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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

Hydrogen peroxide (H2O2) levels 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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Fig2: Hydrogen peroxide (H2O2) levels 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: Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system’s ability to readily detoxify the reactive intermediates. Certain oxidant and antioxidant parameters were evaluated in order to obtain information on the cellular mechanism of oxidative stress in response to TiO2 NP exposure, as well as the effect of TLR3 or TLR4 over-expression. H2O2 is a reactive oxygen metabolic byproduct that serves as a key regulator of a number of oxidative stress-related states. Measurement of this reactive species provides an indication of the modulation of intracellular pathways by oxidative stress during TiO2 NP exposure and TLR3 and TLR4 over-production. In the present study, H2O2 concentrations were elevated 1.9 fold in cells exposed to TiO2 NPs compared to control cells. H2O2 concentration was further increased in cells expressing TLR4 (3.2 fold), whereas cells expressing TLR3 exhibited only a 1.4 fold increase (Figure 2). Our data show that H2O2 is an intermediate in TiO2 NP-induced oxidative stress, regardless of TLR3 or TLR4 over-expression.Figure 2


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)

Hydrogen peroxide (H2O2) levels 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

Fig2: Hydrogen peroxide (H2O2) levels 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: Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system’s ability to readily detoxify the reactive intermediates. Certain oxidant and antioxidant parameters were evaluated in order to obtain information on the cellular mechanism of oxidative stress in response to TiO2 NP exposure, as well as the effect of TLR3 or TLR4 over-expression. H2O2 is a reactive oxygen metabolic byproduct that serves as a key regulator of a number of oxidative stress-related states. Measurement of this reactive species provides an indication of the modulation of intracellular pathways by oxidative stress during TiO2 NP exposure and TLR3 and TLR4 over-production. In the present study, H2O2 concentrations were elevated 1.9 fold in cells exposed to TiO2 NPs compared to control cells. H2O2 concentration was further increased in cells expressing TLR4 (3.2 fold), whereas cells expressing TLR3 exhibited only a 1.4 fold increase (Figure 2). Our data show that H2O2 is an intermediate in TiO2 NP-induced oxidative stress, regardless of TLR3 or TLR4 over-expression.Figure 2

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