Thapsigargin induces apoptosis in cultured human aortic smooth muscle cells

Vascular remodeling is a key feature of many pathologic states, including a therosclerosis, or hypertension. Vascular smooth muscle cells participate i n determining the vessel structure by several mechanisms such as cell migra tion, cell growth, or cell death (necrosis or apoptosis). Here we report th at thapsigargin, an inhibitor of endoplasmic reticulum Ca2+-adenosine triph osphatase (ATPase), is able to induce apoptosis in human vascular smooth mu scle cells (HVSMCs). Apoptosis was assessed by three different methods: dif ferential chromatin binding dye staining, cytoplasmic histone-associated DN A fragments detection by enzyme-linked immunosorbent assay (ELISA) and term inal deoxyribonucleotidyl transferase-mediated dUTP nick-end labeling (TUNE L). When HVSMCs were treated for 1 h with thapsigargin (100 nM-10 muM), the re was a concentration-dependent increase in both parameters 24 h after the thapsigargin pulse, When a time-course experiment was performed, both para meters were significantly enhanced from 3 to 6 h after the exposure to thap sigargin. We conclude that thapsigargin promotes apoptosis in HVSMCs, provi ding a useful tool for the study of programmed cell death in human vascular smooth muscle.