Marmoset cytochrome P450 4A11, a novel arachidonic acid and lauric acid ω-hydroxylase expressed in liver and kidney tissues

Investigation of Functional Cytochrome P450 4A Enzymes in Liver and Kidney of Pigs, Cats, Tree Shrews, and Dogs in Comparison with the Metabolic Capacity of Human P450 4A11

Pigs are sometimes used in preclinical drug metabolism studies, with growing interest, and thus their drug-metabolizing enzymes, including the cytochromes P450 (P450 or CYP; EC 1.14.14.1), need to be examined. In the present study, novel CYP4A cDNAs were isolated and characterized, namely, pig CYP4A23 and CYP4A90; cat CYP4A37 and CYP4A106; and tree shrew CYP4A11a, CYP4A11d, CYP4A11e, CYP4A11f, and CYP4A11g. For comparison, the following known CYP4A cDNAs were also analyzed: pig CYP4A21 and dog CYP4A37, CYP4A38, and CYP4A39. These CYP4A cDNAs all contained open reading frames of 504-513 amino acids and had high amino acid sequence identity (74%-80%) with human CYP4As. Phylogenetic analysis of amino acid sequences revealed that these CYP4As were clustered in each species. All CYP4A genes contained 12 coding exons and formed a gene cluster in the corresponding genomic regions. A range of tissue types were analyzed, and these CYP4A mRNAs were preferentially expressed in liver and/or kidney, except for pig CYP4A90, which showed preferential expression in lung and duodenum. CYP4A enzymes, heterologously expressed in Escherichia coli, preferentially catalyzed lauric acid 12-hydroxylation and arachidonic acid 20-hydroxylation, just as human CYP4A11 does, with the same regioselectivity (i.e., at the ω-position of fatty acids). These results imply that dog, cat, pig, and tree shrew CYP4As have functional characteristics similar to those of human CYP4A11, with minor differences in lauric acid 12-hydroxylation. SIGNIFICANCE STATEMENT: Cytochrome P450 (P450, CYP) 4As are important P450s in human biological processes because of their fatty acid-metabolizing ability. Pig CYP4A21, CYP4A23, and CYP4A90; cat CYP4A37 and CYP4A106; tree shrew CYP4A11a, CYP4A11d, CYP4A11e, CYP4A11f, and CYP4A11g; and dog CYP4A37, CYP4A38, and CYP4A39 cDNAs were isolated and analyzed. These CYP4A cDNAs shared relatively high sequence identities with human CYP4A11 and CYP4A22. Pig, cat, tree shrew, and dog CYP4As in the liver and kidneys are likely to catalyze the ω-hydroxylation of fatty acids.

Polymorphic cytochromes P450 in non-human primates

Cynomolgus macaques (Macaca fascicularis, an Old World monkey) are widely used in drug development because of their genetic and physiological similarities to humans, and this trend has continued with the use of common marmosets (Callithrix jacchus, a New World monkey). Information on the major drug-metabolizing cytochrome P450 (CYP, P450) enzymes of these primate species indicates that multiple forms of their P450 enzymes have generally similar substrate selectivities to those of human P450 enzymes; however, some differences in isoform, activity, and substrate specificity account for limited species differences in drug oxidative metabolism. This review provides information on the P450 enzymes of cynomolgus macaques and marmosets, including cDNA, tissue expression, substrate specificity, and genetic variants, along with age differences and induction. Typical examples of important P450s to be considered in drug metabolism studies include cynomolgus CYP2C19, which is expressed abundantly in liver and metabolizes numerous drugs. Moreover, genetic variants of cynomolgus CYP2C19 affect the individual pharmacokinetic data of drugs such as R-warfarin. These findings provide a foundation for understanding each P450 enzyme and the individual pharmacokinetic and toxicological results in cynomolgus macaques and marmosets as preclinical models. In addition, the effects of induction on some drug clearances mediated by P450 enzymes are also described. In summary, this review describes genetic and acquired individual differences in cynomolgus and marmoset P450 enzymes involved in drug oxidation that may be associated with pharmacological and/or toxicological effects.

