Related Experiment Video

Updated: Aug 3, 2025

Continuous Fluorescence-Based Endonuclease-Coupled DNA Methylation Assay to Screen for DNA Methyltransferase Inhibitors
06:07

Continuous Fluorescence-Based Endonuclease-Coupled DNA Methylation Assay to Screen for DNA Methyltransferase Inhibitors

Published on: August 5, 2022

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DNA damage, demethylation and anticancer activity of DNA methyltransferase (DNMT) inhibitors

Angelo B A Laranjeira1, Melinda G Hollingshead1, Dat Nguyen1

  • 1Division of Cancer Treatment and Diagnosis, National Cancer Institute, Bethesda, MD, USA.

Scientific Reports
|April 12, 2023
PubMed

Insights

DNA methyltransferase inhibitor (DNMTi) anticancer activity depends on DNA damage, not just demethylation. DNMT1 gene deletion reduces drug effectiveness, suggesting patients with these deletions may not benefit from DNMTi treatment.

Area of Science:

  • Oncology
  • Cancer Biology
  • Epigenetics

Background:

  • The precise role of DNA damage and demethylation in the anticancer efficacy of DNA methyltransferase inhibitors (DNMTi) is not fully understood.
  • Investigating the impact of DNMT1 gene status on DNMTi response is crucial for optimizing cancer therapy.

Purpose of the Study:

  • To elucidate the effect of DNMT1 gene deletion/disruption on the anticancer activity of DNMTi.
  • To assess the influence of DNMT1 status on drug-induced DNA damage, cell cycle arrest, apoptosis, and gene expression in various cancer models.

Main Methods:

  • In vitro studies using colon and breast cancer cell lines with and without DNMT1.
  • In vivo studies involving mouse xenograft and patient-derived xenograft (PDX) tumor models.
  • Analysis of human colon cancer samples for DNMT1 gene deletion frequency.

Main Results:

  • DNMT1 gene deletion significantly attenuated the cytotoxicity and growth inhibition caused by decitabine, azacitidine, and aza-T-dCyd.
  • DNMTi induced DNA damage, G2/M cell cycle arrest, apoptosis, and p21 upregulation in DNMT1+/+ cells, effects diminished in DNMT1-/- cells.
  • DNMT1 deletion was observed in approximately 9% of human colon cancers, conferring resistance to DNMTi and impacting treatment response.

Conclusions:

  • DNMT1 gene deletion confers resistance to DNMTi, indicating that their anticancer activity is primarily mediated by DNA damage effects.
  • The re-expression of p16INK4A/p15INK4B via demethylation and histone acetylation occurs independently of DNMT1 status.
  • Patients with DNMT1 gene deletions may exhibit a reduced response to DNMTi therapy, necessitating personalized treatment strategies.

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