Regulation by long-chain fatty acids of the expression of cholesteryl ester transfer protein in HepG2 cells

Cholesteryl ester transfer protein (CETP) is an important determinant of li poprotein function, especially high density lipoprotein (HDL) metabolism, a nd contributes to the regulation of plasma HDL levels. Since saturated and polyunsaturated fatty acids IFA appear to influence the CETP activity diffe rently, we decided to investigate the effects of FA on the expression of CE TP mRNA in HepG2 cells using an RNA blot hybridization analysis. Long-chain FA (> 18 carbons) at a 0.5 mM concentration were added to the medium and i ncubated with cells for 48 h at 37 degreesC under 5% CO2. After treatment w ith 0.5 mM arachidonic (AA), eicosapentaenoic (EPA), and docosahexaenoic ac id (DHA), the levels of CETP mRNA were less than 50% of the control levels (AA, P = 0.0005; EPA, P < 0.01; DHA, P < 0.0001), with a corresponding sign ificant decrease in the CETP mass, These results suggest that FA regulate t he gene expression of CETP in HepG2 and this effect is dependent upon the d egree of unsaturation of the acyl carbon chain in FA.