Superoxide Enhances the Antitumor Combination of AdMnSOD Plus BCNU in Breast Cancer.

Overexpression of manganese superoxide dismutase (MnSOD) can sensitize a variety of cancer cell lines to many anticancer drugs. Recent work has shown that cancer cells can be sensitized to cell killing by raising peroxide levels through increased manganese superoxide dismutase (MnSOD) when combined with inhibition of peroxide removal. Here we utilize the mechanistic property of one such anticancer drug, BCNU, which inhibits glutathione reductase (GR), compromising the glutathione peroxidase system thereby inhibiting peroxide removal.

Mitochondrial ROS and radiation induced transformation in mouse embryonic fibroblasts.

Manganese superoxide dismutase (SOD2) is a nuclear encoded and mitochondria localized antioxidant enzyme that converts mitochondria derived superoxide to hydrogen peroxide. This study investigates the hypothesis that mitochondria derived reactive oxygen species (ROS) regulate ionizing radiation (IR) induced transformation in normal cells. Mouse embryonic fibroblasts (MEFs) with wild type SOD2 (+/+), heterozygous SOD2 (+/-), and homozygous SOD2 (-/-) genotypes were irradiated with equitoxic doses of IR, and assayed for transformation frequency, cellular redox environment, DNA damage, and cell cycle checkpoint activation.

Overexpression of extracellular superoxide dismutase attenuates heparanase expression and inhibits breast carcinoma cell growth and invasion.

Increased expression of heparanase stimulates the progression of various human cancers, including breast cancer. Therefore, a deeper understanding of the mechanisms involved in regulating heparanase is critical in developing effective treatments for heparanase-overexpressing cancers. In this study, we investigated the potential use of extracellular superoxide dismutase (EcSOD) to enhance the inhibitory effects of heparin/low molecular weight heparin (LMWH) in breast cancer cells.

Enhancing the antitumor activity of adriamycin and ionizing radiation.

Overexpression of manganese superoxide dismutase (MnSOD), when combined with certain chemicals that inhibit peroxide removal, increases cancer cell cytotoxicity. Elevating MnSOD levels in cells enhances the conversion of superoxide (O(2)(*-)) to hydrogen peroxide (H(2)O(2)), combined with inhibiting the removal of H(2)O(2), further increases H(2)O(2) levels, leading to increased cytotoxicity. We hypothesized that increasing endogenous O(2)(*-) production in cells that were pretreated with adenoviral MnSOD (AdMnSOD) plus 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) would lead to an increased level of intracellular H(2)O(2) accumulation and increased cell killing.

Increased levels of superoxide and H2O2 mediate the differential susceptibility of cancer cells versus normal cells to glucose deprivation.

Cancer cells, relative to normal cells, demonstrate increased sensitivity to glucose-deprivation-induced cytotoxicity. To determine whether oxidative stress mediated by O(2)(*-) and hydroperoxides contributed to the differential susceptibility of human epithelial cancer cells to glucose deprivation, the oxidation of DHE (dihydroethidine; for O(2)(*-)) and CDCFH(2) [5- (and 6-)carboxy-2',7'-dichlorodihydrofluorescein diacetate; for hydroperoxides] was measured in human colon and breast cancer cells (HT29, HCT116, SW480 and MB231) and compared with that in normal human cells [FHC cells, 33Co cells and HMECs (human mammary epithelial cells)]. Cancer cells showed significant increases in DHE (2-20-fold) and CDCFH(2) (1.

Epigenetic silencing of SOD2 by histone modifications in human breast cancer cells.

Many breast cancer cells typically exhibit lower expression of manganese superoxide dismutase (MnSOD) compared to the normal cells from which they arise. This decrease can often be attributed to a defect in the transcription of SOD2, the gene encoding MnSOD; however, the mechanism responsible for this change remains unclear. Here, we describe how altered histone modifications and a repressive chromatin structure constitute an epigenetic process to down regulate SOD2 in human breast carcinoma cell lines.

Extracellular redox state regulates features associated with prostate cancer cell invasion.

