Cytochrome P450 expression-associated multiple-hit pathogenesis of non-alcoholic fatty liver disease (NAFLD) in HepG2 cells

Abstract

Purpose: To establish a free fatty acid (FFA)-induced non-alcoholic fatty liver disease (NAFLD) model in HepG2 cells.
Methods: HepG2 cells were incubated with 0.1, 1, or 5 mM oleic acid (OA) or palmitic acid (PA) for 24 h. Histological features were examined by oil-red-O staining. Expression levels of metabolic genes (peroxisome proliferator activated receptors α/γ, sterol regulatory element binding proteins 1a/1c, acetyl-CoA carboxylase, acyl-CoA oxidase, and fatty acid synthase), antioxidative genes (catalase and superoxide dismutases 1/2), and  cytochrome P450 genes (CYP1A2, CYP2C19, CYP2D6, CYP2E1, CYP3A4, and CYP4A11) were determined by reverse transcription-real time polymerase chain reaction (RT-qPCR).
Results: Intracellular lipid storage was observed in cells treated with 1 mM OA or PA while cell shrinkage was present at 5 mM concentrations of both. Expression of all metabolic genes were elevated by 1 mM PA and 5 mM OA and PA. Expression of all antioxidative genes were diminished by 5 mM OA whereas 5 mM PA only reduced superoxide dismutase-2 expression. Expression of CYP1A2, CYP2D6, and CYP3A4 genes were down-regulated by both FFAs, CYP2C19 was induced by PA, while CYP2E1 and CYP4A11 were up-regulated in a concentration-dependent manner.
Conclusion: PA was the more potent steatogenic agent in an OA- or PA- induced NAFLD model in HepG2 cells. Increase in intracellular hepatic lipid and expression of metabolic genes, suppression of antioxidative genes, suppression of CYP1A2, CYP2D6, and CYP3A4, and induction of CYP2E1 and
CYP4A11 correlated with the multiple-hit pathogenesis model of NAFLD. These findings suggest that PA-induced NAFLD model in HepG2 cells is a suitable in vitro model for studying novel therapeutic approaches to NAFLD treatment.

Keywords: NAFLD, Multiple-hit pathogenesis, Free fatty acid, Oleic acid, Palmitic acid