title: A selective ATP-binding cassette subfamily G member 2 efflux inhibitor revealed via high-throughput flow cytometry.
abstract: Chemotherapeutics tumor resistance is a principal reason for treatment failure, and clinical and experimental data indicate that multidrug transporters such as ATP-binding cassette (ABC) B1 and ABCG2 play a leading role by preventing cytotoxic intracellular drug concentrations. Functional efflux inhibition of existing chemotherapeutics by these pumps continues to present a promising approach for treatment. A contributing factor to the failure of existing inhibitors in clinical applications is limited understanding of specific substrate/inhibitor/pump interactions. We have identified selective efflux inhibitors by profiling multiple ABC transporters against a library of small molecules to find molecular probes to further explore such interactions. In our primary screening protocol using JC-1 as a dual-pump fluorescent reporter substrate, we identified a piperazine-substituted pyrazolo[1,5-a]pyrimidine substructure with promise for selective efflux inhibition. As a result of a focused structure-activity relationship (SAR)-driven chemistry effort, we describe compound 1 (CID44640177), an efflux inhibitor with selectivity toward ABCG2 over ABCB1. Compound 1 is also shown to potentiate the activity of mitoxantrone in vitro as well as preliminarily in vivo in an ABCG2-overexpressing tumor model. At least two analogues significantly reduce tumor size in combination with the chemotherapeutic topotecan. To our knowledge, low nanomolar chemoreversal activity coupled with direct evidence of efflux inhibition for ABCG2 is unprecedented.
authors.affiliation: Cytometry, University of New Mexico Health Sciences Center, Albuquerque, NM, USA.
authors.forename: J Jacob
authors.initials: JJ
authors.lastname: Strouse
authors.forename: Irena
authors.initials: I
authors.lastname: Ivnitski-Steele
authors.forename: Hadya M
authors.initials: HM
authors.lastname: Khawaja
authors.forename: Dominique
authors.initials: D
authors.lastname: Perez
authors.forename: Jerec
authors.initials: J
authors.lastname: Ricci
authors.forename: Tuanli
authors.initials: T
authors.lastname: Yao
authors.forename: Warren S
authors.initials: WS
authors.lastname: Weiner
authors.forename: Chad E
authors.initials: CE
authors.lastname: Schroeder
authors.forename: Denise S
authors.initials: DS
authors.lastname: Simpson
authors.forename: Brooks E
authors.initials: BE
authors.lastname: Maki
authors.forename: Kelin
authors.initials: K
authors.lastname: Li
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Golden
authors.forename: Terry D
authors.initials: TD
authors.lastname: Foutz
authors.forename: Anna
authors.initials: A
authors.lastname: Waller
authors.forename: Annette M
authors.initials: AM
authors.lastname: Evangelisti
authors.forename: Susan M
authors.initials: SM
authors.lastname: Young
authors.forename: Stephanie E
authors.initials: SE
authors.lastname: Chavez
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Garcia
authors.forename: Oleg
authors.initials: O
authors.lastname: Ursu
authors.forename: Cristian G
authors.initials: CG
authors.lastname: Bologa
authors.forename: Mark B
authors.initials: MB
authors.lastname: Carter
authors.forename: Virginia M
authors.initials: VM
authors.lastname: Salas
authors.forename: Kristine
authors.initials: K
authors.lastname: Gouveia
authors.forename: George P
authors.initials: GP
authors.lastname: Tegos
authors.forename: Tudor I
authors.initials: TI
authors.lastname: Oprea
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Edwards
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Aubé
authors.forename: Richard S
authors.initials: RS
authors.lastname: Larson
authors.forename: Larry A
authors.initials: LA
authors.lastname: Sklar
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002460:Cell Line; D019008:Drug Resistance, Neoplasm; D005434:Flow Cytometry; D057166:High-Throughput Screening Assays; D006801:Humans; D020128:Inhibitory Concentration 50; D051379:Mice; D016513:Mice, SCID; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D054852:Small Molecule Libraries; D013329:Structure-Activity Relationship; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: C513055:ABCB1 protein, human; C116614:ABCG2 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000970:Antineoplastic Agents; C581365:CID 44640177; D009363:Neoplasm Proteins; D011720:Pyrazoles; D011743:Pyrimidines; D054852:Small Molecule Libraries