Reduction of oxidative stress attenuates lipoapoptosis exacerbated by hypoxia in human hepatocytes.

International journal of molecular sciences (2015-02-06)
Sang Youn Hwang, Su Jong Yu, Jeong-Hoon Lee, Hwi Young Kim, Yoon Jun Kim
RESUMEN

Chronic intermittent hypoxia, a characteristic of obstructive sleep apnea (OSA), is associated with the progression of simple hepatic steatosis to necroinflammatory hepatitis. We determined whether inhibition of a hypoxia-induced signaling pathway could attenuate hypoxia-exacerbated lipoapoptosis in human hepatocytes. The human hepatocellular carcinoma cell line (HepG2) was used in this study. Palmitic acid (PA)-treated groups were used for two environmental conditions: Hypoxia (1% O2) and normoxia (20% O2). Following the treatment, the cell viability was determined by the 3,4-(5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt (MTS) assay, and the mechanism of lipoapoptosis was evaluated by Western blotting. Hypoxia exacerbated the suppression of hepatocyte growth induced by palmitic acid via activation of mitochondrial apoptotic pathways as a result of endoplasmic reticulum (ER) and oxidative stresses. Ammonium pyrrolidine dithiocarbamate, a scavenger of reactive oxygen species, attenuated the hypoxia-exacerbated lipoapoptosis in hepatocytes, whereas glycerol, which reduces ER stress, did not. This may have been because inhibition of oxidative stress decreases the expression of pro-apoptotic proteins, such as caspase 9 and cytochrome c. These results suggested that modulation of apoptotic signaling pathways activated by oxidative stress can aid in identifying novel therapeutic strategies for the treatment of nonalcoholic steatohepatitis (NASH) with OSA. Further in vivo studies are necessary to understand the pathophysiologic mechanism of NASH with OSA and to prove the therapeutic effect of the modulation of the signaling pathways.

MATERIALES
Referencia del producto
Marca
Descripción del producto

Sigma-Aldrich
Glycerol, for molecular biology, ≥99.0%
Sigma-Aldrich
Sodium dodecyl sulfate, BioReagent, suitable for electrophoresis, for molecular biology, ≥98.5% (GC)
Sigma-Aldrich
Glycerol, ≥99.5%
Sigma-Aldrich
Sodium dodecyl sulfate, ACS reagent, ≥99.0%
Sigma-Aldrich
Glycerol, ACS reagent, ≥99.5%
Sigma-Aldrich
Sodium dodecyl sulfate, ReagentPlus®, ≥98.5% (GC)
Sigma-Aldrich
Glycerol, ReagentPlus®, ≥99.0% (GC)
Sigma-Aldrich
Palmitic acid, ≥99%
Sigma-Aldrich
Sodium fluoride, ACS reagent, ≥99%
Sigma-Aldrich
Sodium dodecyl sulfate solution, BioUltra, for molecular biology, 10% in H2O
Sigma-Aldrich
Glycerol, BioReagent, suitable for cell culture, suitable for insect cell culture, suitable for electrophoresis, ≥99% (GC)
Sigma-Aldrich
Sodium dodecyl sulfate, ≥99.0% (GC), dust-free pellets
Sigma-Aldrich
Sodium dodecyl sulfate, BioUltra, for molecular biology, ≥99.0% (GC)
Supelco
Glycerin, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Sodium dodecyl sulfate solution, BioUltra, for molecular biology, 20% in H2O
Sigma-Aldrich
Sodium dodecyl sulfate, BioXtra, ≥99.0% (GC)
Sigma-Aldrich
Glycerin, meets USP testing specifications
Sigma-Aldrich
Sodium dodecyl sulfate, 92.5-100.5% based on total alkyl sulfate content basis
Sigma-Aldrich
Glycerol, BioXtra, ≥99% (GC)
Sigma-Aldrich
Glycerol solution, 83.5-89.5% (T)
Sigma-Aldrich
Sodium fluoride, BioXtra, ≥99%
Supelco
Sodium dodecyl sulfate, dust-free pellets, suitable for electrophoresis, for molecular biology, ≥99.0% (GC)
Sigma-Aldrich
Palmitic acid, BioXtra, ≥99%
Supelco
Palmitic acid, analytical standard
Sigma-Aldrich
Glycerol, FCC, FG
Sigma-Aldrich
Glycerol, BioUltra, for molecular biology, anhydrous, ≥99.5% (GC)
Supelco
Palmitic acid, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Sodium Fluoride, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Sodium dodecyl sulfate, suitable for ion pair chromatography, LiChropur, ≥99.0%
Sigma-Aldrich
Sodium dodecyl sulfate, ≥90%