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Chemico-biological Interactions Nov 2016Carboxylesterases (CE) are members of the esterase family of enzymes, and as their name suggests, they are responsible for the hydrolysis of carboxylesters into the... (Review)
Review
Carboxylesterases (CE) are members of the esterase family of enzymes, and as their name suggests, they are responsible for the hydrolysis of carboxylesters into the corresponding alcohol and carboxylic acid. To date, no endogenous CE substrates have been identified and as such, these proteins are thought to act as a mechanism to detoxify ester-containing xenobiotics. As a consequence, they are expressed in tissues that might be exposed to such agents (lung and gut epithelia, liver, kidney, etc.). CEs demonstrate very broad substrate specificities and can hydrolyze compounds as diverse as cocaine, oseltamivir (Tamiflu), permethrin and irinotecan. In addition, these enzymes are irreversibly inhibited by organophosphates such as Sarin and Tabun. In this overview, we will compare and contrast the two human enzymes that have been characterized, and evaluate the biology of the interaction of these proteins with organophosphates (principally nerve agents).
Topics: Animals; Carboxylic Ester Hydrolases; Humans; Inactivation, Metabolic; Models, Molecular; Organophosphates; Substrate Specificity
PubMed: 26892220
DOI: 10.1016/j.cbi.2016.02.011 -
Molecular Pharmaceutics Mar 2021Hydrolytic reactions constitute an important pathway of drug metabolism and a significant route of prodrug activation. Many ophthalmic drugs and prodrugs contain ester...
Hydrolytic reactions constitute an important pathway of drug metabolism and a significant route of prodrug activation. Many ophthalmic drugs and prodrugs contain ester groups that greatly enhance their permeation across several hydrophobic barriers in the eye before the drugs are either metabolized or released, respectively, hydrolysis. Thus, the development of ophthalmic drug therapy requires the thorough profiling of substrate specificities, activities, and expression levels of ocular esterases. However, such information is scant in the literature, especially for preclinical species often used in ophthalmology such as rabbits and pigs. Therefore, our aim was to generate systematic information on the activity and expression of carboxylesterases (CESs) and arylacetamide deacetylase (AADAC) in seven ocular tissue homogenates from these two species. The hydrolytic activities were measured using a generic esterase substrate (4-nitrophenyl acetate) and, in the absence of validated substrates for rabbit and pig enzymes, with selective substrates established for human CES1, CES2, and AADAC (d-luciferin methyl ester, fluorescein diacetate, procaine, and phenacetin). Kinetics and inhibition studies were conducted using these substrates and, again due to a lack of validated rabbit and pig CES inhibitors, with known inhibitors for the human enzymes. Protein expression levels were measured using quantitative targeted proteomics. Rabbit ocular tissues showed significant variability in the expression of CES1 (higher in cornea, lower in conjunctiva) and CES2 (higher in conjunctiva, lower in cornea) and a poor correlation of CES expression with hydrolytic activities. In contrast, pig tissues appear to express only CES1, and CES3 and AADAC seem to be either low or absent, respectively, in both species. The current study revealed remarkable species and tissue differences in ocular hydrolytic enzymes that can be taken into account in the design of esterase-dependent prodrugs and drug conjugates, the evaluation of ocular effects of systemic drugs, and in translational and toxicity studies.
Topics: Animals; Carboxylesterase; Eye; Female; Humans; Hydrolysis; Male; Nitrophenols; Prodrugs; Proteomics; Rabbits; Substrate Specificity; Swine
PubMed: 33595329
DOI: 10.1021/acs.molpharmaceut.0c01154 -
Molecular Metabolism Nov 2022Oral squamous cell carcinoma (OSCC) is characterized by high recurrence and metastasis and places a heavy burden on societies worldwide. Cancer cells thrive in a...
