Apigenin induces apoptosis in human lung cancer H460 cells through caspase- and mitochondria-dependent pathways

Apigenin (4,5,7-trihydroxyflavone), a promising chemopreventive agent presented in fruits and vegetables, has been shown to induce cell cycle arrest and apoptosis in many types of human cancer cell lines. However, there is no available information to address the effects of apigenin on human lung cancer H460 cells. In the present studies, H460 cells were treated with apigenin for different time and then were analyzed for the morphological changes, induction of apoptosis, protein levels associated with apoptosis and results in dose-dependent induction of morphological changes, decrease in the percentage of viability, induced DNA damage and apoptosis; down-modulation of the protein expression of Bid, Bcl-2, procaspase-8; up-regulation of protein levels of Bax, caspase-3, AIF, cytochrome c, GRP78 and GADD153; decreased the levels of mitochondrial membrane potential and increased the productions of reactive oxygen species (ROS) and Ca2+ in H460 cells. Taken together, this is the first systematic in vitro study showing the involvement of apoptosis regulatory proteins as potential molecular targets of apigenin in human lung cancer H460 cells.

Apigenin induces caspase-dependent apoptosis in human lung cancer A549 cells through Bax- and Bcl-2-triggered mitochondrial pathway

The molecular mechanism and possible signaling pathway of apigenin-induced cytotoxicity and apoptosis in human lung cancer cells has not been reported. We investigated the role of ROS, Ca2+, caspases and Bax proteins and mitochondria membrane potential in apigenin-induced apoptosis in A549 cells. Cells were incubated with different concentrations of apigenin then cell morphological changes, DNA damage, cell viability and apoptosis were determined by Comet assay, and flow cytometric analysis. Sub-G1 phase was also examined. Western blot analysis was used to determined the levels of Bax and Bcl-2 and apoptosis associated proteins, and confocal laser microscope for examining the translocation of associated protein after exposed to apigenin. The results indicated that apigenin induced morphological changes, decreased percentage of viable cells and induced apoptosis dose- and time-dependently. DAPI staining and Comet assay also confirmed that apigenin-induced DNA condensation and damage. The levels of caspase-3, -8 and -9 involved in apigenin-induced apoptosis indicating caspase-dependent pathway was induced by apigenin. Western blotting showed that apigenin promoted cytochrome c levels and also induced dysfunction of mitochondria leading to the release of cytochrome c, AIF and Endo G, causing the activation of caspase-9 and -3, then apoptosis in A549 cells.