TP53 induced glycolysis and apoptosis regulator (TIGAR) knockdown results in radiosensitization of glioma cells

• Published in: Radiotherapy and oncology 2011-10, Vol.101 (1), p.132-139
• Main Authors: Peña-Rico, Miguel A, Calvo-Vidal, María Nieves, Villalonga-Planells, Ruth, Martínez-Soler, Fina, Giménez-Bonafé, Pepita, Navarro-Sabaté, Àurea, Tortosa, Avelina, Bartrons, Ramon, Manzano, Anna
• Format: Article
• Language: English
• Subjects: Apoptosis - genetics; Apoptosis Regulatory Proteins - metabolism; Blotting, Western; DNA repair; Down-Regulation; Fluorescent Antibody Technique; Glioblastoma - pathology; Glioblastoma - radiotherapy; Glioma; Gliomas; Glycolysis - genetics; Hematology, Oncology and Palliative Medicine; Humans; Intracellular Signaling Peptides and Proteins - genetics; Intracellular Signaling Peptides and Proteins - metabolism; Oxidative stress; Proteïnes supressores de tumors; Radiation Tolerance - genetics; Radiotherapy; Reactive Oxygen Species - metabolism; RNA, Small Interfering - genetics; RNA, Small Interfering - metabolism; Senescence; Sensitivity and Specificity; TIGAR; Tumor Cells, Cultured - metabolism; Tumor Cells, Cultured - radiation effects; Tumor suppressor protei; Tumor Suppressor Protein p53 - genetics; Tumor Suppressor Protein p53 - metabolism
• ISSN: 0167-8140; 1879-0887
• DOI: 10.1016/j.radonc.2011.07.002

Abstract Background and purpose The TP53 induced glycolysis and apoptosis regulator (TIGAR) functions to lower fructose-2,6-bisphosphate (Fru-2,6-P2 ) levels in cells, consequently decreasing glycolysis and leading to the scavenging of reactive oxygen species (ROS), which correlate with a higher resistance to cell death. The decrease in intracellular ROS levels in response to TIGAR may also play a role in the ability of p53 to protect from the accumulation of genomic lesions. Given these good prospects of TIGAR for metabolic regulation and p53-response modulation, we analyzed the effects of TIGAR knockdown in U87MG and T98G glioblastoma-derived cell lines. Methods/results After TIGAR-knockdown in glioblastoma cell lines, different metabolic parameters were assayed, showing an increase in Fru-2,6-P2 , lactate and ROS levels, with a concomitant decrease in reduced glutathione (GSH) levels. In addition, cell growth was inhibited without evidence of apoptotic or autophagic cell death. In contrast, a clear senescent phenotype was observed. We also found that TIGAR protein levels were increased shortly after irradiation. In addition, avoiding radiotherapy-triggered TIGAR induction by gene silencing resulted in the loss of capacity of glioblastoma cells to form colonies in culture and the delay of DNA repair mechanisms, based in γ-H2AX foci, leading cells to undergo morphological changes compatible with a senescent phenotype. Thus, the results obtained raised the possibility to consider TIGAR as a therapeutic target to increase radiotherapy effects. Conclusion TIGAR abrogation provides a novel adjunctive therapeutic strategy against glial tumors by increasing radiation-induced cell impairment, thus allowing the use of lower radiotherapeutic doses.