OBJECTIVE
Oral squamous cell carcinoma (OSCC) is characterized by high recurrence and metastasis and places a heavy burden on societies worldwide. Cancer cells thrive in a changing microenvironment by reprogramming lipidomic metabolic processes to provide nutrients and energy, activate oncogenic signaling pathways, and manage redox homeostasis to avoid lipotoxicity. The mechanism by which OSCC cells maintain lipid homeostasis during malignant progression is unclear.
METHODS
The altered expression of fatty acid (FA) metabolism genes in OSCC, compared with that in normal tissues, and in OSCC patients with or without recurrence or metastasis were determined using public data from the TCGA and GEO databases. Immunohistochemistry was performed to examine the carboxylesterase 2 (CES2) protein level in our own cohort. CCK-8 and Transwell assays and an in vivo xenograft model were used to evaluate the biological functions of CES2. Mass spectrometry and RNA sequencing were performed to determine the lipidome and transcriptome alterations induced by CES2. Mitochondrial mass, mtDNA content, mitochondrial membrane potential, ROS levels, and oxygen consumption and apoptosis rates were evaluated to determine the effects of CES2 on mitochondrial function in OSCC.
RESULTS
CES2 was downregulated in OSCC patients, especially those with recurrence or metastasis. CES2 OSCC patients showed better overall survival than CES2 OSCC patients. Restoring CES2 expression reduced OSCC cell viability and suppressed their migration and invasion in vitro, and it inhibited OSCC tumor growth in vivo. CES2 reprogrammed lipid metabolism in OSCC cells by hydrolyzing neutral lipid diacylglycerols (DGs) to release free fatty acids and reduce the membrane structure lipid phospholipids (PLs) synthesis. Free FAs were converted to acyl-carnitines (CARs) and transferred to mitochondria for oxidation, which induced reactive oxygen species (ROS) accumulation, mitochondrial damage, and apoptosis activation. Furthermore, the reduction in signaling lipids, e.g., DGs, PLs and substrates, suppressed PI3K/AKT/MYC signaling pathways. Restoring MYC rescued the diminished cell viability, suppressed migratory and invasive abilities, damaged mitochondria and reduced apoptosis rate induced by CES2.
CONCLUSIONS
We demonstrated that CES2 downregulation plays an important role in OSCC by maintaining lipid homeostasis and reducing lipotoxicity during tumor progression and may provide a potential therapeutic target for OSCC.
Topics: Carboxylesterase; Carboxylic Ester Hydrolases; Carcinoma, Squamous Cell; Cell Line, Tumor; Cell Proliferation; DNA, Mitochondrial; Diglycerides; Fatty Acids, Nonesterified; Head and Neck Neoplasms; Homeostasis; Humans; Mitochondria; Mouth Neoplasms; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-myc; Reactive Oxygen Species; Signal Transduction; Sincalide; Squamous Cell Carcinoma of Head and Neck
PubMed: 36113774
DOI: 10.1016/j.molmet.2022.101600 -
Expert Opinion on Therapeutic Patents Aug 2011Carboxylesterases play major roles in the hydrolysis of numerous therapeutically active compounds. This is, in part, due to the prevalence of the ester moiety in these... (Review)
Review
INTRODUCTION
Carboxylesterases play major roles in the hydrolysis of numerous therapeutically active compounds. This is, in part, due to the prevalence of the ester moiety in these small molecules. However, the impact these enzymes may play on drug stability and pharmacokinetics is rarely considered prior to molecule development. Therefore, the application of selective inhibitors of this class of proteins may have utility in modulating the metabolism, distribution and toxicity of agents that are subjected to enzyme hydrolysis.
AREAS COVERED
This review details the development of all such compounds dating back to 1986, but principally focuses on the very recent identification of selective human carboxylesterases inhibitors.
EXPERT OPINION
The implementation of carboxylesterase inhibitors may significantly revolutionize drug discovery. Such molecules may allow for improved efficacy of compounds inactivated by this class of enzymes and/or reduce the toxicity of agents that are activated by these proteins. Furthermore, since lack of carboxylesterase activity appears to have no obvious biological consequence, these compounds could be applied in combination with virtually any esterified drug. Therefore, inhibitors of these proteins may have utility in altering drug hydrolysis and distribution in vivo. The characteristics, chemical and biological properties and potential uses of such agents are discussed here.
