Erlotinib induces the human non–small‐cell lung cancer cells apoptosis via activating ROS‐dependent JNK pathways

Although erlotinib (ERL) has drawn more and more attention toward its anticancer properties effect, the underlying mechanisms of ERL's anticancer properties effect remain unclear yet. So, the aim of this research was to explore the underlying anticancer mechanisms of ERL and to explore whether the reactive oxygen species (ROS)-dependent c-Jun N-terminal kinase (JNK) pathway contributed to the anticancer properties provided by ERL. In our study, we used MTT assay to detect the anticell growth ability of ERL on human non-small-cell lung cancer cell lines (A549). The extent of cell apoptosis was determined by Hoechst 33342 staining and fluorescence-activated cell sorter (FACS) assay. Then, DCFH-DA and JC-1 staining were used to monitor intracellular reactive oxygen species (ROS) and mitochondrial membrane potential (MMP), respectively. Finally, the effect of ERL on phosphorylation state of JNK protein and downstream apoptosis concerned proteins were detected by western blotting assay. Results showed that ERL significantly suppressed the growth and reproduction of A549 cells with the concentration rising up in vitro. Hoechst 33342 staining and FACS assay also confirmed the proapoptosis effect of ERL on A549 cells with the concentration rising up. Furthermore, exposure of A549 cells to ERL increased the intracellular ROS production. As expected, intracellular ROS activated the proapoptotic JNK signaling pathway and inhibited the activation of EFGR signaling pathway. Our results also revealed that ERL could induce cell-cycle arrest at G0/G1 period. Activation of JNK protein decreased MMP and downregulated content of antiapoptotic protein Bcl-2 concomitant with the upregulated content of proapoptotic protein Bax in A549 cells. In addition, c-Jun and cleaved caspase-3 were also activated by the phosphorylated JNK induced by ERL. All of these proapoptosis effect of ERL was reversed by administration of N-acetylcysteine (NAC), which performed as a ROS scavenger. Our results suggest that ERL induces A549 cells apoptosis via activating ROS-dependent JNK pathways in human non-small lung cancer cells that provide a new experimental foundation for cancer therapy.