Characterization of multiple promoters in the human carboxylesterase 2 gene

Wu, Michael H.; Chen, Peixian; Remo, Benjamin F.; Cook, Edwin H.; Das, Soma; Dolan, M. Eileen

doi:10.1097/00008571-200307000-00008

Cited by 38 publications

(32 citation statements)

References 40 publications

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“…A novel SNP 1AϾT found in this study changes the translation start codon ATG to TTG. Wu et al (2003) identified three transcription start sites of CES2, resulting in the synthesis of three transcripts with either 78, 629, or 1187 nucleotides in the 5Ј-UTR. Another inframe ATG codon is present 192 nucleotides upstream of the conventional translational initiation codon, and two longer transcripts with 629 and 1187 nucleotides in the 5Ј-UTR can encode an ORF with 64 additional residues at the amino terminus (NP_003860.2).…”

Section: Discussionmentioning

confidence: 99%

“…Construction of Expression Plasmids. The coding region of CES2L (long form) cDNA starts at an additional ATG translation initiation codon located 192 nucleotides upstream of the conventional ATG codon (Wu et al, 2003) and encodes a 623-amino acid protein found in the National Center for Biotechnology Information database (NP_003860.2). The wild-type CES2L cDNA was amplified by PCR from Human Liver QUICK-Clone cDNA (Clontech, Mountain View, CA) using CES2-specific primers, 5Ј-CACCCAC-CTATGACTGCTCA-3Ј and 5Ј-AGGGAGCTACAGCTCTGTGT-3Ј.…”

Section: Methodsmentioning

confidence: 99%

“…To clarify the functional significance of the novel variant Met 1 Leu (*5), the protein expression level of CES2 carrying the nonsynonymous SNP 1AϾT was examined. Wu et al (2003) reported that transcription of CES2 mRNA was initiated from several transcriptional start sites, resulting in the expression of three CES2 transcripts. Two longer transcripts carry a potential inframe translational initiation codon ATG at Ϫ192 that can encode an open reading frame (ORF) extending 64 residues at the amino terminus, as shown in the reference sequence in the National Center for Biotechnology Information database (NP_003860.2).…”

Section: Haplotypes and Novel Variants Of Human Ces2mentioning

confidence: 99%

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Haplotypes and a Novel Defective Allele of CES2 Found in a Japanese Population