We have examined the possible role of extracellular reduction-oxidation (redox) state in regulation of biological/biochemical features associated with prostate cancer cell invasion. DU145, PC-3, and RWPE1-derived human prostate cancer (WPE1-NB26) cell lines were used for the present in vitro analysis. Increasing levels of nitric oxide using S-nitroso-N-acetylpenicillamine resulted in a decrease in cell invasion ability, whereas increasing levels of extracellular superoxide radical (O(2)(*-)) using xanthine/xanthine oxidase resulted in an increase in cell invasion ability in these three cell lines.

Manganese superoxide dismutase modulates hypoxia-inducible factor-1 alpha induction via superoxide.

Hypoxia-inducible factor 1 (HIF-1) is a transcription factor that plays an important role in O(2) homeostasis. Numerous observations suggest that changes in reactive oxygen species affect HIF-1 alpha stabilization and HIF-1 alpha transcriptional activation in many cell types. The antioxidant enzyme manganese superoxide dismutase (MnSOD) modulates the cellular redox environment by converting superoxide (O(2)(*-)) to hydrogen peroxide and dioxygen.

Manganese superoxide dismutase activity regulates transitions between quiescent and proliferative growth.

In recent years, the intracellular reactive oxygen species (ROS) levels have gained increasing attention as a critical regulator of cellular proliferation. We investigated the hypothesis that manganese superoxide dismutase (MnSOD) activity regulates proliferative and quiescent growth by modulating cellular ROS levels. Decreasing MnSOD activity favored proliferation in mouse embryonic fibroblasts (MEF), while increasing MnSOD activity facilitated proliferating cells' transitions into quiescence.

Increased oxidative stress created by adenoviral MnSOD or CuZnSOD plus BCNU (1,3-bis(2-chloroethyl)-1-nitrosourea) inhibits breast cancer cell growth.

Superoxide dismutases (SODs) have been found to decrease tumor formation and angiogenesis. SOD gene therapy, as with many other gene transfer strategies, may not completely inhibit tumor growth on its own. Thus, concomitant therapies are necessary to completely control the spread of this disease.

2-Deoxyglucose combined with wild-type p53 overexpression enhances cytotoxicity in human prostate cancer cells via oxidative stress.

Overexpression of the tumor suppressor gene, wild-type p53 (wtp53), using adenoviral vectors (Adp53) has been suggested to kill cancer cells by hydroperoxide-mediated oxidative stress [1,2] and nutrient distress induced by the glucose analog, 2-deoxyglucose (2DG), has been suggested to enhance tumor cell killing by agents that induce oxidative stress via disrupting hydroperoxide metabolism [3,4]. In the current study clonogenic cell killing of PC-3 and DU-145 human prostate cancer cells (lacking functional p53) mediated by 4 h exposure to 50 plaque forming units (pfus)/cell of Adp53 (that caused the enforced overexpression of wtp53) was significantly enhanced by treatment with 2DG. Accumulation of glutathione disulfide was found to be significantly greater in both cell lines treated with 2DG+Adp53 and both cell lines treated with 2DG+Adp53 showed a approximately 2-fold increases in dihydroethidine (DHE) and 5-(and-6)-carboxy-2',7'-dichlorodihydrofluorescein diacetate (CDCFH(2)) oxidation, indicative of increased steady-state levels of O(2)(.

Modulation of reactive oxygen species in pancreatic cancer.

Purpose: The aim of the present study was to compare the effects of the three different forms of the antioxidant enzyme superoxide dismutase [i.e., manganese superoxide dismutase (MnSOD), copper zinc superoxide dismutase (CuZnSOD), and extracellular superoxide dismutase (EcSOD)] on the malignant phenotype of human pancreatic cancer.

Superoxide signaling mediates N-acetyl-L-cysteine-induced G1 arrest: regulatory role of cyclin D1 and manganese superoxide dismutase.

Thiol antioxidants, including N-acetyl-L-cysteine (NAC), are widely used as modulators of the intracellular redox state. We investigated the hypothesis that NAC-induced reactive oxygen species (ROS) signaling perturbs cellular proliferation by regulating the cell cycle regulatory protein cyclin D1 and the ROS scavenging enzyme Mn-superoxide dismutase (MnSOD). When cultured in media containing NAC, mouse fibroblasts showed G(1) arrest with decreased cyclin D1 protein levels.

Mutant SOD1-induced neuronal toxicity is mediated by increased mitochondrial superoxide levels.

