Manipulation of the Cellular Redox State: Effects of Antioxidants on TRAIL-induced Apoptosis in Rhabdomyosarcoma Cells
Wagner, Jessie J.
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Cancer is characterized by the dysfunction of numerous proteins associated with the regulation of cell growth, leading to uncontrolled proliferation. Therefore, the selective induction of cell death in transformed (cancerous) cells represents a suitable therapeutic goal. TRAIL, is a unique member of the TNF superfamily of death ligands, as it only targets transformed cells for apoptosis. Upon TRAIL ligand-receptor interaction, procaspase-8 and Fas-associated death domain (FADD) are recruited to the receptor, forming the death inducing signaling complex (DISC) leading to propagation of the death signal and a caspase cascade. By analogy with other family members, this study sought to determine the role of reactive oxygen species (ROS) in the induction of apoptosis. The antioxidants catalase (CAT) and glutathione (GSH) were used to induce a reduced environment in the transformed rhabdomyosarcoma cell line RD, as determined by the quantification of cellular hydrogen peroxide levels through a DCFH-DA assay. Levels of apoptosis were assessed through quantification of subdiploid cells in a DNA cell cycle analysis by flow cytometry. It was found that the induction of a reduced cellular environment by pretreatment with antioxidants sensitized the RD cell line and enhanced TRAIL-induced apoptosis in these transformed cells. Furthermore, the activity of pro-apoptotic proteins associated with TRAIL-induced apoptosis increased, and the activity of anti-apoptotic proteins decreased when cells were treated with the combination of an antioxidant and TRAIL, but not affected when treated with either agent alone. The results of this study implicate a combination treatment of TRAIL with antioxidants as a potential therapeutic option for cancer treatment.