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Updated: Jun 20, 2026
In vivo Dual Substrate Bioluminescent Imaging
Published on: October 11, 2011
In vivo pharmacodynamic imaging of proteasome inhibition
Erin A Kimbrel1, Tina N Davis, James E Bradner
1Department of Pediatric Oncology, Dana-Farber Cancer Institute, and Harvard Medical School, Boston, MA 20115, USA.
Abstract:
Inhibiting the proteolytic activity of the 26S proteasome has been shown to have selective apoptotic effects on cancer cells and to be clinically efficacious in certain malignancies. There is an unmet medical need for additional proteasome inhibitors, and their development will be facilitated by surrogate markers of proteasome function. Toward this end, ectopic fusion of the destruction domain from ornithine decarboxylase (ODC) to reporter proteins is often used for assessing proteasome function. For luciferase-based reporters, we hypothesized that the oxygen-dependent destruction domain (ODD) from hypoxia-inducible factor 1 alpha (HIF-1 alpha) may provide improved sensitivity over luciferase-ODC, owing to its extremely rapid turnover by the proteasome (HIF-1 alpha has a half-life of less than 5 minutes). In the current study, we show that ODD-luciferase affords a greater dynamic range and faster kinetics than luciferase-ODC in sensing proteasome inhibition in vitro. Importantly, ODD-luciferase also serves as an effective in vivo marker of proteasome function in xenograft tumor models, with inhibition being detected by noninvasive imaging within 3 hours of bortezomib administration. These data establish ODD-luciferase as a surrogate marker of proteasome function that can be used both in vitro and in vivo for the development of novel proteasome inhibitors.
Insights
A novel reporter, ODD-luciferase, offers enhanced sensitivity for detecting proteasome inhibition. This tool aids in developing new cancer therapies by providing a faster and more dynamic way to measure proteasome function.
Area of Science:
- Biochemistry
- Molecular Biology
- Cancer Research
Background:
- The 26S proteasome is a validated cancer therapy target, but new inhibitors are needed.
- Current methods for assessing proteasome function rely on markers like ornithine decarboxylase (ODC).
- Improved surrogate markers are crucial for developing novel proteasome inhibitors.
Purpose of the Study:
- To develop a more sensitive reporter for proteasome function.
- To compare the efficacy of a novel oxygen-dependent destruction domain (ODD) reporter with existing ODC reporters.
- To validate ODD-luciferase as a tool for in vitro and in vivo assessment of proteasome inhibition.
Main Methods:
- Constructed ODD-luciferase and ODC-luciferase reporter systems.
- Assessed reporter sensitivity and kinetics in vitro.
- Evaluated ODD-luciferase in vivo using xenograft tumor models and noninvasive imaging after bortezomib administration.
Main Results:
- ODD-luciferase demonstrated a greater dynamic range and faster kinetics than ODC-luciferase in sensing proteasome inhibition.
- In vivo studies showed ODD-luciferase effectively detected proteasome inhibition within 3 hours of bortezomib treatment in xenograft models.
- Noninvasive imaging confirmed the utility of ODD-luciferase as a real-time marker.
Conclusions:
- ODD-luciferase is a superior surrogate marker for proteasome function compared to ODC-luciferase.
- This reporter system facilitates the development and evaluation of novel proteasome inhibitors.
- ODD-luciferase offers a valuable tool for both preclinical research and potential clinical applications.
