BACKGROUND: alpha-Lipoic acid (alpha-LA) has been studied as an anticancer agent as well as a therapeutic agent for diabetes and obesity. We performed this study to evaluate the anticancer effects and mechanisms of alpha-LA in a lung cancer cell line, A549. MATERIALS AND METHODS: alpha-LA-induced apoptosis of A549 cells was detected by fluorescence-activated cell sorting analysis and a DNA fragmentation assay. Expression of apoptosis-related genes was analyzed by western blot and reverse transcription-polymerase chain reaction analyses. RESULTS: alpha-LA induced apoptosis and DNA fragmentation in A549 cells in a dose- and time-dependent manner. alpha-LA increased caspase activity and the degradation of poly (ADP-ribose) polymerase. It induced expression of endoplasmic reticulum (ER) stress-related genes, such as glucose-regulated protein 78, C/EBP-homologous protein, and the short form of X-box binding protein-1, and decreased expression of the anti-apoptotic protein, X-linked inhibitor of apoptosis protein. Reactive oxygen species (ROS) production was induced by alpha-LA, and the antioxidant N-acetyl-L-cysteine decreased the alpha-LA-induced increase in expression of apoptosis and ER stress-related proteins. CONCLUSION: alpha-LA induced ER stress-mediated apoptosis in A549 cells via ROS. alpha-LA may therefore be clinically useful for treating lung cancer.
Acetylcysteine ; Apoptosis ; Blotting, Western ; Cell Death ; Cell Line ; DNA Fragmentation ; Endoplasmic Reticulum ; Flow Cytometry ; Lung Neoplasms ; Obesity ; Reactive Oxygen Species ; Thioctic Acid ; X-Linked Inhibitor of Apoptosis Protein

BACKGROUND: In oxidative stress, reactive oxygen species (ROS) production contributes to cellular dysfunction and initiates the apoptotic cascade. Autophagy is considered the mechanism that decreases ROS concentration and oxidative damage. Propofol shows antioxidant properties, but the mechanisms underlying the effect of propofol preconditioning (PPC) on oxidative injury remain unclear. Therefore, we investigated whether PPC protects against cell damage from hydrogen peroxide (H₂O₂)-induced oxidative stress and influences cellular autophagy. METHOD: COS-7 cells were randomly divided into the following groups: control, cells were incubated in normoxia (5% CO₂, 21% O₂, and 74% N₂) for 24 h without propofol; H₂O₂, cells were exposed to H₂O₂ (400 µM) for 2 h; PPC + H₂O₂, cells pretreated with propofol were exposed to H₂O₂; and 3-methyladenine (3-MA) + PPC + H₂O₂, cells pretreated with 3-MA (1 mM) for 1 h and propofol were exposed to H₂O₂. Cell viability was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide thiazolyl blue (MTT) reduction. Apoptosis was determined using Hoechst 33342 staining and fluorescence microscopy. The relationship between PPC and autophagy was detected using western blot analysis. RESULTS: Cell viability decreased more significantly in the H₂O₂ group than in the control group, but it was improved by PPC (100 µM). Pretreatment with propofol effectively decreased H₂O₂-induced COS-7 cell apoptosis. However, pretreatment with 3-MA inhibited the protective effect of propofol during apoptosis. Western blot analysis showed that the level of autophagy-related proteins was higher in the PPC + H₂O₂ group than that in the H2O2 group. CONCLUSION: PPC has a protective effect on H₂O₂-induced COS-7 cell apoptosis, which is mediated by autophagy activation.
Animals ; Apoptosis* ; Autophagy* ; Blotting, Western ; Cell Survival ; COS Cells* ; Hydrogen Peroxide ; Methods ; Microscopy, Fluorescence ; Oxidative Stress ; Propofol* ; Reactive Oxygen Species