Abstract.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 curcumininduced apoptosis. Our results indicated that curcumin induced apoptosis in A549 cells through a reactive oxygen speciesdependent mitochondrial signaling pathway and independent of MAPK signaling pathway.

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. In the present study, we investigated the in vitro effect of curcumin on cell viability, apoptosis and disorganization of the actin cytoskeleton in A549 cells. Our results showed that curcumin significantly inhibited the viability of A549 cells in a dose- and time-dependent manner by induced apoptosis. The apoptotic process was associated with a disorganization of the architecture of actin microfilaments and a decrease in the levels of F-actin. DMSO-treated control cells exhibited a well-defined F-actin network that was mainly organized into stress fibers. The actin fibers in cells treated with curcumin or the positive control drug cytochalasin B were disorganized, disassembled, or disrupted, however, the disorganization of actin fibers and apoptosis could be prevented by phalloidin, an F-actin stabilizing compound. Thus, these results demonstrated that actin filament disorganization might play a central role in the curcumin-induced apoptosis of A549 cells.