Journal
NANOSCALE
Volume 7, Issue 5, Pages 1820-1829Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/c4nr05843g
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Funding
- Ministry of Science and Technology of Taiwan [NSC 101-2113-M-110-013-MY3, NSC 102-2811-M-110-008]
- Center for Stem Cell Research, Kaohsiung Medical University, Kaohsiung, Taiwan [KMU-TP103G01, KMU-TP103G03, KMU-TP103G04, KMU-TP103G05]
- National Sun Yat-sen University Center for Nanoscience and Nanotechnology
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Copper oxide nanoparticles (CuO NPs) are known to exhibit toxic effects on a variety of cell types and organs. To determine the oxidative impact of CuO NPs on hepatocellular carcinoma (HCC) cells, well-differentiated (HepG2) and poorly differentiated (SK-Hep-1) cells were exposed to CuO NPs. Cell viability assay showed that the median inhibition concentration (IC50) for SK-Hep-1 and HepG2 cells was 25 mu g ml(-1) and 85 mu g ml(-1), respectively. Cellular fluorescence intensity using DCFH-DA staining analysis revealed significant intracellular reactive oxygen species (ROS) generation of up to 242% in SK-Hep-1 cells, compared with 86% in HepG2 cells. HPLC analysis demonstrated that a CuO NP treatment caused cellular GSH depletion of 58% and a GSH/GSSG ratio decrease to similar to 0.1 in SK-Hep-1 cells. The oxidative stress caused by enhanced superoxide anion production was observed in both HepG2 (146%) and SK-Hep-1 (192%) cells. The Griess assay verified that CuO NPs induced NO production (170%) in SK-Hep-1 cells. Comet assay and western blot further demonstrated that CuO NPs induced severe DNA strand breakage (70%) in SK-Hep-1 cells and caused DNA damage via increased gamma-H2AX levels. These results suggest that well-differentiated HepG2 cells possess a robust antioxidant defense system against CuO NP-induced ROS stress and exhibit more tolerance to oxidative stress. Conversely, poorly differentiated SK-Hep-1 cells exhibited a deregulated antioxidant defense system that allowed accumulation of CuO NP-induced ROS and resulted in severe cytotoxicity.
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