JNK Activation Contributes to Oxidative Stress-Induced Parthanatos in Glioma Cells via Increase of Intracellular ROS Production

Abstract

Parthanatos is a form of PARP-1-dependent programmed cell death. The induction of parthanatos is emerging as a new strategy to kill gliomas which are the most common type of primary malignant brain tumor. Oxidative stress is thought to be a critical factor triggering parthanatos, but its underlying mechanism is poorly understood. In this study, we used glioma cell lines and H₂O₂ to investigate the role of JNK in glioma cell parthanatos induced by oxidative stress. We found that exposure to H₂O₂ not only induced intracellular accumulation of ROS but also resulted in glioma cell death in a concentration- and incubation time-dependent manner, which was accompanied with cytoplasmic formation of PAR polymer, expressional upregulation of PARP-1, mitochondrial depolarization, and AIF translocation to nucleus. Pharmacological inhibition of PARP-1 with 3AB or genetic knockdown of its level with siRNA rescued glioma cell death, as well as suppressed cytoplasmic accumulation of PAR polymer and nuclear translocation of AIF, which were consistent with the definition of parthanatos. Moreover, the phosphorylated level of JNK increased markedly with the extension of H₂O₂ exposure time. Either attenuation of intracellular ROS with antioxidant NAC or inhibition of JNK phosphorylation with SP600125 or JNK siRNA could significantly prevent H₂O₂-induced parthanatos in glioma cells. Additionally, inhibition of JNK with SP600125 alleviated intracellular accumulation of ROS and attenuated mitochondrial generation of superoxide. Thus, we demonstrated that JNK activation contributes to glioma cell parthanatos caused by oxidative stress via increase of intracellular ROS generation.

Keywords: Glioma; JNK; Oxidative stress; PARP-1; Parthanatos; ROS.