title: Idarubicin DNA intercalation is reduced by MRP1 and not Pgp.
abstract: Currently available data regarding the substrate specificity of the multi-drug resistance (MDR) mechanisms P-glycoprotein (Pgp) and MDR-associated protein (MRP1) for idarubicin are inconclusive. A multiparameter flow cytometry method was developed which allows simultaneous quantitative measurement of total cellular fluorescence and the amount of anthracyclines intercalated into the DNA. Anthracycline DNA intercalation was measured by fluorescence resonance energy transfer (FRET) between Hoechst 33342 and anthracyclines. Daunorubicin and idarubicin accumulation were studied and compared in established cell lines expressing Pgp and MRP1. The data demonstrate that daunorubicin DNA intercalation is affected by both Pgp and MRP1 whereas idarubicin DNA intercalation is affected only by MRP1. MRP1 and Pgp function could be blocked completely by 5 microM PAK 104P, while higher concentrations of verapamil, PSC 833 and cyclosporin A were necessary to attain complete blocking of MRP1 compared to Pgp. Daunorubicin DNA intercalation correlates better with cell survival and is more sensitive at physiological MDR expression as observed in hematopoietic progenitors than daunorubicin levels measured by total cellular fluorescence. In conclusion, idarubicin DNA intercalation is reduced by MRP1 but not by Pgp. PAK-104P is an effective modulator for both Pgp and MRP1 and may further improve idarubicin efficacy.
authors.affiliation: Division of Hematology and Central Hematology Laboratory, University Hospital Nijmegen, The Netherlands.
authors.forename: M E
authors.initials: ME
authors.lastname: Smeets
authors.forename: R A
authors.initials: RA
authors.lastname: Raymakers
authors.forename: G
authors.initials: G
authors.lastname: Vierwinden
authors.forename: A H
authors.initials: AH
authors.lastname: Pennings
authors.forename: J
authors.initials: J
authors.lastname: Boezeman
authors.forename: H
authors.initials: H
authors.lastname: Minderman
authors.forename: T M
authors.initials: TM
authors.lastname: de Witte
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000502:physiology*; D000903:Antibiotics, Antineoplastic / Q000378:metabolism / Q000494:pharmacology*; D020137:Base Pair Mismatch; D001562:Benzimidazoles; D004268:DNA-Binding Proteins / Q000502:physiology*; D003630:Daunorubicin / Q000378:metabolism; D004735:Energy Transfer; D005434:Flow Cytometry; D005456:Fluorescent Dyes; D006801:Humans; D015255:Idarubicin / Q000378:metabolism / Q000494:pharmacology*; D007364:Intercalating Agents / Q000494:pharmacology*; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D000074081:MutS Homolog 3 Protein; D012235:Rhodamines; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods; D014407:Tumor Cells, Cultured
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D001562:Benzimidazoles; D004268:DNA-Binding Proteins; D003630:Daunorubicin; D005456:Fluorescent Dyes; D015255:Idarubicin; D007364:Intercalating Agents; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D000074081:MutS Homolog 3 Protein; D012235:Rhodamines; C078444:MSH3 protein, human; C017807:bisbenzimide ethoxide trihydrochloride; C421109:multidrug resistance-associated protein 1