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Targeting DNMT1 restores PTEN expression in colorectal cancer cells

Muhamed A El Nobey1, Abdulkader M Shaikh Omar2, Ali Zari3

  • 1Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, 21589, Saudi Arabia.

Molecular and Cellular Probes
|May 22, 2026
PubMed

Insights

5-azacytidine (5-aza-dC) treatment reactivated the tumor suppressor gene PTEN in colorectal cancer models by reducing DNA methyltransferase 1 (DNMT1) and promoter methylation. This epigenetic reprogramming also upregulated miR-29a-3p.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Epigenetics

Background:

  • Epigenetic silencing of tumor suppressor genes (TSGs) drives colorectal cancer (CRC).
  • Phosphatase and tensin homolog (PTEN) is frequently inactivated in CRC via promoter hypermethylation.
  • DNA methyltransferase 1 (DNMT1) plays a role in this aberrant methylation.

Purpose of the Study:

  • To investigate the effects of 5-azacytidine (5-aza-dC) on PTEN reactivation and miR-29a-3p expression in CRC.
  • To explore the association between DNMT1 suppression and PTEN re-expression.
  • To analyze the potential role of miR-29a-3p in the epigenetic response to 5-aza-dC.

Main Methods:

  • Bioinformatic analysis of gene expression and methylation data.
  • In vitro treatment of CRC cell lines (HCT116, SW620) with 5-aza-dC.
  • Cell viability assays (MTT assay) to determine IC50 values.
  • Quantitative real-time PCR (qRT-PCR) for mRNA and miRNA expression analysis.
  • Western blotting for protein level analysis.
  • Methylation-specific PCR (MSP-PCR) to assess PTEN promoter methylation.

Main Results:

  • 5-aza-dC treatment reduced CRC cell viability in a dose-dependent manner.
  • Significant re-expression of PTEN and downregulation of DNMT1 were observed at mRNA and protein levels.
  • MSP-PCR indicated reduced PTEN promoter methylation post-treatment.
  • Expression of miR-29a-3p was significantly upregulated following 5-aza-dC treatment.

Conclusions:

  • 5-aza-dC effectively restores PTEN expression in CRC cells.
  • This restoration is linked to DNMT1 suppression and PTEN promoter demethylation.
  • Upregulation of miR-29a-3p appears to be an associated epigenetic response requiring further investigation.
Keywords:
Colorectal cancerDNA methylationDNMT1PTENmiR-29a-3p

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