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Molecular mechanism of DNA damage induced by titanium dioxide nanoparticles in toll-like receptor 3 or 4 expressing human hepatocarcinoma cell lines.

El-Said KS, Ali EM, Kanehira K, Taniguchi A - J Nanobiotechnology (2014)

Bottom Line: Our results showed evidence for elevated oxidative stress, including the generation of reactive oxygen species (ROS), with increased hydrogen peroxide levels, decreased glutathione peroxidase, and reduced glutathione and activated caspase-3 levels in cells exposed for 48 h to 10 μg/ml TiO2 NPs.These effects were enhanced by TLR4 and reduced by TLR3 over-expression.Our results indicated that TiO2 NPs induced ROS, and the above molecules are implicated in the genotoxicity induced by TiO2 NPs.

View Article: PubMed Central - PubMed

Affiliation: Cell-Material Interaction Group, Biomaterial Unit, Nano-Bio Field, Interaction Center for Material Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Tsukuba, Japan. SAMYELSAIDALI.Karim@nims.go.jp.

ABSTRACT

Background: Titanium dioxide nanoparticles (TiO2 NPs) are widely used in the biological sciences. The increasing use of TiO2 NPs increases the risk of humans and the environment being exposed to NPs. We previously showed that toll-like receptors (TLRs) play an important role in the interactions between NPs and cells. Our previous results indicated that TLR4 increased the DNA damage response induced by TiO2 NPs, due to enhanced NP uptake into the cytoplasm, whereas TLR3 expression decreased the DNA damage response induced by TiO2 NPs because of NP retention in the endosome. In this study, we explored the molecular mechanism of the DNA damage response induced by TiO2 NPs using TLR3 or TLR4 transfected cells. We examined the effect of TLR3 or TLR4 over-expression on oxidative stress and the effect of DNA damage induced by TiO2 NPs on gene expression levels.

Results: Our results showed evidence for elevated oxidative stress, including the generation of reactive oxygen species (ROS), with increased hydrogen peroxide levels, decreased glutathione peroxidase, and reduced glutathione and activated caspase-3 levels in cells exposed for 48 h to 10 μg/ml TiO2 NPs. These effects were enhanced by TLR4 and reduced by TLR3 over-expression. Seventeen genes related to DNA double-strand breaks and apoptosis were induced, particularly IP6K3 and ATM.

Conclusion: Our results indicated that TiO2 NPs induced ROS, and the above molecules are implicated in the genotoxicity induced by TiO2 NPs.

No MeSH data available.


Related in: MedlinePlus

Reactive oxygen species (ROS) generation in TiO2NP-exposed HepG2 cells with and without TLR3 or TLR4 transfection. The transfected cells were exposed to 10 μg/ml TiO2 NPs for 48 h. Each plot was produced from at least 3 replicate measurements. All values are presented as mean ± S.D. (n ≥3), (*P <0.05).
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Fig1: Reactive oxygen species (ROS) generation in TiO2NP-exposed HepG2 cells with and without TLR3 or TLR4 transfection. The transfected cells were exposed to 10 μg/ml TiO2 NPs for 48 h. Each plot was produced from at least 3 replicate measurements. All values are presented as mean ± S.D. (n ≥3), (*P <0.05).

Mentions: In general, ROS generation results in DNA damage. Our aim was to examine TiO2 NP-induced ROS generation and its association with DNA damage responses. ROS generation was measured in HepG2 cells exposed to TiO2 NPs with and without TLR3 or TLR4 over-expression (Figure 1). The results showed that in TiO2 NP-exposed cells, ROS levels were significantly increased (approximately 1.9 fold) compared with control cells (untreated, untransfected HepG2 cells). Cells exposed to TiO2 NPs and over-expressing TLR4 showed a significant increase in ROS levels compared to untransfected cells exposed to TiO2 NPs, reaching an approximately 2.6 fold increase compared to control. In comparison, ROS levels in HepG2 cells exposed to TiO2 NPs with TLR3 over-expression were slightly (≈1.3 fold) increased compared to control cells, as shown in Figure 1. These results indicate that ROS generation is a factor in the DNA damage response induced by TiO2 NPs.Figure 1


Molecular mechanism of DNA damage induced by titanium dioxide nanoparticles in toll-like receptor 3 or 4 expressing human hepatocarcinoma cell lines.

