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Etoposide at different concentrations may open different apoptotic pathways in thymocytes
C Pellicciari1, M G Bottone, V Schaack
1Istituto Scientifico H.S. Raffaele, Milano, Italy.
European Journal of Histochemistry : EJH
|January 1, 1996
Summary
This study investigated thymocyte apoptosis using etoposide, a topoisomerase-II inhibitor. Etoposide induced apoptosis in a dose-dependent manner, affecting specific cell cycle phases and revealing concentration-dependent apoptotic pathways.
Area of Science:
- Cell Biology
- Immunology
- Toxicology
Background:
- Apoptosis, or programmed cell death, is crucial for immune system development.
- Thymocytes undergo apoptosis during T-cell development.
- Etoposide is a topoisomerase-II inhibitor used to study apoptosis.
Purpose of the Study:
- To investigate the morphological, biochemical, and cytometric characteristics of thymocyte apoptosis.
- To examine the effects of the topoisomerase-II inhibitor etoposide on thymocyte apoptosis in vitro.
- To determine if etoposide induces different apoptotic pathways based on concentration.
Main Methods:
- Morphological analysis using electron microscopy.
- Biochemical assays.
- Flow cytometry for cell cycle analysis.
- In vitro exposure of thymocytes to etoposide.
Main Results:
- Etoposide induced thymocyte apoptosis in a dose-dependent manner.
- Apoptotic thymocytes were enriched in S and G2 cell cycle phases after etoposide treatment.
- Nuclear events in apoptosis were similar regardless of the trigger (spontaneous vs. etoposide).
- Low etoposide concentrations mimicked spontaneous apoptosis, while high concentrations caused organelle damage and distinct cytoplasmic changes.
Conclusions:
- Etoposide induces thymocyte apoptosis through pathways influenced by drug concentration.
- Cell cycle phase and nuclear morphology are affected by etoposide-induced apoptosis.
- Plasma membrane integrity is maintained in early apoptotic thymocytes.