title: P-glycoprotein-activity measurements in multidrug resistant cell lines: single-cell versus single-well population fluorescence methods.
abstract: BACKGROUND
  P-gp expression has been linked to the efflux of chemotherapeutic drugs in human cancers leading to multidrug resistance. Fluorescence techniques have been widely applied to measure the P-gp activity. In this paper, there is a comparison between the advantages of two fluorescence approaches of commonly available and affordable instruments: the microplate reader (MPR) and the flow cytometer to detect the P-gp efflux activity using calcein-AM.
  
  
  RESULTS
  The selectivity, sensibility, and reproducibility of the two methods have been defined. Our results showed that the MPR is more powerful for the detection of small inhibition, whereas the flow cytometry method is more reliable at higher concentrations of the inhibitors. We showed that to determine precisely the inhibition efficacy the flow cytometry is better; hence, to get the correct E max and EC50 values, we cannot only rely on the MPR.
  
  
  CONCLUSIONS
  Both techniques can potentially be used extensively in the pharmaceutical industry for high-throughput drug screening and in biology laboratories for academic research, monitoring the P-gp efflux in specific assays.
authors.affiliation: Laboratory of Ecotoxicology UPRES EA 3222, IFRMP 23, University of Le Havre, 76058 Le Havre Cedex, France ; Department of Genetic Medicine, Weill Cornell Medical College, New York, NY 10022, USA ; Stem Cell and Microenvironment Laboratory, Weill Cornell Medical College in Qatar, Doha 24144, Qatar.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Pasquier
authors.affiliation: Laboratory of Ecotoxicology UPRES EA 3222, IFRMP 23, University of Le Havre, 76058 Le Havre Cedex, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Rioult
authors.affiliation: Stem Cell and Microenvironment Laboratory, Weill Cornell Medical College in Qatar, Doha 24144, Qatar.
authors.forename: Nadine
authors.initials: N
authors.lastname: Abu-Kaoud
authors.affiliation: Laboratory of Ecotoxicology UPRES EA 3222, IFRMP 23, University of Le Havre, 76058 Le Havre Cedex, France.
authors.forename: Sabine
authors.initials: S
authors.lastname: Marie
authors.affiliation: Department of Genetic Medicine, Weill Cornell Medical College, New York, NY 10022, USA ; Stem Cell and Microenvironment Laboratory, Weill Cornell Medical College in Qatar, Doha 24144, Qatar.
authors.forename: Arash
authors.initials: A
authors.lastname: Rafii
authors.affiliation: Department of Genetic Medicine, Weill Cornell Medical College, New York, NY 10022, USA ; Stem Cell and Microenvironment Laboratory, Weill Cornell Medical College in Qatar, Doha 24144, Qatar.
authors.forename: Bella S
authors.initials: BS
authors.lastname: Guerrouahen
authors.affiliation: Laboratory of Ecotoxicology UPRES EA 3222, IFRMP 23, University of Le Havre, 76058 Le Havre Cedex, France.
authors.forename: Frank
authors.initials: F
authors.lastname: Le Foll
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000378:metabolism*; D045744:Cell Line, Tumor; D018432:Drug Resistance, Multiple / Q000502:physiology*; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D005452:Fluoresceins / Q000378:metabolism*; D005453:Fluorescence; D006801:Humans; D061986:MCF-7 Cells; D015203:Reproducibility of Results
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D005452:Fluoresceins; C085925:calcein AM