Utility of Common Marmoset (Callithrix jacchus) Embryonic Stem Cells in Liver Disease Modeling, Tissue Engineering and Drug Metabolism

The incidence of liver disease is increasing significantly worldwide and, as a result, there is a pressing need to develop new technologies and applications for end-stage liver diseases. For many of them, orthotopic liver transplantation is the only viable therapeutic option. Stem cells that are capable of differentiating into all liver cell types and could closely mimic human liver disease are extremely valuable for disease modeling, tissue regeneration and repair, and for drug metabolism studies to develop novel therapeutic treatments. Despite the extensive research efforts, positive results from rodent models have not translated meaningfully into realistic preclinical models and therapies. The common marmoset Callithrix jacchus has emerged as a viable non-human primate model to study various human diseases because of its distinct features and close physiologic, genetic and metabolic similarities to humans. C. jacchus embryonic stem cells (cjESC) and recently generated cjESC-derived hepatocyte-like cells (cjESC-HLCs) could fill the gaps in disease modeling, liver regeneration and metabolic studies. They are extremely useful for cell therapy to regenerate and repair damaged liver tissues in vivo as they could efficiently engraft into the liver parenchyma. For in vitro studies, they would be advantageous for drug design and metabolism in developing novel drugs and cell-based therapies. Specifically, they express both phase I and II metabolic enzymes that share similar substrate specificities, inhibition and induction characteristics, and drug metabolism as their human counterparts. In addition, cjESCs and cjESC-HLCs are advantageous for investigations on emerging research areas, including blastocyst complementation to generate entire livers, and bioengineering of discarded livers to regenerate whole livers for transplantation.

Molecular cloning and tissue distribution of marmoset thiopurine S-methyltransferase

The common marmoset (Callithrix jacchus) is a New World monkey that is increasingly used in pharmacological and toxicological studies. Thiopurine S-methyltransferase (TPMT) plays roles in the metabolism of widely used anticancer and anti-inflammatory drugs. Here, we report the isolation and molecular characterization of marmoset TPMT cDNA, which was found to contain an open-reading frame of 245 amino acids that was approximately 92% identical to its human ortholog. Marmoset TPMT was phylogenetically closer to other primate orthologs than to its pig, dog, rabbit, or rodent orthologs. Among the five marmoset tissue types analyzed, marmoset TPMT mRNA was most abundant in kidney and liver, just as human TPMT is. These results suggest that marmoset and human TPMT are similar at the molecular level.

Reused palm oil from frying pork or potato induced expression of cytochrome P450s and the SLCO1B1 transporter in HepG2 cells

Deep frying degrades the oil and generates harmful products. This study evaluated effects of reused palm oil (from frying pork or potato) on expression of cytochrome P450s (CYPs), the transporter (SLCO1B1), and lipid metabolism regulators; proliferator-activated receptors (PPAR) and sterol regulatory element binding protein (SREBP). Human hepatic carcinoma cell line (HepG2) cells were incubated with oleic acid (OA), new palm oil, or reused palm oils for 24 hr. Fatty acid accumulation was examined by Nile red staining. Total RNA was extracted, followed by RT/qPCR of the target genes. Fatty acid accumulation was significantly different between the new and the reused oils. Expression of CYP1A2, CYP2C19, CYP2E1, CYP3A4, CYP4A11, and SLCO1B1 was induced by reused oils. Expression of PPAR-α was strongly increased in all treatments while SREBP-1a and SREBP-1c were suppressed. Modification of CYPs, PPAR-α, and SLCO1B1 by palm oil might increase the risk of fatty acid accumulation with associated oxidative stress. Therefore, consumption of palm oil or reused oil should be limited. PRACTICAL APPLICATIONS: Deep frying degrades the oil and generates harmful products. This study evaluated effects of reused palm oil (from frying pork or potato) on expression of cytochrome P450s (CYPs), the transporter (SLCO1B1), and lipid metabolism regulators; PPAR and SREBP in HepG2 cells. Both of the reused oils-induced profiles of all CYP and SLCO1B1, but the new oil upregulated CYP2E1, CYP3A4, and CYP4A11. PPAR-α was induced while SREBP-1a and SREBP-1c were suppressed by all treatments. Inductions of CYPs with suppression of SREBP-1a and SREBP-1c might contribute to an increased risk of fatty acid accumulation. These findings revealed the impacts of reused palm oil on metabolism via CYPs which related to oxidative stress for further study. Hence, consumption of palm oil or reused cooking oil should be of concern.

