In vivo imaging of early stage apoptosis by measuring real-time caspase-3/7 activation
Matteo Scabini1, Fabio Stellari, Paolo Cappella
1Pharmacology Department, Oncology, Nerviano Medical Sciences, Viale Pasteur 10, 20014 Nerviano, Italy.
Abstract:
In vivo imaging of apoptosis in a preclinical setting in anticancer drug development could provide remarkable advantages in terms of translational medicine. So far, several imaging technologies with different probes have been used to achieve this goal. Here we describe a bioluminescence imaging approach that uses a new formulation of Z-DEVD-aminoluciferin, a caspase 3/7 substrate, to monitor in vivo apoptosis in tumor cells engineered to express luciferase. Upon apoptosis induction, Z-DEVD-aminoluciferin is cleaved by caspase 3/7 releasing aminoluciferin that is now free to react with luciferase generating measurable light. Thus, the activation of caspase 3/7 can be measured by quantifying the bioluminescent signal. Using this approach, we have been able to monitor caspase-3 activation and subsequent apoptosis induction after camptothecin and temozolomide treatment on xenograft mouse models of colon cancer and glioblastoma, respectively. Treated mice showed more than 2-fold induction of Z-DEVD-aminoluciferin luminescent signal when compared to the untreated group. Combining D: -luciferin that measures the total tumor burden, with Z-DEVD-aminoluciferin that assesses apoptosis induction via caspase activation, we confirmed that it is possible to follow non-invasively tumor growth inhibition and induction of apoptosis after treatment in the same animal over time. Moreover, here we have proved that following early apoptosis induction by caspase 3 activation is a good biomarker that accurately predicts tumor growth inhibition by anti-cancer drugs in engineered colon cancer and glioblastoma cell lines and in their respective mouse xenograft models.
Insights
This study introduces a bioluminescence imaging method using Z-DEVD-aminoluciferin to track apoptosis in preclinical cancer models. Early caspase 3 activation monitoring accurately predicts anti-cancer drug efficacy and tumor growth inhibition.
Area of Science:
- Preclinical cancer research
- Translational medicine
- Biomedical imaging
Background:
- In vivo imaging of apoptosis is crucial for anticancer drug development.
- Existing imaging technologies have limitations in monitoring apoptosis effectively.
- Bioluminescence imaging offers a promising approach for real-time apoptosis assessment.
Purpose of the Study:
- To develop and validate a bioluminescence imaging (BLI) approach for monitoring in vivo apoptosis in preclinical cancer models.
- To assess the efficacy of anticancer drugs by quantifying caspase 3/7 activation.
- To establish early apoptosis induction as a predictive biomarker for tumor growth inhibition.
Main Methods:
- Utilized a novel Z-DEVD-aminoluciferin formulation, a caspase 3/7 substrate, with luciferase-expressing tumor cells.
- Administered Z-DEVD-aminoluciferin to xenograft mouse models of colon cancer and glioblastoma treated with camptothecin and temozolomide.
- Quantified bioluminescent signal to measure caspase 3/7 activity and apoptosis induction.
- Combined Z-DEVD-aminoluciferin imaging with D-luciferin imaging to assess both apoptosis and tumor burden.
Main Results:
- Demonstrated successful in vivo monitoring of caspase 3/7 activation and apoptosis induction.
- Observed a >2-fold increase in Z-DEVD-aminoluciferin luminescence in treated mice compared to controls.
- Confirmed the ability to non-invasively track tumor growth inhibition and apoptosis induction simultaneously over time in the same animal.
- Validated early apoptosis induction via caspase 3 activation as a reliable predictor of anti-cancer drug efficacy.
Conclusions:
- The developed BLI method using Z-DEVD-aminoluciferin is effective for in vivo apoptosis monitoring in preclinical cancer settings.
- Caspase 3 activation serves as a valuable early biomarker for predicting anti-cancer drug response and tumor growth inhibition.
- This approach enhances translational medicine by providing real-time insights into drug efficacy and tumor dynamics.
