Hydrogen peroxide and hydroxyl radicals mediate palmitate-induced cytotoxicity to hepatoma cells: relation to mitochondrial permeability transition.
We studied the toxicological responses of a human hepatoblastoma cell line (HepG2/C3A) to various free fatty acids (FFA) in order to identify the relation between reactive oxygen species (ROS) production and mitochondrial permeability transition (MPT). Exposure to the saturated FFA, palmitate, led to a time-dependent ROS production and hydrogen peroxide release as well as a loss of mitochondrial potential. The cytotoxicity of palmitate was significantly reduced by treating with scavengers of hydrogen peroxide, hydroxyl radical and the spin trap alpha-(4-pyridyl-1-oxide)-N-tert-butyl nitrone (POBN). Superoxide dismutase (SOD) mimics, nitric oxide scavenger, and inhibitor of de novo ceramide synthesis had no effect on the toxicity. MPT-inhibitor, cyclosporine, prevented the loss of mitochondrial potential but did not reduce the cytotoxicity. In contrast, inhibiting mitochondrial complexes I and III reduced the early potential loss and the cytotoxicity. These results suggest that palmitate-cytotoxicity to hepatoma cells is mediated through the production of H2O2 and *OH and independent of MPT.
Srivastava
Shireesh
S
Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824, USA. srivas14@msu.edu
Chan
Christina
C
D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D016166:Free Radical Scavengers / Q000494:pharmacology; D006028:Glycosphingolipids / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D017665:Hydroxyl Radical / Q000378:metabolism*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects*; D051336:Mitochondrial Membranes / Q000187:drug effects*; D019308:Palmitic Acid / Q000633:toxicity*; D011725:Pyridines / Q000494:pharmacology; D013113:Spin Labels; D019097:Spin Trapping
D016166:Free Radical Scavengers; D006028:Glycosphingolipids; D011725:Pyridines; D013113:Spin Labels; C043438:alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone; D019308:Palmitic Acid; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide