Characterization of intestinal and hepatic P450 enzymes in cynomolgus monkeys with typical substrates and inhibitors for human P450 enzymes.
ABSTRACT Cynomolgus monkeys are widely used to predict human pharmacokinetic and/or toxic profiles in the drug developmental stage. Characterization of cynomolgus monkey P450s such as the mRNA expression level, substrate specificity, and inhibitor selectivity were conducted to provide helpful information in designing monkey in vivo studies and monkey-to-human extrapolation. The expression levels of 12 monkey P450 mRNAs, which are considered to be important P450 subfamilies in drug metabolism, were investigated in the liver, small intestine (duodenum, jejunum, and ileum), and colon of individual monkeys. 3. In vitro activities and intrinsic clearance values were determined in monkey intestinal and liver microsomes (MIM and MLM, respectively) using nine typical oxidative reactions for human P450s. Paclitaxel 6α-hydroxylation, diclofenac 4′-hydroxylation, and S-mephenytoin 4′-hydroxylation showed low activities in MIM and MLM. IC₅₀ values of eight selective inhibitors of human P450s were determined in MIM and MLM. Inhibitory effects of furafylline and sulfaphenazole were weak in monkeys on phenacetin O-deethylation and diclofenac 4′-hydroxylation, respectively. These results show profiles of monkey P450s in both the intestine and liver in detail and contribute to a better understanding of the species difference in substrate specificity and inhibitor selectivity between cynomolgus monkeys and humans.
Full-textDOI: · Available from: Masateru Miyake, Jan 08, 2015
SourceAvailable from: Eric J Vallender[Show abstract] [Hide abstract]
ABSTRACT: Because of their strong similarities to humans across physiologic, developmental, behavioral, immunologic, and genetic levels, nonhuman primates are essential models for a wide spectrum of biomedical research. But unlike other animal models, nonhuman primates possess substantial outbred genetic variation, reducing statistical power and potentially confounding interpretation of results in research studies. Although unknown genetic variation is a hindrance in studies that allocate animals randomly, taking genetic variation into account in study design affords an opportunity to transform the way that nonhuman primates are used in biomedical research. New understandings of how the function of individual genes in rhesus macaques mimics that seen in humans are greatly advancing the rhesus macaques utility as research models, but epistatic interaction, epigenetic regulatory mechanisms, and the intricacies of gene networks limit model development. We are now entering a new era of nonhuman primate research, brought on by the proliferation and rapid expansion of genomic data. Already the cost of a rhesus macaque genome is dwarfed by its purchase and husbandry costs, and complete genomic datasets will inevitably encompass each rhesus macaque used in biomedical research. Advancing this outcome is paramount. It represents an opportunity to transform the way animals are assigned and used in biomedical research and to develop new models of human disease. The genetic and genomic revolution brings with it a paradigm shift for nonhuman primates and new mandates on how nonhuman primates are used in biomedical research.ILAR journal / National Research Council, Institute of Laboratory Animal Resources 01/2013; 54(2):154-65. DOI:10.1093/ilar/ilt044 · 1.05 Impact Factor
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ABSTRACT: Cynomolgus monkeys are used to predict human pharmacokinetic and/or toxic profiles in the drug developmental stage. Cynomolgus P450s exhibit a high degree of identity (more than 90%) in both cDNA and amino acid sequences with corresponding human P450s. CYP3A protein predominantly exists in cynomolgus monkey liver microsomes, followed by CYP2A, CYP2C, CYP2B6, CYP2E1, and CYP2D. There are many similarities of metabolic properties in cytochrome P450s between cynomolgus monkeys and humans, but the species differences between cynomolgus monkey and human P450s are clearly present in substrate specificity and inhibitor selectivity. Diclofenac 4-hydroxylation (DFOH) in monkey liver and intestinal microsomes shows much lower activities compared with those in human liver and intestinal microsomes. Sulfaphenazole strongly inhibits DFOH in human liver microsomes, but does not effectively inhibit DFOH in monkey liver and intestinal microsomes. Cynomolgus CYP2C19 exhibits higher activity for DFOH than cynomolgus CYP2C9 although this reaction is a marker reaction of human CYP2C9. On the other hand, cynomolgus CYP2C76 orthologue is not expressed in humans and shows 70-72% identity in amino acid sequences of human CYP2C subfamilies. Cynomolgus CYP2C76 metabolizes non-CYP2C substrates, 7-ethoxyresorufin (human CYP1A substrate) and bufuralol (human CYP2D6 substrate). In addition, cynomolgus CYP3A4 and CYP3A5 also exhibits wider substrate selectivity toward human CYP2D6 and CYP2E1 substrates. These enzymes may be responsible for species difference in drug metabolism between cynomolgus monkeys and humans. The comparative data presented here can be helpful for designing in vivo metabolic assays using cynomolgus monkeys in terms of substrate specificity and inhibitor selectivity.Current Drug Metabolism 09/2012; DOI:10.2174/138920013804870664 · 3.49 Impact Factor
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ABSTRACT: Cynomolgus monkeys are a commonly utilized species in preclinical drug discovery, and have high genetic similarity to humans, especially for the drug-metabolizing cytochrome P450s (P450s). However, species differences are frequently observed in the metabolism of drugs between cynomolgus monkeys and humans, and delineating these differences requires expressed and purified CYPs. We have successfully cloned, expressed and purified cynomolgus monkey CYP3A4 (c3A4) in a novel human embryonic kidney (HEK) 293-6E cell suspension system and determined the kinetics of five human CYP3A4 (h3A4) substrates- midazolam (MDZ), testosterone (TST), terfenadine, nifedipine, and triazolam (TRZ). All five substrates were found to be good substrates of c3A4, although some differences were observed in the Km values. Overall, the data suggested a strong substrate similarity between c3A4 and h3A4. Additionally, c3A4 exhibited no activity against non-h3A4 probe substrates, except for a known human CYP2D6 (h2D6) substrate (bufuralol), which suggested potential metabolism of h2D6-substrates by c3A4. Ketoconazole (KTZ) and troleandomycin (TAO) showed similar inhibitory potencies towards c3A4 and h3A4, while non-h3A4 inhibitors did not inhibit c3A4 activity. The availability of a c3A4 preparation, in conjunction with commercially available monkey liver microsomes, will support further characterization of the cynomolgus monkey as a model to assess CYP3A-dependent clearance and drug-drug interactions.Drug metabolism and disposition: the biological fate of chemicals 12/2013; 42(3). DOI:10.1124/dmd.113.055491 · 3.33 Impact Factor