• Corpus ID: 26553503

Characterization of CPT-11 hydrolysis by human liver carboxylesterase isoforms hCE-1 and hCE-2.

  title={Characterization of CPT-11 hydrolysis by human liver carboxylesterase isoforms hCE-1 and hCE-2.},
  author={Rod A. Humerickhouse and Karen Lohrbach and L. Li and William F. Bosron and Mary Eileen Dolan},
  journal={Cancer research},
  volume={60 5},
7-Ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxy-camptothecin (irinotecan; CPT-11) is a prodrug activated by carboxylesterase enzymes. We characterized the hydrolysis of CPT-11 by two recently identified human carboxylesterase (hCE) enzymes, hCE-1 and hCE-2. Km and Vmax for hCE-1 and hCE-2 are 43 microM and 0.53 nmol/min/mg protein and 3.4 microM and 2.5 nmol/min/mg protein, respectively. hCE-2 has a 12.5-fold higher affinity for CPT-11 and a 5-fold higher maximal rate of CPT-11… 

Irinotecan activation by human carboxylesterases in colorectal adenocarcinoma cells.

The data support the notion that hCE-2 plays a substantial role in irinotecan activation in human tissue at relevant pharmacologic concentrations and cloned both cDNAs into the human colorectal adenocarcinoma cell line HT29.

An improved human carboxylesterase for enzyme/prodrug therapy with CPT-11

A mutant human CE (hCE1m6), based on the human liver CE hCE1, that can activate CPT-11 approximately 70-fold more efficiently than the wild-type protein and can be expressed at high levels in mammalian cells is developed.

Proficient metabolism of irinotecan by a human intestinal carboxylesterase.

Results suggest that gut toxicity from CPT-11 may be due in part to direct drug conversion by CEs present within the small intestine.

Hydrolysis of irinotecan and its oxidative metabolites, 7-ethyl-10-[4-N-(5-aminopentanoic acid)-1-piperidino] carbonyloxycamptothecin and 7-ethyl-10-[4-(1-piperidino)-1-amino]-carbonyloxycamptothecin, by human carboxylesterases CES1A1, CES2, and a newly expressed carboxylesterase isoenzyme, CES3.

It is found that CPT-11, APC, and NPC can all be metabolized by carboxylesterases to SN-38, a potent topoisomerase I inhibitor.

Structural constraints affect the metabolism of 7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin (CPT-11) by carboxylesterases.

Computer predictive modeling indicated that the ability of each enzyme to activate CPT-11 was dependent on the size of the entrance to the active site, and Kinetic studies with a series of nitrophenyl and naphthyl esters confirmed these predictions, indicating that activation of C PT-11 by a CE is constrained by size-limited access of the drug to theactive site catalytic amino acid residues.


It is found that CPT-11, APC, and NPC can all be metabolized by carboxylesterases to SN-38, a potent topoisomerase I inhibitor.

Characterization of inhibitors of specific carboxylesterases: development of carboxylesterase inhibitors for translational application.

The goal of this study was to develop small molecule inhibitors selective for hiCE to circumvent or treat the toxic side effects of CPT-11, and to identify specific inhibitors of each enzyme.

Expression and Characterization of a Human Carboxylesterase 2 Splice Variant

It is found that the CES2Δ458–473 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.

Activation of a camptothecin prodrug by specific carboxylesterases as predicted by quantitative structure-activity relationship and molecular docking studies.

Comparative molecular field analysis, comparative molecular similarity index analysis, and docking studies were used to predict the biological activity of a 4-benzylpiperazine derivative of CPT-11 in U373MG glioma cell lines transfected with plasmids encoding rCE or hiCE.

Human carboxylesterase isozymes: catalytic properties and rational drug design.

  • T. Imai
  • Biology
    Drug metabolism and pharmacokinetics
  • 2006
The expression pattern of CES in Caco-2 cell monolayer, a useful in vitro model for rapid screening of human intestinal drug absorption, is completely different from that in human small intestine but very similar to human liver that expresses a much higher level of hCE-1 and lower level ofhCE-2.



Metabolic activation of CPT-11, 7-ethyl-10-[4-(1-piperidino)-1- piperidino]carbonyloxycamptothecin, a novel antitumor agent, by carboxylesterase.

The plasma level of SN-38 was decreased in the BNPP-pretreated group compared with these of non- pretreated group, indicating that the esterase involved in CPT-11 metabolism is a carboxylesterase, while in studies on the kinetic parameters of the hydrolysis the highest Vmax value of the isozymes was found in human HU1 and the smallest was seen in rat RL1.

Overexpression of a rabbit liver carboxylesterase sensitizes human tumor cells to CPT-11.

CPT-11 [7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin ] is a prodrug that is converted to the active metabolite SN-38 by carboxylesterases. In its active form, the drug inhibits

Binding and hydrolysis of meperidine by human liver carboxylesterase hCE-1.

Human liver carboxylesterases catalyze the hydrolysis of apolar drug or xenobiotic esters into more soluble acid and alcohol products for elimination and hCE-1 in human liver microsomes may play an important role in meperidine elimination.

Bioactivation of the anticancer agent CPT-11 to SN-38 by human hepatic microsomal carboxylesterases and the in vitro assessment of potential drug interactions.

Of the compounds tested above, based on these in vitro data, only the potent inhibitors of carboxylesterase (BNPP, physostigmine) have the potential to inhibit CPT-11 bioactivation if administered concurrently.

Comparison of activation of CPT-11 by rabbit and human carboxylesterases for use in enzyme/prodrug therapy.

  • M. DanksC. Morton P. Potter
  • Biology, Medicine
    Clinical cancer research : an official journal of the American Association for Cancer Research
  • 1999
Rabbit carboxylesterase/CPT-11 may be a useful enzyme/prodrug combination for activating the prodrug 7-ethyl-10-[4-(1-piper-idino)-1- piperidino]carbonyloxycamptothe cin (CPT -11).

Intracellular roles of SN-38, a metabolite of the camptothecin derivative CPT-11, in the antitumor effect of CPT-11.

The results indicate that CPT-11 itself possesses a marginal antiproliferative effect but that SN-38 plays an essential role in the mechanism of action of C PT-11.

Metabolic fate of irinotecan in humans: correlation of glucuronidation with diarrhea.

Modulation of glucuronidation may be effective in increasing the therapeutic index of CPT-11, and the relatively higher index values, suggestive of higher biliary concentrations of SN-38, were possibly due to low glucuronidated rates.

Cellular localization domains of a rabbit and a human carboxylesterase: influence on irinotecan (CPT-11) metabolism by the rabbit enzyme.

It is determined that an 18-amino acid NH2-terminal hydrophobic signal peptide is responsible for the localization of these proteins to the endoplasmic reticulum by PCR-mediated mutagenesis of a rabbit liver and human alveolar macrophage CE cDNA and subsequent immunohistochemical localization.

Hydrolytic profile for ester- or amide-linkage by carboxylesterases pI 5.3 and 4.5 from human liver.

The results suggested that carboxylesterases pI 5.3 and 4.5 may be involved in the metabolism of various drugs containing an ester-linkage, and that the deduced amino acid sequence from the cDNA registered as human car boxylesterase (hCE-2) in GenBank is identical to that from cDNA for HU1.