Differential effects of eicosapentaenoic acid on glycerolipid and apolipoprotein B metabolism in primary human hepatocytes compared to HepG2 cells and primary rat hepatocytes

Abstract

We compared the effects of eicosapentaenoic acid (EPA) and oleic acid (OA) on glycerolipid and apolipoprotein B (apoB) metabolism in primary human hepatocytes, HepG2 cells and primary rat hepatocytes. Cells were incubated for 1 to 5 h with 0.25 mM bovine serum albumin in the absence (control) or presence of 1 mM of EPA or OA. Synthesis and secretion of [3H]glycerolipid were determined after 1 h incubation with [3H]glycerol. Cellular and medium apoB abundance was semi-quantitatively estimated in human cells by Western blotting. The following observations were made. (1) Compared to control, OA induced a 7-fold increase in [3H]triacylglycerol (TG) synthesis in human hepatocytes and a 4-fold increase in rat hepatocytes and HepG2 cells. EPA enhanced [3H]TG synthesis about 2-fold in all three cell types although it stimulated [3H]diacylglycerol (DG) synthesis to an extent (i.e., 2.5- to 5-fold) similar to OA. (2) In contrast to OA, which stimulated VLDL-associated [3H]TG secretion 2.5- to 3-fold in the three cell types relative to control, EPA did not alter [3H]TG secretion in HepG2 and rat hepatocytes and suppressed [3H]TG secretion by 75% in primary human hepatocytes. (3) In primary human hepatocytes, both OA and EPA did not alter cellular apoB abundance but EPA decreased apoB secretion by 44% as compared to control. In contrast, both EPA and OA increased cellular and medium apoB abundance 2- to 2.5-fold in HepG2 cells, although medium apoB tended to be lower in EPA-treated cells.(ABSTRACT TRUNCATED AT 250 WORDS)