title: Enhanced reactive oxygen species overexpression by CuO nanoparticles in poorly differentiated hepatocellular carcinoma cells.
abstract: 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 μg ml(-1) and 85 μg 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 ∼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 γ-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.
authors.affiliation: Department of Chemistry, National Sun Yat-sen University, Kaohsiung 804, Taiwan. shsieh@facmail.nsysu.edu.tw.
authors.forename: Mei-Lang
authors.initials: ML
authors.lastname: Kung
authors.forename: Shu-Ling
authors.initials: SL
authors.lastname: Hsieh
authors.forename: Chih-Chung
authors.initials: CC
authors.lastname: Wu
authors.forename: Tian-Huei
authors.initials: TH
authors.lastname: Chu
authors.forename: Yu-Chun
authors.initials: YC
authors.lastname: Lin
authors.forename: Bi-Wen
authors.initials: BW
authors.lastname: Yeh
authors.forename: Shuchen
authors.initials: S
authors.lastname: Hsieh
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology; D002374:Catalase / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003300:Copper / Q000737:chemistry*; D004249:DNA Damage / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D005978:Glutathione / Q000378:metabolism; D056945:Hep G2 Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology; D053768:Metal Nanoparticles / Q000737:chemistry*; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; C468783:H2AX protein, human; D006657:Histones; D017382:Reactive Oxygen Species; D013481:Superoxides; D009569:Nitric Oxide; D003300:Copper; D002374:Catalase; D013482:Superoxide Dismutase; D005978:Glutathione; C030973:cupric oxide