Titanium dioxide nanoparticles trigger p53-mediated damage response in peripheral blood lymphocytes

Area of Science:

• Environmental Science
• Toxicology
• Nanotechnology

Background:

• Titanium dioxide nanoparticles (nano-TiO2) are utilized in environmental remediation.
• The precise cytotoxic mechanisms of nano-TiO2 remain incompletely understood.
• Investigating nano-TiO2 toxicity in human cells is crucial for risk assessment.

Purpose of the Study:

• To elucidate the mechanism of nano-TiO2-induced cytotoxicity in human peripheral blood lymphocytes.
• To assess the genotoxic effects and DNA damage response pathways activated by nano-TiO2.
• To determine the role of reactive oxygen species (ROS) in nano-TiO2 toxicity.

Main Methods:

• Genotoxicity was evaluated using alkaline single-cell gel electrophoresis (Comet assay) and cytokinesis-block micronucleus (CBMN) assay.
• Protein analysis via Western blot identified key proteins in the p53 DNA damage response pathway.
• Reactive oxygen species (ROS) generation was measured, and the effect of N-acetylcysteine (NAC) was assessed.

Main Results:

• Nano-TiO2 treatment significantly increased micronucleus formation and DNA breakage in lymphocytes.
• Accumulation of p53 and activation of DNA damage checkpoint kinases were observed.
• While ROS generation was confirmed, downstream p53 targets (p21, bax) were unaffected, and NAC mitigated DNA damage.
• These findings suggest ROS mediate nano-TiO2 genotoxicity and p53 activation.

Conclusions:

• Nano-TiO2 induces cytotoxicity in lymphocytes primarily through ROS generation, leading to DNA damage.
• The p53 pathway is activated at the checkpoint signaling level but not via transactivation of downstream genes.
• Understanding this mechanism is vital for evaluating the safety of nano-TiO2 in environmental and biomedical applications.