title: A novel energy dependent mechanism reducing daunorubicin accumulation in acute myeloid leukemia.
abstract: Using cyclosporin A (CsA) to inhibit P-glycoprotein (P-gp) function we showed previously that there was a discordance between the ability of acute myeloid leukemic (AML) blast cells to accumulate daunorubicin and P-gp antigen expression (Xie et al, Leukemia 1995; 9:1882-1887). This discordance suggests that a CsA-sensitive drug efflux mechanism distinct from P-gp is expressed in many clinical samples. In the present study using the ATP depleting agents cyanide, azide, or dinitrophenol to inhibit energy dependent transport processes, we observed even larger increases in daunorubicin accumulation than were seen with CsA. Similar patterns were seen in a wide range of P-gp negative human cancer cell lines. Also the observed cyanide effect did not correlate with the expression of mRNA for multidrug resistance-associated protein (MRP), the only other member of the ABC family of membrane transporters that is known to be capable of effluxing daunorubicin. Thse results suggest that daunorubicin accumulation in many cases of AML is modulated by one or more novel energy-dependent processes that are distinct from P-gp or MRP. We speculate that this novel drug transport mechanism(s) may influence the response of AML patients to daunorubicin and other therapeutic agents.
authors.affiliation: Ontario Cancer Institute/Princess Margaret Hospital, Department of Medical Biophysics, University of Toronto, Canada.
authors.forename: D W
authors.initials: DW
authors.lastname: Hedley
authors.forename: S X
authors.initials: SX
authors.lastname: Xie
authors.forename: M D
authors.initials: MD
authors.lastname: Minden
authors.forename: C H
authors.initials: CH
authors.lastname: Choi
authors.forename: H
authors.initials: H
authors.lastname: Chen
authors.forename: V
authors.initials: V
authors.lastname: Ling
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D000208:Acute Disease; D000255:Adenosine Triphosphate / Q000378:metabolism; D000903:Antibiotics, Antineoplastic / Q000378:metabolism*; D001752:Blast Crisis / Q000378:metabolism*; D016572:Cyclosporine / Q000494:pharmacology*; D003630:Daunorubicin / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D007951:Leukemia, Myeloid / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D011190:Potassium Cyanide / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D012333:RNA, Messenger; D016572:Cyclosporine; D000255:Adenosine Triphosphate; D011190:Potassium Cyanide; D003630:Daunorubicin