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Continuous Fluorescence-Based Endonuclease-Coupled DNA Methylation Assay to Screen for DNA Methyltransferase Inhibitors
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Effect of titanium dioxide nanoparticles on DNA methylation in multiple human cell lines
Marta Pogribna1, Nathan A Koonce2, Ammu Mathew2
1Division of Biochemical Toxicity, FDA/National Center for Toxicological Research, Jefferson, AR, USA.
Nanotoxicology
|February 8, 2020
Summary
Titanium dioxide (TiO2) nanoparticles alter DNA methylation, a key epigenetic mechanism, across various human cell types. This epigenetic disruption is linked to potential health risks, highlighting the need for further toxicity assessments.
Area of Science:
- Environmental Health Sciences
- Toxicology
- Epigenetics
Background:
- Nanoscale titanium dioxide (TiO2) is widely used in consumer products.
- Significant toxicity concerns exist for TiO2 nanoparticles, posing risks to human health.
- Epigenetic alterations, particularly DNA methylation changes, are critical for fully assessing nanoparticle toxicity.
Purpose of the Study:
- To investigate the impact of TiO2 nanoparticle exposure on DNA methylation.
- To assess effects on global and gene-specific methylation in relevant human cell models.
- To evaluate changes in the expression of key epigenetic regulatory genes.
Main Methods:
- Utilized in vitro cellular models representing human exposure portals (colorectal, liver, lung, skin).
- Assessed global DNA methylation using ELISA-based immunochemical analysis.
- Evaluated gene promoter methylation via EpiTect Methyl II Signature PCR Array.
- Quantified expression of DNA methyltransferases (DNMT1, DNMT3a, DNMT3b), MBD2, and UHRF1 using qRT-PCR.
Main Results:
- TiO2 nanoparticle exposure led to decreased global DNA methylation in Caco-2, HepG2, and A-431 cells.
- Promoter methylation was observed in eight genes (e.g., CDKN1A, TP53) across cell lines.
- Aberrant expression of epigenetic regulatory genes (DNMTs, MBD2, UHRF1) was cell type-dependent.
Conclusions:
- TiO2 nanoparticle exposure significantly impacts DNA methylation in multiple human cell types.
- Observed epigenetic alterations suggest a role in TiO2 nanoparticle toxicity.
- Epigenetic studies are crucial for a comprehensive risk assessment of nanoparticle exposure.
