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ZnO Nanoparticles Treatment Induces Apoptosis by Increasing Intracellular ROS Levels in LTEP-a-2 Cells.

Wang C, Hu X, Gao Y, Ji Y - Biomed Res Int (2015)

Bottom Line: Both intracellular reactive oxygen species (ROS) and reduced glutathione (GSH) were examined by a microplate-reader method.Results showed that ZnO NPs (≥ 0.01 μg/mL) significantly inhibited proliferation (P < 0.05) and induced substantial apoptosis in LTEP-a-2 cells after 4 h of exposure.The intracellular ROS level rose up to 30-40% corresponding to significant depletion (approximately 70-80%) in GSH content in LTEP-a-2 cells (P < 0.05), suggesting that ZnO NPs induced apoptosis mainly through increased ROS production.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, 17 Chunhui Road, Laishan District, Yantai 264003, China ; University of Chinese Academy of Sciences, Beijing 100049, China.

ABSTRACT
Owing to the wide use of novel nanoparticles (NPs) such as zinc oxide (ZnO) in all aspects of life, toxicological research on ZnO NPs is receiving increasing attention in these days. In this study, the toxicity of ZnO NPs in a human pulmonary adenocarcinoma cell line LTEP-a-2 was tested in vitro. Log-phase cells were exposed to different levels of ZnO NPs for hours, followed by colorimetric cell viability assay using tetrazolium salt and cell survival rate assay using trypan blue dye. Cell morphological changes were observed by Giemsa staining and light microscopy. Apoptosis was detected by using fluorescence microscopy and caspase-3 activity assay. Both intracellular reactive oxygen species (ROS) and reduced glutathione (GSH) were examined by a microplate-reader method. Results showed that ZnO NPs (≥ 0.01 μg/mL) significantly inhibited proliferation (P < 0.05) and induced substantial apoptosis in LTEP-a-2 cells after 4 h of exposure. The intracellular ROS level rose up to 30-40% corresponding to significant depletion (approximately 70-80%) in GSH content in LTEP-a-2 cells (P < 0.05), suggesting that ZnO NPs induced apoptosis mainly through increased ROS production. This study elucidates the toxicological mechanism of ZnO NPs in human pulmonary adenocarcinoma cells and provides reference data for application of nanomaterials in the environment.

No MeSH data available.


Related in: MedlinePlus

Increased production of intracellular reactive oxygen species (ROS) in LTEP-a-2 cells after 4 h of exposure to ZnO nanoparticles. (a) ROS level determined via spectrophotometry and (b) fluorescence intensity measured by microscopy.
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fig6: Increased production of intracellular reactive oxygen species (ROS) in LTEP-a-2 cells after 4 h of exposure to ZnO nanoparticles. (a) ROS level determined via spectrophotometry and (b) fluorescence intensity measured by microscopy.

Mentions: Oxidative stress is considered one of the causative factors of apoptosis in pathogenesis and aggressiveness of most cancers [32]. A moderate rise in ROS level often induces cell proliferation whereas excessive amounts of ROS induce apoptosis [33]. To clarify the mechanism through which ZnO NPs induce apoptosis in LTEP-a-2 cells, we determined the intracellular ROS level by measuring the oxidation of nonfluorescent DCFH-DA to its highly fluorescent derivative DCF. Results showed that ZnO NPs stimulated ROS formation in cells following a concentration-dependent manner (Figure 6(a)). Under a fluorescence microscope, strong green fluorescence was observed in LTEP-a-2 control cells, whereas blue fluorescence was observed in cells after exposure to ZnO NPs. With increasing concentrations of ZnO NPs, the blue fluorescence was greatly strengthened accompanied by the appearance of apoptosis vesicles (Figure 6(b)). Together, these results demonstrate that ZnO NPs induce apoptosis in LTEP-a-2 cells through increased production of ROS, consistent with previous findings in macrophages and human liver cells [8, 9], as well as in vivo and in vitro tests of a wide range of NPs species [34, 35].


