Hemistepsin A induces apoptosis by modulating the reactive oxygen species-dependent PI3K/Akt signaling pathway in human lung carcinoma A549 cells.

Hemistepsin A is a sesquiterpene lactone isolated from plants of the family. Recently, this compound was reported to be a bioactive compound that is beneficial for numerous health problems without side effects; however, its effect on lung cancer cells has not yet been studied. Therefore, in this study, we investigated the anticancer activity of hemistepsin A in human lung carcinoma A549 cells. This study showed that treatment with hemistepsin A induces apoptosis by activating caspase cascade and reducing the expression of inhibitors of apoptotic protein family members. Additionally, hemistepsin A disrupted mitochondrial integration by altering the levels of Bcl-2 family proteins to increase the cytoplasmic release of cytochrome c. Moreover, hemistepsin A reduced the activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway, and pretreatment with a PI3K inhibitor markedly augmented the cytotoxic effect of hemistepsin A on A549 cells. Furthermore, hemistepsin A significantly enhanced the production of intracellular and mitochondrial reactive oxygen species (ROS), whereas ROS scavengers restored the reduced viability by attenuating DNA damage and apoptosis by blocking the hemistepsin A-mediated inactivation of the PI3K/Akt pathway. Our findings demonstrate that hemistepsin A induces apoptosis in A549 cells by generating ROS, which subsequently inhibits the PI3K/Akt pathway, suggesting that ROS generation is involved as an early inducer of hemistepsin A-mediated anticancer activity.