Enhanced GLUT2 gene expression in an oleic acid-induced in vitro fatty liver model

Previous reports have shown that the liver-type glucose transporter GLUT2 gene expression is upregulated in the liver of obese and diabetic animals and in human subjects. This phenomenon is correlated with an increased glucose output from the liver; however, the regulatory mechanism is not clear. To investigate the relationship between hepatic steatosis, frequently found in obese and diabetic patients, and GLUT2 gene expression, we developed an oleic acid-induced in vitro fatty liver model. Lipid-accumulated cells morphologically mimicking hepatic steatosis were successfully induced in the human HepG2 cell line by 24-h culture with oleic acid at 1 mM. The cells with steatosis showed increased levels of intracellular triglycerides and apolipoprotein B, which were reduced in the presence of bezafibrate at 100 &mgr;g/ml. GLUT2 mRNA expression estimated by semi-quantitative reverse transcription polymerase chain reaction was increased in the cells with steatosis. Bezafibrate inhibited GLUT2 mRNA expression in the cells with and without steatosis. These results suggest that hepatic steatosis causes the enhancement of hepatic GLUT2 mRNA expression, which may be associated with gluconeogenesis and insulin resistance.