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Cisplatin sensitivity correlates with its ability to cause cell cycle arrest via a wee1 kinase-dependent pathway in
F Thiebaut1, R Enns, S B Howell
1Department of Medicine, University of California, San Diego, La Jolla 92093.
Abstract:
Mutants of Schizosaccharomyces pombe were used to define genes involved in the cell cycle arrest produced by cisplatin (DDP), an agent that causes both DNA damage and inhibition of DNA synthesis. Previous work has demonstrated that strains with defective or absent wee1+ function fail to arrest in G2 when DNA is damaged, but do arrest when DNA synthesis is inhibited (Rowley et al., 1992a, Nature, 356:353-355). Strains defective in wee1+ function, or in the ability of the wee1+ kinase to regulate cdc2, failed to arrest following DDP exposure, as did a rad1-1 mutant. All strains failing to arrest in G2 were hypersensitive to DDP. Thus, DNA damage rather than inhibition of DNA synthesis is causative of DDP-induced cell cycle arrest. In addition, this work shows that the wee1+ and rad1+ gene products are required for successful DDP-induced arrest, and suggests that the ability of S. pombe to arrest is a major determinant of sensitivity to DDP.
Insights
Cisplatin (DDP) causes DNA damage and cell cycle arrest in fission yeast. Genes like wee1+ and rad1+ are crucial for this arrest, and their absence increases sensitivity to DDP.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Cisplatin (DDP) is a chemotherapy drug that induces DNA damage and inhibits DNA synthesis.
- Previous studies showed that wee1+ deficient strains of Schizosaccharomyces pombe do not arrest in G2 after DNA damage.
- Cell cycle arrest is a critical cellular response to genotoxic stress.
Purpose of the Study:
- To identify genes in Schizosaccharomyces pombe involved in the cell cycle arrest response to cisplatin (DDP).
- To determine whether DNA damage or inhibition of DNA synthesis is the primary trigger for DDP-induced arrest.
- To investigate the role of wee1+ and rad1+ in DDP sensitivity.
Main Methods:
- Utilized mutant strains of Schizosaccharomyces pombe.
- Exposed mutants to cisplatin (DDP) to observe cell cycle progression.
- Assessed cell cycle arrest in G2 phase.
- Determined sensitivity to DDP in various mutant backgrounds.
Main Results:
- Strains with defective wee1+ function or impaired wee1+ kinase regulation of cdc2 failed to arrest in G2 after DDP exposure.
- A rad1-1 mutant also failed to arrest.
- All strains that did not arrest were hypersensitive to DDP.
- DNA damage, not inhibition of DNA synthesis, was identified as the cause of DDP-induced cell cycle arrest.
Conclusions:
- The wee1+ and rad1+ gene products are essential for a successful DDP-induced cell cycle arrest in Schizosaccharomyces pombe.
- The ability of S. pombe to arrest its cell cycle is a key factor determining its sensitivity to DDP.
- This study highlights the importance of cell cycle checkpoints in mediating responses to DNA-damaging agents.