PUB - Publikationen an der Universität Bielefeld

Apoptosis of vascular smooth muscle cells is critically involved in progression of atherosclerosis and may prevent intimal hyperplasia in restenosis and vascular remodeling. Nitric oxide (NO) is known to induce apoptosis, but the signaling pathways still remain unclear. We investigated p53 accumulation, protein kinase C (PKC) activation and nuclear transcription factor (NF-ĸB) binding activity as possible signaling mechanisms of NO-induced apoptosis. Apoptosis was induced dose-dependently with the NO-donors sodiumnitroprusside (SNP: 232±48%) and SIN-1 (241±90% of actinomycin D induced apoptosis; means ± SEM, * p£0.05 vs. control) in HSMC. Inhibition of PKC significantly attenuated NO-induced apoptosis. Staurosporine reduced SIN-1/SNP-mediated DNA fragmentation by 55.3±13.8% and 38.3±13.9% respectively. Comparable results were obtained for calphostin C. However, NO-mediated induction of apoptosis was not preceded by p53 accumulation. SNP decreased NF-ĸB binding activity in HSMC. These results suggest that induction of apoptosis by exogenous NO in HSMC is not dependent on p53 accumulation but involves protein kinase C signaling and regulation of NF-ĸB binding activity. This opens a new therapeutical approach in preventing restenosis after angioplasty.