodrugs in the human lung. More specifically, CatA exhibited a nearly 4-fold higher hydrolytic activity towards TAF than SBV, whereas the CES1 activity on hydrolyzing TAF was slightly lower than that for SBV. Overall, TAF had a nearly 4-fold higher hydrolysis rate in human lung S9 than SBV. We further analyzed protein expression levels of CatA and CES1 in the human lung, liver, and primary cells of the two tissues using proteomics data extracted from the literature. The relative protein abundance of CatA to CES1 was considerably higher in the human lung and primary human airway epithelial cells than in the human liver and primary human hepatocytes. The findings demonstrated that the high susceptivity of TAF to CatA-mediated hydrolysis resulted in efficient TAF hydrolysis in the human lung, suggesting that CatA could be utilized as a target activating enzyme when designing antiviral ester prodrugs for the treatment of respiratory virus infection.
ESTHER : Li_2021_Pharmaceutics_13_
PubMedSearch : Li_2021_Pharmaceutics_13_
PubMedID: 34683949
Gene_locus related to this paper: human-CTSA

Title : Impact of carboxylesterase 1 genetic polymorphism on trandolapril activation in human liver and the pharmacokinetics and pharmacodynamics in healthy volunteers - Wang_2021_Clin.Transl.Sci__
Author(s) : Wang X , Her L , Xiao J , Shi J , Wu AH , Bleske BE , Zhu HJ
Ref : Clin Transl Sci , : , 2021
Abstract : Trandolapril, an angiotensin-converting enzyme inhibitor prodrug, needs to be activated by carboxylesterase 1 (CES1) in the liver to exert its intended therapeutic effect. A previous in vitro study demonstrated that the CES1 genetic variant G143E (rs71647871) abolished CES1-mediated trandolapril activation in cells transfected with the variant. This study aimed to determine the effect of the G143E variant on trandolapril activation in human livers and the pharmacokinetics (PKs) and pharmacodynamics (PDs) in human subjects. We performed an in vitro incubation study to assess trandolapril activation in human livers (5 G143E heterozygotes and 97 noncarriers) and conducted a single-dose (1 mg) PK and PD study of trandolapril in healthy volunteers (8 G143E heterozygotes and 11 noncarriers). The incubation study revealed that the mean trandolapril activation rate in G143E heterozygous livers was 42% of those not carrying the variant (p = 0.0015). The clinical study showed that, relative to noncarriers, G143E carriers exhibited 20% and 15% decreases, respectively, in the peak concentration (C(max) ) and area under the curve from 0 to 72 h (AUC(0-72 h) ) of the active metabolite trandolaprilat, although the differences were not statistically significant. Additionally, the average maximum reductions of systolic blood pressure and diastolic blood pressure in carriers were ~ 22% and 23% less than in noncarriers, respectively, but the differences did not reach a statistically significant level. In summary, the CES1 G143E variant markedly impaired trandolapril activation in the human liver under the in vitro incubation conditions; however, this variant had only a modest impact on the PK and PD of trandolapril in healthy human subjects.
ESTHER : Wang_2021_Clin.Transl.Sci__
PubMedSearch : Wang_2021_Clin.Transl.Sci__
PubMedID: 33660934

Title : Transcriptional regulation of carboxylesterase 1 (CES1) in human liver: role of the nuclear receptor NR1H3 (LXRalpha) and its splice isoforms - Collins_2021_Drug.Metab.Dispos__
Author(s) : Collins JM , Lu R , Wang X , Zhu HJ , Wang D
Ref : Drug Metabolism & Disposition: The Biological Fate of Chemicals , : , 2021
Abstract : Carboxylesterase 1 (CES1) is the predominant carboxylesterase in the human liver, involved in metabolism of both xenobiotics and endogenous substrates. Genetic or epigenetic factors that alter CES1 activity or expression are associated with changes in drug response, lipid, and glucose homeostasis. However, the transcriptional regulation of CES1 in the human liver remains uncertain. By applying both the random forest and Sobol's Sensitivity Indices (SSI) to analyze existing liver RNA expression microarray data (GSE9588), we identified NR1H3 (LXRalpha) as a key factor regulating constitutive CES1 expression. This model prediction was validated using siRNA knockdown and CRISPR-mediated transcriptional activation of NR1H3 in Huh7 and HepG2 cells. We found that NR1H3's activation of CES1 is splice isoform-specific, namely that increased expression of the NR1H3-211 isoform increased CES1 expression while NR1H3-201 did not. Also, in human liver samples, expression of NR1H3-211 and CES1 are correlated, while NR1H3-201 and CES1 are not. This trend also occurs during differentiation of induced pluripotent stem cells (iPSCs) to hepatocytes, where only expression of the NR1H3-211 isoform parallels expression of CES1 Moreover, we found that treatment with the NR1H3 agonist T0901317 in HepG2 cells had no effect on CES1 expression. Overall, our results demonstrate a key role of NR1H3 in maintaining the constitutive expression of CES1 in the human liver. Furthermore, our results support that the effect of NR1H3 is splice isoform-specific and appears to be ligand independent. Significance Statement Despite the central role of CES1 in metabolism of numerous medications, little is known about its transcriptional regulation. Here we identify NR1H3 as a key regulator of constitutive CES1 expression, and therefore is a potential target for future studies to understand inter-person variabilities in CES1 activity and drug metabolism.
ESTHER : Collins_2021_Drug.Metab.Dispos__
PubMedSearch : Collins_2021_Drug.Metab.Dispos__
PubMedID: 34697082
Gene_locus related to this paper: human-CES1

Title : Contributions of Cathepsin A and Carboxylesterase 1 to the hydrolysis of Tenofovir Alafenamide in the Human Liver, and the Effect of CES1 Genetic Variation on Tenofovir Alafenamide Hydrolysis - Li_2021_Drug.Metab.Dispos__
Author(s) : Li J , Shi J , Xiao J , Tran L , Wang X , Zhu HJ
Ref : Drug Metabolism & Disposition: The Biological Fate of Chemicals , : , 2021
Abstract : The prodrug tenofovir alafenamide (TAF) is a first-line antiviral agent for the treatment of chronic hepatitis B infection. TAF activation involves multiple steps, and the first step is an ester hydrolysis reaction catalyzed by hydrolases. This study was to determine the contributions of carboxylesterase 1 (CES1) and cathepsin A (CatA) to TAF hydrolysis in the human liver. Our in vitro incubation studies showed that both CatA and CES1 catalyzed TAF hydrolysis in a pH-dependent manner. At their physiological pH environment, the activity of CatA (pH 5.2) was approximately 1,000-fold higher than that of CES1 (pH 7.2). Given that the hepatic protein expression of CatA was approximately 200-fold lower than that of CES1, the contribution of CatA to TAF hydrolysis in the human liver was estimated to be much greater than that of CES1, which is contrary to the previous perception that CES1 is the primary hepatic enzyme hydrolyzing TAF. The findings were further supported by a TAF incubation study with the CatA inhibitor telaprevir and the CES1 inhibitor bis-(p-nitrophenyl) phosphate. Moreover, an in vitro study revealed that the CES1 variant G143E (rs71647871) is a loss-of-function variant for CES1-mediated TAF hydrolysis. In summary, our results suggest that CatA may play a more important role in the hepatic activation of TAF than CES1. Additionally, TAF activation in the liver could be affected by CES1 genetic variation, but the magnitude of impact appears to be limited due to the major contribution of CatA to hepatic TAF activation. Significance Statement Contrary to the general perception that carboxylesterase 1 (CES1) is the major enzyme responsible for tenofovir alafenamide (TAF) hydrolysis in the human liver, the present study demonstrated that cathepsin A (CatA) may play a more significant role in TAF hepatic hydrolysis. Furthermore, the CES1 variant G143E (rs71647871) was found to be a loss-of-function variant for CES1-mediated TAF hydrolysis.
ESTHER : Li_2021_Drug.Metab.Dispos__
PubMedSearch : Li_2021_Drug.Metab.Dispos__
PubMedID: 34933885
Gene_locus related to this paper: human-CES1 , human-CTSA

