Lipopolysaccharide down-regulates carbolesterases 1 and 2 and reduces hydrolysis activity in vitro and in vivo via p38MAPK-NF-κB pathway

Cisplatin increases carboxylesterases through increasing PXR mediated by the decrease of DEC1

cis-Diamminedichloroplatinum (CDDP) is widely used for the treatment of various solid cancers. Here we reported that CDDP increased the expression and enzymatic activities of carboxylesterase 1 (CES1) and carboxylesterase 2 (CES2), along with the upregulation of pregnane X receptor (PXR) and the downregulation of differentiated embryonic chondrocyte-expressed gene 1 (DEC1) in human hepatoma cells, primary mouse hepatocytes, mouse liver and intestine. The overexpression or knockdown of PXR alone upregulated or downregulated the CES1 and CES2 expression, respectively. The increases in CES1 and CES2 expression levels induced by CDDP abolished or enhanced by PXR knockdown or overexpression, implying that CDDP induces carboxylesterases through the activation of PXR. Likewise, the overexpression or knockdown of DEC1 alone significantly decreased or increased PXR and its targets. Moreover, the increases of PXR and its targets induced by CDDP were abolished or alleviated by the overexpression or knockdown of DEC1. The overexpression or knockdown of DEC1 affected the response of PXR to CDDP, but not vice versa, suggesting that CDDP increases carboxylesterases by upregulating PXR mediated by the decrease of DEC1. In addition, CDDP did not increase DEC1 mRNA degradation but suppressed DEC1 promoter reporter activity, indicating that it suppresses DEC1 transcriptionally. The combined use of CDDP and irinotecan had a synergistic effect on two cell lines, especially when CDDP was used first.

IL-6 downregulates hepatic carboxylesterases via NF-κB activation in dextran sulfate sodium-induced colitis

Ulcerative colitis (UC) is associated with increased levels of inflammatory factors, which is attributed to the abnormal expression and activity of enzymes and transporters in the liver, affecting drug disposition in vivo. This study aimed to examine the impact of intestinal inflammation on the expression of hepatic carboxylesterases (CESs) in a mouse model of dextran sulfate sodium (DSS)-induced colitis. Two major CESs isoforms, CES1 and CES2, were down-regulated, accompanied by decreases in hepatic microsomal metabolism of clopidogrel and irinotecan. Meanwhile, IL-6 levels significantly increased compared with other inflammatory factors in the livers of UC mice. In contrast, using IL-6 antibody simultaneously reversed the down-regulation of CES1, CES2, pregnane X receptor (PXR), and constitutive androstane receptor (CAR), as well as the nuclear translocation of NF-κB in the liver. We further confirmed that treatment with NF-κB inhibitor abolished IL-6-induced down-regulation of CES1, CES2, PXR, and CAR in vitro. Thus, it was concluded that IL-6 represses hepatic CESs via the NF-κB pathway in DSS-induced colitis. These findings indicate that caution should be exercised concerning the proper and safe use of therapeutic drugs in patients with UC.

Prognostic Impact of Carboxylesterase 2 in Cholangiocarcinoma

Carboxylesterase 2 (CES2) is instrumental for conversion of ester-containing prodrugs in cancer treatment. Novel treatment strategies are exceedingly needed for cholangiocarcinoma (CCA) patients. Here, we assessed CES2 expression by immunohistochemistry in a CCA cohort comprising 171 non-liver fluke associated, intrahepatic (n = 72) and extrahepatic (perihilar: n = 56; distal: n = 43) CCAs. Additionally, 80 samples of high-grade biliary intraepithelial neoplastic tissues and 158 corresponding samples of histological normal, non-neoplastic biliary tract tissues were included. CES2 expression was highest in non-neoplastic biliary tissue and significantly decreased in CCA. Patients showing any CES2 expression in tumor cells had a significantly better overall survival compared to negative cases (p = 0.008). This survival benefit was also maintained after stratification of CES2-positive cases, by comparing low, medium and high CES2 expression levels (p-trend = 0.0006). Evaluation of CCA subtypes showed the survival difference to be restricted to extrahepatic tumors. Correlation of CES2 expression with data of tumor-infiltrating immune cells showed that particularly CD8+ T cells were more frequently detected in CES2-positive CCAs. Furthermore, treatment of CCA cell lines with the prodrug Irinotecan reduced cell viability, increased cytotoxicity and modulated inflammatory gene expression. In conclusion, reduced CES2 expression is associated with poor outcome and low CD8+ T cell infiltration in CCA patients. Further clinical studies could show, whether CES2 expression may serve as a predictive marker in patients treated with prodrugs converted by CES2.

