Hispidulin exhibits potent anticancer activity in vitro and in vivo through activating ER stress in non-small-cell lung cancer cells

Hispidulin is a medicinal natural compound isolated from S. involucrata, which exhibits potent anticancer properties. However, there are few reports on its effects on lung cancer cells. Therefore, the current study investigated the effects of hispidulin on cell viability and apoptosis in human non-small-cell lung cancer (NSCLC) cell lines NCI-H460 and A549 in vitro and in vivo. Methyl thiazolyl tetrazolium, colony formation assay, Hoechst 33342 staining, flow cytometry and western blotting were performed on Human NCI-H460 and A549 cells. A mouse xenograft model was also established using NCI-H460 cells. The results showed that the growth of NCI-H460 and A549 cells was inhibited, while apoptosis was promoted by hispidulin via increased generation of reactive oxygen species (ROS) in a dose-dependent manner. Furthermore, hispidulin triggered apoptosis in NSCLC cells through upregulating the expression of cleaved caspase-3 and cleaved poly [ADP-ribose] polymerase. All these effects were reversed upon pretreatment with glutathione, a selective ROS inhibitor. In addition, endoplasmic reticulum stress (ER stress) in NCI-H460 cells was activated by hispidulin. Pretreatment with tauroursodeoxycholic acid, a specific ER stress inhibitor, effectively reduced the cell apoptosis induced by hispidulin. In conclusion, hispidulin induces ROS-mediated apoptosis via activating the ER stress pathway. The current study provides theoretical basis for the antitumor effect of hispidulin in NSCLC.