Related Experiment Video
Updated: Jul 5, 2026
Synthesis of an In vivo MRI-detectable Apoptosis Probe
Published on: July 31, 2012
Noninvasive imaging of apoptosis and its application in cancer therapeutics
Julia M Coppola1, Brian D Ross, Alnawaz Rehemtulla
1Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
Purpose:
Activation of the apoptotic cascade plays an important role in the response of tumors to therapy. Noninvasive imaging of apoptosis facilitates optimization of therapeutic protocols regarding dosing and schedule and enables identification of efficacious combination therapies.
Experimental Design:
We describe a hybrid polypeptide that reports on caspase-3 activity in living cells and animals in a noninvasive manner. This reporter, ANLucBCLuc, constitutes a fusion of small interacting peptides, peptide A and peptide B, with the NLuc and CLuc fragments of luciferase with a caspase-3 cleavage site (DEVD) between pepANLuc (ANLuc) and pepBCLuc (BCLuc). During apoptosis, caspase-3 cleaves the reporter, enabling separation of ANLuc from BCLuc. A high-affinity interaction between peptide A and peptide B restores luciferase activity by NLuc and CLuc complementation. Using a D54 glioma model, we show the utility of the reporter in imaging of apoptosis in living subjects in response to various chemotherapy and radiotherapy regimens.
Results:
Treatment of live cells and mice carrying D54 tumor xenografts with chemotherapeutic agents such as temozolomide and perifosine resulted in induction of bioluminescence activity, which correlated with activation of caspase-3. Treatment of mice with combination therapy of temozolomide and radiation resulted in increased bioluminescence activity over individual treatments and increased therapeutic response due to enhanced apoptosis.
Conclusion:
The data provided show the utility of the ANLucBCLuc reporter in dynamic, noninvasive imaging of apoptosis and provides a rationale for use of this technology to optimize dose and schedule of novel therapies or to develop novel combination therapies using existing drugs.
Insights
A novel ANLucBCLuc reporter enables noninvasive imaging of apoptosis by detecting caspase-3 activity. This tool can optimize cancer therapy by monitoring treatment response and guiding combination therapies.
Area of Science:
- Biomedical imaging
- Molecular biology
- Oncology
Background:
- Apoptosis is crucial for tumor response to therapy.
- Noninvasive apoptosis imaging aids in optimizing treatment protocols and identifying effective combination therapies.
Purpose of the Study:
- To develop and validate a novel hybrid polypeptide reporter, ANLucBCLuc, for noninvasive imaging of caspase-3 activity.
- To demonstrate the reporter's utility in monitoring apoptosis in response to various cancer therapies in living subjects.
Main Methods:
- Constructed a hybrid polypeptide reporter (ANLucBCLuc) by fusing luciferase fragments (NLuc, CLuc) with interacting peptides and a caspase-3 cleavage site.
- Utilized NLuc-CLuc complementation upon caspase-3 mediated cleavage to generate bioluminescence signal.
- Applied the reporter in a D54 glioma model in mice to image apoptosis induced by chemotherapy and radiotherapy.
Main Results:
- ANLucBCLuc reporter successfully detected bioluminescence activity in cells and tumor xenografts upon treatment with chemotherapeutic agents, correlating with caspase-3 activation.
- Combination therapy (temozolomide and radiation) showed enhanced bioluminescence and therapeutic response compared to individual treatments, indicating increased apoptosis.
Conclusions:
- The ANLucBCLuc reporter is effective for dynamic, noninvasive imaging of apoptosis.
- This technology can guide the optimization of therapeutic dosing and scheduling and facilitate the development of novel combination therapies.