El-Said KS, Ali EM, Kanehira K, Taniguchi A - J Nanobiotechnology (2014)

Reactive oxygen species (ROS) generation in TiO2NP-exposed HepG2 cells with and without TLR3 or TLR4 transfection. The transfected cells were exposed to 10 μg/ml TiO2 NPs for 48 h. Each plot was produced from at least 3 replicate measurements. All values are presented as mean ± S.D. (n ≥3), (*P <0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4260178&req=5

Fig1: Reactive oxygen species (ROS) generation in TiO2NP-exposed HepG2 cells with and without TLR3 or TLR4 transfection. The transfected cells were exposed to 10 μg/ml TiO2 NPs for 48 h. Each plot was produced from at least 3 replicate measurements. All values are presented as mean ± S.D. (n ≥3), (*P <0.05).
Mentions: In general, ROS generation results in DNA damage. Our aim was to examine TiO2 NP-induced ROS generation and its association with DNA damage responses. ROS generation was measured in HepG2 cells exposed to TiO2 NPs with and without TLR3 or TLR4 over-expression (Figure 1). The results showed that in TiO2 NP-exposed cells, ROS levels were significantly increased (approximately 1.9 fold) compared with control cells (untreated, untransfected HepG2 cells). Cells exposed to TiO2 NPs and over-expressing TLR4 showed a significant increase in ROS levels compared to untransfected cells exposed to TiO2 NPs, reaching an approximately 2.6 fold increase compared to control. In comparison, ROS levels in HepG2 cells exposed to TiO2 NPs with TLR3 over-expression were slightly (≈1.3 fold) increased compared to control cells, as shown in Figure 1. These results indicate that ROS generation is a factor in the DNA damage response induced by TiO2 NPs.Figure 1

Bottom Line: Our results showed evidence for elevated oxidative stress, including the generation of reactive oxygen species (ROS), with increased hydrogen peroxide levels, decreased glutathione peroxidase, and reduced glutathione and activated caspase-3 levels in cells exposed for 48 h to 10 μg/ml TiO2 NPs.These effects were enhanced by TLR4 and reduced by TLR3 over-expression.Our results indicated that TiO2 NPs induced ROS, and the above molecules are implicated in the genotoxicity induced by TiO2 NPs.

View Article: PubMed Central - PubMed

Affiliation: Cell-Material Interaction Group, Biomaterial Unit, Nano-Bio Field, Interaction Center for Material Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Tsukuba, Japan. SAMYELSAIDALI.Karim@nims.go.jp.

ABSTRACT

Background: Titanium dioxide nanoparticles (TiO2 NPs) are widely used in the biological sciences. The increasing use of TiO2 NPs increases the risk of humans and the environment being exposed to NPs. We previously showed that toll-like receptors (TLRs) play an important role in the interactions between NPs and cells. Our previous results indicated that TLR4 increased the DNA damage response induced by TiO2 NPs, due to enhanced NP uptake into the cytoplasm, whereas TLR3 expression decreased the DNA damage response induced by TiO2 NPs because of NP retention in the endosome. In this study, we explored the molecular mechanism of the DNA damage response induced by TiO2 NPs using TLR3 or TLR4 transfected cells. We examined the effect of TLR3 or TLR4 over-expression on oxidative stress and the effect of DNA damage induced by TiO2 NPs on gene expression levels.

Results: Our results showed evidence for elevated oxidative stress, including the generation of reactive oxygen species (ROS), with increased hydrogen peroxide levels, decreased glutathione peroxidase, and reduced glutathione and activated caspase-3 levels in cells exposed for 48 h to 10 μg/ml TiO2 NPs. These effects were enhanced by TLR4 and reduced by TLR3 over-expression. Seventeen genes related to DNA double-strand breaks and apoptosis were induced, particularly IP6K3 and ATM.

Conclusion: Our results indicated that TiO2 NPs induced ROS, and the above molecules are implicated in the genotoxicity induced by TiO2 NPs.

No MeSH data available.


Related in: MedlinePlus