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Resistance to 5-aza-2'-deoxycytidine in genic regions compared to non-genic repetitive sequences

Hui Wen Lim1, Misa Iwatani, Naoko Hattori

  • 1Laboratory of Cellular Biochemistry, Animal Resource Sciences/Veterinary Medical Sciences, The University of Tokyo, Japan.

The Journal of Reproduction and Development
|December 10, 2009
PubMed

Insights

The DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5azadC) demethylates repetitive DNA sequences and specific genes. Optimal dosing is crucial for targeted gene recovery and avoiding unintended genomic effects.

Area of Science:

  • Epigenetics
  • Cancer Biology
  • Molecular Biology

Background:

  • 5-aza-2 -deoxycytidine (5azadC) is a DNA methyltransferase inhibitor used in cancer therapy.
  • It reactivates silenced tumor suppressor genes but may affect non-targeted genomic regions.
  • Understanding 5azadC's effects on repetitive sequences and gene loci is crucial.

Purpose of the Study:

  • To investigate the impact of 5azadC on repetitive DNA sequences and specific gene loci in mouse cells.
  • To determine the dose-dependent effects of 5azadC on DNA methylation and gene activation.
  • To explore associated histone modifications during 5azadC treatment.

Main Methods:

  • Treatment of mouse NIH/3T3 fibroblast cells with varying concentrations of 5azadC (0.001–5 microM).
  • Analysis of DNA methylation levels in repetitive sequences and selected gene loci (Oct-4, Sall3, Per1, Clu, Dpep1, Igf2r).
  • Assessment of gene activation and associated histone modifications (H3K9me3, AcH3).

Main Results:

  • 5azadC induced concentration-dependent demethylation of minor satellite repeats and endogenous viruses, strongest at 1 and 5 microM.
  • Genic regions showed demethylation primarily at 0.1 microM, with minimal changes at other concentrations.
  • Gene activation correlated with increased H3K9me3 and decreased AcH3, an effect absent in Dnmt knockout cells.

Conclusions:

  • 5azadC exhibits differential effects on repetitive sequences versus genic regions.
  • Repetitive elements are strongly demethylated, while genic regions require specific effective doses.
  • Appropriate 5azadC dosage is critical for targeted gene recovery and minimizing off-target effects.

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