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Updated: Apr 16, 2026
Two- and Three-Dimensional Live Cell Imaging of DNA Damage Response Proteins
Published on: September 28, 2012
Cellular responses to a prolonged delay in mitosis are determined by a DNA damage response controlled by Bcl-2 family
Didier J Colin1, Karolina O Hain1, Lindsey A Allan1
1Division of Cancer Research, Medical Research Institute, University of Dundee, Jacqui Wood Cancer Centre, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK.
Abstract:
Anti-cancer drugs that disrupt mitosis inhibit cell proliferation and induce apoptosis, although the mechanisms of these responses are poorly understood. Here, we characterize a mitotic stress response that determines cell fate in response to microtubule poisons. We show that mitotic arrest induced by these drugs produces a temporally controlled DNA damage response (DDR) characterized by the caspase-dependent formation of γH2AX foci in non-apoptotic cells. Following exit from a delayed mitosis, this initial response results in activation of DDR protein kinases, phosphorylation of the tumour suppressor p53 and a delay in subsequent cell cycle progression. We show that this response is controlled by Mcl-1, a regulator of caspase activation that becomes degraded during mitotic arrest. Chemical inhibition of Mcl-1 and the related proteins Bcl-2 and Bcl-xL by a BH3 mimetic enhances the mitotic DDR, promotes p53 activation and inhibits subsequent cell cycle progression. We also show that inhibitors of DDR protein kinases as well as BH3 mimetics promote apoptosis synergistically with taxol (paclitaxel) in a variety of cancer cell lines. Our work demonstrates the role of mitotic DNA damage responses in determining cell fate in response to microtubule poisons and BH3 mimetics, providing a rationale for anti-cancer combination chemotherapies.
Insights
Anti-cancer drugs trigger a DNA damage response (DDR) during mitotic arrest, impacting cell fate. Combining DDR inhibitors with chemotherapy enhances anti-cancer effects by promoting apoptosis.
Area of Science:
- Cell Biology
- Molecular Oncology
- Cancer Therapeutics
Background:
- Anti-cancer drugs targeting mitosis inhibit cell proliferation and induce apoptosis through poorly understood mechanisms.
- Microtubule poisons are a class of anti-cancer agents that disrupt cell division.
- Understanding the precise molecular pathways governing cell fate during mitotic arrest is crucial for developing effective cancer therapies.
Purpose of the Study:
- To characterize the mitotic stress response that determines cell fate following treatment with microtubule poisons.
- To elucidate the role of the DNA damage response (DDR) in mediating cell fate decisions during mitotic arrest.
- To investigate the potential of combining DDR inhibitors with existing chemotherapies for enhanced anti-cancer efficacy.
Main Methods:
- Induction of mitotic arrest using microtubule poisons in cancer cell lines.
- Assessment of DNA damage response (DDR) markers, including γH2AX foci formation and p53 phosphorylation.
- Analysis of caspase activation and Mcl-1 protein levels during mitotic arrest.
- Treatment with BH3 mimetics and DDR protein kinase inhibitors, alone and in combination with taxol (paclitaxel).
Main Results:
- Mitotic arrest induced by microtubule poisons triggers a caspase-dependent DNA damage response (DDR) characterized by γH2AX foci formation in non-apoptotic cells.
- Following delayed mitosis, this response activates DDR protein kinases, phosphorylates p53, and delays cell cycle progression.
- Mcl-1 degradation during mitotic arrest controls caspase activation; its inhibition enhances the mitotic DDR and p53 activation.
- Combined treatment with DDR inhibitors or BH3 mimetics and taxol synergistically promotes apoptosis across various cancer cell lines.
Conclusions:
- Mitotic DNA damage responses play a critical role in determining cancer cell fate when treated with microtubule poisons.
- The degradation of Mcl-1 is a key regulator of caspase activation and subsequent cell fate decisions during mitotic arrest.
- BH3 mimetics and DDR inhibitors enhance the anti-cancer effects of taxol by promoting apoptosis, providing a strong rationale for combination chemotherapy strategies.
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