Trapidil derivatives and low density lipoprotein metabolism by human skin fibroblasts and by human hepatoma cell line Hep G2

The effect of trapidil (RocornalR) and some of its newly developed derivatives (AR 12456, AR 12463, AR 12465, AR 12464) on the receptor-mediated low density lipoprotein (LDL) binding, uptake and degradation was studied in human skin fibroblasts (HSF) and in human hepatoma cell line Hep G2. Compound AR 12456 influenced this pathway in a selective way: it enhanced the uptake and degradation of 125I-LDL by Hep G2 cells in a dose-dependent manner, but inhibited it in HSF. Scatchard analysis of the saturable LDL binding in Hep G2 indicates that the effect of compound AR 12456 is the result of an increased number of LDL binding sites. Compound AR 12465 was less effective on LDL catabolism. Trapidil and the other derivatives were inactive under the same experimental conditions. When Ar 12456 was preincubated with Hep G2 cells and then the incubation medium was transferred to HSF, a stimulation of specific LDL pathway occurred also in this cell line. These findings suggest that a metabolite(s) of AR 12456 might be responsible for the enhanced expression of LDL receptors in cultured human cells.