Several studies have shown that curcumin can induce apoptosis and inhibit growth in human A549 lung adenocarcinoma cells. However, the mechanism is not completely understood yet. The present study was designed to investigate the effects of curcumin on A549 cells to better understand its apoptosis and apoptosis-related factors in vitro. The apoptosis induction, intracellular reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) were examined by confocal fluorescence microscope and flow cytometry. The MAPK protein expression was examined by Western blot analysis. After treatment with curcumin, apoptosis were observed. Curcumin-induced apoptosis was accompanied by an increase of intracellular ROS level and a loss of MMP. In addition, induction of apoptosis was also accompanied by sustained phosphorylation and activation of JNK, p38 and ERK. However, pretreatment with MAPK inhibitors had no effect upon curcumin-induced apoptosis. GSH and NAC, an anti-oxidant agent, blocked the curcumin-induced ROS production, MMP loss and rescued cells from curcumin-induced apoptosis. Our results indicated that curcumin induced apoptosis in A549 cells through a reactive oxygen species-dependent mitochondrial signaling pathway and independent of MAPK signaling pathway.

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