Comparative pharmacokinetic study of pyranocoumarins and khellactone in normal and acute lung injury rats after oral administration of Peucedanum praeruptorum Dunn extracts using a rapid and sensitive liquid chromatography-tandem mass spectrometry method

Pyranocoumarins are the main constitutes in Peucedanum praeruptorum Dunn and possess various biological activities. In this article, we developed and validated a rapid and sensitive liquid chromatography-tandem mass spectrometry method for the targeted quantification of the pyranocoumarins, praeruptorin A, praeruptorin B and praeruptorin E, and khellactone, which is a common metabolite of these pyranocoumarins in rat plasma samples. We then performed a comparative pharmacokinetic study of these pyranocoumarins and khellactone in normal and lipopolysaccharide-induced acute lung injury (ALI) in rats following oral administration of P. praeruptorum Dunn extracts. Calibration curves gave desirable linearity (r > 0.99) and the lower limit of quantifications were sufficient for quantitative analysis. The precision and accuracy were assessed by intra-batch and inter-batch assays, and the relative standard deviations were all within 10.23% and the accuracy (relative error) was between -5.52% and 8.68%. The extraction recoveries, matrix effects and stability were also acceptable. The pharmacokinetic study revealed that the area under the concentration-time curve (0-t) of khellactone in ALI rats was significantly decreased compared with the normal rats. Meanwhile, the systemic exposures of these pyranocoumarins were slightly higher in the ALI rats than those in normal rats were. The pharmacokinetic study in the pathological state might provide information that was more comprehensive to guide the clinical usage of P. praeruptorum Dunn.

Suppression of carboxylesterases by imatinib mediated by the down-regulation of pregnane X receptor

BACKGROUND AND PURPOSE

Imatinib mesylate (IM) is a first-line treatment for chronic myeloid leukaemia (CML) as a specific inhibitor of BCR-ABL tyrosine kinase. As IM is widely used in CML, in combination with other drugs, the effects of IM on drug-metabolizing enzymes (DMEs) are crucial to the design of rational drug administration. Carboxylesterases (CESs) are enzymes catalysing the hydrolytic biotransformation of several clinically useful drugs. Although IM is known to inhibit cytochromes P450 (CYPs), its effects on DMEs, and CESs in particular, are still largely undefined.

EXPERIMENTAL APPROACH

Hepatoma cell lines (HepG2 and Huh7) and primary mouse hepatocytes were used. mRNA and protein expression were evaluated by quantitative RT-PCR and Western blot analysis. Reporter luciferase activity was determined by transient co-transfection experiment. Pregnane X receptor (PXR) expression was regulated by overexpression and RNA interference. The activity of CESs was determined by enzymic and toxicological assays. Mice were treated with a range of doses of IM to analyse expression of CESs in mouse liver.

KEY RESULTS

The expression and activity of CESs were markedly repressed by IM, along with the down-regulation of PXR and inhibited expression and activity of CYP3A4 and P-gp.

CONCLUSIONS AND IMPLICATIONS

Down-regulation of PXR mediates IM-induced suppression of CESs. IM may inhibit expression of other genes targeted by PXR, thus inducing a wide range of potential drug-drug interactions during treatment of CML. The data deserve further elucidation including clinical trials.

