ABCG2/BCRP Expression Modulates d-Luciferin–Based Bioluminescence Imaging

Abstract

Bioluminescence imaging (BLI) is becoming indispensable to the study of transgene expression during development and, in many in vivo models of disease such as cancer, for high throughput drug screening in vitro. Because reaction of D-luciferin with firefly luciferase ( fLuc) produces photons of sufficiently long wavelength to permit imaging in intact animals, use of this substrate and enzyme pair has become the method of choice for performing BLI in vivo. We now show that expression of the ATP-binding cassette (ABC) family transporter ABCG2/BCRP affects BLI signal output from the substrate D-luciferin. In vitro studies show that D-luciferin is a substrate for ABCG2/BCRP but not for the MDR1 P-glycoprotein (ABCB1/Pgp), multidrug resistance protein 1 (MRP1/ ABCC1), or multidrug resistance protein 2 (MRP2/ABCC2). D-Luciferin uptake within cells is shown to be modulated by ABC transporter inhibitors, including the potent and selective ABCG2/BCRP inhibitor fumitremorgin C. Images of xenografts engineered to express transgenic ABCG2/BCRP, as well as xenografts derived from the human prostate cancer cell line 22Rv1 that naturally express ABCG2/BCRP, show that ABCG2/ BCRP expression and function within regions of interest substantially influence D-luciferin-dependent bioluminescent output in vivo. These findings highlight the need to consider ABCG2/BCRP effects during D-luciferin-based BLI and suggest novel high throughput methods for identifying new ABCG2/

In Vivo Imaging of Human MDR1 Transcription in the Brain and Spine of MDR1-Luciferase Reporter Mice

“…3). Since D-luciferin is a substrate of Bcrp (Zhang et al, 2007), a transporter that can limit brain availability of D-luciferin at the BBB (Bakhsheshian et al, 2013), we treated mice with an oral dose of elacridar (100 mg/kg) for 4 hours in order to maximize the brain-to-plasma concentration (Sane et al, 2012). Elacridar increased the total MDR1-luc bioluminescent signal up to 2-fold in vehicle-and drug-treated mice (Fig.…”

E2F1 drives chemotherapeutic drug resistance via ABCG2

“…13 MDA-MB-231 cells were therefore engineered to express E2F1-ER and also the gene for luciferase. Cells were then injected into mice to form a xenograft.…”

“…In vivo efflux was quantified relative to the chemiluminescence 10 min after the injection of luciferin. 13 Statistical analyses were undertaken via a Student's t-test.…”

“…Experiments were conducted on the basis of previously published data. 13 A number of 5 Â 10 6 MDA-MB-231 E2F1-ER cells were injected into both flanks of 6-to 8-week-old athymic, nude mice. E2F1 was induced 24 h later by intraperitoneal injection of TAM (0.1 mg) or an equal volume of ETOH/sunflower oil solvent in control mice (n ¼ 5 in each group).…”

Molecular Imaging of Membrane Transporters’ Activity in Cancer: a Picture is Worth a Thousand Tubes

“…First, BCRP expression and function were found to have substantial influence on D-luciferin-dependent bioluminescent output in vivo in mice bearing BCRP-overexpressing and control tumor xenografts (54) (Fig. 3; Table III).…”