Oxyresveratrol activates parallel apoptotic and autophagic cell death pathways in neuroblastoma cells

• Published in: Biochimica et biophysica acta. General subjects Vol. 1861; no. 2; pp. 23 - 36
• Main Authors: Rahman, Md. Ataur, Bishayee, Kausik, Sadra, Ali, Huh, Sung-Oh
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.02.2017
• Subjects: Animals; antioxidants; apoptosis; Apoptosis - drug effects; Apoptosis Regulatory Proteins - metabolism; autophagy; Autophagy - drug effects; Caspase 3 - metabolism; caspase-3; Caspase-independent; cell cycle; Cell Line; Cell Line, Tumor; Cell Survival - drug effects; cell viability; cytotoxicity; dose response; drug resistance; HEK293 Cells; Humans; immunocytochemistry; Macroautophagy; membrane potential; mitochondrial membrane; mitogen-activated protein kinase; mTOR signaling; neoplasms; Neuroblastoma; Neuroblastoma - drug therapy; Neuroblastoma - metabolism; Oxyresveratrol; p38 MAPK; p38 Mitogen-Activated Protein Kinases - metabolism; phosphatidylinositol 3-kinase; Phosphatidylinositol 3-Kinases - metabolism; Phosphorylation - drug effects; Plant Extracts - pharmacology; protein synthesis; proteins; Proto-Oncogene Proteins c-akt - metabolism; Rats; Reactive Oxygen Species - metabolism; Signal Transduction - drug effects; small interfering RNA; Stilbenes - pharmacology; TOR Serine-Threonine Kinases - metabolism; Tumor Suppressor Protein p53 - metabolism; Western blotting; Oxyresveratrol; Caspase-independent; Neuroblastoma; mTOR signaling; Macroautophagy; p38 MAPK
• ISSN: 0304-4165; 1872-8006
• DOI: 10.1016/j.bbagen.2016.10.025

Drug resistance from apoptosis is a challenging issue with different cancer types, and there is an interest in identifying other means of inducing cytotoxicity. Here, treatment of neuroblastoma cells with oxyresveratrol (OXYRES), a natural antioxidant, led to dose-dependent cell death and increased autophagic flux along with activation of caspase-dependent apoptosis. For cell viability, we performed the CCK-8 assay. Protein expression changes were with Western blot and immunocytochemistry. Silencing of proteins was with siRNA. The readouts for cell cycle, mitochondria membrane potential, caspase-3, autophagy and apoptosis were performed with flow cytometry. Phosphorylation of p38 MAPK increased with OXYRES treatment and inhibition of p38 reduced autophagy and cell death from OXYRES. In contrast, PI3K/AKT/mTOR signaling decreased in the target cells with OXYRES and inhibition of PI3K or mTOR enhanced OXYRES-mediated cytotoxicity with increased levels of autophagy. Modulation of either of the apoptosis and autophagy flux pathways affected the extent of cell death by OXYRES, but did not affect the indicators of these pathways with respect to each other. Both pathways were independent of ROS generation or p53 activation. OXYRES led to cell death from autophagy, which was independent of apoptosis induction. The OXYRES effects were due to changes in the activity levels of p38 MAPK and PI3K/AKT/mTOR. With two independent and parallel pathways for cytotoxicity induction in target cells, this study puts forward a potential utility for OXYRES or the pathways it represents as novel means of inducing cell death in neuroblastoma cells. [Display omitted] •OXYRES significantly inhibited cellular viability and cell cycle.•It depolarized mitochondrial membrane and induces caspase pathway.•Inactivation of caspase rescued cell viability without impairing autophagy.•Autophagy inhibitor prevented autophagy exclusive of apoptosis.•Role of PI3K/AKT/mTOR and p38 in autophagy was independent of apoptosis