Involvement of pregnane X receptor in the suppression of carboxylesterases by metformin in vivo and in vitro, mediated by the activation of AMPK and JNK signaling pathway

Type 2 diabetes mellitus (T2D) is a complex metabolic disorder requiring polypharmacy treatment in clinic, with metformin being widely used antihyperglycemic drug. However, the mechanisms of metformin as a perpetrator inducing potential drug-drug interactions and adverse drug reactions are scarcely known to date. Carboxylesterases (CESs) are major hydrolytic enzymes highly expressed in the liver, including mouse carboxylesterase 1d (Ces1d) and Ces1e. In the present study, experiments are designed to investigate the effects and mechanisms of metformin on Ces1d and Ces1e in vivo and in vitro. In results, metformin suppresses the expression and activity of Ces1d and Ces1e in a dose- and time-dependent manner. The decreased expression of nuclear receptor PXR and its target gene P-gp indicates the involvements of PXR in the suppressed expression of carboxylesterases by metformin. Furthermore, metformin significantly suppresses the phosphorylation of AMPK and JNK, and the suppression of carboxylesterases induced by metformin is repeatedly abolished by AMPK inhibitor Compound C and JNK inhibitor SP600125. It implies that the activation of AMPK and JNK pathways mediates the suppression of carboxylesterases by metformin. The findings deserve further elucidation including clinical trials and have a potential to make contribution for the rational medication in the treatment of T2D patients.

Gambogic acid potentiates clopidogrel-induced apoptosis and attenuates irinotecan-induced apoptosis through down-regulating human carboxylesterase 1 and -2

1. In this study, we report that gambogic acid (GA), a promising anticancer agent, potentiates clopidogrel-induced apoptosis and attenuates CPT-11-induced apoptosis by down-regulating human carboxylesterase (CES) 1 and -2 via ERK and p38 MAPK pathway activation, which provides a molecular explanation linking the effect of drug combination directly to the decreased capacity of hydrolytic biotransformation. 2. The expression levels of CES1 and CES2 decreased significantly in a concentration- and time-dependent manner in response to GA in Huh7 and HepG2 cells; hydrolytic activity was also reduced. 3. The results showed that pretreatment with GA potentiated clopidogrel-induced apoptosis by down-regulating CES1. Moreover, the GA-mediated repression of CES2 attenuated CPT-11-induced apoptosis. 4. Furthermore, the ERK and p38 MAPK pathways were involved in the GA-mediated down-regulation of CES1 and CES2. 5. Taken together, our data suggest that GA is a potent repressor of CES1 and CES2 and that combination with GA will affect the metabolism of drugs containing ester bonds.

Individualization of treatments with drugs metabolized by CES1: combining genetics and metabolomics

CES1 is involved in the hydrolysis of ester group-containing xenobiotic and endobiotic compounds including several essential and commonly used drugs. The individual variation in the efficacy and tolerability of many drugs metabolized by CES1 is considerable. Hence, there is a large interest in individualizing the treatment with these drugs. The present review addresses the issue of individualized treatment with drugs metabolized by CES1. It describes the composition of the gene encoding CES1, reports variants of this gene with focus upon those with a potential effect on drug metabolism and provides an overview of the protein structure of this enzyme bringing notice to mechanisms involved in the regulation of enzyme activity. Subsequently, the review highlights drugs metabolized by CES1 and argues that individual differences in the pharmacokinetics of these drugs play an important role in determining drug response and tolerability suggesting prospects for individualized drug therapies. Our review also discusses endogenous substrates of CES1 and assesses the potential of using metabolomic profiling of blood to identify proxies for the hepatic activity of CES1 that predict the rate of drug metabolism. Finally, the combination of genetics and metabolomics to obtain an accurate prediction of the individual response to CES1-dependent drugs is discussed.

Aspafilioside B induces G2/M cell cycle arrest and apoptosis by up-regulating H-Ras and N-Ras via ERK and p38 MAPK signaling pathways in human hepatoma HepG2 cells

