Cocaine induces apoptosis in human coronary artery endothelial cells

This study was designed to determine the direct cytotoxic effect of cocaine on human coronary artery endothelial cells (HCAECs). Cocaine treatment of cultured HCAECs induced a time- and dose-dependent increase in apoptotic ce ll death in HCAECs. Cocaine-induced surface exposure of phosphatidylserine in HCAECs was seen as early as at 6 h. With prolonged treatment less than o r equal to 72 h, cocaine (10-500 mu M) produced a dose-dependent increase i n apoptosis in the cells. Corresponding DNA fragmentation induced by cocain e was demonstrated in situ by terminal deoxynucleotidyl transferase (Tdt) U TP nick end-labeling TUNEL assay and by electrophoresis of labeled DNA frag ments, showing the characteristic apoptotic ladders. Both caspase-9 (Z-LEHD -FMK) and caspase-3 (Ac-DEVD-CHO) inhibitors blocked cocaine-induced apopto sis, In addition, cyclosporin A inhibited cocaine-induced apoptosis in a co ncentration-dependent manner with a median inhibitory concentration (IC50) of 0.3 mu M. The maximum of 62% inhibition was obtained with 3 mu M cyclosp orin A. Cocaine-induced apoptosis also was blocked by naloxone and nifedipi ne in a dose-dependent manner. These findings suggest that cocaine induces apoptosis in cultured HCAECs, which may be mediated by opioid receptors. Th e release of cytochrome c from the mitochondria and its subsequent activati on of caspase-9 and caspase-3 may play a key role in cocaine-induced apopto sis.