Generation and Characterization of Novel Cytochrome P450 Cyp2c Gene Cluster Knockout and CYP2C9 Humanized Mouse Lines

Abstract

Compared with rodents and many other animal species, the human cytochrome P450 (P450) Cyp2c gene cluster varies significantly in the multiplicity of functional genes and in the substrate specificity of its enzymes. As a consequence, the use of wild-type animal models to predict the role of human CYP2C enzymes in drug metabolism and drug-drug interactions is limited. Within the human CYP2C cluster CYP2C9 is of particular importance, because it is one of the most abundant P450 enzymes in human liver, and it is involved in the metabolism of a wide variety of important drugs and environmental chemicals. To investigate the in vivo functions of cytochrome P450 Cyp2c genes and to establish a model for studying the functions of CYP2C9 in vivo, we have generated a mouse model with a deletion of the murine Cyp2c gene cluster and a corresponding humanized model expressing CYP2C9 specifically in the liver. Despite the high number of functional genes in the mouse Cyp2c cluster and the reported roles of some of these proteins in different biological processes, mice deleted for Cyp2c genes were viable and fertile but showed certain phenotypic alterations in the liver. The expression of CYP2C9 in the liver also resulted in viable animals active in the metabolism and disposition of a number of CYP2C9 substrates. These mouse lines provide a powerful tool for studying the role of Cyp2c genes and of CYP2C9 in particular in drug disposition and as a factor in drug-drug interaction.

Identification of Novel Pathways of Osimertinib Disposition and Potential Implications for the Outcome of Lung Cancer Therapy

“…However, in early clinical studies, the human value was found to be approximately of osimertinib in HLM was much greater than in MLM ( Figure 3A). To determine the reason for this species difference in metabolism, we analysed osimertinib stability in liver microsomes from Cyp2c, Cyp2d and Cyp3a gene cluster knockout mice, and from a combined Cyp2c/2d/3a triple-cluster knockout line (19)(20)(21)(22). Osimertinib stability was greatly increased in Cyp2d KO ( Figure 3A) and Cyp2c/2d/3a KO (not shown) microsomes but not in any of the other KO microsomes.…”

“…The generation and characterisation of Cyp2cKO, Cyp2dKO, Cyp3aKO, Cyp2c/2d/3aKO, hCYP2D6*2 and hPXR/hCAR/hCYP3A4/3A7 mice has been described previously (19)(20)(21)(22). For the humanized lines, briefly, the hCYP2D6*2 line contains a targeted insertion of an expression cassette containing 9kb of the CYP2D6 promoter, along with all exons, introns and 5' and 3' untranslated regions, into the murine Cyp2d locus, from which all nine functional murine Cyp2d genes have been deleted (20).…”

Opioid Analgesia in P450 Gene Cluster Knockout Mice: A Search for Analgesia-Relevant Isoforms

“…Among these subfamilies, Cyp3a13 (Hasegawa et al, 2011) and Cyp2c44 (Scheer et al, 2012a) gene products were not studied because these genes were not deleted in the present KO mice. The latter is a well-known epoxygenase that deserves further study (Capdevila et al, 2007).…”

“…Experiments with these new models (Cyp2c, Cyp2d, and Cyp3a KO mice) are clarifying the roles for enzyme families in the metabolism of xenobiotics. Presently, we used these three lines of KO mice to study two P450-related problems: (1) assessing possible mechanistic roles for CYP2C, CYP2D, and/or CYP3A subfamilies in the pain-relieving actions of morphine, and (2) , Taconic 9177-M) contain homozygous deletions of 14 full-length P450 genes (Cyp2c55, Cyp2c65, Cyp2c66, Cyp2c29, Cyp2c38, Cyp2c39, Cyp2c67, Cyp2c68, Cyp2c40, Cyp2c69, Cyp2c37, Cyp2c54, Cyp2c50, and Cyp2c70), but retain a functional Cyp2c44 (Scheer et al, 2012a). Cyp2d KOs [C57BL/6-Del(15Cyp2d22-Cyp2d26)1Arte, Taconic 9178-M] contain homozygous deletions of nine full-length P450 genes (Cyp2d22, Cyp2d11, Cyp2d10, Cyp2d9, Cyp2d12, Cyp2d34, Cyp2d13, Cyp2d40, and Cyp2d26) as recently described (Scheer et al, 2012b).…”

Characterization of the Tissue Distribution of the MouseCyp2cSubfamily by Quantitative PCR Analysis

“…These mice are viable and healthy, although some animals exhibited liver inflammation. They also have significantly reduced metabolism of known CYP2C substrates such as tolbutamide (Scheer et al, 2012). Together, these models will be important for elucidating the roles of mouse CYPC enzymes in cardiovascular physiology and xenobiotic metabolism.…”