We recently establish that aspafilioside B, a steroidal saponin extracted from Asparagus filicinus, is an active cytotoxic component. However, its antitumor activity is till unknown. In this study, the anticancer effect of aspafilioside B against HCC cells and the underlying mechanisms were investigated. Our results showed that aspafilioside B inhibited the growth and proliferation of HCC cell lines. Further study revealed that aspafilioside B could significantly induce G2 phase cell cycle arrest and apoptosis, accompanying the accumulation of reactive oxygen species (ROS), but blocking ROS generation with N-acetyl-l-cysteine (NAC) could not prevent G2/M arrest and apoptosis. Additionally, treatment with aspafilioside B induced phosphorylation of extracellular signal-regulated kinase (ERK) and p38 MAP kinase. Moreover, both ERK inhibitor PD98059 and p38 inhibitor SB203580 almost abolished the G2/M phase arrest and apoptosis induced by aspafilioside B, and reversed the expression of cell cycle- and apoptosis-related proteins. We also found that aspafilioside B treatment increased both Ras and Raf activation, and transfection of cells with H-Ras and N-Ras shRNA almost attenuated aspafilioside B-induced G2 phase arrest and apoptosis as well as the ERK and p38 activation. Finally, in vivo, aspafilioside B suppressed tumor growth in mouse xenograft models, and the mechanism was the same as in vitro study. Collectively, these findings indicated that aspafilioside B may up-regulate H-Ras and N-Ras, causing c-Raf phosphorylation, and lead to ERK and p38 activation, which consequently induced the G2 phase arrest and apoptosis. This study provides the evidence that aspafilioside B is a promising therapeutic agent against HCC.

CES1A -816C as a genetic marker to predict greater platelet clopidogrel response in patients with percutaneous coronary intervention

This study was designed to determine whether CES1A -816A/C polymorphism could be associated with altered clopidogrel response. Recruited patients were pretreated with 300 mg clopidogrel loading dose before undergoing percutaneous coronary intervention for stenting and genotyped with CYP2C19 *2, *3, or *17, and CES1A -816A/C, respectively. Adenosine diphosphate-induced maximum platelet aggregation (MPA) was determined on day 3 after initiation of daily clopidogrel maintenance doses. The clinical primary end point was the 1-year incidence of definite stent thrombosis (ST). Multivariable linear regression revealed that the CES1A -816A/C polymorphism was independently associated with MPA measures with an absolute β value of 6.76. Of 617 patients, a subcohort of 249 patients not carrying CYP2C19 *2, *3, or *17 were categorized into 3 groups based on the -816A/C genotype. The median MPA value was lower in 125 carriers of the -816C variant than in 124 noncarriers (21.5% vs. 31.7%, P = 0.001). The 1-year definite ST occurred in 7 patients in that subcohort, and only 1 ST case was one of carriers of the -816 A/A that was associated with higher MPA values. The CES1A -816C would be used to predict greater platelet response to clopidogrel than the CES1A -816A in percutaneous coronary intervention-treated patients not carrying CYP2C19 variants.

Fluoxetine suppresses AMP-activated protein kinase signaling pathway to promote hepatic lipid accumulation in primary mouse hepatocytes

In the previous study, we demonstrated that fluoxetine (FLX) regulated lipogenic and lipolytic genes to promote hepatic lipid accumulation. On this basis, underlying mechanisms were investigated by focusing on the intracellular signaling transduction in the present study using primary mouse hepatocytes. The expression of lipogenesis- and lipolysis-related genes was evaluated with the application of specific activators and inhibitors. Activation status of respective signaling pathway and the lipid accumulation in hepatocytes were analyzed. We provided evidence that AMP-activated protein kinase (AMPK) activator AICAR (5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside) significantly suppressed the increased expression of representative lipogenesis-related genes, acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) by FLX, while increased the repressed expression of lipolysis-related genes, carboxylesterases. In the meanwhile, FLX regulated the above genes in the same way as AMPK inhibitor Compound C did. Furthermore, AICAR inhibited the proteolytic activation of SREBP1c induced by FLX, resulting in the decreased level of nuclear SREBP1c. Further studies demonstrated that FLX significantly suppressed the phosphorylation of AMPK and subsequent phosphorylation of ACC, following the inhibited phosphorylation and nuclear export of liver kinase B1 (LKB1). As a functional analysis, FLX-induced lipid accumulation in hepatocytes was repeatedly abolished by AICAR. In conclusion, FLX-induced hepatic lipid accumulation is mediated by the suppression of AMPK signaling pathway. The findings not only provide new insight into the understanding of the mechanisms for selective serotonin reuptake inhibitors-mediated dyslipidemia effects, but also suggest a novel therapeutic target to interfere.

