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Thermal tolerance during S phase for cell killing and chromosomal aberrations
1Radiation Oncology Research Laboratory, University of California, San Francisco 94143-0806.
Radiation Research
|May 1, 1990
Summary
Heating Chinese hamster ovary cells during early S phase induces thermotolerance, protecting against cell killing and chromosomal aberrations. This protective effect, observed in synchronized cells, suggests heat exposure during S phase primarily causes damage via chromosomal aberrations.
Area of Science:
- Cell Biology
- Genetics
- Radiation Biology
Background:
- Thermotolerance is a protective response to heat stress.
- The S phase of the cell cycle is a critical period for DNA replication and is sensitive to various damaging agents.
Purpose of the Study:
- To investigate whether thermotolerance can be induced in Chinese hamster ovary (CHO) cells during early S phase.
- To determine the effect of induced thermotolerance on cell killing and chromosomal aberrations following heat treatment.
- To test the hypothesis that heat-induced cell death during S phase is primarily mediated by chromosomal aberrations.
Main Methods:
- Synchronized CHO cells in early S phase were obtained using aphidicolin.
- Cells were subjected to a single heat dose (control) or a priming heat dose followed by a second heat dose.
- Flow cytometry was used to confirm cell cycle position.
- Cell survival and chromosomal aberrations were assessed after heat treatments.
Main Results:
- Heating CHO cells in early S phase induced thermotolerance, requiring a twofold greater thermal dose for 10% survival compared to non-thermotolerant cells.
- Thermotolerance protected against both cell killing and the induction of chromosomal aberrations.
- The induced thermotolerance was specific to the S phase of the cell cycle.
Conclusions:
- Heating during early S phase effectively induces thermotolerance in CHO cells.
- Thermotolerance acquired during S phase mitigates heat-induced cell death and chromosomal damage.
- These findings support the hypothesis that heat exposure during S phase leads to cell death primarily through the induction of chromosomal aberrations.