Title : Carboxylesterase 1 and Precision Pharmacotherapy: Pharmacogenetics and Nongenetic Regulators - Her_2020_Drug.Metab.Dispos_48_230
Author(s) : Her L , Zhu HJ
Ref : Drug Metabolism & Disposition: The Biological Fate of Chemicals , 48 :230 , 2020
Abstract : Carboxylesterase (CES) 1 is the most abundant drug-metabolizing enzyme in human livers, comprising approximately 1% of the entire liver proteome. CES1 is responsible for 80%-95% of total hydrolytic activity in the liver and plays a crucial role in the metabolism of a wide range of drugs (especially ester-prodrugs), pesticides, environmental pollutants, and endogenous compounds. Expression and activity of CES1 vary markedly among individuals, which is a major contributing factor to interindividual variability in the pharmacokinetics (PK) and pharmacodynamics (PD) of drugs metabolized by CES1. Both genetic and nongenetic factors contribute to CES1 variability. Here, we discuss genetic polymorphisms, including single-nucleotide polymorphisms (SNPs), and copy number variants and nongenetic contributors, such as developmental status, genders, and drug-drug interactions, that could influence CES1 functionality and the PK and PD of CES1 substrates. Currently, the loss-of-function SNP G143E (rs71647871) is the only clinically significant CES1 variant identified to date, and alcohol is the only potent CES1 inhibitor that could alter the therapeutic outcomes of CES1 substrate medications. However, G143E and alcohol can only explain a small portion of the interindividual variability in the CES1 function. A better understanding of the regulation of CES1 expression and activity and identification of biomarkers for CES1 function in vivo could lead to the development of a precision pharmacotherapy strategy to improve the efficacy and safety of many CES1 substrate drugs. SIGNIFICANCE STATEMENT: The clinical relevance of CES1 has been well demonstrated in various clinical trials. Genetic and nongenetic regulators can affect CES1 expression and activity, resulting in the alteration of the metabolism and clinical outcome of CES1 substrate drugs, such as methylphenidate and clopidogrel. Predicting the hepatic CES1 function can provide clinical guidance to optimize pharmacotherapy of numerous medications metabolized by CES1.
ESTHER : Her_2020_Drug.Metab.Dispos_48_230
PubMedSearch : Her_2020_Drug.Metab.Dispos_48_230
PubMedID: 31871135
Gene_locus related to this paper: human-CES1

Title : Chemoproteomic Identification of Serine Hydrolase RBBP9 as a Valacyclovir-Activating Enzyme - Shenoy_2020_Mol.Pharm_17_1706
Author(s) : Shenoy VM , Thompson BR , Shi J , Zhu HJ , Smith DE , Amidon GL
Ref : Mol Pharm , 17 :1706 , 2020
Abstract : Prodrug discovery and development in the pharmaceutical industry have been hampered by a lack of knowledge of prodrug activation pathways. Such knowledge would minimize the risks of prodrug failure by enabling proper selection of preclinical animal models, prediction of pharmacogenomic variability, and identification of drug-drug interactions. Technologies for annotation of activating enzymes have not kept pace with the growing need. Activity-based protein profiling (ABPP) has matured considerably in recent decades, leading to widespread use in the pharmaceutical industry. Here, we report the extension of competitive ABPP (cABPP) to prodrug-activating enzyme identification in stable isotope-labeled cell lysates using a modified fluorophosphonate probe. Focusing on the antiviral ester prodrug valacyclovir (VACV), we identified serine hydrolase RBBP9 as an activating enzyme in Caco-2 cells via shotgun proteomics, validating the activity via the selective inhibitor emetine (EME). Kinetic characterization of RBBP9 revealed a catalytic efficiency (k(cat).K(M)(-1) = 104 mM(-1).s(-1)) comparable to that of BPHL, the only known VACV-activating enzyme prior to this work. EME incubation in wild-type and Bphl-knockout jejunum and liver lysates demonstrated the near-exclusivity of VACV activation by RBBP9 in the intestine. Additionally, these studies showed that RBBP9 and BPHL are the two major and coequal VACV-activating enzymes in the liver. Single-pass intestinal perfusions of VACV +/- EME in mice showed EME coperfusion significantly inhibited the intestinal activation of VACV, implying the in vivo relevance of RBBP9-mediated VACV activation. We envision that others might use the cABPP approach in the future for global, rapid, and efficient discovery of prodrug-activating enzymes.
ESTHER : Shenoy_2020_Mol.Pharm_17_1706
PubMedSearch : Shenoy_2020_Mol.Pharm_17_1706
PubMedID: 32196348
Gene_locus related to this paper: human-RBBP9

Title : FRACPRED-2D-PRM: A fraction prediction algorithm-assisted two-dimensional liquid chromatography-based parallel reaction monitoring-mass spectrometry approach for measuring low-abundance proteins in human plasma - Shi_2020_Proteomics__e2000175
Author(s) : Shi J , Xiao J , Li J , Wang X , Her L , Sorensen MJ , Zhu HJ
Ref : Proteomics , :e2000175 , 2020
Abstract : Multidimensional fractionation-based enrichment methods improve the sensitivity of proteomic analysis for low-abundance proteins. However, a major limitation of conventional multidimensional proteomics is the extensive labor and instrument time required for analyzing many fractions obtained from the first dimension separation. Here, we present a fraction prediction algorithm-assisted two-dimensional LC-based parallel reaction monitoring-mass spectrometry (FRACPRED-2D-PRM) approach for measuring low-abundance proteins in human plasma. Plasma digests were separated by the first dimension high-pH RP-LC with data-dependent acquisition (DDA). We then used the FRACPRED algorithm to predict the retention time of undetectable target peptides according to those of other abundant plasma peptides during the first dimension separation. Fractions predicted to contain target peptides were analyzed by the second dimension low-pH nano RP-LC PRM. We demonstrated the accuracy and robustness of fraction prediction with the FRACPRED algorithm by measuring two low-abundance proteins, aldolase B and carboxylesterase 1, in human plasma. The FRACPRED-2D-PRM proteomics approach demonstrated markedly improved efficiency and sensitivity over conventional 2D-LC proteomics assays. We expect that this approach will be widely used in the study of low-abundance proteins in plasma and other complex biological samples. This article is protected by copyright. All rights reserved.
ESTHER : Shi_2020_Proteomics__e2000175
PubMedSearch : Shi_2020_Proteomics__e2000175
PubMedID: 33085175

Title : Label-free absolute protein quantification with data-independent acquisition - He_2019_J.Proteomics_200_51
Author(s) : He B , Shi J , Wang X , Jiang H , Zhu HJ
Ref : J Proteomics , 200 :51 , 2019
Abstract : Despite data-independent acquisition (DIA) has been increasingly used for relative protein quantification, DIA-based label-free absolute quantification method has not been fully established. Here we present a novel DIA method using the TPA algorithm (DIA-TPA) for the absolute quantification of protein expressions in human liver microsomal and S9 samples. To validate this method, both data-dependent acquisition (DDA) and DIA experiments were conducted on 36 individual human liver microsome and S9 samples. The MS2-based DIA-TPA was able to quantify approximately twice as many proteins as the MS1-based DDA-TPA method, whereas protein concentrations determined by the two approaches were comparable. To evaluate the accuracy of the DIA-TPA method, we absolutely quantified carboxylesterase 1 concentrations in human liver S9 fractions using an established SILAC internal standard-based proteomic assay; the SILAC results were consistent with those obtained from DIA-TPA analysis. Finally, we employed a unique algorithm in DIA-TPA to distribute the MS signals from shared peptides to individual proteins or isoforms and successfully applied the method to the absolute quantification of several drug-metabolizing enzymes in human liver microsomes. In sum, the DIA-TPA method not only can absolutely quantify entire proteomes and specific proteins, but also has the capability quantifying proteins with shared peptides. SIGNIFICANCE: Data independent acquisition (DIA) has emerged as a powerful approach for relative protein quantification at the whole proteome level. However, DIA-based label-free absolute protein quantification (APQ) method has not been fully established. In the present study, we present a novel DIA-based label-free APQ approach, named DIA-TPA, with the capability absolutely quantifying proteins with shared peptides. The method was validated by comparing the quantification results of DIA-TPA with that obtained from stable isotope-labeled internal standard-based proteomic assays.
ESTHER : He_2019_J.Proteomics_200_51
PubMedSearch : He_2019_J.Proteomics_200_51
PubMedID: 30880166

Title : Functional study of Carboxylesterase 1 protein isoforms - Wang_2018_Proteomics__e1800288
Author(s) : Wang X , Shi J , Zhu HJ
Ref : Proteomics , :e1800288 , 2018
Abstract : Carboxylesterase1 (CES1) is a primary human hepatic hydrolase involved in hydrolytic biotransformation of numerous medications. Considerable interindividual variability in CES1 expression and activity has been consistently reported. Four isoforms of the CES1 protein are produced by alternative splicing (AS). In the current study, we examined the activity and expression of each CES1 isoform using transfected cell lines and determined CES1 isoform composition and its impact on CES1 activity in human livers. In transfected cells, isoforms 3 and 4 showed mRNA and protein expressions comparable to isoforms 1 and 2, but had significantly impaired activity when hydrolyzing enalapril and clopidogrel. In individual human liver samples, isoforms 1 and 2 were the major forms, contributing 73%-90% of total CES1 protein expression. In addition, the protein expression ratios of isoforms 1 and 2 to isoforms 3 and 4 were positively associated with CES1 activity in the livers, suggesting that CES1 isoform composition is a factor contributing to the variability in hepatic CES1 function. Further investigations of the regulation of CES1 AS would improve our understanding of CES1 variability and help develop a strategy to optimize the pharmacotherapy of many CES1 substrate medications. This article is protected by copyright. All rights reserved.
ESTHER : Wang_2018_Proteomics__e1800288
PubMedSearch : Wang_2018_Proteomics__e1800288
PubMedID: 30520264

