Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2018 Aug 31:6:280-288.
doi: 10.1016/j.isci.2018.08.006. Epub 2018 Aug 11.

Visualizing Ligand Binding to a GPCR In Vivo Using NanoBRET

Diana C Alcobia  1 , Alexandra I Ziegler  2 , Alexander Kondrashov  3 , Eleonora Comeo  4 , Sarah Mistry  4 , Barrie Kellam  4 , Aeson Chang  2 , Jeanette Woolard  5 , Stephen J Hill  6 , Erica K Sloan  7
Affiliations

Visualizing Ligand Binding to a GPCR In Vivo Using NanoBRET

Diana C Alcobia et al. iScience. .

Abstract

The therapeutic action of a drug depends on its ability to engage with its molecular target in vivo. However, current drug discovery strategies quantify drug levels within organs rather than determining the binding of drugs directly to their specific molecular targets in vivo. This is a particular problem for assessing the therapeutic potential of drugs that target malignant tumors where access and binding may be impaired by disrupted vasculature and local hypoxia. Here we have used triple-negative human breast cancer cells expressing β2-adrenoceptors tagged with the bioluminescence protein NanoLuc to provide a bioluminescence resonance energy transfer approach to directly quantify ligand binding to a G protein-coupled receptor in vivo using a mouse model of breast cancer.

Keywords: Biological Sciences Tools; Cancer; Molecular Interaction; Optical Imaging.

