Individual Metabolic Capacity Evaluation of Cytochrome P450 2C19 by Protein and Activity in the Small Intestinal Mucosa of Japanese Pancreatoduodenectomy Patients

Abstract

Some P450 enzymes are expressed not only in the liver but also in the small intestine, and these enzymes play an important role in first-pass drug metabolism in the small intestine. Cytochrome P450 (CYP)2C19 has been confirmed to exist in the small intestine of white people, but not yet in Japanese. We investigated the mRNA level, protein level, and activity of CYP2C19 in the small intestine in a Japanese population. Samples were obtained from the healthy portions of resected small intestines from 18 patients who had undergone pancreatoduodenectomy. The microsomes were extracted from the epithelium of the small intestinal tissues. CYP2C19 mRNA and protein levels were analyzed using real-time reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting. CYP2C19 activity in the microsomes was evaluated based on the 5-hydroxylation of lansoprazole using HPLC. CYP2C19 mRNA and protein levels and activities in the small intestine showed interindividual differences. CYP2C19 mRNA levels were not correlated with protein levels or its activity. On the other hand, there was significant correlation between CYP2C19 protein levels and its activity. Further, CYP2C19 protein levels and activities in the small intestine were approximately equal to those in liver. These results suggest the metabolic capacity of CYP2C19 in Japanese small intestine may play as important a role as the liver in drug metabolism. Analyses of the protein level or protein activity of CYP2C19 rather than its mRNA level should be required for predicting the individual metabolic capacity of CYP2C19 in the small intestine.

Simultaneous Absolute Protein Quantification of Transporters, Cytochromes P450, and UDP-Glucuronosyltransferases as a Novel Approach for the Characterization of Individual Human Liver: Comparison with mRNA Levels and Activities

“…For example, Sumida et al (1999) have demonstrated that mRNA expression of CYP3A4 was well correlated with activity in human liver samples, whereas mRNA expression of CYP2E1 did not show such a correlation. Several other reports have demonstrated poor correlations between mRNA expression and activity of CYP2B6, CYP2D6, CYP2E1, and CYP3A4 (Rodríguez-Antona et al, 2001;Sy et al, 2002;Hayashi et al, 2011).…”

“…Sy et al (2002) have demonstrated that protein expression of CYP3A4 correlated well with activity but not with mRNA expression in human liver samples. Hayashi et al (2011) also reported that protein expression of CYP2E1, but not mRNA expression, correlated with activity in samples of human intestinal tissue. Despite these advantages, the limited availability of specific antibodies, among other factors, has restricted quantitative analyses of drugmetabolizing enzymes and drug transporters at the protein level.…”

A-Subclass ATP-Binding Cassette Proteins in Brain Lipid Homeostasis and Neurodegeneration

“…(ii) ApoE is the most abundant apolipoprotein in the CNS and present in HDL-like particles in the cerebrospinal fluid (Hayashi, 2011). (iii) The major apoE isoforms (apoE2, apoE3, and apoE4) are highly associated with disposition to and onset of AD (Hirsch-Reinshagen et al, 2009).…”

“…Initial clues for an interdependency between apoE and ABCA1 came from experiments showing that Abca1 expression induced by liver X receptor (LXR) and retinoid X receptor (RXR) agonists increases efflux of cholesterol to lipid-free apoA-I and apoE3 in isolated mouse neurons, astrocytes, and microglia (Koldamova et al, 2003). Despite the fact that apoE is mainly secreted from astrocytes (Hayashi, 2011), further studies identified ABCA1-dependent loading of apoE with cholesterol as a mechanism by which cholesterol is targeted to neurons (Kim et al, 2007). Importantly, ABCA1 also appears to enhance the reverse process, the removal of cholesterol from neurons.…”

Evaluation of CYP2D6 Protein Expression and Activity in the Small Intestine to Determine Its Metabolic Capability in the Japanese Population

“…e-mail: takebay@marianna-u.ac.jp Recently, we reported that the protein level and activity of CYP must be determined to estimate its metabolic capacity because we could not predict the metabolic capacity based on the CYP mRNA level and polymorphism in the human small intestine. 18) A major purpose of this study was to evaluate the CYP2D6 metabolic capacity in the small intestine of Japanese individuals. We then examined CYP2D6 mRNA and protein levels and activity in small intestine tissue of Japanese surgical patients.…”