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Updated: Aug 13, 2025
10:23
Evaluation of Caspase Activation to Assess Innate Immune Cell Death
Published on: January 20, 2023
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Cell survival following direct executioner-caspase activation.
Maddalena Nano1,2, James A Mondo1, Jacob Harwood1
1Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, CA 93106.
Summary
Cells can survive direct executioner-caspase activation, challenging the apoptosis point-of-no-return. Cellular state, not just caspase activity levels, determines survival outcomes, impacting cancer treatment efficacy.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Executioner-caspase activation is traditionally viewed as irreversible in apoptosis.
- Studies indicate cell survival post-caspase activation following drug or radiation treatment.
- The capacity for cells to recover from direct caspase activation without pro-survival signals remains unclear.
Purpose of the Study:
- To investigate if cells can survive direct executioner-caspase activation independently of pro-survival stress responses.
- To quantify the relationship between caspase activity levels and cell death/survival.
- To identify factors influencing cell fate after direct caspase activation.
Main Methods:
- Engineered a HeLa cell line for inducible caspase-3 expression.
- Utilized a quantitative reporter to measure caspase activity.
- Administered varying doses of caspase activity to assess cell survival rates.
Main Results:
- High caspase activity led to complete cell death; low activity resulted in complete survival.
- Intermediate caspase activity levels (killing 15-30% of cells) allowed 70-85% survival.
- Neither caspase activity rate, peak level, nor total amount predicted cell death versus survival outcomes.
Conclusions:
- Cells possess the ability to survive direct executioner-caspase activation.
- Cellular state heterogeneity significantly modifies the outcome of potentially lethal caspase activity.
- These survival mechanisms may explain incomplete tumor cell killing in apoptosis-inducing cancer therapies.
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