Resveratrol mobilizes Ca2+ from intracellular stores and induces c-Jun N-terminal kinase activation in tumoral AR42J cells

Resveratrol (3,4',5-trihydroxy-trans-stilbene), a phytoalexin naturally found in grapes and red wine, is a redox-active compound endowed with significant positive activities. In this study, the effects of resveratrol on intracellular free Ca2+ concentration ([Ca2+](c)) and on cell viability in tumoral AR42J pancreatic cells are examined. The results show that resveratrol (100 mu M and 1 mM) induced changes in [Ca2+](c), that consisted of single or short lasting spikes followed by a slow reduction toward a value close to the resting level. Lower concentrations of resveratrol (1 and 10 mu M) did not show detectable effects on [Ca2+](c). Depletion of intracellular Ca2+ stores by stimulation of cells with 1 nM CCK-8, 20 pM CCK-8 or 1 mu M thapsigargin, blocked Ca2+ responses evoked by resveratrol. Conversely, prior stimulation of cells with resveratrol inhibited Ca2+ mobilization in response to a secondary application of CCK-8 or thapsigargin. In addition, resveratrol inhibited oscillations in [Ca2+](c) evoked by a physiological concentration of CCK-8 (20 pM). On the other hand, incubation of cells in the presence of resveratrol induced a reduction of cell viability. Finally, incubation of AR42J cells in the presence of resveratrol led to activation of c-Jun N-terminal kinase (JNK), a mitogen-activated protein kinase responsive to stress stimuli. Activation of JNK was reduced in the absence of extracellular Ca2+. In summary, the results show that resveratrol releases Ca2+ from intracellular stores, most probably from the endoplasmic reticulum, and reduces AR42J cells viability. Reorganization of cell's survival/death processes in the presence of resveratrol may involve Ca2+-mediated JNK activation.