Alteration of CYP4A11 expression in renal cell carcinoma: diagnostic and prognostic implications

Background: Cytochrome P-450 4A11 (CYP4A11) and peroxisome proliferator-activated receptor-α (PPARα) are expressed at high levels in renal proximal tubules, and upregulation of CYP4A11 protein levels is known to be influenced by PPAR agonists. The goal of this study was to evaluate the clinicopathological role of CYP4A11 expression in renal cell carcinoma (RCC).

Methods: We performed immunohistochemical analysis of CYP4A11, CYP4A22 and PPARα and correlated the results with the clinicopathological features of RCC (n=139). Reverse transcription digital droplet polymerase chain reaction (RT-ddPCR) against CYP4A11 and CYP4A22 was also performed.

Results: CYP4A11 mRNA expression levels were higher in non-neoplastic kidney tissues than in matched tumor tissues in 12 matched pairs of freshly frozen primary clear-cell RCC (ccRCC) and nontumor tissue (p=0.002). Immunohistochemical staining showed that CYP4A11 expression was significantly lower in ccRCC than in non-ccRCCs, including papillary, chromophobe, and unclassified RCCs (p<0.001). CYP4A11 expression was associated with PPARα expression, males and high nuclear histologic grades (p=0.001, p=0.018 and p<0.001). Univariate and multivariate analyses revealed that CYP4A11 expression was correlated with short overall survival (p=0.007 and p=0.010).

Conclusion: These findings suggest that CYP4A11 expression is a potential poor prognostic factor of RCC. The considerable decrease in CYP4A11 expression is a predictive diagnostic factor of ccRCC, and CYP4A11 metabolism in ccRCC might be different from that in non-ccRCCs.

mRNA levels of drug-metabolizing enzymes in 11 brain regions of cynomolgus macaques

The cynomolgus macaque is an important nonhuman primate species in drug metabolism studies, in part because of its evolutionary closeness to humans. Cytochromes P450 (P450s) have been investigated in the major drug-metabolizing organs, i.e., the liver and small intestine, but have not been fully investigated in the brain. However, recent investigations have indicated possible important roles for P450s in the brain. In this study, by using the quantitative polymerase chain reaction, we measured the mRNA levels of 38 cynomolgus drug-metabolizing enzymes, including 19 P450s, 10 UDP-glycosyltransferases, and 9 other enzymes, in 11 brain regions. Among these drug-metabolizing enzymes, expression of 32 enzyme mRNAs were detected in one or more brain regions, indicating their possible roles in the brain. Further investigation of metabolic activities would facilitate better understanding of the importance of these enzymes in the brain.

The marmoset cytochrome P450 superfamily: Sequence/phylogenetic analyses, genomic structure, and catalytic function

