The synthesis and secretion of fatty acid ethyl esters from HepG2 cells are stimulated by lipoproteins and albumin

Background: Fatty acid ethyl esters (FAEEs) are nonoxidative metabolites of ethanol produced by theesterification of fatty acids and ethanol. FAEEs have been implicated as mediators of ethanol-induced organ damage in vivo and in vitro. They are detectable in the blood and in many organs after ethanol ingestion, and on this basis they are useful markers of ethanol intake in living patients as well as subjects at autopsy. FAEEs found in human plasma, after ethanol ingestion bind to lipoproteins and albumin. Methods: In this study, we used a hepatoblastoma cell model (HepG2) to determine if lipoproteins or albumin stimulates the synthesis and/or secretion of FAEEs from HepG2 cells. Because FAEEs have been shown to decrease HepG2 cellular proliferation and protein synthesis, their removal from cells potentially could reestablish normal cell activity. HepG2 cells were incubated with 100 mM ethanol and 6 nM H-3 oleic acid to generate H-3-FAEEs within the cells. Dose response and time course studies were performed by using low density lipoproteins, high density lipoproteins, and albumin as FAEE accepters. Results: The results indicate that FAEEs are extracted efficiently by each of these FAEE carriers and that FAEE synthesis also is stimulated by the addition of FAEE carriers to the extracellular medium. Conclusion: These observations indicate that lipoproteins and albumin can extract ethyl esters from HepG2 cells and thereby may limit alcohol-induced liver damage.