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Updated: May 20, 2026
Measuring Caspase Activity Using a Fluorometric Assay or Flow Cytometry
Published on: March 24, 2023
Quantitative profiling of caspase-cleaved substrates reveals different drug-induced and cell-type patterns in
Kazutaka Shimbo1, Gerald W Hsu, Huy Nguyen
1Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94114, USA.
Abstract:
Proapoptotic drugs are a mainstay of cancer drug treatment. These drugs stress cells and ultimately trigger the activation of caspases, cysteine-class proteases that cleave after aspartic acid and deconstruct the cell. It is well known that cells respond differently to proapoptotic cancer drug treatments. Here, using a global and unbiased quantitative N-terminomics technology, we show that ~500 products of caspase cleavage and their kinetics vary dramatically between cell type and cytotoxic drug treatment. It is likely that variations arise from differences in baseline proteome composition of the cell type and the alterations induced by drug treatments to yield a unique cohort of proteins that caspases finally target. Many targets are specific to both drug treatment and cell type, providing candidate-specific biomarkers for apoptosis. For example, in multiple myeloma cells treated with the proteasome inhibitor bortezomib, levels of activating transcription factor-4 increase dramatically early in drug treatment and then decrease upon cleavage by activated caspases. Thus, caspase-derived cleavage products are a sensitive reflection of cell-type and drug-induced stress, and provide useful fingerprints for mechanisms of drug action and response.
Insights
Cancer drugs trigger caspases, but caspase cleavage products vary by cell type and drug. This study reveals ~500 caspase targets, offering potential biomarkers for drug response and mechanisms.
Area of Science:
- Biochemistry
- Molecular Biology
- Cancer Research
Background:
- Proapoptotic drugs are crucial in cancer therapy, inducing cell death via caspase activation.
- Cells exhibit diverse responses to these cancer drug treatments.
- Caspases are proteases that cleave target proteins after aspartic acid residues, leading to cellular dismantling.
Purpose of the Study:
- To investigate the variability of caspase cleavage products and their kinetics across different cell types and cytotoxic drug treatments.
- To identify potential biomarkers for apoptosis and drug action mechanisms.
Main Methods:
- Utilized a global and unbiased quantitative N-terminomics technology.
- Analyzed ~500 products of caspase cleavage and their kinetics.
Main Results:
- Significant variations in caspase cleavage products and kinetics were observed between different cell types and drug treatments.
- Identified numerous drug- and cell-type-specific caspase targets.
- Demonstrated that caspase-derived cleavage products serve as sensitive indicators of cellular stress.
Conclusions:
- Caspase cleavage products provide unique fingerprints reflecting cell-type and drug-induced stress.
- These products can serve as valuable biomarkers for understanding drug mechanisms and predicting treatment response.
- The study highlights the potential of N-terminomics in cancer drug discovery and personalized medicine.
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