The metabolism in vitro of human low-density lipoprotein by the human hepatoma cell line Hep G2

Abstract

The human hepatoma cell line Hep G2 was studied with respect to metabolism of human low-density lipoprotein (LDL). The Hep G2 cells bind, take up and degrade human LDL with a high-affinity saturable and with a low-affinity non-saturable component. The high-affinity binding possesses a Kd of 25 nM-LDL and a maximal amount of binding of .apprx. 70 ng of LDL-apoprotein/mg of cell protein. The high-affinity binding, uptake and degradation of LDL by Hep G2 cells is dependent on the extracellular Ca2+ concentration and is down-regulated by the presence of fairly high concentrations of extracellular LDL. Incubation of the Hep G2 cells with LDL results in suppression of the intracellular cholesterol synthesis. The human hepatoma cell line Hep G2 evidently possesses specific LDL receptors similar to the LDL receptors demonstrated on extrahepatic tissue cells.