The common marmoset (Callithrix jacchus) is a New World monkey that has attracted much attention as a potentially useful primate model for preclinical testing. A total of 36 marmoset cytochrome P450 (P450) isoforms in the P450 1-51 subfamilies have been identified and characterized by the application of genome analysis and molecular functional characterization. In this mini-review, we provide an overview of the genomic structures, sequence identities, and substrate selectivities of marmoset P450s compared with those of human P450s. Based on the sequence identity, phylogeny, and genomic organization of marmoset P450s, orthologous relationships were established between human and marmoset P450s. Twenty-four members of the marmoset P450 1A, 2A, 2B, 2C, 2D, 2E, 3A, 4A, and 4F subfamilies shared high degrees of homology in terms of cDNA (>89%) and amino acid sequences (>85%) with the corresponding human P450s; P450 2C76 was among the exceptions. Phylogenetic analysis using amino acid sequences revealed that marmoset P450s in the P450 1-51 families were located in the same clades as their human and macaque P450 homologs. This finding underlines the evolutionary closeness of marmoset P450s to their human and macaque homologs. Most marmoset P450 1-4 enzymes catalyzed the typical drug-metabolizing reactions of the corresponding human P450 homologs, except for some differences of P450 2A6 and 2B6. Consequently, it appears that the substrate specificities of enzymes in the P450 1-4 families are generally similar in marmosets and humans. The information presented here supports a better understanding of the functional characteristics of marmoset P450s and their similarities and differences with human P450s. It is hoped that this mini-review will facilitate the successful use of marmosets as primate models in drug metabolism and pharmacokinetic studies.

Expression levels of microRNAs that are potential cytochrome P450 regulators in cynomolgus macaques

1. Although the cynomolgus macaque is an important non-human primate species used in drug metabolism studies, cynomolgus macaque microRNA expressions have not been fully investigated.2. The expressions of 11 cynomolgus microRNAs, all orthologues of P450 regulators in humans, were measured by quantitative polymerase chain reaction in adrenal gland, brain, heart, jejunum, kidney, liver, ovary, testis and uterus. mfa-miR-122 and mfa-miR-192, potentially important biomarkers for liver toxicity, were also analyzed.3. Several cynomolgus microRNAs showed preferential tissue expressions: mfa-miR-1 in heart, mfa-miR-122 in liver and mfa-miR-21 and mfa-miR-192 in jejunum. The remaining nine microRNAs had more ubiquitous expressions. All 13 cynomolgus microRNAs were expressed in liver. Among the 10 animals investigated, inter-individual microRNA expression levels in liver varied from 1.5- to 5.3-fold. mfa-miR-18b was the most variable microRNA. Sex differences in expression levels were <2.0-fold, and the difference was only significant for mfa-miR-29 [1.6-fold difference (p < .05)]. Six cynomolgus microRNAs (mfa-miR-18b, mfa-miR-27a, mfa-miR-132, mfa-miR-27b, mfa-miR-122 and mfa-miR-29) were significantly correlated with P450 mRNAs: mfa-miR-18b and mfa-miR-27a were each correlated with seven P450 mRNAs.4. Expression of these cynomolgus microRNAs in liver might indicate their possible roles in this tissue, and further investigation will clarify their involvement in P450 regulation.

Survey of Drug Oxidation Activities in Hepatic and Intestinal Microsomes of Individual Common Marmosets, a New Nonhuman Primate Animal Model

BACKGROUND

Common marmosets (Callithrix jacchus) are potentially useful nonhuman primate models for preclinical studies. Information for major drug-metabolizing cytochrome P450 (P450) enzymes is now available that supports the use of this primate species as an animal model for drug development. Here, we collect and provide an overview of information on the activities of common marmoset hepatic and intestinal microsomes with respect to 28 typical human P450 probe oxidations.

RESULTS

Marmoset P450 2D6/8-dependent R-metoprolol O-demethylation activities in hepatic microsomes were significantly correlated with those of midazolam 1'- and 4-hydroxylations, testosterone 6β-hydroxylation, and progesterone 6β-hydroxylation, which are probe reactions for marmoset P450 3A4/5/90. In marmosets, the oxidation activities of hepatic microsomes and intestinal microsomes were roughly comparable for midazolam and terfenadine. Overall, multiple forms of marmoset P450 enzymes in livers and intestines had generally similar substrate recognition functionalities to those of human and/or cynomolgus monkey P450 enzymes.

