Mitochondrial cytochrome c release and caspase-9-like protease activation during indomethacin-induced apoptosis in rat gastric mucosal cells

Indomethacin (IND), a nonsteroidal anti-inflammatory drug, has been known t o cause gastric mucosal injury as a side effect. Using a rat gastric mucosa l cell line, RGM1, we determined whether apoptosis is involved in IND-media ted gastropathy, and whether caspase activation and mitochondrial cytochrom e c release play an important role in producing apoptosis of IND-treated RG M1 cells in the presence of serum. IND caused caspase-3-like protease activ ation followed by apoptosis in a dose- and time-dependent manner. Caspase-1 -like protease activity did not change during IND-induced apoptosis. IND al so increased mitochondrial cytochrome c release in a time-dependent fashion . Mitochondrial cytochrome c efflux occurred just before or at the same tim e as caspase3-like protease activation, and preceded the Increase in apopto tic cell numbers. Z-VAD-FMK, a caspase inhibitor, inhibited both the increa se in caspase-3-like protease activity and apoptosis in IND-treated RGM1 ce lls but did not affect caspase-1-like protease activity or mitochondrial cy tochrome c release. These observations suggest that the apoptosis of gastri c mucosal cells could be involved in IND-induced gastropathy, that cytochro me c is released from mitochondria into the cytosol during the early phase of IND-mediated apoptosis, and that subsequent activation of caspase-1-like protease, but not caspase-1-like protease, is required for the execution o f apoptosis.