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Updated: Aug 25, 2026
Continuous Fluorescence-Based Endonuclease-Coupled DNA Methylation Assay to Screen for DNA Methyltransferase Inhibitors
Published on: August 5, 2022
Azacitidine induces demethylation of the Epstein-Barr virus genome in tumors
Anthony T C Chan1, Qian Tao, Keith D Robertson
1Department of Clinical Oncology, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin NT, Hong Kong SAR, China.
Purpose:
To determine whether therapy with a DNA methyltransferase inhibitor is effective in achieving demethylation and gene re-expression in tumor DNA in patients.
Methods:
Biopsy specimens were obtained from patients with Epstein-Barr virus-associated tumors, enrolled on a clinical trial of 5-azacitidine, within 72 hours of the conclusion of the last infusion of the first cycle of therapy, and compared to pretreatment specimens. Methylation-specific polymerase chain reaction, bisulfite genomic sequencing, and immunohistochemistry were used to assess demethylation and gene re-expression.
Results:
Substantial degrees of demethylation were detected in all latent and lytic Epstein-Barr virus promoters examined. Immunohistochemistry suggested activation of a previously silent viral antigen expression in one instance.
Conclusion:
Pharmacologic reversal of dense CpG methylation in tumor tissue can be achieved in patients.
Insights
This study shows that 5-azacitidine therapy effectively reverses DNA methylation in tumor cells, leading to gene re-expression in patients with Epstein-Barr virus-associated tumors.
Area of Science:
- Oncology
- Molecular Biology
- Epigenetics
Background:
- Epigenetic modifications, including DNA methylation, play a crucial role in cancer development.
- Epstein-Barr virus (EBV)-associated tumors represent a significant area of oncological research.
- Understanding the mechanisms of gene regulation in tumors is vital for developing novel therapies.
Purpose of the Study:
- To evaluate the efficacy of DNA methyltransferase inhibitors in achieving tumor DNA demethylation.
- To assess the potential for gene re-expression following treatment with epigenetic modifiers.
- To investigate the impact of 5-azacitidine on EBV-associated tumor DNA.
Main Methods:
- Utilized biopsy specimens from patients undergoing a clinical trial of 5-azacitidine.
- Compared pre-treatment and post-treatment tumor specimens.
- Employed methylation-specific polymerase chain reaction, bisulfite genomic sequencing, and immunohistochemistry to analyze DNA methylation and gene expression.
Main Results:
- Demonstrated significant demethylation across latent and lytic EBV promoters in tumor DNA.
- Observed evidence of previously silent viral antigen expression, indicating gene re-expression.
- Confirmed the ability of the therapeutic agent to impact tumor epigenetics.
Conclusions:
- Pharmacological reversal of dense CpG methylation in tumor tissue is achievable in patients.
- DNA methyltransferase inhibitors hold promise for epigenetic therapy in cancer treatment.
- This approach may offer new avenues for managing EBV-associated malignancies.
