p53 Dependent apoptosis in glioma cell lines in response to hydrogen peroxide induced oxidative stress

Abstract

Generation of reactive oxygen species (ROS) is an important mode of action of many chemotherapeutic agents. Hydrogen peroxide (H₂O₂) is a model oxidant that has been used to study the response of cells to oxidative stress. The role of p53 in ROS induced cell death has not been consistent and has been shown to be cell type dependent. Study of cellular and molecular parameters and mechanisms involved in H₂O₂ induced cell death in glioma cells will contribute to the understanding of response of these cells to oxidative stress. We investigated induction of cell death by H₂O₂, and its relation to p53 in two human glial tumor derived cell lines U87MG (wild type p53) and U373MG (mutated p53). We observed that H₂O₂ was able to induce apoptosis (as shown by morphology, flow cytometry and DNA fragmentation studies) in U87MG in a dose dependent manner. Dimethyl sulfoxide (DMSO), a known ROS scavenger, was protective to the cells. H₂O₂ induced cell death was significantly reduced by antisense p53 oligonucleotide. Pretreatment with pyrrolidine dithiocarbamate (PDTC), an inhibitor of the redox sensitive transcription factor NF-κB, abrogated the increased expression of p53 protein in response to H₂O₂, and enhanced cell survival. The U373MG cell line, having mutated p53, was comparatively resistant to H₂O₂ induced cell death. We conclude from the study that p53, activated by NF-κB, is essential for H₂O₂ induced apoptosis in glioma cells.