Related Experiment Video
Updated: Jul 9, 2026
Measuring Caspase Activity Using a Fluorometric Assay or Flow Cytometry
Published on: March 24, 2023
A microscopic technique to study kinetics and concentration-response of drug-induced caspase-3 activation on a single
Jens Martin Werner1, Hans Jürgen Steinfelder
1Institute of Pharmacology & Toxicology, University of Göttingen, Göttingen, Germany. jens.werner@klinik.uni-regensburg.de
Introduction:
Induction of apoptosis is perceived as the main intention of drug regimens for tumour therapy. Thus, the concentration- and time-dependence of drug-induced apoptosis should be carefully evaluated for experimental as well as for standard anti-tumour agents. A main feature of apoptosis is the activation of caspases which is a specific phenomenon of the individual cell. Since caspase-3 is one of the key enzymes we developed a fluorescence microscopy technique to detect caspase-3 activity on the single cell level. The results obtained with this technique were compared to a biochemical procedure investigating caspase-3 activation in a cell population.
Methods:
For the single cell assay LoVo adenocarcinoma cells were stably transfected with the vector pCaspase3-Sensor. The activated caspase-3 cleaves the cytosolic fusion protein and its EYFP part translocates into the nucleus. Thus, each individual apoptotic cell displays a labelled nucleus and affected cells can be visually quantified by the use of a fluorescence microscope. To study kinetics and concentration-response of drug-induced caspase-3 activation we exposed cells towards trans-beta-nitrostyrene, a rapidly acting experimental agent, as well as towards 5-fluorouracil, a standard agent with slow pro-apoptotic kinetics.
Results:
Viability tests confirmed a comparable cytotoxic sensitivity of the transfected LoVo(EYFP) and the parental non-transfected cells towards trans-beta-nitrostyrene, a rapidly acting experimental agent, as well as towards 5-fluorouracil, a standard agent with slow kinetics. When comparing both caspase-3 assays at the same time points and concentrations of both agents, the new microscopic assay proved to be more sensitive, especially at lower concentrations and at earlier time points.
Discussion:
Thus, visual detection of caspase activation in each affected cells enabled a more careful evaluation of the concentration- and time-dependence of drug-induced apoptosis which should also be useful with other experimental or standard agents or with other tumour cells.
Insights
A new fluorescence microscopy technique accurately detects caspase-3 activity in single cancer cells, offering a more sensitive method for evaluating drug-induced apoptosis compared to traditional assays.
Area of Science:
- Cell Biology
- Biochemistry
- Cancer Research
Background:
- Apoptosis induction is a primary goal of cancer drug therapy.
- Evaluating drug-induced apoptosis requires understanding concentration and time-dependence.
- Caspase activation is a key indicator of apoptosis, with caspase-3 being a crucial enzyme.
Purpose of the Study:
- To develop and validate a novel fluorescence microscopy technique for detecting caspase-3 activity at the single-cell level.
- To compare the sensitivity of this new assay with a conventional biochemical assay for caspase-3 activation.
- To assess the concentration- and time-dependence of drug-induced apoptosis using the new single-cell assay.
Main Methods:
- LoVo adenocarcinoma cells were stably transfected to express a caspase-3 sensor (pCaspase3-Sensor).
- Activated caspase-3 cleaves the sensor, causing EYFP translocation to the nucleus for visual detection via fluorescence microscopy.
- Cells were treated with trans-beta-nitrostyrene and 5-fluorouracil to study drug-induced caspase-3 activation kinetics and concentration-response.
Main Results:
- The fluorescence microscopy assay demonstrated higher sensitivity than the biochemical assay, particularly at lower drug concentrations and earlier time points.
- Viability tests confirmed similar cytotoxic sensitivity between transfected and parental cells, validating the sensor's impact.
- The single-cell assay allowed for more precise evaluation of apoptosis induction dynamics.
Conclusions:
- Visual detection of caspase activation in individual cells provides a more sensitive and detailed assessment of drug-induced apoptosis.
- This technique offers a valuable tool for evaluating various anti-cancer agents and tumor cell types.
- The method enhances the understanding of apoptosis mechanisms in cancer therapy.