Title : Effect of biphenyl hydrolase-like (BPHL) gene disruption on the intestinal stability, permeability and absorption of valacyclovir in wildtype and Bphl knockout mice - Hu_2018_Biochem.Pharmacol_156_147
Author(s) : Hu Y , Epling D , Shi J , Song F , Tsume Y , Zhu HJ , Amidon GL , Smith DE
Ref : Biochemical Pharmacology , 156 :147 , 2018
Abstract : Biphenyl hydrolase-like protein (BPHL) is a novel human serine hydrolase that was originally cloned from a breast carcinoma cDNA library and shown to convert valacyclovir to acyclovir and valganciclovir to ganciclovir. However, the exclusivity of this process has not been determined and, indeed, it is possible that a number of esterases/proteases may mediate the hydrolysis of valacyclovir and similar prodrugs. The objectives of the present study were to evaluate the in situ intestinal permeability and stability of valacyclovir in wildtype (WT) and Bphl knockout (KO) mice, as well as the in vivo oral absorption and intravenous disposition of valacyclovir and acyclovir in the two mouse genotypes. We found that Bphl knockout mice had no obvious phenotype and that Bphl ablation did not alter the jejunal permeability of valacyclovir during in situ perfusions (i.e., 0.54x10(-4) in WT vs. 0.53x10(-4)cm/s in KO). Whereas no meaningful changes occurred between genotypes in the gene expression of proton-coupled oligopeptide transporters (i.e., PepT1, PepT2, PhT1, PhT2), enzymatic upregulation of Cyp3a11, Cyp3a16, Abhd14a and Abhd14b was observed in some tissues of Bphl knockout mice. Most importantly, we found that valacyclovir was rapidly and efficiently hydrolyzed to acyclovir in the absence of BPHL, and that hydrolysis was more extensive after the oral vs. intravenous route of administration (for both genotypes). Taken as a whole, BPHL is not obligatory for the conversion of valacyclovir to acyclovir either presystemically or systemically.
ESTHER : Hu_2018_Biochem.Pharmacol_156_147
PubMedSearch : Hu_2018_Biochem.Pharmacol_156_147
PubMedID: 30121252
Gene_locus related to this paper: human-BPHL

Title : A Comprehensive Functional Assessment of Carboxylesterase 1 Nonsynonymous Polymorphisms - Wang_2017_Drug.Metab.Dispos_45_1149
Author(s) : Wang X , Rida N , Shi J , Wu AH , Bleske BE , Zhu HJ
Ref : Drug Metabolism & Disposition: The Biological Fate of Chemicals , 45 :1149 , 2017
Abstract : Carboxylesterase 1 (CES1) is the predominant human hepatic hydrolase responsible for the metabolism of many clinically important medications. CES1 expression and activity vary markedly among individuals; and genetic variation is a major contributing factor to CES1 interindividual variability. In this study, we comprehensively examined the functions of CES1 nonsynonymous single nucleotide polymorphisms (nsSNPs) and haplotypes using transfected cell lines and individual human liver tissues. The 20 candidate variants include CES1 nsSNPs with a minor allele frequency >0.5% in a given population or located in close proximity to the CES1 active site. Five nsSNPs, including L40Ter (rs151291296), G142E (rs121912777), G147C (rs146456965), Y170D (rs148947808), and R171C (rs201065375), were loss-of-function variants for metabolizing the CES1 substrates clopidogrel, enalapril, and sacubitril. In addition, A158V (rs202121317), R199H (rs2307243), E220G (rs200707504), and T290M (rs202001817) decreased CES1 activity to a lesser extent in a substrate-dependent manner. Several nsSNPs, includingL40Ter (rs151291296), G147C (rs146456965), Y170D (rs148947808), and R171C (rs201065375), significantly reduced CES1 protein and/or mRNA expression levels in the transfected cells. Functions of the common nonsynonymous haplotypes D203E-A269S and S75N-D203E-A269S were evaluated using cells stably expressing the haplotypes and a large set of the human liver. Neither CES1 expression nor activity was affected by the two haplotypes. In summary, this study revealed several functional nsSNPs with impaired activity on the metabolism of CES1 substrate drugs. Clinical investigations are warranted to determine whether these nsSNPs can serve as biomarkers for the prediction of therapeutic outcomes of drugs metabolized by CES1.
ESTHER : Wang_2017_Drug.Metab.Dispos_45_1149
PubMedSearch : Wang_2017_Drug.Metab.Dispos_45_1149
PubMedID: 28838926
Gene_locus related to this paper: human-CES1

Title : Ethanol Interactions With Dexmethylphenidate and dl-Methylphenidate Spheroidal Oral Drug Absorption Systems in Healthy Volunteers - Zhu_2017_J.Clin.Psychopharmacol_37_419
Author(s) : Zhu HJ , Patrick KS , Straughn AB , Reeves OT, 3rd , Bernstein H , Shi J , Johnson HJ , Knight JM , Smith AT , Malcolm RJ , Markowitz JS
Ref : J Clin Psychopharmacol , 37 :419 , 2017
Abstract : BACKGROUND/PURPOSE: Ethanol coadministered with immediate-release dl-methylphenidate (dl-MPH) or dexmethylphenidate (d-MPH) significantly increases the geomean maximum plasma concentration (Cmax) of d-MPH 22% and 15%, respectively, and elevates overall drug exposure and psychostimulant effects. We asked the question: Are these ethanol-MPH interactions based more fundamentally on (1) inhibition of postabsorption d-MPH metabolism or (2) acceleration of MPH formulation gastric dissolution by ethanol in the stomach? This was investigated using the pulsatile, distinctly biphasic, spheroidal oral drug absorption systems of dl-MPH and d-MPH.
METHODS: In a randomized, 4-way crossover study, 14 healthy subjects received pulsatile dl-MPH (40 mg) or d-MPH (20 mg), with or without ethanol (0.6 g/kg), dosed 4 hours later. These 4 hours allowed the delayed-release second MPH pulse to reach a more distal region of the gut to preclude gastric biopharmaceutical influences. Plasma was analyzed using a highly sensitive chiral method. Subjective/physiological effects were recorded. FINDINGS/RESULTS: Ethanol increased the second pulse of d-MPH Cmax for dl-MPH by 35% (P < 0.01) and the partial area under the plasma concentration curve from 4 to 8 hours by 25% (P < 0.05). The respective values for enantiopure d-MPH were 27% (P = 0.001) and 20% (P < 0.01). The carboxylesterase 1-mediated transesterification metabolite ethylphenidate served as a biomarker for coexposure. Ethanol significantly potentiated stimulant responses to either formulation. IMPLICATIONS/
CONCLUSIONS: These findings support drug dispositional interactions between ethanol and MPH as dominant over potential biopharmaceutical considerations. Understanding the pharmacology underlying the frequent coabuse of MPH-ethanol provides rational guidance in the selection of first-line pharmacotherapy for comorbid attention-deficit/hyperactivity disorder-alcohol use disorder.
ESTHER : Zhu_2017_J.Clin.Psychopharmacol_37_419
PubMedSearch : Zhu_2017_J.Clin.Psychopharmacol_37_419
PubMedID: 28590363

Title : Sacubitril Is Selectively Activated by Carboxylesterase 1 (CES1) in the Liver and the Activation Is Affected by CES1 Genetic Variation - Shi_2016_Drug.Metab.Dispos_44_554
Author(s) : Shi J , Wang X , Nguyen J , Wu AH , Bleske BE , Zhu HJ
Ref : Drug Metabolism & Disposition: The Biological Fate of Chemicals , 44 :554 , 2016
Abstract : Sacubitril was recently approved by the Food and Drug Administration for use in combination with valsartan for the treatment of patients with heart failure with reduced ejection fraction. As a prodrug, sacubitril must be metabolized (hydrolyzed) to its active metabolite sacubitrilat (LBQ657) to exert its intended therapeutic effects. Thus, understanding the determinants of sacubitril activation will lead to the improvement of sacubitril pharmacotherapy. The objective of this study was to identify the enzyme(s) responsible for the activation of sacubitril, and determine the impact of genetic variation on sacubitril activation. First, an incubation study of sacubitril with human plasma and the S9 fractions of human liver, intestine, and kidney was conducted. Sacubitril was found to be activated by human liver S9 fractions only. Moreover, sacubitril activation was significantly inhibited by the carboxylesterase 1 (CES1) inhibitor bis-(p-nitrophenyl) phosphate in human liver S9. Further incubation studies with recombinant human CES1 and carboxylesterase 2 confirmed that sacubitril is a selective CES1 substrate. The in vitro study of cell lines transfected with wild-type CES1 and the CES1 variant G143E (rs71647871) demonstrated that G143E is a loss-of-function variant for sacubitril activation. Importantly, sacubitril activation was significantly impaired in human livers carrying the G143E variant. In conclusion, sacubitril is selectively activated by CES1 in human liver. The CES1 genetic variant G143E can significantly impair sacubitril activation. Therefore, CES1 genetic variants appear to be an important contributing factor to interindividual variability in sacubitril activation, and have the potential to serve as biomarkers to optimize sacubitril pharmacotherapy.
ESTHER : Shi_2016_Drug.Metab.Dispos_44_554
PubMedSearch : Shi_2016_Drug.Metab.Dispos_44_554
PubMedID: 26817948
Gene_locus related to this paper: human-CES1

