title: Translational value of liquid chromatography coupled with tandem mass spectrometry-based quantitative proteomics for in vitro-in vivo extrapolation of drug metabolism and transport and considerations in selecting appropriate techniques.
abstract: BACKGROUND
  Drug-metabolizing enzymes and transporters play an important role in drug absorption, distribution, metabolism and excretion and, consequently, they influence drug efficacy and toxicity. Quantification of drug-metabolizing enzymes and transporters in various tissues is therefore essential for comprehensive elucidation of drug absorption, distribution, metabolism and excretion. Recent advances in liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) have improved the quantification of pharmacologically relevant proteins.
  
  
  METHODS
  This report presents an overview of mass spectrometry-based methods currently used for the quantification of drug-metabolizing enzymes and drug transporters, mainly focusing on applications and cost associated with various quantitative strategies based on stable isotope-labeled standards (absolute quantification peptide standards, quantification concatemers, protein standards for absolute quantification) and label-free analysis.
  
  
  CONCLUSIONS
  In mass spectrometry, there is no simple relationship between signal intensity and analyte concentration. Proteomic strategies are therefore complex and several factors need to be considered when selecting the most appropriate method for an intended application, including the number of proteins and samples. Quantitative strategies require appropriate mass spectrometry platforms, yet choice is often limited by the availability of appropriate instrumentation. Quantitative proteomics research requires specialist practical skills and there is a pressing need to dedicate more effort and investment to training personnel in this area. Large-scale multicenter collaborations are also needed to standardize quantitative strategies in order to improve physiologically based pharmacokinetic models.
authors.affiliation: a 1 Manchester Pharmacy School, University of Manchester , Oxford Road, Manchester, M13 9PT, UK.
authors.forename: Hajar
authors.initials: H
authors.lastname: Al Feteisi
authors.forename: Brahim
authors.initials: B
authors.lastname: Achour
authors.forename: Amin
authors.initials: A
authors.lastname: Rostami-Hodjegan
authors.forename: Jill
authors.initials: J
authors.lastname: Barber
mesh_terms: D001692:Biological Transport; D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D026901:Membrane Transport Proteins / Q000378:metabolism; D004364:Pharmaceutical Preparations / Q000378:metabolism; D011506:Proteins / Q000032:analysis; D040901:Proteomics / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D057170:Translational Research, Biomedical
chemical_list: D026901:Membrane Transport Proteins; D004364:Pharmaceutical Preparations; D011506:Proteins
keywords: drug transporters; drug-metabolizing enzymes; label-free strategies; quantitative proteomics; stable-isotope dilution strategies (AQUA/QconCAT/PSAQ)