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Published on: June 9, 2017
p21(WAF1/CIP1) induction by 5-azacytosine nucleosides requires DNA damage
A Jiemjit1, T E Fandy, H Carraway
1The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD 21231, USA.
Decitabine (DAC) upregulates p21(WAF1/CIP1) expression through a DNA damage pathway, independent of DNA methyltransferase inhibition. This mechanism involves the ATM/p53 axis, leading to cell cycle arrest and apoptosis in leukemia cells.
Area of Science:
- Molecular Biology
- Cancer Research
- Pharmacology
Background:
- Decitabine (DAC) and 5-azacitidine are approved for myelodysplastic syndrome treatment.
- Their pharmacodynamic effects beyond DNA methyltransferase (DNMT) inhibition require further study.
- p21(WAF1/CIP1) has a promoter with a potential CpG island.
Purpose of the Study:
- To investigate decitabine's effect on p21(WAF1/CIP1) expression.
- To explore the mechanism of p21(WAF1/CIP1) upregulation by DAC.
- To determine if this effect is DNMT-dependent.
Main Methods:
- Promoter methylation analysis of p21(WAF1/CIP1) in leukemia cells.
- Dose-response studies of DAC on p21(WAF1/CIP1) expression and cell cycle.
- Investigating the role of DNA damage, ATM, and p53 pathways.
- Assessing synergistic effects with histone deacetylase inhibitors.
Main Results:
- Promoter methylation of p21(WAF1/CIP1) was absent in leukemia cells.
- DAC upregulated p21(WAF1/CIP1) in a dose-dependent manner, inducing G2/M arrest and apoptosis.
- DAC induced gamma-H2AX expression at low doses.
- Upregulation of p21(WAF1/CIP1) was DNMT-independent but p53-dependent.
- The DNA damage/ATM/p53 axis mediated DAC-induced p21(WAF1/CIP1) upregulation.
Conclusions:
- Decitabine upregulates p21(WAF1/CIP1) via a DNMT-independent pathway.
- The DNA damage response pathway involving ATM and p53 is crucial for this effect.
- This provides new insights into decitabine's non-epigenetic mechanisms in cancer therapy.
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