Vascular smooth muscle cell apoptosis induced by 7-ketocholesterol was mediated via Ca2+ and inhibited by the calcium channel blocker nifedipine.
Previous reports indicate that 7-ketocholesterol (7KCHO) induces apoptosis of cultured human vascular smooth muscle cells (SMCs). We hypothesized that calcium channel blockers will inhibit SMC apoptosis induced by 7KCHO because caspase-3 activity is Ca2+ dependent and 7KCHO stimulates caspase-3 and SMC apoptosis. So, the protective effect of the calcium channel blocker nifedipine on SMC apoptosis induced by 7KCHO was investigated. When 7KCHO (50 micromol/L) was added to SMCs, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP)-biotin nick end-labeling was positive. DNA extracted from SMCs exposed to 7KCHO showed a ladder pattern on agarose electrophoresis. In the presence of extracellular Ca2+, the Ca2+ influx, caspase-3 activity, and fragmented DNA also increased in SMCs incubated with 7KCHO dose-dependently. However, in the absence of extracellular Ca2+, no effects of 7KCHO on caspase-3 activity and fragmented DNA were observed. In the presence of nifedipine, the 7KCHO-induced increases in Ca2+ influx, caspase-3 activity, and the amount of fragmented DNA decreased significantly. These results suggest that 7KCHO-induced apoptosis of SMCs is inhibited by calcium channel blockade, and that Ca2+ influx into cells mediated by 7KCHO plays an important role in 7KCHO-induced apoptosis.
Sasaki
Hidehisa
H
Department of Pharmacy, Sakura Hospital, School of Medicine, Toho University, Chiba 285-8741, Japan.
Watanabe
Fusako
F
Murano
Takeyoshi
T
Miyashita
Yoh
Y
Shirai
Kohji
K
D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism; D006801:Humans; D020287:In Situ Nick-End Labeling; D007653:Ketocholesterols / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects*; D009543:Nifedipine / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D007653:Ketocholesterols; D053148:Caspase 3; D009543:Nifedipine; C003001:7-ketocholesterol; D002118:Calcium