Involvement of intracellular Ca2+ levels in nonsteroidal anti-inflammatory drug-induced apoptosis.
We recently reported that nonsteroidal anti-inflammatory drug (NSAID)-induced gastric lesions involve NSAID-induced apoptosis of gastric mucosal cells, which in turn involves the endoplasmic reticulum stress response, in particular the up-regulation of CCAAT/enhancer-binding protein homologous transcription factor (CHOP). In this study, we have examined the molecular mechanism governing this NSAID-induced apoptosis in primary cultures of gastric mucosal cells. Various NSAIDs showed membrane permeabilization activity that correlated with their apoptosis-inducing activity. Various NSAIDs, particularly celecoxib, also increased intracellular Ca2+ levels. This increase was accompanied by K+ efflux from cells and was virtually absent when extracellular Ca2+ had been depleted. These data indicate that the increase in intracellular Ca2+ levels that is observed in the presence of NSAIDs is due to the stimulation of Ca2+ influx across the cytoplasmic membrane, which results from their membrane permeabilization activity. An intracellular Ca2+ chelator partially inhibited celecoxib-induced release of cytochrome c from mitochondria, reduced the magnitude of the celecoxib-induced decrease in mitochondrial membrane potential and inhibited celecoxib-induced apoptotic cell death. It is therefore likely that an increase in intracellular Ca2+ levels is involved in celecoxib-induced mitochondrial dysfunction and the resulting apoptosis. An inhibitor of calpain, a Ca2+-dependent cysteine protease, partially suppressed mitochondrial dysfunction and apoptosis in the presence of celecoxib. Celecoxib-dependent CHOP-induction was partially inhibited by the intracellular Ca2+ chelator but not by the calpain inhibitor. These results suggest that Ca2+-stimulated calpain activity and CHOP expression play important roles in celecoxib-induced apoptosis in gastric mucosal cells.
Graduate School of Medical and Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973, USA.
Ken-Ichiro
K
Tanaka
Wataru
W
Tomisato
Tatsuya
T
Hoshino
Tomoaki
T
Ishihara
Takushi
T
Namba
Mayuko
M
Aburaya
Takashi
T
Katsu
Keitarou
K
Suzuki
Shinji
S
Tsutsumi
Tohru
T
Mizushima
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D001692:Biological Transport / Q000502:physiology; D022762:CCAAT-Enhancer-Binding Proteins / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002154:Calpain / Q000378:metabolism; D000068579:Celecoxib; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D002614:Chelating Agents / Q000378:metabolism; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D005753:Gastric Mucosa / Q000166:cytology / Q000187:drug effects; D006168:Guinea Pigs; D008081:Liposomes / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D008928:Mitochondria / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D011720:Pyrazoles / Q000378:metabolism / Q000494:pharmacology; D013449:Sulfonamides / Q000378:metabolism / Q000494:pharmacology; D051742:Transcription Factor CHOP; D014157:Transcription Factors / Q000378:metabolism
D000894:Anti-Inflammatory Agents, Non-Steroidal; D022762:CCAAT-Enhancer-Binding Proteins; D002614:Chelating Agents; D008081:Liposomes; D011720:Pyrazoles; D013449:Sulfonamides; D014157:Transcription Factors; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D051742:Transcription Factor CHOP; D004533:Egtazic Acid; D002154:Calpain; D000068579:Celecoxib; D011188:Potassium; D002118:Calcium