PubMed Disclaimer

Figures

None
Graphical abstract
Figure 1
Figure 1
Binding of Fluorescent Propranolol (Propranolol-(β-Ala-β-Ala)-X-BODIPY630/650; Prop-BY630) to Triple-Negative Human Breast Cancer Cells (MDA-MB-231HM cells) (A) Fluorescence imaging of the binding of 50 nM Prop-BY630 to non-transfected MDA-MB-231HM cells (upper panels) or MDA-MB-231HM cells expressing NanoLuc-tagged human β2-adrenoceptors (lower panels). Cells were pre-treated with Hoechst 33342 nuclear stain (2 μg/mL; blue labeling) and then labeled for 30 min with Prop-BY630 (red labeling). Upper right and bottom right panels show cells pre-incubated with 10 μM unlabelled propranolol before labeling with fluorescent propranolol (50 nM Prop-BY630). Cells were washed just before imaging to remove unbound fluorescent ligand. Data are representative images from 3 independent experiments. Scale bar represents 50μm. (B) Bioluminescence imaging (Olympus LV200) of NanoLuc-tagged β2-adrenoceptors. MDA-MB-231HM Nluc-β2AR cells treated with 400 nM furimazine substrate alone (upper panels) to detect luminescence in the absence of added fluorescent ligand using an open channel (20 s exposure time; 420 nm longpass filter; upper left panel) or a Cy5 channel (4 min exposure time; 600/50 nm bandpass filter; upper right panel) to detect BRET generated by binding of fluorescent ligand, when present. Middle and lower panels show images from cells treated with 50 nM Prop-BY630, in the presence (lower panels) or absence (middle panels) of unlabelled ICI 118551 (10 μM). Images shown were acquired with an open channel (middle and lower left panels) and the Cy5 channel (middle and lower right panels). Scale bar represents 50 μm. (C) BRET ratios obtained using bioluminescence imaging using ImageJ time series analyzer. Data show the mean and SE obtained in 3 independent experiments. **p < 0.01 compared with basal or in the presence of 10 μM ICI 118551 (one-way ANOVA with Tukey's multiple comparisons).
Figure 2
Figure 2
Quantitative Analysis of Ligand Binding to NanoLuc-Tagged Human β2-Adrenoceptors Expressed in MDA-MB-231HM Cells Using NanoBRET (A) Binding of increasing concentrations of Propranolol-(β-Ala-β-Ala)-X-BODIPY630/650 (Prop-BY630) to NanoLuc-tagged human β2-adrenoceptors in MDA-MB-231HM cells measured using a CLARIOstar plate reader. Non-specific binding was defined with 10 μM unlabelled ICI 118551. Data are mean ± SE from 6 separate experiments. Total (open circles) and non-specific binding (closed circles) curves were fitted simultaneously as described in the Transparent Methods. The dotted line shows the specific binding component derived from this analysis. (B) Real-time kinetic analyses of Prop-BY630 binding to NanoLuc-tagged human β2-adrenoceptors expressed in MDA-MB-231HM cells using 25, 50, 100, and 200 nM fluorescent ligand. BRET ratios for kinetic studies have been baseline-corrected to specific binding (after subtraction of non-specific binding) at time 0. Data are mean ± SE of triplicate determinations in a representative experiment. Similar data were obtained in 4 additional experiments. (C) Inhibition of the specific binding of 50 nM Prop-BY630 to NanoLuc-tagged human β2-adrenoceptors in MDA-MB-231HM cells by increasing the concentrations of ICI 118551, un-labelled propranolol, and CGP20712A. Data are mean ± SE from 5 separate experiments.
Figure 3
Figure 3
Whole-Animal Bioluminescence Imaging of NanoLuc-β2AR MDA-MB-231HM Tumor Growth and Metastasis Development (A) Female BALB/c nu/nu mice (7-week-old) were injected in the fourth left mammary fat pad with 5 × 105 MDA-MB-231HM triple-negative human breast cancer cells that stably express the NanoLuc-tagged human β2-adrenoceptor. Tumor development was monitored by bioluminescence imaging (left y axis) 5 min after IV injection of the NanoLuc substrate furimazine (100 μL in PBS, circa 0.37 mg/kg) or by caliper measurements (right y axis) over 35 days. (B) Representative bioluminescence images of primary tumors. (C) Bioluminescence monitoring of the development of metastasis in lungs and axillary lymph nodes. Inset: representative images of lung and lymph node metastasis. Data were obtained from 11 mice and are expressed as mean ± SE. *p < 0.05, **p < 0.005, ***p < 0.0001 (two-way ANOVA with Tukey's multiple comparisons with respect to day 8 baseline). For luminescence measurements, the statistical analysis was applied to the log transformed values.
Figure 4
Figure 4