Topics: Animals; Carboxylic Ester Hydrolases; Drug Interactions; Drug Stability; Enzyme Inhibitors; Humans; Hydrolysis; Pharmacokinetics; Structure-Activity Relationship
PubMed: 21609191
DOI: 10.1517/13543776.2011.586339 -
Expert Opinion on Drug Metabolism &... Mar 2010Emerging evidence demonstrates that several nuclear receptor (NR) family members regulate drug-inducible expression and activity of several important carboxylesterase... (Review)
Review
IMPORTANCE OF THE FIELD
Emerging evidence demonstrates that several nuclear receptor (NR) family members regulate drug-inducible expression and activity of several important carboxylesterase (CES) enzymes in mammalian liver and intestine. Numerous clinically prescribed anticancer prodrugs, carbamate and pyrethroid insecticides, environmental toxicants and procarcinogens are substrates for CES enzymes. Moreover, a key strategy used in rational drug design frequently utilizes an ester linkage methodology to selectively target a prodrug, or to improve the water solubility of a novel compound.
AREAS COVERED IN THIS REVIEW
This review summarizes the current state of knowledge regarding NR-mediated regulation of CES enzymes in mammals and highlights their importance in drug metabolism, drug-drug interactions and toxicology.
WHAT THE READER WILL GAIN
New knowledge regarding the transcriptional regulation of CES enzymes by NR proteins pregnane x receptor (NR1I2) and constitutive androstane receptor (NR1I3) has recently come to light through the use of knockout and transgenic mouse models. Novel insights regarding the species-specific cross-regulation of glucocorticoid receptor (NR3C1) and PPAR-alpha (NR1C1) signaling and CES gene expression are discussed.
TAKE HOME MESSAGE
Elucidation of the role of NR-mediated regulation of CES enzymes in liver and intestine will have a significant impact on rational drug design and the development of novel prodrugs, especially for patients on combination therapy.
Topics: Animals; Carboxylic Ester Hydrolases; Constitutive Androstane Receptor; Gene Expression Regulation, Enzymologic; Humans; Pharmaceutical Preparations; Receptors, Cytoplasmic and Nuclear
PubMed: 20163318
DOI: 10.1517/17425250903483215 -
Toxins Nov 2022Gossypol is a polyphenolic toxic secondary metabolite derived from cotton. Free gossypol in cotton meal is remarkably harmful to animals. Furthermore, microbial...
Gossypol is a polyphenolic toxic secondary metabolite derived from cotton. Free gossypol in cotton meal is remarkably harmful to animals. Furthermore, microbial degradation of gossypol produces metabolites that reduce feed quality. We adopted an enzymatic method to degrade free gossypol safely and effectively. We cloned the gene encoding carboxylesterase (CarE) into pPICZαA and transformed it into GS115. The target protein was successfully obtained, and CarE could effectively degrade free gossypol with a degradation rate of 89%. When esterase was added, the exposed toxic groups of gossypol reacted with different amino acids and amines to form bound gossypol, generating substances with (M + H) / ratios of 560.15, 600.25, and 713.46. The molecular formula was CHO, CHNO, and CHNO. The observed instability of the hydroxyl groups caused the substitution and shedding of the group, forming a substance with / of 488.26 and molecular formula CHO. These properties render the CarE a valid candidate for the detoxification of cotton meal. Furthermore, the findings help elucidate the degradation process of gossypol in vitro.
Topics: Animals; Carboxylesterase; Gossypol; Moths; Pichia; Biotransformation; Recombinant Proteins
PubMed: 36548713
DOI: 10.3390/toxins14120816 -
The AAPS Journal Nov 2016Over the years, significant progress has been made in reducing metabolic instability due to cytochrome P450-mediated oxidation. High-throughput metabolic stability... (Review)
Review
Challenges and Opportunities with Non-CYP Enzymes Aldehyde Oxidase, Carboxylesterase, and UDP-Glucuronosyltransferase: Focus on Reaction Phenotyping and Prediction of Human Clearance.
