The
cholesteryl oleate-POPC dispersions (1:3, mol/mol, mean particle size 110+/-20 nm) were taken up by the human
hepatoma line Hep G2 cells via endocytosis. Internalization of the
cholesteryl oleate-POPC dispersions by Hep G2 cells was dependent on the incubation time and dispersion concentration. At the
cholesteryl oleate concentration 100 microM, its total uptake and internalization were found to be 1.5 nmol and 0.8 nmol per 1 mg of cell
protein/24 h, respectively. Intracellular cleavage of the
cholesteryl oleate incorporated in dispersions resulted in accumulation of free
cholesterol capable of being released into the medium and metabolized to water-soluble polar products, presumably
bile acids;
oleic acid released is, apparently, involved in biosynthesis of triacylglycerides. The
low-density lipoprotein receptor is not involved in internalization of
lipid dispersions, and the presence of the
cholesteryl oleate-POPC dispersions has no effect on the receptor-dependent internalization of
cholesteryl esters of the
low-density lipoproteins. The obtained data allow us to consider nonspecific internalization of
cholesteryl esters by hepatocytes as a substantial part of the nonpolar
lipid clearance.