Title : Dabigatran etexilate activation is affected by the CES1 genetic polymorphism G143E (rs71647871) and gender - Shi_2016_Biochem.Pharmacol_119_76
Author(s) : Shi J , Wang X , Nguyen JH , Bleske BE , Liang Y , Liu L , Zhu HJ
Ref : Biochemical Pharmacology , 119 :76 , 2016
Abstract : The oral anticoagulant prodrug dabigatran etexilate (DABE) is sequentially metabolized by intestinal carboxylesterase 2 (CES2) and hepatic carboxylesterase 1 (CES1) to form its active metabolite dabigatran (DAB). A recent genome-wide association study reported that the CES1 single nucleotide polymorphisms (SNPs) rs2244613 and rs8192935 were associated with lower DAB plasma concentrations in the Randomized Evaluation of Long-term Anticoagulation Therapy (RE-LY) study participants. In addition, gender differences in exposure to DAB were observed in clinical studies. The aim of this study was to examine the effect of CES1 genetic polymorphisms and gender on DABE activation using several in vitro approaches. The genotypes of the CES1 SNPs rs2244613, rs8192935, and the known loss-of-function CES1 variant rs71647871 (G143E), and the activation of DABE and its intermediate metabolites M1 and M2 were determined in 104 normal human liver samples. DABE, M1, and M2 activations were found to be impaired in human livers carrying the G143E variant. However, neither rs2244613 nor rs8192935 was associated with the activation in human livers. The incubation study of DABE with supernatant fractions (S9) prepared from the G143E-transfected cells showed that the G143E is a loss-of-function variant for DABE metabolism. Moreover, hepatic CES1 activity on M2 activation was significantly higher in female liver samples than male. Our data suggest that CES1 genetic variants and gender are important contributing factors to variability in DABE activation in humans. A personalized DABE treatment approach based on patient-specific CES1 genotypes and sex may have the potential to improve the efficacy and safety of DABE pharmacotherapy.
ESTHER : Shi_2016_Biochem.Pharmacol_119_76
PubMedSearch : Shi_2016_Biochem.Pharmacol_119_76
PubMedID: 27614009
Gene_locus related to this paper: human-CES1

Title : Association of Oseltamivir Activation with Gender and Carboxylesterase 1 Genetic Polymorphisms - Shi_2016_Basic.Clin.Pharmacol.Toxicol_119_555
Author(s) : Shi J , Wang X , Eyler RF , Liang Y , Liu L , Mueller BA , Zhu HJ
Ref : Basic Clin Pharmacol Toxicol , 119 :555 , 2016
Abstract : Oseltamivir, an inactive anti-influenza virus prodrug, is activated (hydrolysed) in vivo by carboxylesterase 1 (CES1) to its active metabolite oseltamivir carboxylate. CES1 functions are significantly associated with certain CES1 genetic variants and some non-genetic factors. The purpose of this study was to investigate the effect of gender and several CES1 genetic polymorphisms on oseltamivir activation using a large set of individual human liver samples. CES1-mediated oseltamivir hydrolysis and CES1 genotypes, including the G143E (rs71647871), rs2244613, rs8192935, the -816A>C (rs3785161) and the CES1P1/CES1P1VAR, were determined in 104 individual human livers. The results showed that hepatic CES1 protein expression in females was 17.3% higher than that in males (p = 0.039), while oseltamivir activation rate in the livers from female donors was 27.8% higher than that from males (p = 0.076). As for CES1 genetic polymorphisms, neither CES1 protein expression nor CES1 activity on oseltamivir activation was significantly associated with the rs2244613, rs8192935, -816A>C or CES1P1/CES1P1VAR genotypes. However, oseltamivir hydrolysis in the livers with the genotype 143G/E was approximately 40% of that with the 143G/G genotype (0.7 +/- 0.2 versus 1.8 +/- 1.1 nmole/mg protein/min, p = 0.005). In summary, the results suggest that hepatic oseltamivir activation appears to be more efficient in females than that in males, and the activation can be impaired by functional CES1 variants, such as the G143E. However, clinical implication of CES1 gender differences and pharmacogenetics in oseltamivir pharmacotherapy warrants further investigations.
ESTHER : Shi_2016_Basic.Clin.Pharmacol.Toxicol_119_555
PubMedSearch : Shi_2016_Basic.Clin.Pharmacol.Toxicol_119_555
PubMedID: 27228223
Gene_locus related to this paper: human-CES1

Title : CES1 genetic variation affects the activation of angiotensin-converting enzyme inhibitors - Wang_2016_Pharmacogenomics.J_16_220
Author(s) : Wang X , Wang G , Shi J , Aa JY , Comas R , Liang Y , Zhu HJ
Ref : Pharmacogenomics J , 16 :220 , 2016
Abstract : The aim of the study was to determine the effect of carboxylesterase 1 (CES1) genetic variation on the activation of angiotensin-converting enzyme inhibitor (ACEI) prodrugs. In vitro incubation study of human liver, intestine and kidney s9 fractions demonstrated that the ACEI prodrugs enalapril, ramipril, perindopril, moexipril and fosinopril are selectively activated by CES1 in the liver. The impact of CES1/CES1VAR and CES1P1/CES1P1VAR genotypes and diplotypes on CES1 expression and activity on enalapril activation was investigated in 102 normal human liver samples. Neither the genotypes nor the diplotypes affected hepatic CES1 expression and activity. Moreover, among several CES1 nonsynonymous variants studied in transfected cell lines, the G143E (rs71647871) was a loss-of-function variant for the activation of all ACEIs tested. The CES1 activity on enalapril activation in human livers with the 143G/E genotype was approximately one-third of that carrying the 143G/G. Thus, some functional CES1 genetic variants (for example, G143E) may impair ACEI activation, and consequently affect therapeutic outcomes of ACEI prodrugs.
ESTHER : Wang_2016_Pharmacogenomics.J_16_220
PubMedSearch : Wang_2016_Pharmacogenomics.J_16_220
PubMedID: 26076923
Gene_locus related to this paper: human-CES1

Title : Targeted absolute quantitative proteomics with SILAC internal standards and unlabeled full-length protein calibrators (TAQSI) - Wang_2016_Rapid.Commun.Mass.Spectrom_30_553
Author(s) : Wang X , Liang Y , Liu L , Shi J , Zhu HJ
Ref : Rapid Commun Mass Spectrom , 30 :553 , 2016
Abstract : RATIONALE: Liquid Chromatography/Mass Spectrometry (LC/MS)-based proteomics for absolute protein quantification has been increasingly utilized in both basic and clinical research. There is a great need to overcome some major hurdles of current absolute protein quantification methods, such as significant inter-assay variability and the high cost associated with the preparation of purified stable-isotope-labeled peptide/protein standards.
METHODS: We developed a novel targeted absolute protein quantification method, named TAQSI, utilizing full-length isotope-labeled protein internal standards generated from SILAC (stable isotope labeling by amino acid in cell culture) and unlabeled full-length protein calibrators. This approach was applied to absolute quantification of carboxylesterase 1 (CES1), the primary human hepatic hydrolase, in a large set of human liver samples. Absolute CES1 quantities were derived from the standard calibration curves established from unlabeled CES1 protein calibrators and the isotope-labeled CES1 internal standards obtained from SILAC HepG2 cells.
RESULTS: The TAQSI assay was found to be accurate, precise, reproducible, and cost-effective. Importantly, protein quantification was not affected by various protein extraction and digestion protocols, and measurement errors associated with nonsynonymous variants can be readily identified and avoided. Furthermore, the TAQSI approach significantly simplifies the procedure of identifying the best performance surrogate peptides.
CONCLUSIONS: The TAQSI assay can be widely used for targeted absolute protein quantification in various biomedical research and clinical practice settings. Copyright (c) 2016 John Wiley & Sons, Ltd.
ESTHER : Wang_2016_Rapid.Commun.Mass.Spectrom_30_553
PubMedSearch : Wang_2016_Rapid.Commun.Mass.Spectrom_30_553
PubMedID: 26842578

