Cell killing, chromosomal aberrations, and division delay as thermal sensitivity is modified during the cell cycle

Area of Science:

• Cell Biology
• Radiation Biology
• Molecular Biology

Background:

• Hyperthermia, or heat treatment, is a known cellular stressor.
• Cellular responses to heat can manifest as chromosomal aberrations, cell killing, and division delay.
• The cell cycle phase (G1 or S) influences cellular sensitivity to various treatments.

Purpose of the Study:

• To investigate the protective and sensitizing effects of cycloheximide and procaine hydrochloride on heat-induced cellular damage.
• To determine if these effects vary depending on the cell cycle phase (G1 or S).
• To elucidate the underlying mechanisms of heat-induced cellular damage.

Main Methods:

• Synchronous Chinese hamster ovary cells were used.
• Cells were treated with cycloheximide (protein synthesis inhibitor) or procaine hydrochloride (membrane-affecting agent).
• Cells were heated at 43°C during G1 or S phase, with or without drug treatment, and endpoints like chromosomal aberrations, cell killing, and division delay were assessed.

Main Results:

• Both cycloheximide and procaine hydrochloride modified heat damage, with cycloheximide offering protection and procaine hydrochloride causing sensitization.
• These effects were consistent across different endpoints and cell cycle phases.
• Heat induced chromosomal aberrations in S phase but not G1 phase.
• Division delay was similar for G1 and S phases during heating, contrasting with radiation responses.

Conclusions:

• Heat-induced cellular damage, including division delay, chromosomal aberrations, and cell killing, may result from a common intracellular event like protein denaturation or aggregation.
• Cycloheximide and procaine hydrochloride can modulate heat sensitivity through distinct mechanisms.
• Cell cycle phase differentially impacts heat-induced aberrations but not division delay or drug modulation of heat effects.