ZnO Nanoparticles Treatment Induces Apoptosis by Increasing Intracellular ROS Levels in LTEP-a-2 Cells.

Wang C, Hu X, Gao Y, Ji Y - Biomed Res Int (2015)

Increased production of intracellular reactive oxygen species (ROS) in LTEP-a-2 cells after 4 h of exposure to ZnO nanoparticles. (a) ROS level determined via spectrophotometry and (b) fluorescence intensity measured by microscopy.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4538331&req=5

fig6: Increased production of intracellular reactive oxygen species (ROS) in LTEP-a-2 cells after 4 h of exposure to ZnO nanoparticles. (a) ROS level determined via spectrophotometry and (b) fluorescence intensity measured by microscopy.
Mentions: Oxidative stress is considered one of the causative factors of apoptosis in pathogenesis and aggressiveness of most cancers [32]. A moderate rise in ROS level often induces cell proliferation whereas excessive amounts of ROS induce apoptosis [33]. To clarify the mechanism through which ZnO NPs induce apoptosis in LTEP-a-2 cells, we determined the intracellular ROS level by measuring the oxidation of nonfluorescent DCFH-DA to its highly fluorescent derivative DCF. Results showed that ZnO NPs stimulated ROS formation in cells following a concentration-dependent manner (Figure 6(a)). Under a fluorescence microscope, strong green fluorescence was observed in LTEP-a-2 control cells, whereas blue fluorescence was observed in cells after exposure to ZnO NPs. With increasing concentrations of ZnO NPs, the blue fluorescence was greatly strengthened accompanied by the appearance of apoptosis vesicles (Figure 6(b)). Together, these results demonstrate that ZnO NPs induce apoptosis in LTEP-a-2 cells through increased production of ROS, consistent with previous findings in macrophages and human liver cells [8, 9], as well as in vivo and in vitro tests of a wide range of NPs species [34, 35].

Bottom Line: Both intracellular reactive oxygen species (ROS) and reduced glutathione (GSH) were examined by a microplate-reader method.Results showed that ZnO NPs (≥ 0.01 μg/mL) significantly inhibited proliferation (P < 0.05) and induced substantial apoptosis in LTEP-a-2 cells after 4 h of exposure.The intracellular ROS level rose up to 30-40% corresponding to significant depletion (approximately 70-80%) in GSH content in LTEP-a-2 cells (P < 0.05), suggesting that ZnO NPs induced apoptosis mainly through increased ROS production.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, 17 Chunhui Road, Laishan District, Yantai 264003, China ; University of Chinese Academy of Sciences, Beijing 100049, China.

ABSTRACT
Owing to the wide use of novel nanoparticles (NPs) such as zinc oxide (ZnO) in all aspects of life, toxicological research on ZnO NPs is receiving increasing attention in these days. In this study, the toxicity of ZnO NPs in a human pulmonary adenocarcinoma cell line LTEP-a-2 was tested in vitro. Log-phase cells were exposed to different levels of ZnO NPs for hours, followed by colorimetric cell viability assay using tetrazolium salt and cell survival rate assay using trypan blue dye. Cell morphological changes were observed by Giemsa staining and light microscopy. Apoptosis was detected by using fluorescence microscopy and caspase-3 activity assay. Both intracellular reactive oxygen species (ROS) and reduced glutathione (GSH) were examined by a microplate-reader method. Results showed that ZnO NPs (≥ 0.01 μg/mL) significantly inhibited proliferation (P < 0.05) and induced substantial apoptosis in LTEP-a-2 cells after 4 h of exposure. The intracellular ROS level rose up to 30-40% corresponding to significant depletion (approximately 70-80%) in GSH content in LTEP-a-2 cells (P < 0.05), suggesting that ZnO NPs induced apoptosis mainly through increased ROS production. This study elucidates the toxicological mechanism of ZnO NPs in human pulmonary adenocarcinoma cells and provides reference data for application of nanomaterials in the environment.

No MeSH data available.


Related in: MedlinePlus