Title : CES1P1 variant -816A>C is not associated with hepatic carboxylesterase 1 expression and activity or antihypertensive effect of trandolapril - Zhu_2016_Eur.J.Clin.Pharmacol_72_681
Author(s) : Zhu HJ , Langaee TY , Gong Y , Wang X , Pepine CJ , Cooper-DeHoff RM , Johnson JA , Markowitz JS
Ref : European Journal of Clinical Pharmacology , 72 :681 , 2016
Abstract : PURPOSE: The majority of angiotensin-converting enzyme inhibitors (ACEIs) are synthesized as ester prodrugs that must be converted to their active forms in vivo in order to exert therapeutic effects. Hepatic carboxylesterase 1 (CES1) is the primary enzyme responsible for the bioactivation of ACEI prodrugs in humans. The genetic variant -816A>C (rs3785161) is a common variant located in the promoter region of the CES1P1 gene. Previous studies report conflicting results with regard to the association of this variant and therapeutic outcomes of CES1 substrate drugs. The purpose of this study was to determine the effect of the variant -816A>C on the activation of the ACEI prodrug trandolapril in human livers and the blood pressure (BP)-lowering effect of trandolapril in hypertensive patients.
METHODS: The -816A>C genotypes and CES1 expression and activity on trandolapril activation were determined in 100 individual human liver samples. Furthermore, the association of the -816A>C variant and the BP lowering effect of trandolapril was evaluated in hypertensive patients who participated in the International Verapamil SR Trandolapril Study (INVEST).
RESULTS: Our in vitro study demonstrated that hepatic CES1 expression and activity did not differ among different -816A>C genotypes. Moreover, we were unable to identify a clinical association between the BP lowering effects of trandolapril and -816A>C genotypes.
CONCLUSIONS: We conclude that the -816A>C variant is not associated with interindividual variability in CES1 expression and activity or therapeutic response to ACEI prodrugs.
ESTHER : Zhu_2016_Eur.J.Clin.Pharmacol_72_681
PubMedSearch : Zhu_2016_Eur.J.Clin.Pharmacol_72_681
PubMedID: 26915813
Gene_locus related to this paper: human-CES1

Title : Regulatory effects of genomic translocations at the human carboxylesterase-1 (CES1) gene locus - Sanford_2016_Pharmacogenet.Genomics_26_197
Author(s) : Sanford JC , Wang X , Shi J , Barrie ES , Wang D , Zhu HJ , Sadee W
Ref : Pharmacogenet Genomics , 26 :197 , 2016
Abstract : OBJECTIVE: CES1 encodes carboxylesterase-1, an important drug-metabolizing enzyme with high expression in the liver. Previous studies have reported a genomic translocation of the 5' region from the poorly expressed pseudogene CES1P1, to CES1, yielding the structural variant CES1VAR. The aim of this study was to characterize this translocation and its effect on CES1 expression in the human liver. MATERIALS AND
METHODS: Experiments were conducted in human liver tissues and cell culture (HepG2). The promoter and exon 1 of CES1 were sequenced by Sanger and Ion Torrent sequencing to identify gene translocations. The effects of CES1 5'UTRs on mRNA and protein expression were assessed by quantitative real-time PCR, allelic ratio mRNA analysis by primer extension (SNaPshot), quantitative targeted proteomics, and luciferase reporter gene assays.
RESULTS: Sequencing of CES1 identified two translocations: first, CES1VAR (17% minor allele frequency) comprising the 5'UTR, exon 1, and part of intron 1. A second shorter translocation, CES1SVAR, was observed excluding exon 1 and intron 1 regions (<0.01% minor allele frequency). CES1VAR is associated with 2.6-fold decreased CES1 mRNA and approximately 1.35-fold lower allelic mRNA. Luciferase reporter constructs showed that CES1VAR decreases luciferase activity 1.5-fold, whereas CES1SVAR slightly increases activity. CES1VAR was not associated with CES1 protein expression or metabolism of the CES1 substrates enalapril, clopidogrel, or methylphenidate in the liver. CONCLUSION: The frequent translocation variant CES1VAR reduces mRNA expression of CES1 in the liver by approximately 30%, but protein expression and metabolizing activity in the liver were not detectably altered - possibly because of variable CES1 expression masking small allelic effects. Whether drug therapies are affected by CES1VAR will require further in-vivo studies.
ESTHER : Sanford_2016_Pharmacogenet.Genomics_26_197
PubMedSearch : Sanford_2016_Pharmacogenet.Genomics_26_197
PubMedID: 26871237
Gene_locus related to this paper: human-CES1

Title : Carboxylesterase 1-Mediated Drug-Drug Interactions between Clopidogrel and Simvastatin - Wang_2015_Biol.Pharm.Bull_38_292
Author(s) : Wang X , Zhu HJ , Markowitz JS
Ref : Biol Pharm Bull , 38 :292 , 2015
Abstract : Patients with coronary artery disease often receive concurrent treatment with clopidogrel and a hydroxymethylglutaryl (HMG)-CoA reductase inhibitor medication. Accordingly, potential drug-drug interactions associated with the concomitant use of these agents present an area of concern. Both CYP enzymes and carboxylesterase 1 (CES1) are involved in the metabolism of clopidogrel, while CES1 is believed to be the enzyme responsible for the activation of simvastatin. Some in vitro studies have suggested that simvastatin could attenuate clopidogrel activation via inhibiting CYP3A activity. However, these findings have not found support in several recently published clinical investigations. The present study addresses these inconsistencies by exploring the potential role of CES1 in the metabolism of clopidogrel and simvastatin. Our in vitro human liver s9 fraction incubation study demonstrated that simvastatin significantly enhanced the formation of the intermediate metabolite 2-oxo-clopidogrel, and inhibited the CES1-mediated hydrolysis of clopidogrel, 2-oxo-clopidogrel, and the active metabolite. However, the production of the active metabolite remained unchanged. Conversely, clopidogrel was not found to influence the CES1 mediated hydrolysis (activation) of simvastatin. Moreover, we provided evidence that CES1 is not an efficient enzyme for catalyzing simvastatin activation. In summary, the inhibitory effect of simvastatin on the hydrolysis of clopidogrel and its principal metabolites may have offset the influence of simvastatin-mediated inhibition of CYP3A, and permitted the unaltered formation of the clopidogrel active metabolite. These data help explain the conflicting accounts in previous reports regarding clopidogrel and simvastatin interactions by taking into consideration CES1; they suggest that the interactions are unlikely to significantly influence clinical outcomes.
ESTHER : Wang_2015_Biol.Pharm.Bull_38_292
PubMedSearch : Wang_2015_Biol.Pharm.Bull_38_292
PubMedID: 25747989

Title : Clopidogrel Bioactivation and Risk of Bleeding in Patients Cotreated With Angiotensin-Converting Enzyme Inhibitors After Myocardial Infarction: A Proof-of-Concept Study - Kristensen_2014_Clin.Pharmacol.Ther_96_713
Author(s) : Kristensen KE , Zhu HJ , Wang X , Gislason GH , Torp-Pedersen C , Rasmussen HB , Markowitz JS , Hansen PR
Ref : Clinical Pharmacology & Therapeutics , 96 :713 , 2014
Abstract : Clopidogrel is an oral antiplatelet prodrug, the majority of which is hydrolyzed to an inactive metabolite by hepatic carboxylesterase 1 (CES1). Most angiotensin-converting enzyme inhibitors (ACEIs) are also metabolized by this enzyme. We examined the effects of ACEIs on clopidogrel bioactivation in vitro and linked the results with a pharmacoepidemiological study. In vitro, ACEIs inhibited CES1-mediated hydrolysis of a model substrate, and trandolapril and enalapril increased formation of clopidogrel active metabolite. In 70,934 patients with myocardial infarction, hazard ratios for clinically significant bleeding in ACEI-treated patients cotreated with or without clopidogrel were 1.10 (95% confidence interval (CI): 0.97-1.25, P = 0.124) and 0.90 (95% CI: 0.81-0.99, P = 0.025), respectively, as compared with patients who did not receive ACEIs. This difference was statistically significant (P = 0.002). We conclude that cotreatment with selected ACEIs and clopidogrel may increase the risk of bleeding. Combination of in vitro and pharmacoepidemiological studies may be a useful paradigm for assessment of drug-drug interactions.
ESTHER : Kristensen_2014_Clin.Pharmacol.Ther_96_713
PubMedSearch : Kristensen_2014_Clin.Pharmacol.Ther_96_713
PubMedID: 25222620

