Study of Glycated Low Density Lipoprotein Metabolism in Human Hepatoma Cells (HepG2 Cells)

Abstract

Metabolism of glycated low density lipoprotein (glcLDL) was studied in a human hepatoma cell line (Hep-G2 cells). In the presence of 40μg/ml glcLDL, neither cultured human fibroblasts nor J774 cells accumulated cholesterol ester from 14C-oleate. In HepG2 cells, 14C-oleate was significantly incorporated into cholesterol ester in the presence of glcLDL, but the rates were small compared with those with native LDL. Studies using 125I-labeled lipoprotein showed similar results. However, 125I-glc-LDL degradation was similarly replaced by both native LDL and glcLDL, suggesting that the metabolic pathway is non-specific. Incorporation of 14C-oleate into cholesterol ester in the presence of 40μg/ml LDL was inhibited in HepG2 cells by IgG-C7, an antibody against LDL-receptors (0.7±0.4 n mole/mg prot. vs. 1.2±0.3 n mole/mg prot.). However, in the presence of 40μg glcLDL, the inhibition was not observed (0.4±0.1 n mole/mg prot. vs. 0.3±0.1 n mole/mg prot.). These results suggest that glcLDL is degraded in HepG2 cells through a metabolic pathway other than the classical LDL pathway.