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Inactivation of p53 in normal human cells increases G2/M arrest and sensitivity to DNA-damaging agents
J Céraline1, G Deplanque, B Duclos
1Laboratoire d'Oncologie Moléculaire, Institut de Recherche contre les Cancers de l'Appareil Digestif, Hôpitaux Universitaires de Strasbourg, France.
Abstract:
p53 mutations are found in about 70% of human cancers. In order to evaluate the role of these mutations in response to chemotherapeutic agents, it is important to distinguish between p53 response to DNA-damaging agents in normal and in tumour cells. Here, using normal human fibroblasts (NHFs), we show that cisplatin and UV radiation induce G2/M arrest which is temporally linked to p53-protein induction. To study the contribution of p53 to this G2/M arrest, we inhibited p53 induction in NHFs using p53 anti-sense oligonucleotides. Following exposure of NHFs to UV radiation, the inhibition of p53-protein induction leads to a greater accumulation of cells in the G2/M phase, but also to a decreased fraction of cells in the G1 phase. We propose that p53 does not induce G2/M arrest directly, and that the extent of this arrest may depend on the fraction of cells that do not stop at the G1 phase following exposure to DNA-damaging agents. Furthermore, inhibition of p53-protein induction leads to increased sensitivity of NHFs to UV radiation. These results suggest that inhibition of p53 protein enhances sensitivity to DNA-damaging agents in normal human cells.
Insights
Inhibition of p53 protein in normal human cells increases sensitivity to DNA-damaging agents like UV radiation. This suggests p53 protein inhibition could enhance cancer chemotherapy effectiveness.
Area of Science:
- Molecular Biology
- Cancer Research
- Cell Cycle Regulation
Background:
- p53 mutations are prevalent in human cancers, impacting treatment response.
- Understanding p53's role in normal versus tumor cells is crucial for chemotherapy development.
Purpose of the Study:
- To investigate the role of p53 protein induction in the G2/M cell cycle arrest response to DNA-damaging agents.
- To determine if inhibiting p53 protein affects normal human cell sensitivity to DNA-damaging agents.
Main Methods:
- Normal human fibroblasts (NHFs) were treated with cisplatin and UV radiation.
- p53 protein induction was inhibited using p53 anti-sense oligonucleotides.
- Cell cycle progression (G1 and G2/M phases) was analyzed.
Main Results:
- Cisplatin and UV radiation induced G2/M arrest correlated with p53 protein induction in NHFs.
- Inhibiting p53 induction led to increased G2/M accumulation and decreased G1 fraction after UV exposure.
- Inhibition of p53 protein induction enhanced NHF sensitivity to UV radiation.
Conclusions:
- p53 protein may not directly induce G2/M arrest; the extent of arrest might depend on G1 phase checkpoint function.
- Inhibiting p53 protein enhances DNA-damaging agent sensitivity in normal human cells.
- Targeting p53 inhibition could be a strategy to improve chemotherapy efficacy.