Kim

Sai²,

Tanaka-Kagawa³

et al. 2007

Drug Metab Dispos

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ABSTRACT:Human carboxylesterase 2 (hCE-2) is a member of the serine esterase superfamily and is responsible for hydrolysis of a wide variety of xenobiotic and endogenous esters. hCE-2 also activates an anticancer drug, irinotecan (7-ethyl-10-[4-(1-piperidino)-1-piperidino]-carbonyloxycamptothecin, CPT-11), into its active metabolite, 7-ethyl-10-hydroxycamptothecin (SN-38). In this study, a comprehensive haplotype analysis of the CES2 gene, which encodes hCE-2, in a Japanese population was conducted. Human carboxylesterases are members of the serine esterase superfamily and are responsible for hydrolysis of a wide variety of xenobiotic and endogenous esters. They metabolize esters, thioesters, carbamates, and amides to yield soluble acids and alcohols or amines (Satoh and Hosokawa, 1998;Satoh et al., 2002). In the human liver, two major isoforms of carboxylesterase, hCE-1 and hCE-2, have been identified (Shibata et al., 1993;Schwer et al., 1997). hCE-2 is a 60-kDa monomeric enzyme with a pI value of approximately 4.9 and shares 48% amino acid sequence identity with hCE-1 (Pindel et al., 1997;Schwer et al., 1997;Takai et al., 1997). The CES2 gene, which encodes hCE-2, is located on chromosome 16q22.1 and consists of 12 exons. Distribution of hCE-2 is relatively limited to several tissues, such as the small intestine, colon, heart, kidney, and liver, whereas hCE-1 is ubiquitously expressed (Satoh et al., 2002;Xie et al., 2002).Although both hCE-1 and hCE-2 show broad substrate specificities, hCE-2 is relatively specific for heroin, cocaine (benzoyl ester), 6-acetylmorphine, procaine, and oxybutynin (Pindel et al., 1997;Takai et al., 1997;Satoh et al., 2002). In addition, hCE-2 is reported to play a major role in the metabolic activation of the antitumor drug irinotecan (7-ethyl-10-[4-(1-piperidino)-1-piperidino]-carbonyloxycamptothecin; CPT-11). Irinotecan is a water-soluble derivative of the plant alkaloid camptothecin and is widely used for treatment of several types of cancer. Irinotecan is converted to 7-ethyl-10-hydroxy- camptothecin (SN-38), a topoisomerase inhibitor, by carboxylesterases (Humerickhouse et al., 2000) and further conjugated by hepatic uridine diphosphate glucuronosyltransferase to form the inactive metabolite SN-38 glucuronide (SN-38G) (Iyer et al., 1998). To a lesser extent, irinotecan is also converted to 7-ethyl-10-[4-N-(5-aminopentanoic acid)-1-piperidino]carbonyloxycamptothecin and 7-ethyl-10-(4-amino-1-piperidino)carbonyloxycamptothecin by cytochrome P450 3A4 (Dodds et al., 1998;Santos et al., 2000). Irinotecan and its metabolites are excreted by the efflux transporters, ABCB1 (P-glycoprotein), ABCC2 (canalicular multispecific organic anion transporter), and ABCG2 (breast cancer resistance protein), via a hepatobiliary pathway (Mathijssen et al., 2001). Although irinotecan metabolism is rather complex, hCE-2 is a key enzyme that determines the plasma levels of the active metabolite SN-38. Hepatic hCE-2 activity toward irinotecan varies 3-fold in microsomes obtained from a panel of human ...

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Haplotypes and Novel Variants Of Human Ces2mentioning

confidence: 99%

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Haplotypes and a Novel Defective Allele of CES2 Found in a Japanese Population

Kim

Sai²,

Tanaka-Kagawa³

et al. 2007

Drug Metab Dispos

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“…Although enzymes can be purified from human liver (Humerickhouse et al, 2000), recent studies indicate the presence of genetic variants (Munger et al, 1991;Shibata et al, 1993;Wu et al, 2003) that could influence enzyme expression or catalytic activity. The first successful expression of human carboxylesterase CES1A1 in the Sf9 insect cell system was reported by Kroetz et al (1993).…”

Section: Discussionmentioning

confidence: 99%

Methylphenidate Is Stereoselectively Hydrolyzed by Human Carboxylesterase CES1A1

Sun

Murry

Sanghani

et al. 2004

J Pharmacol Exp Ther

180

125

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Methylphenidate is an important stimulant prescribed to treat attention-deficit hyperactivity disorder. It has two chiral centers, but most current commercial formulations consist of the racemic mixture of the threo pair of methylphenidate isomers (d-, l-threo-methylphenidate). The d-isomer is the pharmacologically active component. Numerous studies reported that oral administration of the methylphenidate racemate undergoes first-pass, stereoselective clearance in humans with l-methylphenidate being eliminated faster than d-methylphenidate. Accordingly, the kinetics of hydrolysis of individual enantiomers by purified native and recombinant human liver carboxylesterases CES1A1 and CES2 and a colon isoenzyme CES3 were examined with a liquid chromatography/mass spectrometry assay. The expression of CES1A1, CES2, and CES3 in Sf9 cells and the methods for purification of the three isoenzymes are reported. CES1A1 has a high catalytic efficiency for both d-and l-enantiomers of methylphenidate. No catalytic activity was detected with CES2 and CES3 for either enantiomer. The catalytic efficiency of CES1A1 for l-methylphenidateHence, the catalytic efficiency of CES1A1 for methylphenidate enantiomers agrees with stereoselective clearance of methylphenidate reported in human subjects. Both enantiomers of methylphenidate can be fit into the three-dimensional model of CES1A1 to form productive complexes in the active site. We conclude that CES1A1 is the major enzyme responsible for the first-pass, stereoselective metabolism of methylphenidate.