Title : Carboxylesterase 1 as a determinant of clopidogrel metabolism and activation - Zhu_2013_J.Pharmacol.Exp.Ther_344_665
Author(s) : Zhu HJ , Wang X , Gawronski BE , Brinda BJ , Angiolillo DJ , Markowitz JS
Ref : Journal of Pharmacology & Experimental Therapeutics , 344 :665 , 2013
Abstract : Clopidogrel pharmacotherapy is associated with substantial interindividual variability in clinical response, which can translate into an increased risk of adverse outcomes. Clopidogrel, a recognized substrate of hepatic carboxylesterase 1 (CES1), undergoes extensive hydrolytic metabolism in the liver. Significant interindividual variability in the expression and activity of CES1 exists, which is attributed to both genetic and environmental factors. We determined whether CES1 inhibition and CES1 genetic polymorphisms would significantly influence the biotransformation of clopidogrel and alter the formation of the active metabolite. Coincubation of clopidogrel with the CES1 inhibitor bis(4-nitrophenyl) phosphate in human liver s9 fractions significantly increased the concentrations of clopidogrel, 2-oxo-clopidogrel, and clopidogrel active metabolite, while the concentrations of all formed carboxylate metabolites were significantly decreased. As anticipated, clopidogrel and 2-oxo-clopidogrel were efficiently hydrolyzed by the cell s9 fractions prepared from wild-type CES1 transfected cells. The enzymatic activity of the CES1 variants G143E and D260fs were completely impaired in terms of catalyzing the hydrolysis of clopidogrel and 2-oxo-clopidogrel. However, the natural variants G18V, S82L, and A269S failed to produce any significant effect on CES1-mediated hydrolysis of clopidogrel or 2-oxo-clopidogrel. In summary, deficient CES1 catalytic activity resulting from CES1 inhibition or CES1 genetic variation may be associated with higher plasma concentrations of clopidogrel-active metabolite, and hence may enhance antiplatelet activity. Additionally, CES1 genetic variants have the potential to serve as a biomarker to predict clopidogrel response and individualize clopidogrel dosing regimens in clinical practice.
ESTHER : Zhu_2013_J.Pharmacol.Exp.Ther_344_665
PubMedSearch : Zhu_2013_J.Pharmacol.Exp.Ther_344_665
PubMedID: 23275066
Gene_locus related to this paper: human-CES1

Title : Isopropylphenidate: an ester homolog of methylphenidate with sustained and selective dopaminergic activity and reduced drug interaction liability - Markowitz_2013_J.Child.Adolesc.Psychopharmacol_23_648
Author(s) : Markowitz JS , Zhu HJ , Patrick KS
Ref : J Child Adolesc Psychopharmacol , 23 :648 , 2013
Abstract : Abstract Objective: The most widely utilized pharmacological treatment of attention-deficit/hyperactivity disorder (ADHD) is the psychostimulant methylphenidate (MPH). Most MPH formulations consist of the racemic mixture of d-threo-(R, R)-MPH and l-threo-(S, S)-MPH isomers. MPH is characterized by its low bioavailability and short half-life (2-3 hours). Additionally, significant inter-individual variability in MPH pharmacokinetics has been consistently documented. Accordingly, efforts have been directed at developing alternatives to MPH as therapeutic agents. A wide range of MPH analogues (dl-alpha-[2-piperidyl]-phenylacetic acid esters) have been synthesized with the dopamine transporter (DAT) and norepinephrine transporter (NET) as principle neuropharmacological targets. The present study investigated the metabolic profiles and pharmacological activity of the isopropyl ester derivative of MPH, dl-isopropylphenidate (IPH), both in vitro and in vivo. Methods: The synthesis, monoaminergic transporter binding, cellular uptake profiles, and assessment of metabolic hydrolysis and transesterification in the presence of ethanol are described using MPH as a comparator. Additionally, an in vivo assessment of IPH stimulant effects (vs. saline) in rats was performed with locomotor activity as a pharmacodynamic outcome. Results: IPH displayed unique pharmacological characteristics including greater DAT than NET binding and cellular uptake activity, and greater resistance to hydrolysis and transesterification via carboxylesterase 1 relative to MPH. Further, sustained psychostimulant properties offer the prospect of an enhanced duration of action. Conclusions: Our findings are consistent with IPH exhibiting attributes distinguishing it from MPH and warranting further study and development of IPH as a novel psychotherapeutic agent.
ESTHER : Markowitz_2013_J.Child.Adolesc.Psychopharmacol_23_648
PubMedSearch : Markowitz_2013_J.Child.Adolesc.Psychopharmacol_23_648
PubMedID: 24261661

Title : Carboxylesterase 1 (CES1) genetic polymorphisms and oseltamivir activation -
Author(s) : Zhu HJ , Markowitz JS
Ref : European Journal of Clinical Pharmacology , 69 :733 , 2013
PubMedID: 22847618

Title : Prediction and in vitro evaluation of selected protease inhibitor antiviral drugs as inhibitors of carboxylesterase 1: a potential source of drug-drug interactions - Rhoades_2012_Pharm.Res_29_972
Author(s) : Rhoades JA , Peterson YK , Zhu HJ , Appel DI , Peloquin CA , Markowitz JS
Ref : Pharm Res , 29 :972 , 2012
Abstract : PURPOSE: To predict and determine whether the protease inhibitors (PIs) nelfinavir, amprenavir, atazanavir, ritonavir, and saquinavir could serve as metabolic inhibitors of the human CES1 (hCES1) using both molecular modeling techniques and in vitro inhibition assays. METHODS: Initially, a molecular modeling approach was utilized to predict whether the selected PIs could serve as hCES1 inhibitors. The inhibitory effects of these PIs on hCES1 activity were then further evaluated utilizing previously established in vitro assay. RESULTS: Pharmacophore and 2D-QSAR modeling predicted that nelfinavir would serve as a potent hCES1 inhibitor. This hypothesis was validated by in vitro hCES1 inhibition studies. Other PIs (amprenavir, atazanavir, ritonavir, saquinavir) were evaluated and also shown to be hCES1 inhibitors in vitro, although substantially less potent relative to nelfinavir. CONCLUSION: Computational molecular modeling is a valid approach to identify potential hCES1 inhibitors as candidates for further assessment using validated in vitro techniques. DDIs could occur when nelfinavir is co-administered with drugs metabolized by hCES1.
ESTHER : Rhoades_2012_Pharm.Res_29_972
PubMedSearch : Rhoades_2012_Pharm.Res_29_972
PubMedID: 22161308

Title : A discriminative analytical method for detection of CES1A1 and CES1A2\/CES1A3 genetic variants - Zhu_2012_Pharmacogenet.Genomics_22_215
Author(s) : Zhu HJ , Brinda B , Froehlich TE , Markowitz JS
Ref : Pharmacogenet Genomics , 22 :215 , 2012
Abstract : Human carboxylesterase 1 (hCES1), encoded by the CES1 gene, is the predominant hepatic hydrolase responsible for the metabolism of many therapeutic agents, toxins, and endogenous substances. Genetic variants of CES1 can affect hCES1 function and expression and ultimately influence clinical response to drugs serving as hCES1 substrates. The CES1 gene consists of three isoforms including the functional CES1A1 and CES1A2 genes and the nonfunctional pseudogene CES1A3. Natural variants of these isoforms exert differing impacts on hCES1 function. However, the existing CES1 genotyping methods are incapable of determining whether these variants belong to CES1A1, CES1A2, or CES1A3 because of the high similarity among these three genes, as a consequence they are unable to discriminate between heterozygotes and homozygotes. We report the development of a novel long-range PCR-based, discriminative genotyping assay capable of specifically detecting the variants among CES1A1, CES1A2, and CES1A3 genes. The comparison of the genotyping results between this novel assay and those previously reported methods highlighted the necessity of applying the discriminative genotyping assay in pharmacogenetic studies involving CES1 gene.
ESTHER : Zhu_2012_Pharmacogenet.Genomics_22_215
PubMedSearch : Zhu_2012_Pharmacogenet.Genomics_22_215
PubMedID: 22237548
Gene_locus related to this paper: human-CES1