Expression of proteins associated with adipocyte lipolysis was significantly changed in the adipose tissues of the obese spontaneously hypertensive/NDmcr-cp rat

BACKGROUND

The etiology of the metabolic syndrome is complex, and is determined by the interplay of both genetic and environmental factors. The present study was designed to identify genes and proteins in the adipose tissues with altered expression in the spontaneously hypertensive/NIH -corpulent rat, SHR/NDmcr-cp (CP) and to find possible molecular targets associated with the pathogenesis or progression of obesity related to the metabolic syndrome.

METHODS

We extracted RNAs and proteins from the epididymal adipose tissues in CP, SHR/Lean (Lean), and Wistar Kyoto (WKY) rats and performed microarray analysis and two-dimensional difference in gel electrophoresis (2D-DIGE) linked to a matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF/TOF MS).

RESULTS

The results showed different mRNA and protein expression levels in the adipose tissue: oligo DNA microarray identified 33 genes that were significantly (P < 0.01) up-regulated and 17 genes significantly down-regulated in CP compared with WKY and Lean rats at both 6 and 25 weeks of age. The affected genes-proteins were associated with lipolytic enzymes stimulated by peroxisome proliferator-activated receptor (PPAR) signaling. Further analysis using the 2D-DIGE connected with MALDI-TOF/TOF analysis, the expression of monoglyceride lipase (MGLL) was significantly up-regulated and that of carboxylesterase 3 (CES3) was significantly down-regulated in 6- and 25-week-old CP compared with age-matched control (WKY and Lean rats).

CONCLUSIONS

Our results suggest the possible involvement of proteins associated with adipocyte lipolysis in obesity related to the metabolic syndrome.

Fluoxetine induces hepatic lipid accumulation via both promotion of the SREBP1c-related lipogenesis and reduction of lipolysis in primary mouse hepatocytes

AIMS

In this study, we investigated the peripheral mechanisms underlying the metabolic side effects of fluoxetine (FLX) by focusing on hepatic lipid metabolism.

METHODS

Primary mouse hepatocytes were prepared from male mice by the two-step perfusion method. The lipid accumulation in primary mouse hepatocytes was analyzed via neutral oil staining. And the lipid metabolism enzymes were determined with RT-PCR and Western blot.

RESULTS

Fluoxetine significantly induced the lipid accumulation in primary mouse hepatocytes. Moreover, FLX increased the acetyl-CoA carboxylase 1 (ACC1) and fatty acid synthase (FAS) expression, which are important enzymes in lipogenesis. Oppositely, Fluoxetine significantly decreased the carboxylesterase 3 (CES3) and carboxylesterase 1 (CES1) expression, which are related to lipolysis. Further study demonstrated FLX-activated SREBP1c, which is one of the most important transcription factors conducting coordinated transcriptional regulation of lipogenesis gene such as ACC1 and FAS. And the increase of lipogenesis gene (ACC1) was abolished by SB203580 but not by pyrrolidine dithiocarbamate (PDTC), suggesting through p38-MAPK pathway.

CONCLUSION

Fluoxetine induces hepatic lipid accumulation via both promotion of the SREBP1c-related lipogenesis and reduction of lipolysis in primary mouse hepatocytes.

Age-related inducibility of carboxylesterases by the antiepileptic agent phenobarbital and implications in drug metabolism and lipid accumulation

Carboxylesterases (CES) constitute a class of hydrolytic enzymes that play critical roles in drug metabolism and lipid mobilization. Previous studies with a large number of human liver samples have suggested that the inducibility of carboxylesterases is inversely related with age. To directly test this possibility, neonatal (10 days of age) and adult mice were treated with the antiepileptic agent phenobarbital. The expression and hydrolytic activity were determined on six major carboxylesterases including ces1d, the ortholog of human CES1. Without exception, all carboxylesterases tested were induced to a greater extent in neonatal than adult mice. The induction was detected at mRNA, protein and catalytic levels. Ces1d was greatly induced and found to rapidly hydrolyze the antiplatelet agent clopidogrel and support the accumulation of neutral lipids. Phenobarbital represents a large number of therapeutic agents that induce drug metabolizing enzymes and transporters in a species-conserved manner. The higher inducibility of carboxylesterases in the developmental age likely represents a general phenomenon cross species including human. Consequently, individuals in the developmental age may experience greater drug-drug interactions. The greater induction of ces1d also provides a molecular explanation to the clinical observation that children on antiepileptic drugs increase plasma lipids.