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“…Large interpatient variability in plasma levels of SN-38 could be indicative of genetic polymorphism. However, pharmacogenomics studies for CES2 have not come to a consensus on the association of SNPs with CES2 expression or activity (Wu et al, 2003;Charasson et al, 2004;Marsh et al, 2004;Kubo et al, 2005).…”

mentioning

confidence: 99%

Expression and Characterization of a Human Carboxylesterase 2 Splice Variant

Schiel

Green²,

Davis³

et al. 2007

J Pharmacol Exp Ther

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(1-piperidino)-1-piperidino] carbonyloxycamptothecin or Irinotecan] is a carbamate prodrug that is activated in vivo by carboxylesterase (CES)-2 to SN-38 (7-ethyl-10-hydroxycamptothecin), a potent topoisomerase I inhibitor. There is high interindividual variation when CPT-11 is used in the treatment of colorectal cancer. Several splice variants of CES2 are reported in the expressed sequence tag database. Real-time polymerase chain reaction was used to determine the abundance of the CES2 and splice variant of human carboxylesterase 2 (CES2⌬ 458 -473 ) transcripts in 10 paired samples of human tumor and normal colon tissue. The results showed that the CES2⌬ 458 -473 transcript accounts for an average of 6% of total CES2 transcripts in colon tissue, and there is large interindividual variation in CES2 expression in both tumor and normal colon samples. The carboxylesterase activity of the colon samples was determined by 4-methylumbelliferyl acetate hydrolysis assays and nondenaturing polyacrylamide gel electrophoresis followed by activity staining. Significant, positive correlations were found between CES2 expression levels and both measures of carboxylesterase activity. We cloned and expressed the CES2⌬ 458 -473 protein in Sf9 insect cells. The purification profiles and preliminary characterization of the CES2⌬ 458 -473 protein indicated that the expressed protein is folded and glycosylated like CES2. However, in vitro assays show that the CES2⌬ 458 -473 protein lacks 4-methylumbelliferyl acetate and irinotecan hydrolase activities. In conclusion, we found that the CES2⌬ 458 -473 protein is an inactive splice variant of CES2 and that its transcript is spliced at a relatively constant rate in tumor and normal colon tissue.CPT-11 is a semisynthetic camptothecin derivative that is approved for the treatment of metastatic colorectal cancer. Currently, several studies are evaluating the efficacy of CPT-11 in the treatment of solid tumors (Conroy et al., 2005;Delord et al., 2005;Reardon et al., 2005;Stathopoulos et al., 2005). Metabolism of CPT-11 is complex with the involvement of several enzymatic reactions (Rivory, 2000;Slatter et al., 2000). CYP3A4-dependent oxidation of CPT-11 results in the formation of APC and NPC (Haaz et al., 1998;Sai et al., 2001); carboxylesterase-dependent hydrolysis of CPT-11 and NPC results in the formation of the active metabolite SN-38 (Humerickhouse et al., 2000;Khanna et al., 2000;Sanghani et al., 2004) and UGT1A1 glucuronidates SN-38 to form the inactive SN-38-glucuronide (Hanioka et al., 2001). The key step in the metabolism of CPT-11 is its activation by carboxylesterases. There are three known human carboxylesterases, CES1, CES2, and CES3. CES2 has 100-and 2000-fold greater catalytic efficiency for irinotecan hydrolysis than CES1 and CES3, respectively . Therefore, CES2, which is predominantly expressed in the liver, small intestines, and colon (Satoh et al., 2002), is the most important carboxylesterase for the activation of CPT-11. Clinical data, reported by Xu et al....

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Characterization of multiple promoters in the human carboxylesterase 2 gene

Cited by 38 publications

References 40 publications

Haplotypes and a Novel Defective Allele of CES2 Found in a Japanese Population

Haplotypes and a Novel Defective Allele of CES2 Found in a Japanese Population

Methylphenidate Is Stereoselectively Hydrolyzed by Human Carboxylesterase CES1A1

Expression and Characterization of a Human Carboxylesterase 2 Splice Variant

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