title: Global Proteomic Analysis of Human Liver Microsomes: Rapid Characterization and Quantification of Hepatic Drug-Metabolizing Enzymes.
abstract: Many genetic and environmental factors lead to interindividual variations in the metabolism and transport of drugs, profoundly affecting efficacy and toxicity. Precision dosing, that is, targeting drug dose to a well characterized subpopulation, is dependent on quantitative models of the profiles of drug-metabolizing enzymes (DMEs) and transporters within that subpopulation, informed by quantitative proteomics. We report the first use of ion mobility-mass spectrometry for this purpose, allowing rapid, robust, label-free quantification of human liver microsomal (HLM) proteins from distinct individuals. Approximately 1000 proteins were identified and quantified in four samples, including an average of 70 DMEs. Technical and biological variabilities were distinguishable, with technical variability accounting for about 10% of total variability. The biological variation between patients was clearly identified, with samples showing a range of expression profiles for cytochrome P450 and uridine 5'-diphosphoglucuronosyltransferase enzymes. Our results showed excellent agreement with previous data from targeted methods. The label-free method, however, allowed a fuller characterization of the in vitro system, showing, for the first time, that HLMs are significantly heterogeneous. Further, the traditional units of measurement of DMEs (pmol mg-1HLM protein) are shown to introduce error arising from variability in unrelated, highly abundant proteins. Simulations of this variability suggest that up to 1.7-fold variation in apparent CYP3A4 abundance is artifactual, as are background positive correlations of up to 0.2 (Spearman correlation coefficient) between the abundances of DMEs. We suggest that protein concentrations used in pharmacokinetic predictions and scaling to in vivo clinical situations (physiologically based pharmacokinetics and in vitro-in vivo extrapolation) should be referenced instead to tissue mass.
authors.affiliation: Centre for Applied Pharmacokinetic Research, Division of Pharmacy and Optometry, School of Health Sciences, University of Manchester, Manchester (B.A., H.A.F., A.R.-H., J.B.), Waters Corporation, Wilmslow, Cheshire East (F.L.), and Simcyp Limited (a Certara Company), Blades Enterprise Centre, Sheffield (A.R.-H.), United Kingdom.
authors.forename: Brahim
authors.initials: B
authors.lastname: Achour
authors.affiliation: Centre for Applied Pharmacokinetic Research, Division of Pharmacy and Optometry, School of Health Sciences, University of Manchester, Manchester (B.A., H.A.F., A.R.-H., J.B.), Waters Corporation, Wilmslow, Cheshire East (F.L.), and Simcyp Limited (a Certara Company), Blades Enterprise Centre, Sheffield (A.R.-H.), United Kingdom.
authors.forename: Hajar
authors.initials: H
authors.lastname: Al Feteisi
authors.affiliation: Centre for Applied Pharmacokinetic Research, Division of Pharmacy and Optometry, School of Health Sciences, University of Manchester, Manchester (B.A., H.A.F., A.R.-H., J.B.), Waters Corporation, Wilmslow, Cheshire East (F.L.), and Simcyp Limited (a Certara Company), Blades Enterprise Centre, Sheffield (A.R.-H.), United Kingdom.
authors.forename: Francesco
authors.initials: F
authors.lastname: Lanucara
authors.affiliation: Centre for Applied Pharmacokinetic Research, Division of Pharmacy and Optometry, School of Health Sciences, University of Manchester, Manchester (B.A., H.A.F., A.R.-H., J.B.), Waters Corporation, Wilmslow, Cheshire East (F.L.), and Simcyp Limited (a Certara Company), Blades Enterprise Centre, Sheffield (A.R.-H.), United Kingdom.
authors.forename: Amin
authors.initials: A
authors.lastname: Rostami-Hodjegan
authors.affiliation: Centre for Applied Pharmacokinetic Research, Division of Pharmacy and Optometry, School of Health Sciences, University of Manchester, Manchester (B.A., H.A.F., A.R.-H., J.B.), Waters Corporation, Wilmslow, Cheshire East (F.L.), and Simcyp Limited (a Certara Company), Blades Enterprise Centre, Sheffield (A.R.-H.), United Kingdom Jill.Barber@manchester.ac.uk.
authors.forename: Jill
authors.initials: J
authors.lastname: Barber
mesh_terms: D000328:Adult; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D005260:Female; D006801:Humans; D008099:Liver / Q000201:enzymology* / Q000378:metabolism*; D008297:Male; D026901:Membrane Transport Proteins / Q000378:metabolism; D008657:Metabolic Clearance Rate / Q000502:physiology; D008862:Microsomes, Liver / Q000201:enzymology* / Q000378:metabolism*; D008875:Middle Aged; D040901:Proteomics / Q000379:methods
chemical_list: D026901:Membrane Transport Proteins; D003577:Cytochrome P-450 Enzyme System