Fatty liver mediated by peroxisome proliferator-activated receptor-α DNA methylation can be reversed by a methylation inhibitor and curcumin

Objective: Our studies in vitro and in vivo aimed to investigate the influence of DNA methylation of peroxisome proliferator activated receptor-α (PPAR-α) gene in non-alcoholic fatty liver disease (NAFLD) pathogenesis and to observe whether the DNA methylation inhibitor 5-Aza-2'-deoxycytidine (5-Aza-CdR) and the herbal medicine curcumin might reverse the effect both in vivo and in vitro.

Methods: Steatotic hepatocyte model of cell lines and NAFLD rat models were established following protocols documented in previous studies. Subsequently, the models received 5-Aza-CdR and curcumin treatment. Morphological, histological and laboratory variables in each group were determined by routine methods, including PPAR-α mRNA expression by polymerase chain reaction (PCR), PPAR-α protein expression by Western blot and DNA methylation by pyrosequencing.

Results: The steatotic hepatocyte model and NAFLD rat model were completely established. The expressions of PPAR-α mRNA and protein were significantly lower in the steatotic hepatocyte and NAFLD rat model groups than in the controls (P < 0.05). The mean DNA methylation levels of the PPAR-α gene were significantly higher in the two steatotic model groups than in the controls, especially at several CpG sites (P < 0.05). 5-Aza-CdR and curcumin treatment significantly reversed the DNA methylation levels, increased PPAR-α mRNA and protein expression, and improved lipid accumulation in the two steatotic models (P < 0.05).

Conclusions: DNA methylation at the PPAR-α gene is involved in the pathogenesis of NAFLD and is possibly reversible by 5-Aza-CdR and curcumin. Curcumin may be a promising candidate for NAFLD therapy.