Abstract

Apoptosis is defined as controlled programmed cell death that occurs as physiological process in the development and morphogenesis of multi-cellular organisms, but is also implicated in various diseases, including acute pancreatitis. Apoptosis can be induced by a wide range of stimuli. Using pharmacological inhibitors, our previous results suggest that the cytosolic calcium-dependent cysteine protease calpain-2 plays a crucial role in hydrogen peroxide (H2O2)-induced apoptosis in pancreatic AR42J cells by activating caspases-12, -8 and -3. The present study aimed to corroborate these results using the small interfering RNA (siRNA) technology to knockdown the calpain-2 gene. AR42J cells were incubated with or without calpain-2 siRNA for 48 h, followed by apoptosis induction using H2O2 for 1 h. Calpain-2 downregulation was assessed by immunoblot and immunofluorescence analyses. The effect of calpain-2 downregulation was evaluated by the degree of caspase activation and cell damage. siRNA-induced calpain-2 gene silencing diminished caspase activation and cell damage, leading to an increased viability of the AR42J cells. Our results indicate that calpain-2 plays an important regulatory role in H2O2-induced apoptosis by activating caspases, thus corroborating our previous findings. The molecular mechanisms proposed for H2O2-induced apoptosis in the pancreatic acinar cell model could well also be of great importance in the pathogenesis of acute pancreatitis.

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