Rapid reactive oxygen species (ROS) generation induced by curcumin leads to caspase-dependent and -independent apoptosis in L929 cells

Abstract

Evidence that curcumin may have anticancer activities has renewed interest in its potential to prevent and treat disease. In this study, we show that curcumin-mediated rapid generation of reactive oxygen species (ROS) leads to apoptosis by modulating different apoptotic pathways in mouse fibroblast L929 cells. We show for the first time that curcumin-induced rapid ROS generation causes the release of apoptosis inducing factor (AIF) from the mitochondria to the cytosol and nucleus, hence, leading to caspase 3-independent apoptosis. However, our studies also show that curcumin induces the release of cytochrome c from mitochondria, causing activation of caspase 3, and concomitant PARP cleavage, which is the hallmark of caspase-dependent apoptosis. Furthermore, curcumin-induced ROS generation leads to the induction of the proapoptotic protein p53 and its effector protein p21 and down-regulation of cell cycle regulatory proteins such as Rb and cyclin D1 and D3. Both glutathione (GSH) and N-acetylcysteine (NAC) pretreatment resulted in the complete inhibition of curcumin-induced ROS generation, AIF release from mitochondria, and caspase activation. Additionally, pretreatment of L929 cells with these antioxidants completely blocked the induction of p53-dependent p21 accumulation. In conclusion, our data show that in addition to caspase 3 activation, curcumin-induced rapid ROS generation leads to AIF release, and the activation of the caspase-independent apoptotic pathway.