CONCLUSION

The marmoset could be a model animal for humans with respect to the first-pass extraction of terfenadine and related substrates. These findings provide a foundation for understanding individual pharmacokinetic and toxicological results in nonhuman primates as preclinical models and will help to further support understanding of the molecular mechanisms of human P450 function.

Terfenadine t-butyl hydroxylation catalyzed by human and marmoset cytochrome P450 3A and 4F enzymes in livers and small intestines

1. Roles of human cytochrome P450 (P450) 3A4 in oxidation of an antihistaminic drug terfenadine have been previously investigated in association with terfenadine-ketoconazole interaction. Several antihistamine drugs have been recently identified as substrates for multiple P450 enzymes. In this study, overall roles of P450 3A4, 2J2, and 4F12 enzymes in terfenadine t-butyl hydroxylation were investigated in small intestines and livers from humans, marmosets, and/or cynomolgus monkeys. 2. Human liver microsomes and liver and small intestine microsomes from marmosets and cynomolgus monkeys effectively mediated terfenadine t-butyl hydroxylation. Ketoconazole and N-hydroxy-N'-(4-butyl-2-methylphenyl)-formamidine (a P450 4A/F inhibitor) almost completely and moderately inhibited these activities, respectively, in human liver microsomes; however, these chemicals did not show substantially suppression in marmoset liver. Anti-human P450 3A and 4F antibodies showed the roughly supportive inhibitory effects. 3. Recombinant P450 3A4/90 and 4F12 showed high terfenadine t-butyl hydroxylation activities with substrate inhibition constants of 84-144 μM (under 26-76 μM of K_m values), in similar manners to liver and intestine microsomes. 4. These results suggest that human and marmoset P450 3A4/90 and 4F12 in livers or small intestines played important roles in terfenadine t-butyl hydroxylation. Marmosets could be a model for humans during first pass extraction of terfenadine and related substrates.

Marmoset Cytochrome P450 3A4 Ortholog Expressed in Liver and Small-Intestine Tissues Efficiently Metabolizes Midazolam, Alprazolam, Nifedipine, and Testosterone

Common marmosets (Callithrix jacchus), small New World primates, are increasingly attracting attention as potentially useful animal models for drug development. However, characterization of cytochrome P450 (P450) 3A enzymes involved in the metabolism of a wide variety of drugs has not investigated in marmosets. In this study, sequence homology, tissue distribution, and enzymatic properties of marmoset P450 3A4 ortholog, 3A5 ortholog, and 3A90 were investigated. Marmoset P450 3A forms exhibited high amino acid sequence identities (88-90%) to the human and cynomolgus monkey P450 3A orthologs and evolutionary closeness to human and cynomolgus monkey P450 3A orthologs compared with other P450 3A enzymes. Among the five marmoset tissues examined, P450 3A4 ortholog mRNA was abundant in livers and small intestines where P450 3A4 ortholog proteins were immunologically detected. Three marmoset P450 3A proteins heterologously expressed in Escherichia coli membranes catalyzed midazolam 1'- and 4-hydroxylation, alprazolam 4-hydroxylation, nifedipine oxidation, and testosterone 6β-hydroxylation, similar to cynomolgus monkey and human P450 3A enzymes. Among the marmoset P450 3A enzymes, P450 3A4 ortholog effectively catalyzed midazolam 1'-hydroxylation, comparable to microsomes from marmoset livers and small intestines. Correlation analyses with 23 individual marmoset liver microsomes suggested contributions of P450 3A enzymes to 1'-hydroxylation of both midazolam (human P450 3A probe) and bufuralol (human P450 2D6 probe), similar to cynomolgus monkey P450 3A enzymes. These results indicated that marmoset P450 3A forms had functional characteristics roughly similar to cynomolgus monkeys and humans in terms of tissue expression patterns and catalytic activities, suggesting marmosets as suitable animal models for P450 3A-dependent drug metabolism.