Over the years, significant progress has been made in reducing metabolic instability due to cytochrome P450-mediated oxidation. High-throughput metabolic stability screening has enabled the advancement of compounds with little to no oxidative metabolism. Furthermore, high lipophilicity and low aqueous solubility of presently pursued chemotypes reduces the probability of renal excretion. As such, these low microsomal turnover compounds are often substrates for non-CYP-mediated metabolism. UGTs, esterases, and aldehyde oxidase are major enzymes involved in catalyzing such metabolism. Hepatocytes provide an excellent tool to identify such pathways including elucidation of major metabolites. To predict human PK parameters for P450-mediated metabolism, in vitro-in vivo extrapolation using hepatic microsomes, hepatocytes, and intestinal microsomes has been actively investigated. However, such methods have not been sufficiently evaluated for non-P450 enzymes. In addition to the involvement of the liver, extrahepatic enzymes (intestine, kidney, lung) are also likely to contribute to these pathways. While there has been considerable progress in predicting metabolic pathways and clearance primarily mediated by the liver, progress in characterizing extrahepatic metabolism and prediction of clearance has been slow. Well-characterized in vitro systems or in vivo animal models to assess drug-drug interaction potential and intersubject variability due to polymorphism are not available. Here we focus on the utility of appropriate in vitro studies to characterize non-CYP-mediated metabolism and to understand the enzymes involved followed by pharmacokinetic studies in the appropriately characterized surrogate species. The review will highlight progress made in establishing in vitro-in vivo correlation, predicting human clearance and avoiding costly clinical failures when non-CYP-mediated metabolic pathways are predominant.
Topics: Aldehyde Oxidase; Animals; Carboxylesterase; Forecasting; Glucuronosyltransferase; Humans; Metabolic Clearance Rate; Pharmaceutical Preparations; Phenotype
PubMed: 27495117
DOI: 10.1208/s12248-016-9962-6 -
Toxicology Letters Oct 2021Carboxylesterases (CES) are an important class of enzymes involved in the hydrolysis of a range of chemicals and show large inter-individual variability in vitro. An... (Comparative Study)
Comparative Study Meta-Analysis Review
Carboxylesterases (CES) are an important class of enzymes involved in the hydrolysis of a range of chemicals and show large inter-individual variability in vitro. An extensive literature search was performed to identify in vivo probe substrates for CES1 and CES2 together with their protein content and enzymatic activity. Human pharmacokinetic (PK) data on Cmax, clearance, and AUC were extracted from 89 publications and Bayesian meta-analysis was performed using a hierarchical model to derive CES-related variability distributions and related uncertainty factors (UF). The CES-related variability indicated that 97.5% of healthy adults are covered by the kinetic default UF (3.16), except for clopidogrel and dabigatran etexilate. Clopidogrel is metabolised for a small amount by the polymorphic CYP2C19, which can have an impact on the overall pharmacokinetics, while the variability seen for dabigatran etexilate might be due to differences in the absorption, since this can be influenced by food intake. The overall CES-related variability was moderate to high in vivo (
Topics: Adolescent; Adult; Aged; Bayes Theorem; Carboxylesterase; Carboxylic Ester Hydrolases; Environmental Exposure; Female; Healthy Volunteers; Humans; Male; Middle Aged; Protein Isoforms; Risk Assessment; Uncertainty; Young Adult
PubMed: 34256091
DOI: 10.1016/j.toxlet.2021.07.005 -
Protein & Cell Feb 2018Mammalian carboxylesterases hydrolyze a wide range of xenobiotic and endogenous compounds, including lipid esters. Physiological functions of carboxylesterases in lipid... (Review)
Review
Mammalian carboxylesterases hydrolyze a wide range of xenobiotic and endogenous compounds, including lipid esters. Physiological functions of carboxylesterases in lipid metabolism and energy homeostasis in vivo have been demonstrated by genetic manipulations and chemical inhibition in mice, and in vitro through (over)expression, knockdown of expression, and chemical inhibition in a variety of cells. Recent research advances have revealed the relevance of carboxylesterases to metabolic diseases such as obesity and fatty liver disease, suggesting these enzymes might be potential targets for treatment of metabolic disorders. In order to translate pre-clinical studies in cellular and mouse models to humans, differences and similarities of carboxylesterases between mice and human need to be elucidated. This review presents and discusses the research progress in structure and function of mouse and human carboxylesterases, and the role of these enzymes in lipid metabolism and metabolic disorders.
