Arenobufagin Promoted Oxidative Stress-Associated Mitochondrial Pathway Apoptosis in A549 Non-Small-Cell Lung Cancer Cell Line

Arenobufagin (ARE) has demonstrated potent anticancer activity in various types of tumor, but the role and mechanism of ARE for lung cancer remain unclear. Oxidative stress exists under normal conditions and is an inevitable state in the body. A variety of noxious stimuli can break the equilibrium state of oxidative stress and promote apoptosis. Here, we used a CCK-8 assay to examine cell viability. We determined oxidative stress damage by measuring levels of intracellular ROS and levels of GSH, SOD, and MDA. Annexin V-FITC/PI double staining assay, as well as the Hoechst 33258 staining, was used to detect ARE-induced apoptosis in A549 cell. Evaluation of the expression level of the specified molecule was indicated by Western blot and qRT-PCR. Loss of function experiment was carried out using NAC pretreatment. The experimental results show that ARE significantly declines in the viability of A549 cells and increases the apoptosis rate of A549 cells. As reflected in cell morphology, the A549 cells showed features of shrinkage and had incompletely packed membranes; the same phenomenon is manifested in Hoechst 33258 staining. Following ARE treatment, the ROS level in A549 cells was rising in a concentration-dependent manner, and so were MDA and GSH levels, while the SOD level was decreasing. Moreover, we found that ARE can decrease mitochondrial membrane potential (MMP), and a cascade of apoptotic processes can be triggered by decreased MMP. Importantly, we found significant changes in protein expression levels and mRNA levels of apoptosis-related proteins. Furthermore, when we used NAC to restrain oxidative stress, the expression levels of apoptosis-related proteins have also changed accordingly. Our data demonstrate that apoptosis in the non-small-cell lung cancer (NSCLC) cell line A549 is caused by oxidative stress due to ARE. Our research also shows that ARE may have the potential to become a targeted therapeutic for the treatment of NSCLC in the future.