title: Pgp and MRP activities using calcein-AM are prognostic factors in adult acute myeloid leukemia patients.
abstract: Thirteen cell lines with different levels of Pgp and MRP expression were used to assess the ability of calcein acetoxymethyl ester (calcein-AM) uptake and calcein efflux to measure Pgp and MRP functions, respectively. There was a good correlation between MRP expression and the modulatory effect of probenecid (a specific modulator of MRP) on the calcein efflux (r = .91, P = .0003) and between Pgp expression and the modulatory effect of CsA on calcein-AM uptake (r = .96, P < .0001). In light of the high correlations for both proteins, we tested calcein-AM uptake and efflux in fresh myeloid leukemic cells. In 53 acute myeloid leukemia (AML) patients, there was also a good correlation between MRP expression (measured by reverse transcription-polymerase chain reaction and by MRPm6 expression by flow cytometry) and the modulatory effect of probenecid on the calcein fluorescence (r = .92, P < .0001) and between Pgp expression as measured by UIC2 antibody binding on flow cytometry and the modulatory effect of cyclosporin A on calcein-AM uptake (r = .83, P < .0001). Pgp activity was higher in CD34+ leukemia than in CD34- leukemia (2.26 +/- 1.50 v 1.46 +/- 1.21, respectively; P = .003), and MRP activity was higher in CD34- leukemia than in CD34+ leukemia (1.77 +/- 0.40 v 1.4 +/- 0. 29, respectively; P = .004). Pgp expression and activity (P = .004 and P = .01, respectively) and MRP activity (P = .03) but not MRP expression were prognostic factors for achievement of complete remission. These results suggest that functional testing (with calcein-AM +/- modulators) for the presence of both MRP and Pgp activities is of prognostic value and that MRP contributes to drug resistance in AML.
authors.affiliation: Service d'Hématologie Clinique, the Service d'Hématologie Biologique, and the Formation de Recherche Associée Claude Bernard sur le Traitement des Hémopathies Malignes, Laboratoire Universitaire Paris VI, Paris, France.
authors.forename: O
authors.initials: O
authors.lastname: Legrand
authors.forename: G
authors.initials: G
authors.lastname: Simonin
authors.forename: J Y
authors.initials: JY
authors.lastname: Perrot
authors.forename: R
authors.initials: R
authors.lastname: Zittoun
authors.forename: J P
authors.initials: JP
authors.lastname: Marie
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis* / Q000235:genetics*; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis* / Q000235:genetics*; D000208:Acute Disease; D000328:Adult; D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D018432:Drug Resistance, Multiple / Q000235:genetics*; D005434:Flow Cytometry; D005452:Fluoresceins / Q000378:metabolism*; D006801:Humans; D007951:Leukemia, Myeloid / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism* / Q000503:physiopathology; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011379:Prognosis; D014407:Tumor Cells, Cultured
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D005452:Fluoresceins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C107991:ABCB6 protein, human; C007740:fluorexon