Topics: Amino Acid Sequence; Animals; Carboxylic Ester Hydrolases; Humans; Intracellular Space; Lipid Metabolism; Mice; Polymorphism, Single Nucleotide; Protein Domains
PubMed: 28677105
DOI: 10.1007/s13238-017-0437-z -
Bioorganic & Medicinal Chemistry Jan 2009Carboxylesterases are enzymes that hydrolyze a broad suite of endogenous and exogenous ester-containing compounds to the corresponding alcohol and carboxylic acid. These... (Comparative Study)
Comparative Study
Carboxylesterases are enzymes that hydrolyze a broad suite of endogenous and exogenous ester-containing compounds to the corresponding alcohol and carboxylic acid. These enzymes metabolize a number of therapeutics including the anti-tumor agent CPT-11, the anti-viral drug oseltamivir, and the anti-thrombogenic agent clopidogrel as well as many agrochemicals. In addition, carboxylesterases are involved in lipid homeostasis, including cholesterol metabolism and transport with a proposed role in the development of atherosclerosis. Several different scaffolds capable of inhibiting carboxylesterases have been reported, including organophosphates, carbamates, trifluoromethyl ketone-containing structures (TFKs), and aromatic ethane-1,2-diones. Of these varied groups, only the 1,2-diones evidence carboxylesterase isoform-selectivity, which is an important characteristic for therapeutic application and probing biological mechanisms. This study constructed a series of classical and 3D-QSAR models to examine the physiochemical parameters involved in the observed selectivity of three mammalian carboxylesterases: human intestinal carboxylesterase (hiCE), human carboxylesterase 1 (hCE1), and rabbit carboxylesterase (rCE). CoMFA-based models for the benzil-analogs described 88%, 95% and 76% of observed activity for hiCE, hCE1 and rCE, respectively. For TFK-containing compounds, two distinct models were constructed using either the ketone or gem-diol form of the inhibitor. For all three enzymes, the CoMFA ketone models comprised more biological activity than the corresponding gem-diol models; however the differences were small with described activity for all models ranging from 85-98%. A comprehensive model incorporating both benzil and TFK structures described 92%, 85% and 87% of observed activity for hiCE, hCE1 and rCE, respectively. Both classical and 3D-QSAR analysis showed that the observed isoform-selectivity with the benzil-analogs could be described by the volume parameter. This finding was successfully applied to examine substrate selectivity, demonstrating that the relative volumes of the alcohol and acid moieties of ester-containing substrates were predictive for whether hydrolysis was preferred by hiCE or hCE1. Based upon the integrated benzil and TFK model, the next generation inhibitors should combine the A-ring and the 1,2-dione of the benzil inhibitor with the long alkyl chain of the TFK-inhibitor in order to optimize selectivity and potency. These new inhibitors could be useful for elucidating the role of carboxylesterase activity in fatty acid homeostasis and the development of atherosclerosis as well as effecting the controlled activation of carboxylesterase-based prodrugs in situ.
Topics: Carboxylesterase; Carboxylic Ester Hydrolases; Enzyme Inhibitors; Humans; Ketones; Quantitative Structure-Activity Relationship
PubMed: 19062296
DOI: 10.1016/j.bmc.2008.11.008