Regulation of the oxidative balance with coenzyme Q10 sensitizes human glioblastoma cells to radiation and temozolomide.

OBJECTIVES: To investigate how the modulation of the oxidative balance affects cytotoxic therapies in glioblastoma, in vitro. MATERIAL AND METHODS: Human glioblastoma U251 and T98 cells and normal astrocytes C8D1A were loaded with coenzyme Q10 (CoQ). Mitochondrial superoxide ion (O2-) and H2O2 were measured by fluorescence microscopy. OXPHOS performance was assessed in U251 cells with an oxytherm Clark-type electrode. Radio- and chemotherapy cytotoxicity was assessed by immunostaining of γH2AX (24 h), annexin V and nuclei morphology, at short (72 h) and long (15 d) time. Hif-1α, SOD1, SOD2 and NQO1 were determined by immunolabeling. Catalase activity was measured by classic enzymatic assay. Glutathione levels and total antioxidant capacity were quantified using commercial kits. RESULTS: CoQ did not affect oxygen consumption but reduced the level of O2- and H2O2 while shifted to a pro-oxidant cell status mainly due to a decrease in catalase activity and SOD2 level. Hif-1α was dampened, echoed by a decrease lactate and several key metabolites involved in glutathione synthesis. CoQ-treated cells were twofold more sensitive than control to radiation-induced DNA damage and apoptosis in short and long-term clonogenic assays, potentiating TMZ-induced cytotoxicity, without affecting non-transformed astrocytes. CONCLUSIONS: CoQ acts as sensitizer for cytotoxic therapies, disarming GBM cells, but not normal astrocytes, against further pro-oxidant injuries, being potentially useful in clinical practice for this fatal pathology.

CTV to PTV margins for prostate irradiation. Three-dimensional quantitative assessment of interfraction uncertainties using portal imaging and serial CT scans.

PURPOSE: To determine the magnitude of setup and organ motion errors from a subset of prostate cancer patients treated with conventional conformal radiotherapy, and to estimate the CTV-PTV margin according to published margin recipes. METHODS AND MATERIALS: Twenty prostate cancer patients were treated with external radiotherapy using electronic portal images (EPIs). Weekly treatment EPIs and pelvic CT scans were obtained. These data allowed interfractional analysis of prostate centre of mass motion and setup error. The margins needed to compensate these uncertainties were calculated. RESULTS: Tattoo localisation requires a margin of 9-10.5 mm (LR), 15.2-17.8 mm (anterior-posterior (AP)) and 10.6-12.4 mm (superior-inferior (S-I)). Systematic displacements due to prostatic motion, with standard deviations of 2.4 mm (LR), 4.2 mm (AP) and 3.1 mm (S-I) were found to be larger than setup errors (1.8, 3.0 and 1.7 mm respectively). CONCLUSIONS: Customised PTV margin definition has been possible through in-house measurements of geometrical clinical uncertainties involved in the conventional conformal radiotherapy process. Uncertainty measurements in our department have proved to be larger than those used in common practice. Additional margin reduction procedures are needed in order to accomplish conformal radiotherapy goals.