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Updated: Jun 12, 2026
Viability Assays for Cells in Culture
Published on: January 20, 2014
Checkpoint bypass and cell viability
Jon H Chung1, Yonggang Zhang, Fred Bunz
1Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Abstract:
DNA damage impairs cell growth by delaying or preventing critical processes such as DNA replication and chromosome segregation. In normal proliferating cells, initiation of these processes is controlled by genetically-defined pathways known as checkpoints. Tumors often acquire mutations that disable checkpoints and cancer cells can therefore progress unimpeded into S-phase, through G2 and into mitosis with chromosomal DNA damage. Checkpoint bypass in cancer cells is associated with cell death and loss of proliferative capacity and therefore is believed to contribute to the efficacy of DNA-damaging therapies. Are cancer cell clones that bypass checkpoints invariably more sensitive to DNA damage than checkpoint-proficient cells in normal tissues? We present evidence that the inherent survival of damaged human cells can be surprisingly independent of checkpoint control.
Insights
Cancer cells with disabled checkpoints can survive DNA damage, challenging the assumption that checkpoint control dictates sensitivity. This suggests inherent cellular survival mechanisms may be independent of checkpoint pathways.
Area of Science:
- Cell Biology
- Genetics
- Cancer Research
Background:
- DNA damage halts cell growth by impeding DNA replication and chromosome segregation.
- Cellular checkpoints normally regulate these processes, preventing damaged cells from progressing.
- Tumors often disable checkpoints, allowing damaged cells to divide, which is linked to therapy efficacy.
Purpose of the Study:
- To investigate if cancer cells that bypass checkpoints are always more sensitive to DNA damage than normal cells.
- To explore the relationship between checkpoint proficiency and cellular survival following DNA damage.
Main Methods:
- Analysis of checkpoint-proficient normal cells and checkpoint-deficient cancer cells.
- Assessment of cellular responses to DNA-damaging agents.
- Evaluation of cell survival and proliferation after DNA damage induction.
Main Results:
- Evidence suggests that the survival of damaged human cells can be independent of checkpoint control.
- Checkpoint bypass in cancer cells does not invariably lead to greater sensitivity to DNA damage compared to normal cells.
- Inherent cellular survival mechanisms may play a significant role.
Conclusions:
- Cellular survival following DNA damage is not solely dependent on checkpoint function.
- Checkpoint deficiency in cancer cells does not guarantee increased sensitivity to DNA-damaging therapies.
- Further research is needed to understand the mechanisms of inherent DNA damage resistance.
