title: Bioluminescent imaging of drug efflux at the blood-brain barrier mediated by the transporter ABCG2.
abstract: ATP-binding cassette (ABC) transporters are a group of transmembrane proteins that maintain chemical homeostasis through efflux of compounds out of organelles and cells. Among other functions, ABC transporters play a key role in protecting the brain parenchyma by efflux of xenobiotics from capillary endothelial cells at the blood-brain barrier (BBB). They also prevent the entry of therapeutic drugs at the BBB, thereby limiting their efficacy. One of the key transporters playing this role is ABCG2. Although other ABC transporters can be studied through various imaging modalities, no specific probe exists for imaging ABCG2 function in vivo. Here we show that D-luciferin, the endogenous substrate of firefly luciferase, is a specific substrate for ABCG2. We hypothesized that ABCG2 function at the BBB could be evaluated by using bioluminescence imaging in transgenic mice expressing firefly luciferase in the brain. Bioluminescence signal in the brain of mice increased with coadministration of the ABCG2 inhibitors Ko143, gefitinib, and nilotinib, but not an ABCB1 inhibitor. This method for imaging ABCG2 function at the BBB will facilitate understanding of the function and pharmacokinetic inhibition of this transporter.
authors.affiliation: Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
authors.forename: Joshua
authors.initials: J
authors.lastname: Bakhsheshian
authors.forename: Bih-Rong
authors.initials: BR
authors.lastname: Wei
authors.forename: Ki-Eun
authors.initials: KE
authors.lastname: Chang
authors.forename: Suneet
authors.initials: S
authors.lastname: Shukla
authors.forename: Suresh V
authors.initials: SV
authors.lastname: Ambudkar
authors.forename: R Mark
authors.initials: RM
authors.lastname: Simpson
authors.forename: Michael M
authors.initials: MM
authors.lastname: Gottesman
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Hall
mesh_terms: D016475:3T3 Cells; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001812:Blood-Brain Barrier / Q000166:cytology / Q000378:metabolism*; D045744:Cell Line, Tumor; D054659:Diketopiperazines; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D049454:Firefly Luciferin / Q000493:pharmacokinetics* / Q000494:pharmacology; D000077156:Gefitinib; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics; D057809:HEK293 Cells; D006576:Heterocyclic Compounds, 4 or More Rings; D006801:Humans; D049409:Luciferases, Firefly / Q000096:biosynthesis / Q000235:genetics; D049408:Luminescent Agents / Q000493:pharmacokinetics* / Q000494:pharmacology; D008163:Luminescent Measurements; D051379:Mice; D008822:Mice, Transgenic; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D011799:Quinazolines / Q000494:pharmacology; D015262:Xenobiotics / Q000493:pharmacokinetics / Q000494:pharmacology
chemical_list: C541506:3-(6-isobutyl-9-methoxy-1,4-dioxo-1,2,3,4,6,7,12,12a-octahydropyrazino(1',2'-1,6)pyrido(3,4-b)indol-3-yl)propionic acid tert-butyl ester; 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; C501412:Abcg2 protein, mouse; D054659:Diketopiperazines; D006576:Heterocyclic Compounds, 4 or More Rings; D049408:Luminescent Agents; D009363:Neoplasm Proteins; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D011799:Quinazolines; D015262:Xenobiotics; D049454:Firefly Luciferin; D049409:Luciferases, Firefly; C498826:nilotinib; D000241:Adenosine; D000077156:Gefitinib