Cancer cells, relative to normal cells, demonstrate increased sensitivity to glucose deprivation-induced cytotoxicity. To determine if oxidative stress mediated by O2•− and hydroperoxides contributed to the differential susceptibility of human epithelial cancer cells to glucose deprivation, oxidation of dihydroethidine (DHE; for O2•−) and 5-(and-6)-carboxy-2', 7'-dichlorodihydrofluorescein diacetate (CDCFH2; for hydroperoxides) were measured in human colon and breast cancer cells (HT29, HCT116, SW480, MB231) and compared to normal human cells (FHC, 33Co, HMEC). Cancer cells showed significant increases in DHE (2–20 fold) and CDCFH2 (1.8–10 fold) oxidation, relative to normal cells that were more pronounced in the presence of the mitochondrial electron transport chain blocker, antimycin A. Furthermore, HCT116 and MB231 cells were more susceptible to glucose deprivation-induced cytotoxicity and oxidative stress, relative to 33Co and HMEC. HT-29 cells were also more susceptible to 2-deoxyglucose-(2DG)-induced cytotoxicity, relative to FHC. Over expression of manganese superoxide dismutase and mitochondrially targeted catalase significantly protected HCT116 and MB231 cells from glucose deprivation-induced cytotoxicity and oxidative stress, as well as protecting HT-29 cells from 2DG-induced cytotoxicity. These results show cancer cells (relative to normal cells) demonstrate increased steady-state levels of reactive oxygen species (ROS, i.e. O2•− and H2O2) that contribute to differential susceptibility to glucose deprivation-induced cytotoxicity and oxidative stress. These studies support the hypotheses that cancer cells increase glucose metabolism to compensate for excess metabolic production of ROS as well as that inhibition of glucose and hydroperoxide metabolism may provide a biochemical target for selectively enhancing cytotoxicity and oxidative stress in human cancer cells.

Abstract-Angiotensin II (Ang II) has profound effects in the central nervous system (CNS), including promotion of thirst, regulation of vasopressin secretion, and modulation of sympathetic outflow. Despite its importance in cardiovascular and volume homeostasis, angiotensinergic mechanisms are incompletely understood in the CNS. Recently, a novel signaling mechanism for Ang II involving reactive oxygen species (ROS) has been identified in a variety of peripheral tissues, but the involvement of ROS as second messengers in Ang II-mediated signaling in the CNS has not been reported. The hypothesis that superoxide is a key mediator of the actions of Ang II in the CNS was tested in mice using adenoviral vector-mediated expression of superoxide dismutase (AdSOD). Changes in blood pressure, heart rate, and drinking elicited by injection of Ang II in the CNS were abolished by prior treatment with AdSOD in the brain, whereas the cardiovascular responses to carbachol, another central vasopressor agent, were unaffected. In addition, Ang II stimulated superoxide generation in primary CNS cell cultures, and this was prevented by the Ang II receptor (

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Glucose deprivation has been hypothesized to cause cytotoxicity by inducing metabolic oxidative stress in human cancer cells. The current work tests the hypothesis that 2-deoxy-Dglucose (2DG) combined with cisplatin [cis-diamminedichloroplatinum(II)] can enhance cytotoxicity in human head and neck cancer cells (FaDu) by mechanisms involving oxidative stress. Exposure of FaDu cells to the combination of 2DG and cisplatin resulted in a significant decrease in cell survival when compared with 2DG or cisplatin alone. Treatment with 2DG and cisplatin also caused perturbations in parameters indicative of oxidative stress, including decreased intracellular total glutathione and increased percentage of glutathione disulfide. Simultaneous treatment with the thiol antioxidant N-acetylcysteine (NAC) inhibited parameters indicative of oxidative stress, as well as protected FaDu cells from the cytotoxic effects of cisplatin alone and the combination of 2DG and cisplatin. In addition, polyethylene glycol-conjugated antioxidant enzymes (PEG-superoxide dismutase and PEG-catalase) also protected FaDu cells from 2DG toxicity. An inhibitor of glutathione synthesis, L-buthionine-[S,R]-sulfoximine (BSO), sensitized FaDu cells to the cytotoxic effects of 2DG and cisplatin, and these effects were inhibited by NAC. Furthermore, the combination of 2DG, cisplatin, and BSO significantly increased the percentage of glutathione disulfide, which was also inhibited by NAC. These results support the hypothesis that exposure of human head and neck cancer cells to 2DG combined with cisplatin enhances cytotoxicity via metabolic oxidative stress. These findings provide a strong biochemical rationale for evaluating inhibitors of glucose and hydroperoxide metabolism in combination with cisplatin for the treatment of head and neck cancer. [Cancer Res 2007;67(7):3364-70]

Purpose Cancer cells (relative to normal cells) demonstrate increased steady-state levels of hydroperoxides that are compensated for by increased glucose and hydroperoxide metabolism. The current study determined if inhibitors of glucose and hydroperoxide metabolism could induce chemo-radio-sensitization by enhancing oxidative stress in lung cancer cells. Experimental Design A549 and NCI-H292 human lung carcinoma cells were treated with 2-Deoxy-D-glucose (2DG) combined with carboplatin (carbo) + ionizing radiation (IR). Lung cancer cells were further sensitized with inhibitors of glutathione- and thioredoxin-dependent metabolism [buthionine sulfoximine (BSO) and auranofin (Au), respectively] in vitro and in vivo. Results When 2DG was combined with carbo+IR, clonogenic cell killing was enhanced in A549 and NCI-H292 cells and this combination was more effective than paclitaxel+carbo+IR. The thiol antioxidant (N-acetylcysteine, NAC) was capable of protecting cancer cells from 2DG+carbo-induced cell killing. Simultaneous treatment of cancer cells with BSO and Au, at doses that were not toxic as single agents also enhanced lung cancer cell killing and sensitivity to 2DG+carbo. This treatment combination also increased both glutathione and thioredoxin oxidation which were inhibited by NAC. Mice treated with Au+BSO showed no alterations in circulating leukocytes or red blood cells. Xenograft lung tumor growth in mice was more effectively inhibited by treatment with Au+BSO+carbo when compared to animals treated with carbo or Au+BSO alone. Conclusions These results show in vitro and in vivo that simultaneous inhibition of glutathione and thioredoxin metabolism can effectively inhibit lung cancer cell growth and induce chemo-sensitization by a mechanism that involves thiol mediated oxidative stress.