title: Imatinib mesylate and nilotinib (AMN107) exhibit high-affinity interaction with ABCG2 on primitive hematopoietic stem cells.
abstract: The majority of chronic phase chronic myeloid leukemia (CML) patients treated with the tyrosine kinase inhibitor (TKI) imatinib mesylate maintain durable responses to the drug. However, most patients relapse after withdrawal of imatinib and advanced stage patients often develop drug resistance. As CML is considered a hematopoietic stem cell cancer, it has been postulated that inherent protective mechanisms lead to relapse in patients. The ATP binding-cassette transporters ABCB1 (MDR-1; P-glycoprotein) and ABCG2 are highly expressed on primitive hematopoietic stem cells (HSCs) and have been shown to interact with TKIs. Herein we demonstrate a dose-dependent, reversible inhibition of ABCG2-mediated Hoechst 33342 dye efflux in primary human and murine HSC by both imatinib and nilotinib (AMN107), a novel aminopyrimidine inhibitor of BCR-ABL. ABCG2-transduced K562 cells were protected from imatinib and nilotinib-mediated cell death and from downregulation of P-CRKL. Moreover, photoaffinity labeling revealed interaction of both TKIs with ABCG2 at the substrate binding sites as they compete with the binding of [(125)I] IAAP and also stimulate the transporter's ATPase activity. Therefore, our evidence suggests for the role of ABC transporters in resistance to TKI on primitive HSCs and CML stem cells and provides a rationale how TKI resistance can be overcome in vivo.
authors.affiliation: Department of Hematology, Oncology and Immunology, Philipps-University Marburg, Baldingerstrasse, Marburg, Germany. brendelc@mailer.uni-marburg.de
authors.forename: C
authors.initials: C
authors.lastname: Brendel
authors.forename: C
authors.initials: C
authors.lastname: Scharenberg
authors.forename: M
authors.initials: M
authors.lastname: Dohse
authors.forename: R W
authors.initials: RW
authors.lastname: Robey
authors.forename: S E
authors.initials: SE
authors.lastname: Bates
authors.forename: S
authors.initials: S
authors.lastname: Shukla
authors.forename: S V
authors.initials: SV
authors.lastname: Ambudkar
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: G
authors.initials: G
authors.lastname: Wennemuth
authors.forename: A
authors.initials: A
authors.lastname: Burchert
authors.forename: U
authors.initials: U
authors.lastname: Boudriot
authors.forename: A
authors.initials: A
authors.lastname: Neubauer
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000970:Antineoplastic Agents / Q000493:pharmacokinetics; D001549:Benzamides; D001665:Binding Sites; D019008:Drug Resistance, Neoplasm; D006412:Hematopoietic Stem Cells; D006801:Humans; D000068877:Imatinib Mesylate; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy* / Q000473:pathology; D051379:Mice; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D010879:Piperazines / Q000493:pharmacokinetics*; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines / Q000493:pharmacokinetics*; D012008:Recurrence; D014161:Transduction, Genetic
chemical_list: C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000970:Antineoplastic Agents; D001549:Benzamides; D009363:Neoplasm Proteins; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D000068877:Imatinib Mesylate; C498826:nilotinib