Title : Enantiospecific determination of dl-methylphenidate and dl-ethylphenidate in plasma by liquid chromatography-tandem mass spectrometry: Application to human ethanol interactions - Zhu_2011_J.Chromatogr.B.Analyt.Technol.Biomed.Life.Sci_879_783
Author(s) : Zhu HJ , Patrick KS , Markowitz JS
Ref : Journal of Chromatography B Analyt Technol Biomed Life Sciences , 879 :783 , 2011
Abstract : In humans, concomitant DL-methylphenidate (DL-MPH) and ethanol results in the carboxylesterase 1 (hCES1) mediated biotransformation of MPH to the transesterification metabolite DL-ethylphenidate (DL-EPH). The separate enantiomers of MPH and EPH are found at low ng/ml to pg/ml plasma concentrations. Substantial pharmacological differences exist between D- and L-isomers of MPH and EPH, both in terms of pharmacological potencies and receptor selectivity, as well as in pharmacokinetic properties. Accordingly, a sensitive, accurate and precise enantiospecific analytical method is required in order to fully explore pharmacokinetic-pharmacodynamic correlations regarding the MPH-ethanol interaction. The present study describes a novel liquid chromatographic-tandem mass spectrometric method for simultaneous analysis of D- and L-MPH as well as D- and L-EPH concentrations from human plasma. This assay provides baseline resolution of the individual MPH and EPH isomers utilizing a vancomycin-based chiral column. The lower limit of quantification was 0.025 ng/ml for each isomer when extracting 0.5 ml plasma aliquots. Calibration curves were linear over the range from 0.025 ng/ml to 25 ng/ml for all analytes (r(2)>0.995). Assay accuracy and precision were excellent and stability studies and assessment of potential matrix effects contributed to the validation of the method. Application of the method to human plasma samples collected after the administration of dl-MPH with or without ethanol is included, and the implications of this pharmacokinetic drug interaction discussed.
ESTHER : Zhu_2011_J.Chromatogr.B.Analyt.Technol.Biomed.Life.Sci_879_783
PubMedSearch : Zhu_2011_J.Chromatogr.B.Analyt.Technol.Biomed.Life.Sci_879_783
PubMedID: 21402502

Title : Identification of selected therapeutic agents as inhibitors of carboxylesterase 1: potential sources of metabolic drug interactions - Zhu_2010_Toxicology_270_59
Author(s) : Zhu HJ , Appel DI , Peterson YK , Wang Z , Markowitz JS
Ref : Toxicology , 270 :59 , 2010
Abstract : A series of studies were designed and carried out in order to explore the potential for the major human hepatic hydrolase, carboxylesterase 1 (hCES1), to serve as a target of metabolic inhibition by a variety of medications. The risk of adverse drug-drug interaction(s) is present when metabolic inhibitors are combined with known or suspected substrates of a given enzyme. In the present report the abundantly expressed hepatic enzyme, hCES1, was examined as a potential target of metabolic inhibition by a number of routinely prescribed medications. hCES1 has been seldom assessed in this regard despite its role in the metabolism and detoxification of many compounds. The psychostimulant methylphenidate (MPH) was chosen as an hCES1 selective substrate. In vitro studies were performed using previously developed cell lines which overexpress hCES1 with both p-nitrophenyl acetate and d-MPH serving as known substrates. Aripiprazole, perphenazine, thioridazine, and fluoxetine were determined to be the potent hCES1 inhibitors. A complementary animal study followed in vitro screening studies to further evaluate the inhibitory effect of aripiprazole on CES1 activity in FVB mice. The results suggest that the concurrent administration of racemic (i.e. dl-) MPH with aripiprazole significantly increased the plasma concentrations of both total MPH as well as the less active l-isomer. The ratio of d-MPH and l-MPH plasma concentrations was significantly decreased in the mice treated with aripiprazole compared to the control animals, indicating an overall decrease of CES1 catalytic activity in aripiprazole treated animals. Additionally, a quantitative structure-activity relationship based analysis identified a number of structural similarities of CES1 inhibitors. In conclusion, drug-drug interactions with MPH are likely mediated via CES1 inhibition as a result of concomitant drug therapies. CES1 inhibition represents an overlooked and little studied source of variability in MPH disposition, tolerability, and response.
ESTHER : Zhu_2010_Toxicology_270_59
PubMedSearch : Zhu_2010_Toxicology_270_59
PubMedID: 20097249

Title : Age- and sex-related expression and activity of carboxylesterase 1 and 2 in mouse and human liver - Zhu_2009_Drug.Metab.Dispos_37_1819
Author(s) : Zhu HJ , Appel DI , Jiang Y , Markowitz JS
Ref : Drug Metabolism & Disposition: The Biological Fate of Chemicals , 37 :1819 , 2009
Abstract : Carboxylesterase (CES) 1 and CES2 are two major hepatic hydrolases responsible for the metabolism of numerous endogenous and exogenous compounds. In this study, age- and sex-dependent expression and activity of CES1 and CES2 were investigated using both animal models and individual human liver s9 samples. The expression and activity of mouse CES1 (mCES1) and mCES2 in the liver were markedly lower in newborns relative to adults and increased gradually with age, approximating levels of adult animals by age 2 to 4 weeks. Likewise, the average human CES1 (hCES1) expression in the subjects <1 year of age was significantly lower than that of pooled samples. In particular, hCES1 expression in the 13-day and 1-month-old subjects was just 20.3 and 11.1%, respectively, of the pooled sample values. In addition, the subjects <1 year of age exhibited a trend suggestive of low hCES2 expression, but this difference failed to reach statistical significance because of large interindividual variability. The expression and activity of mCES1 and mCES2 were not significantly altered after the animals were treated with human growth hormone, indicating growth hormone may not be associated with the low level of CES expression during early developmental stages. No significant differences of the expression and activity of mCES1 and mCES2 were observed between sexually mature male and female mice. In conclusion, the expression and activity of CES1 and CES2 are age-related but independent of growth hormone level. Sex seems to be an unlikely factor contributing to the regulation of CES1 and CES2.
ESTHER : Zhu_2009_Drug.Metab.Dispos_37_1819
PubMedSearch : Zhu_2009_Drug.Metab.Dispos_37_1819
PubMedID: 19487248

Title : Activation of the antiviral prodrug oseltamivir is impaired by two newly identified carboxylesterase 1 variants - Zhu_2009_Drug.Metab.Dispos_37_264
Author(s) : Zhu HJ , Markowitz JS
Ref : Drug Metabolism & Disposition: The Biological Fate of Chemicals , 37 :264 , 2009
Abstract : Oseltamivir phosphate is an ethyl ester prodrug widely used in the treatment and prevention of both Influenzavirus A and B infections. The conversion of oseltamivir to its active metabolite oseltamivir carboxylate is dependent on ester hydrolysis mediated by carboxylesterase 1 (CES1). We recently identified two functional CES1 variants p.Gly143Glu and p.Asp260fs in a research subject who displayed significant impairment in his ability to metabolize the selective CES1 substrate, methylphenidate. In vitro functional studies demonstrated that the presence of either of the two mutations can result in severe reductions in the catalytic efficiency of CES1 toward methylphenidate, which is required for hydrolysis and pharmacological deactivation. The aim of the present study was to investigate the function of these mutations on activating (hydrolyzing) oseltamivir to oseltamivir carboxylate using the cell lines expressing wild type (WT) and each mutant CES1. In vitro incubation studies demonstrated that the S9 fractions prepared from the cells transfected with WT CES1 and human liver tissues rapidly convert oseltamivir to oseltamivir carboxylate. However, the catalytic activity of the mutant hydrolases was dramatically hindered. The V(max) value of p.Gly143Glu was approximately 25% of that of WT enzyme, whereas the catalytic activity of p.Asp260fs was negligible. These results suggest that the therapeutic efficacy of oseltamivir could be compromised in treated patients expressing either functional CES1 mutation. Furthermore, the potential for increased adverse effects or toxicity as a result of exposure to high concentrations of the nonhydrolyzed prodrug should be considered.
ESTHER : Zhu_2009_Drug.Metab.Dispos_37_264
PubMedSearch : Zhu_2009_Drug.Metab.Dispos_37_264
PubMedID: 19022936
Gene_locus related to this paper: human-CES1

Title : Role of carboxylesterase 1 and impact of natural genetic variants on the hydrolysis of trandolapril - Zhu_2009_Biochem.Pharmacol_77_1266
Author(s) : Zhu HJ , Appel DI , Johnson JA , Chavin KD , Markowitz JS
Ref : Biochemical Pharmacology , 77 :1266 , 2009
Abstract : Carboxylesterase 1 (CES1) and carboxylesterase 2 (CES2) are the major hydrolytic enzymes responsible for the metabolism of numerous therapeutic agents as well as endogenous substrates. CES1 and CES2 differ distinctly in their substrate specificity and tissue distribution. In this study, we investigated the role of CES1 and CES2 in converting the antihypertensive prodrug trandolapril to its more active form trandolaprilat, and determined the influence of two newly identified CES1 mutations p.Gly143Glu and p.Asp260fs on trandolapril metabolism. Western blot analysis demonstrated that CES1 is expressed in human liver microsomes (HLM) but not in human intestinal microsomes (HIM). In vitro incubation studies were conducted to contrast the enzymatic activity of HLM as well as HIM upon trandolapril hydrolysis. Trandolapril was rapidly hydrolyzed to its principal active metabolite trandolaprilat after incubation with HLM. In contrast, in HIM, where CES2 is predominantly expressed, incubations did not produce any detectable trandolapril hydrolysis. Furthermore, hydrolysis of trandolapril catalyzed by wild type (WT) and mutant CES1 were assessed utilizing transfected Flp-In-293 cells stably expressing WT CES1 and two variants. WT CES1 efficiently hydrolyzed trandolapril to trandolaprilat with V(max) and K(m) values of 103.6+/-2.2 nmole/min/mg protein and 639.9+/-32.9muM, respectively. However, no appreciable trandolapril hydrolysis could be found after incubation with both p.Gly143Glu and p.Asp260fs variants. Thus, trandolapril appears to be a CES1 selective substrate while CES2 exerts little to no catalytic activity towards this compound. CES1 mutations p.Gly143Glu and p.Asp260fs are essentially dysfunctional enzymes with regard to the conversion of trandolapril to its more active metabolite trandolaprilat.
ESTHER : Zhu_2009_Biochem.Pharmacol_77_1266
PubMedSearch : Zhu_2009_Biochem.Pharmacol_77_1266
PubMedID: 19185566
Gene_locus related to this paper: human-CES1