NanoBRET to Monitor Specific Ligand-Receptor Binding In Vivo in Primary MDA-MB-231HM Tumors (A) Female BALB/c nu/nu mice (7-week-old) were injected in the fourth left mammary fat pad with 5 × 105 MDA-MB-231 triple-negative human breast cancer cells stably expressing Nluc-β2AR. Once tumor size reached >200 mm3; BRET ratios were determined from mice administered fluorescent propranolol-(β-Ala-β-Ala)-X-BODIPY630/650 alone (Prop-BY630 at 0.1 mg/kg intra-tumor, IT; red circles) or from mice receiving both Prop-BY630 (0.1 mg/kg IT) and 0.3 mg/kg ICI 118551 (IT; blue circles). ICI 118551 was administered 45 min before the fluorescent propranolol. Control represents measurements taken 5 min after IV injection (in 100 μL; circa 0.37 mg/kg) of the furimazine substrate 24 hr before administration of any β2-adrenoceptor-directed ligands. BRET measurements of ligand binding were made 1 hr after injection of Prop-BY630 (treated condition). Furimazine substrate was injected IV 5 min before mice were imaged. Data represent mean ± SE of 6 mice in each group. **p < 0.0001 (two-way ANOVA with Tukey's multiple comparison test) compared with both control datasets and the 1 hr treatment with Prop-BY630. (B) Representative images showing single mice exposed to Prop-BY630 only (left panel) or to 0.3 mg/kg (IT) ICI 118551 and 0.1 mg/kg (IT) Prop-BY630 (right panel). Upper panels shown in (B) show BRET images and lower panels show the total bioluminescence (BLI) from the NanoLuc. (C) BRET ratios determined from mice administered with fluorescent ligand alone (Prop-BY630 0.1 mg/kg IT; red circles) or from mice receiving both Prop-BY630 (0.1 mg/kg IT) and 10 mg/kg ICI 118551 (IV; blue circles). ∗∗p<0.0001 (two-way ANOVA with Tukey's multiple comparison test) compared with both control datasets. ∗p<0.001 compared to 1h treatment with Prop-BY630. (D) Representative images showing mice exposed to 0.1 mg/kg Prop-BY630 (IT) alone or to 10 mg/kg ICI 118551 (IV) and 0.1 mg/kg Prop-BY630. Data represent mean ± SE of 6 mice in each group.
Figure 5
Figure 5
Effect of Selective β1- and β2-Adrenoceptor Antagonists on Prop-BY630 Binding to MDA-MB-231HM Cells In Vivo Drug-receptor engagement in the primary tumor region was investigated using 0.1 mg/kg (IT) Prop-BY630 in mice treated with the β2-selective antagonist ICI 118551 or the β1-selective antagonist CGP20712A. At 45 min before fluorescent ligand injection, mice were administered (IV) with either PBS (100 μL), CGP201712A (100 μL; 10 mg/kg in PBS), or ICI 118551 (100 μL; 1 mg/kg in PBS). Data represent mean ± SE of 6 mice in each group. Measurements were made 1 hr after administration of Prop-BY630. Baseline measurements were obtained on the previous day in each mouse when furimazine was administered via the tail vein, but Prop-BY630 was not injected into the tumor. *p < 0.05 or #p < 0.001 with respect to the baseline (t = 0) signal in each group. *p < 0.05 versus control Prop-BY630 binding (1 hr PBS). One-way ANOVA with Tukey's posthoc tests.
Figure 6
Figure 6
Dose-Dependent Binding of Prop-BY630 to β2-Adrenoceptors and Subsequent Ligand Dissociation In Vivo To monitor fluorescent ligand dissociation over time in the primary tumors, mice were administered with 3 different doses of propranolol-(β-Ala-β-Ala)-X-BY630/650 (0.01, 0.03, or 0.1 mg/kg; IT). At 1, 24, 48, and 72 hr after fluorescent ligand injection, mice were injected with furimazine substrate (IV, 100 μL in PBS, circa 0.37 mg/kg) and imaged 5 min later using the IVIS Lumina II camera system. Imaging was performed by capturing sequential luminescence (open channel, 30 s exposure time) and fluorescence (Cy5.5 channel, 5 min exposure times) images. All mice were also imaged on the day before fluorescent ligand injection following an IV injection of furimazine to determine luminescence (and BRET) baseline (t = 0). Data represent mean ± SE of 6 mice in each group. *p < 0.05. **p < 0.01 or #p < 0.001 compared with corresponding time 0 controls. Two-way ANOVA with repeated measures and Dunnett multiple comparisons.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Armaiz-Pena G.N., Allen J.K., Cruz A., Stone R.L., Nick A.M., Lin Y.G., Han L.Y., Mangala L.S., Villares G.J., Vivas-Mejia P. Src activation by beta-adrenoreceptors is a key switch for tumour metastasis. Nat. Commun. 2013;4:1403. - PMC - PubMed
    1. Baker J.G., Adams L., Salchow K., Mistry S., Middleton R., Hill S.J., Kellam B. Synthesis and characterization of high-affinity 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-labelled fluorescent ligands for human beta-adrenoceptors. J. Med. Chem. 2011;54:6874–6887. - PMC - PubMed
    1. Bar-Shavit R., Maoz M., Kancharla A., Nag J.K., Agranovich D., Grisaru-Granovsky S., Uziely B. G protein-coupled receptors in cancer. Int. J. Mol. Sci. 2016;17:1320. - PMC - PubMed
    1. Carmeliet P., Jain R.K. Molecular mechanisms and clinical applications of angiogenesis. Nature. 2011;7347:298–307. - PMC - PubMed
    1. Chang A., Le C.P., Walker A.K., Creed S.J., Pon C.K., Albold S., Carroll D., Halls M.L., Lane J.R., Riedel B. β2-adrenoceptors on tumor cells play a critical role in stress-enhanced metastasis in a mouse model of breast cancer. Brain Behav. Immun. 2016;57:106–115. - PMC - PubMed