title: Differences in assessment of macrolide interaction with human MDR1 (ABCB1, P-gp) using rhodamine-123 efflux, ATPase activity and cellular accumulation assays.
abstract: In this study five macrolide antibiotics (azithromycin, erythromycin, clarithromycin, roxithromycin and telithromycin) were compared based on their ability to interact with human MDR1 (ABCB1, P-glycoprotein), studied from two main aspects: by determining the influence of macrolide antibiotics on MDR1 function, as well as the influence of MDR1 on macrolide accumulation in MES-SA/Dx5 cells overexpressing human MDR1. At higher micromolar concentrations five tested macrolides were shown to inhibit MDR1 function in terms of rhodamine-123 efflux and verapamil-activated ATPase function, whereas at lower concentrations they activated MDR1 ATPase. They were confirmed to be substrates of MDR1 and to compete with each other, as well as with verapamil for transport via this transporter. Expression of MDR1 on cells decreased macrolide accumulation in cells from 2- to 80-fold with the most pronounced change observed for azithromycin and erythromycin. Moreover, presence of active MDR1 highly affected the relative ranking of tested macrolides according to their accumulation in cells. In conclusion, out of seven applied methods and assessed parameters, four of them gave similar rough evaluation on the strength of interaction of five macrolides with MDR1, with clarithromycin, roxithromycin and telithromycin showing stronger interaction than azithromycin and erythromycin.
authors.affiliation: GlaxoSmithKline Research Centre Zagreb Ltd, Prilaz baruna Filipovića 29, HR-10000 Zagreb, Croatia. vesna.y.munic@gsk.com
authors.forename: Vesna
authors.initials: V
authors.lastname: Munić
authors.forename: Zeljko
authors.initials: Z
authors.lastname: Kelnerić
authors.forename: Lara
authors.initials: L
authors.lastname: Mikac
authors.forename: Vesna
authors.initials: V
authors.lastname: Eraković Haber
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D001483:Base Sequence; D015153:Blotting, Western; D017931:DNA Primers; D005434:Flow Cytometry; D006801:Humans; D018942:Macrolides / Q000737:chemistry*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020112:Rhodamine 123 / Q000378:metabolism*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D017931:DNA Primers; D018942:Macrolides; D020112:Rhodamine 123; D000251:Adenosine Triphosphatases