Title : Enantiospecific gas chromatographic-mass spectrometric analysis of urinary methylphenidate: implications for phenotyping - LeVasseur_2008_J.Chromatogr.B.Analyt.Technol.Biomed.Life.Sci_862_140
Author(s) : LeVasseur NL , Zhu HJ , Markowitz JS , DeVane CL , Patrick KS
Ref : Journal of Chromatography B Analyt Technol Biomed Life Sciences , 862 :140 , 2008
Abstract : A chiral derivatization gas chromatographic-mass spectrometric (GC-MS) method for urine methylphenidate (MPH) analysis was developed and validated to investigate preliminary findings regarding a novel MPH poor metabolizer (PM). Detection was by electron impact (EI) ionization-selected ion monitoring of the N-trifluoroacetylprolylpiperidinium fragments from MPH and the piperidine-deuterated MPH internal standard. The PM eliminated approximately 70 times more l-MPH in urine (9% of the dose over 0-10h), and approximately 5 times more of the d-isomer (10% of the dose), than the mean values determined from 10 normal metabolizers of MPH. Only minor amounts of the metabolite p-hydroxy-MPH were found in the urine of both the PM and normal metabolizers, while the concentration of MPH lactam was not high enough to be detectable. The described method indirectly gauges the functional carboxylesterase-1 status of patients receiving MPH based on the evaluation of relative urine concentrations of d-MPH:l-MPH. Clinical implications concerning rational drug selection for an identified or suspected MPH PM are discussed.
ESTHER : LeVasseur_2008_J.Chromatogr.B.Analyt.Technol.Biomed.Life.Sci_862_140
PubMedSearch : LeVasseur_2008_J.Chromatogr.B.Analyt.Technol.Biomed.Life.Sci_862_140
PubMedID: 18155648

Title : Two CES1 gene mutations lead to dysfunctional carboxylesterase 1 activity in man: clinical significance and molecular basis - Zhu_2008_Am.J.Hum.Genet_82_1241
Author(s) : Zhu HJ , Patrick KS , Yuan HJ , Wang JS , Donovan JL , DeVane CL , Malcolm R , Johnson JA , Youngblood GL , Sweet DH , Langaee TY , Markowitz JS
Ref : American Journal of Human Genetics , 82 :1241 , 2008
Abstract : The human carboxylesterase 1 (CES1) gene encodes for the enzyme carboxylesterase 1, a serine esterase governing both metabolic deactivation and activation of numerous therapeutic agents. During the course of a study of the pharmacokinetics of the methyl ester racemic psychostimulant methylphenidate, profoundly elevated methylphenidate plasma concentrations, unprecedented distortions in isomer disposition, and increases in hemodynamic measures were observed in a subject of European descent. These observations led to a focused study of the subject's CES1 gene. DNA sequencing detected two coding region single-nucleotide mutations located in exons 4 and 6. The mutation in exon 4 is located in codon 143 and leads to a nonconservative substitution, p.Gly143Glu. A deletion in exon 6 at codon 260 results in a frameshift mutation, p.Asp260fs, altering residues 260-299 before truncating at a premature stop codon. The minor allele frequency of p.Gly143Glu was determined to be 3.7%, 4.3%, 2.0%, and 0% in white, black, Hispanic, and Asian populations, respectively. Of 925 individual DNA samples examined, none carried the p.Asp260fs, indicating it is an extremely rare mutation. In vitro functional studies demonstrated the catalytic functions of both p.Gly143Glu and p.Asp260fs are substantially impaired, resulting in a complete loss of hydrolytic activity toward methylphenidate. When a more sensitive esterase substrate, p-nitrophenyl acetate was utilized, only 21.4% and 0.6% catalytic efficiency (V(max)/K(m)) were determined in p.Gly143Glu and p.Asp260fs, respectively, compared to the wild-type enzyme. These findings indicate that specific CES1 gene variants can lead to clinically significant alterations in pharmacokinetics and drug response of carboxylesterase 1 substrates.
ESTHER : Zhu_2008_Am.J.Hum.Genet_82_1241
PubMedSearch : Zhu_2008_Am.J.Hum.Genet_82_1241
PubMedID: 18485328
Gene_locus related to this paper: human-CES1

Title : Protective effect of an endothelial lipase gene variant on coronary artery disease in a Chinese population - Tang_2008_J.Lipid.Res_49_369
Author(s) : Tang NP , Wang LS , Yang L , Zhou B , Gu HJ , Sun QM , Cong RH , Zhu HJ , Wang B
Ref : J Lipid Res , 49 :369 , 2008
Abstract : The aim of the present study was to assess the influence of the endothelial lipase (EL) gene 584C/T variant, which results in a change at codon 111 of the EL gene from threonine to isoleucine, on the risk of coronary artery disease (CAD) in a Chinese population. The study population consisted of 265 CAD patients and 265 age- and sex-matched control subjects. The T allele frequency was significantly lower among CAD patients than among control subjects (18.3% vs. 29.8%; P < 0.001). In both the CAD and control groups, the T allele carriers had higher high density lipoprotein cholesterol (HDL-C) levels than homozygote C allele carriers. In a multiple logistic regression model adjusted for age, sex, body mass index, smoking, hypertension, diabetes, hyperlipidemia, and low density lipoprotein cholesterol, a significantly decreased risk of developing CAD was found in subjects carrying a variant CT or TT genotype (odds ratio = 0.496, 95% confidence interval = 0.341-0.723; P < 0.001), and the significance persisted after further adjustment for HDL-C. In conclusion, our observation that the EL 584T allele was associated with protection from CAD in this Chinese population replicates the findings in a Japanese study, which found a similar association of this allele with acute myocardial infarction, independent of HDL-C levels.
ESTHER : Tang_2008_J.Lipid.Res_49_369
PubMedSearch : Tang_2008_J.Lipid.Res_49_369
PubMedID: 17986713
Gene_locus related to this paper: human-LIPG

Title : Derivatives of vibralactone from cultures of the basidiomycete Boreostereum vibrans - Jiang_2008_Chem.Pharm.Bull.(Tokyo)_56_1286
Author(s) : Jiang MY , Wang F , Yang XL , Fang LZ , Dong ZJ , Zhu HJ , Liu JK
Ref : Chem Pharm Bull (Tokyo) , 56 :1286 , 2008
Abstract : Four new natural products possessing vibralactone skeleton, 1,5-secovibralactone (1), vibralactone B (2), vibralactone C (3) and acetylated vibralactone (4), together with known compound vibralactone (5), had been isolated from cultures of the basidiomycete Boreostereum vibrans. The structures of 1-4 were elucidated on the basis of spectroscopic methods. The absolute configuration of 1 was suggested to be S by computational methods.
ESTHER : Jiang_2008_Chem.Pharm.Bull.(Tokyo)_56_1286
PubMedSearch : Jiang_2008_Chem.Pharm.Bull.(Tokyo)_56_1286
PubMedID: 18758102

Title : Vibralactone: a lipase inhibitor with an unusual fused beta-lactone produced by cultures of the basidiomycete Boreostereum vibrans - Liu_2006_Org.Lett_8_5749
Author(s) : Liu DZ , Wang F , Liao TG , Tang JG , Steglich W , Zhu HJ , Liu JK
Ref : Org Lett , 8 :5749 , 2006
Abstract : The structure and absolute configuration of vibralactone (1) from the cultures of the Basidiomycete Boreostereum vibrans were established by spectroscopic methods and computational methods. Vibralactone, an unusual fused beta-lactone-type metabolite, was found to inhibit pancreatic lipase with an IC50 of 0.4 microg/mL. [structure: see text]
ESTHER : Liu_2006_Org.Lett_8_5749
PubMedSearch : Liu_2006_Org.Lett_8_5749
PubMedID: 17134263