In Vivo Pretargeted Imaging of HER2 and TAG-72 Expression Using the HaloTag Enzyme

A novel pretargeted SPECT imaging strategy based on the HaloTag enzyme has been evaluated for the first time in a living system. To determine the efficacy of this approach, two clinically relevant cancer biomarkers, HER2 and TAG-72, were selected to represent models of internalizing and noninternalizing antigens, respectively. In MDA-MB-231/H2N (HER2-expressing) and LS174T (TAG-72-expressing) xenograft tumors in mice, pretargeting experiments were performed in which HaloTag-conjugated derivatives of the antibodies trastuzumab (anti-HER2) or CC49 (anti-TAG-72) were utilized as primary agents, and the small molecule HaloTag ligands ¹¹¹In-HTL-1, -2, and -3 were evaluated as secondary agents. While this approach was not sufficiently sensitive to detect the internalizing HER2 antigen, pretargeting experiments involving the most optimal secondary agent, ¹¹¹In-HTL-3, were successful in detecting the noninternalizing antigen TAG-72 and provided high-contrast SPECT images at 4 and 24 h postinjection

Engineered Luciferase Reporter from a Deep Sea Shrimp Utilizing a Novel Imidazopyrazinone Substrate

Bioluminescence methodologies have been extraordinarily useful due to their high sensitivity, broad dynamic range, and operational simplicity. These capabilities have been realized largely through incremental adaptations of native enzymes and substrates, originating from luminous organisms of diverse evolutionary lineages. We engineered both an enzyme and substrate in combination to create a novel bioluminescence system capable of more efficient light emission with superior biochemical and physical characteristics. Using a small luciferase subunit (19 kDa) from the deep sea shrimp <i>Oplophorus gracilirostris</i>, we have improved luminescence expression in mammalian cells ∼2.5 million-fold by merging optimization of protein structure with development of a novel imidazopyrazinone substrate (furimazine). The new luciferase, NanoLuc, produces glow-type luminescence (signal half-life >2 h) with a specific activity ∼150-fold greater than that of either firefly (<i>Photinus pyralis</i>) or <i>Renilla</i> luciferases similarly configured for glow-type assays. In mammalian cells, NanoLuc shows no evidence of post-translational modifications or subcellular partitioning. The enzyme exhibits high physical stability, retaining activity with incubation up to 55 °C or in culture medium for >15 h at 37 °C. As a genetic reporter, NanoLuc may be configured for high sensitivity or for response dynamics by appending a degradation sequence to reduce intracellular accumulation. Appending a signal sequence allows NanoLuc to be exported to the culture medium, where reporter expression can be measured without cell lysis. Fusion onto other proteins allows luminescent assays of their metabolism or localization within cells. Reporter quantitation is achievable even at very low expression levels to facilitate more reliable coupling with endogenous cellular processes

Engineered Luciferase Reporter from a Deep Sea Shrimp Utilizing a Novel Imidazopyrazinone Substrate

Bioluminescence methodologies have been extraordinarily useful due to their high sensitivity, broad dynamic range, and operational simplicity. These capabilities have been realized largely through incremental adaptations of native enzymes and substrates, originating from luminous organisms of diverse evolutionary lineages. We engineered both an enzyme and substrate in combination to create a novel bioluminescence system capable of more efficient light emission with superior biochemical and physical characteristics. Using a small luciferase subunit (19 kDa) from the deep sea shrimp <i>Oplophorus gracilirostris</i>, we have improved luminescence expression in mammalian cells ∼2.5 million-fold by merging optimization of protein structure with development of a novel imidazopyrazinone substrate (furimazine). The new luciferase, NanoLuc, produces glow-type luminescence (signal half-life >2 h) with a specific activity ∼150-fold greater than that of either firefly (<i>Photinus pyralis</i>) or <i>Renilla</i> luciferases similarly configured for glow-type assays. In mammalian cells, NanoLuc shows no evidence of post-translational modifications or subcellular partitioning. The enzyme exhibits high physical stability, retaining activity with incubation up to 55 °C or in culture medium for >15 h at 37 °C. As a genetic reporter, NanoLuc may be configured for high sensitivity or for response dynamics by appending a degradation sequence to reduce intracellular accumulation. Appending a signal sequence allows NanoLuc to be exported to the culture medium, where reporter expression can be measured without cell lysis. Fusion onto other proteins allows luminescent assays of their metabolism or localization within cells. Reporter quantitation is achievable even at very low expression levels to facilitate more reliable coupling with endogenous cellular processes

Engineered Luciferase Reporter from a Deep Sea Shrimp Utilizing a Novel Imidazopyrazinone Substrate

