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DNA topoisomerase inhibitors induce reversible senescence in normal human fibroblasts
E Michishita1, K Nakabayashi, H Ogino
1Kihara Institute for Biological Research and Graduate School of Integrated Science, Yokohama City University, Yokohama, Japan.
Abstract:
Inhibitors of DNA topoisomerases I and II induced arrest in cell division in normal human fibroblasts depending on cell divisions. Arrested cells showed morphology similar to those of normally senesced cells and strongly induced senescence-associated beta-galactosidase. In these cells, p16ink4a was upregulated, whereas p21waf1 or p53 was not altered. Upon removal of the inhibitors, the cells resumed growth but their cumulative population doublings were reduced dose dependently. Accelerated telomere shortening was not observed in the arrested cells. These results suggest that DNA topoisomerase inhibitors are efficient and reversible inducers of premature senescence in normal human cells.
Insights
DNA topoisomerase inhibitors trigger premature senescence in human cells, mimicking natural aging. This effect is reversible, with cells resuming growth but exhibiting reduced division potential.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Cellular senescence is a state of irreversible growth arrest.
- DNA topoisomerases are crucial enzymes involved in DNA replication and transcription.
- Understanding inducers of premature senescence is vital for aging research.
Purpose of the Study:
- To investigate the effects of DNA topoisomerase I and II inhibitors on normal human fibroblasts.
- To determine if these inhibitors can induce premature cellular senescence.
- To characterize the molecular markers and reversibility of the induced senescence.
Main Methods:
- Treatment of normal human fibroblasts with DNA topoisomerase inhibitors.
- Assessment of cell division arrest, senescence-associated beta-galactosidase activity, and protein expression (p16ink4a, p21waf1, p53).
- Evaluation of cell recovery and cumulative population doublings post-inhibitor removal.
- Analysis of telomere length in arrested cells.
Main Results:
- DNA topoisomerase inhibitors induced cell division arrest and premature senescence in human fibroblasts.
- Senescent cells exhibited characteristic morphology and elevated senescence-associated beta-galactosidase.
- Upregulation of p16ink4a was observed, while p21waf1 and p53 remained unchanged.
- Inhibitor removal allowed cell growth resumption, but with dose-dependent reduction in population doublings.
- No accelerated telomere shortening was detected in arrested cells.
Conclusions:
- DNA topoisomerase inhibitors are effective and reversible inducers of premature senescence in normal human cells.
- The senescence induced by these inhibitors involves specific molecular pathways, including p16ink4a upregulation.
- These findings provide insights into the mechanisms of cellular aging and potential therapeutic targets.