title: Mitochondrial function in human neuroblastoma cells is up-regulated and protected by NQO1, a plasma membrane redox enzyme.
abstract: BACKGROUND
  Recent findings suggest that NADH-dependent enzymes of the plasma membrane redox system (PMRS) play roles in the maintenance of cell bioenergetics and oxidative state. Neurons and tumor cells exhibit differential vulnerability to oxidative and metabolic stress, with important implications for the development of therapeutic interventions that promote either cell survival (neurons) or death (cancer cells).
  
  
  RESULTS
  Here we used human neuroblastoma cells with low or high levels of the PMRS enzyme NADH-quinone oxidoreductase 1 (NQO1) to investigate how the PMRS modulates mitochondrial functions and cell survival. Cells with elevated NQO1 levels exhibited higher levels of oxygen consumption and ATP production, and lower production of reactive oxygen species. Cells overexpressing NQO1 were more resistant to being damaged by the mitochondrial toxins rotenone and antimycin A, and exhibited less oxidative/nitrative damage and less apoptotic cell death. Cells with basal levels of NQO1 resulted in increased oxidative damage to proteins and cellular vulnerability to mitochondrial toxins. Thus, mitochondrial functions are enhanced and oxidative stress is reduced as a result of elevated PMRS activity, enabling cells to maintain redox homeostasis under conditions of metabolic and energetic stress.
  
  
  CONCLUSIONS
  These findings suggest that NQO1 is a potential target for the development of therapeutic agents for either preventing neuronal degeneration or promoting the death of neural tumor cells.
authors.affiliation: Department of Life Science, College of Natural Sciences, Ewha Womans University, Seoul, South Korea.
authors.forename: Jiyeong
authors.initials: J
authors.lastname: Kim
authors.forename: Su-Kyung
authors.initials: SK
authors.lastname: Kim
authors.forename: Hwa-Kyung
authors.initials: HK
authors.lastname: Kim
authors.forename: Mark P
authors.initials: MP
authors.lastname: Mattson
authors.forename: Dong-Hoon
authors.initials: DH
authors.lastname: Hyun
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D017209:Apoptosis / Q000235:genetics; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D002470:Cell Survival / Q000235:genetics; D045222:Electron Transport Chain Complex Proteins / Q000235:genetics / Q000378:metabolism; D004734:Energy Metabolism / Q000235:genetics; D006801:Humans; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics* / Q000378:metabolism*; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D009474:Neurons / Q000378:metabolism / Q000502:physiology; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000235:genetics; D010101:Oxygen Consumption / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D045222:Electron Transport Chain Complex Proteins; D017382:Reactive Oxygen Species; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D000255:Adenosine Triphosphate; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human