Bioluminescence methodologies have been extraordinarily useful due to their high sensitivity, broad dynamic range, and operational simplicity. These capabilities have been realized largely through incremental adaptations of native enzymes and substrates, originating from luminous organisms of diverse evolutionary lineages. We engineered both an enzyme and substrate in combination to create a novel bioluminescence system capable of more efficient light emission with superior biochemical and physical characteristics. Using a small luciferase subunit (19 kDa) from the deep sea shrimp <i>Oplophorus gracilirostris</i>, we have improved luminescence expression in mammalian cells ∼2.5 million-fold by merging optimization of protein structure with development of a novel imidazopyrazinone substrate (furimazine). The new luciferase, NanoLuc, produces glow-type luminescence (signal half-life >2 h) with a specific activity ∼150-fold greater than that of either firefly (<i>Photinus pyralis</i>) or <i>Renilla</i> luciferases similarly configured for glow-type assays. In mammalian cells, NanoLuc shows no evidence of post-translational modifications or subcellular partitioning. The enzyme exhibits high physical stability, retaining activity with incubation up to 55 °C or in culture medium for >15 h at 37 °C. As a genetic reporter, NanoLuc may be configured for high sensitivity or for response dynamics by appending a degradation sequence to reduce intracellular accumulation. Appending a signal sequence allows NanoLuc to be exported to the culture medium, where reporter expression can be measured without cell lysis. Fusion onto other proteins allows luminescent assays of their metabolism or localization within cells. Reporter quantitation is achievable even at very low expression levels to facilitate more reliable coupling with endogenous cellular processes

Assessing drug sensitivity of rare and transient cell populations.

<p>A) FACS analysis of dissociated D54 cells sorted into CD133⁺ and CD133⁻ populations, P3 represents the CD133 expressing cell population. B) to E) Bioluminescence assay of CD133⁺ and CD133⁻ sorted D54 cells incubated with 200 ng/ml TRAIL (B), 50 µM MNS (C), 50 µM MK886 (D) or 12.5 µM GW7647 (E). Bioluminescence was plotted as fold induction over values obtained from vehicle treated cells. Experiments were performed in triplicates and plotted as mean ± SEM. Paired t-test was performed for all experiments and * denotes p<0.05 value at indicated time points.</p

Validation of HTS hits.

<p>A) Bioluminescence activity of cells treated with MNS was measured at 12 hours post treatment and plotted as fold induction. Experiments were performed at least in triplicates (mean ± SEM). B) Representative western blots for Luciferase, cleaved Caspase 3 and PARP or β-Actin as loading control of D54 cells treated with (25 µM) MNS for 12 hrs. C) Bioluminescence activity of cells treated with increasing concentrations of CV3988 at 12 hours post treatment. Data are plotted as fold induction over values obtained from vehicle treated cells. Experiments were performed in triplicates (mean ± SEM). D and E). Bioluminescence activity was measured at various time points using 1833 (D) or D54 (E) cells treated with CV3988 (12.5 µM), Z-VAD (20 µM) or a combination of Z-VAD plus CV3988 for 24 hrs. Data are plotted as fold induction and experiments were performed in triplicates and plotted as mean ± SEM. F) Representative western blots of Luciferase, Caspase 3, PARP or β-actin were performed on lysates obtained from D54 cells. Cells were either treated with CV3988 (12.5 µM), pre-treated with Z-VAD (20 µM) or treated with Z-VAD and CV3988 for 12 hrs.</p

High throughput screening for inducers Caspase 3/7.

<p>Glosensor expressing 1833 or D54 cells (A and B respectively) were used to screen a library of 1,280 pharmacologically active compounds (LOPAC). Fold induction of bioluminescence signal intensity over values obtained from vehicle treated cells was plotted at maximal induction (mean ± SEM).</p

Transgenic reporter mice expressing Caspase 3/7 GloSensor.

<p>A) Schematic of the pCLEX Caspase 3/7 GloSensor transgene construct. B) Excision of the floxed EGFP-stop cassette when crossed with a Cre expressing mouse strain should result in tissue specific transcription of the reporter. C) Representative bioluminescence images of bi-transgenic (for the reporter and p48-Cre) or mono-transgenic (transgenic for the reporter in the absence of Cre) animals pre- and 30 hrs post-cerulein injection (75 ug/kg, total of 12 injections in 48 hrs). D) Quantification of BLI signal induction upon cerulein treatment. E) Representative bioluminescent and fluorescent (EGFP) ex-vivo images of pancreata from mono- or bi-transgenic animals. F) Representative bioluminescence images of bi-transgenic (right) or mono-transgic (left) animals.</p

Utility of Caspase 3/7 GloSensor for assessment of cell death in cells.

<p>A) Schematic of the Caspase 3/7 GloSensor reporter containing an N-terminus coding for the C-Luc domain (358–544) of luciferase and a C-terminus coding for the N-Luc domain (4–354) of luciferase and a adjoining sequence, DEVD, the Caspase 3/7 recognition sequence. B) The functional basis of the reporter, wherein Caspase 3/7 mediated cleavage at the DEVD sequence results in release of the luciferase peptides and reconstitution of the enzymatic activity and an increase in luminescence signal. C) Bioluminescence analysis of cells treated with 200 ng/ml TRAIL. Data is plotted as fold induction standardized to values obtained from vehicle treated cells. D) Western blot for Caspase 3 cleavage using D54 cells treated with TRAIL for 6 hrs. β-Actin was used to standardize loading. E) Bioluminescence analysis of D54 cells treated with varying concentrations (25–100 ng/ml) of an agonist anti-Fas antibody. Data is plotted as fold induction over values obtained from vehicle treated cells at every hour. F) Bioluminescence analysis of cells treated with a pan-Caspase inhibitor Z-VAD (20 µM), 50 µM Docetaxel or with Z-VAD and Docetaxel combined. Data is plotted as fold induction. Experiments were performed at least in triplicates and mean values were plotted ± SEM.</p