Amyotrophic lateral sclerosis (ALS), the most common motor neuron disease in adults, is characterized by the selective degeneration and death of motor neurons leading to progressive paralysis and eventually death. Approximately 20% of familial ALS cases are associated with mutations in SOD1, the gene encoding Cu/Zn-superoxide dismutase (CuZnSOD). Previously, we reported that overexpression of the mitochondrial antioxidant manganese superoxide dismutase (MnSOD or SOD2) attenuates cytotoxicity induced by expression of the G37R-SOD1 mutant in a human neuroblastoma cell culture model of ALS.

Overexpression of Akt converts radial growth melanoma to vertical growth melanoma.

Melanoma is the cancer with the highest increase in incidence, and transformation of radial growth to vertical growth (i.e., noninvasive to invasive) melanoma is required for invasive disease and metastasis.

Mitochondrial production of reactive oxygen species mediate dicumarol-induced cytotoxicity in cancer cells.

Dicumarol is a naturally occurring anticoagulant derived from coumarin that induces cytotoxicity and oxidative stress in human pancreatic cancer cells (Cullen, J. J., Hinkhouse, M.

Inactivation of primary antioxidant enzymes in mouse keratinocytes by photodynamically generated singlet oxygen.

Cellular antioxidant enzymes protect against damage caused by exposure to endogenous or exogenous prooxidants. Singlet oxygen ((1)O(2)) is a reactive form of oxygen that can be produced in vivo either in normal and pathophysiologic conditions or by photosensitizing chemicals, as during photodynamic treatment. We hypothesized that photodynamically generated (1)O(2) would decrease the enzymatic activities of cellular antioxidants.

Enzymatic activity is necessary for the tumor-suppressive effects of MnSOD.

The antioxidant protein manganese-containing superoxide dismutase (MnSOD) has been found to be a new type of tumor-suppressor protein. Overexpression of the cDNA for this gene in various types of cancer via plasmid transfection or adenovirus transduction leads to growth suppression both in vitro and in vivo. The growth-suppressive effect of MnSOD overexpression has been presumed to be due to the enzymatic activity of the MnSOD protein, but could be due to a number of other mechanisms, including a regulatory effect of the RNA or protein produced.

Overexpression of manganese or copper-zinc superoxide dismutase inhibits breast cancer growth.

We have studied the effects of overexpression of superoxide dismutase (SOD), a tumor suppressor protein that dismutes superoxide radical to H2O2, on breast cancer cell growth in vitro and xenograft growth in vivo. No previous work has directly compared the growth-suppressive effects of manganese SOD (MnSOD) and copper-zinc SOD (CuZnSOD). We hypothesized that either adenoviral MnSOD (AdMnSOD) or adenoviral CuZnSOD (AdCuZnSOD) gene therapy would suppress the growth of human breast cancer cells.

Dual-expressing adenoviral vectors encoding the sodium iodide symporter for use in noninvasive radiological imaging of therapeutic gene transfer.

Introduction: Noninvasive analysis of therapeutic transgene expression is important for the development of clinical translational gene therapy strategies against cancer. To image p53 and MnSOD gene transfer noninvasively, we used radiologically detectable dual-expressing adenoviral vectors with the human sodium iodide symporter (hNIS) as the reporter gene.

Methods: Dual-expressing adenoviral vectors were constructed with hNIS cloned into E3 region and therapeutic genes, either MnSOD or p53, recombined into the E1 region.

Delayed radioprotection by nuclear transcription factor kappaB -mediated induction of manganese superoxide dismutase in human microvascular endothelial cells after exposure to the free radical scavenger WR1065.

The free radical scavenger WR1065 (SH) is the active thiol form of the clinically approved cytoprotector amifostine. At doses of 40 microM and 4 mM it can activate the redox-sensitive nuclear transcription factor kappaB (NFkappaB) and elevate the expression of the antioxidant gene manganese superoxide dismutase (MnSOD) in human microvascular endothelial cells (HMEC). MnSOD contains binding motifs for a number of transcription factors other than NFkappaB and codes for a potent antioxidant enzyme localized in the mitochondria that is known to confer enhanced radiation resistance to cells.

Metastatic progression of pancreatic cancer: changes in antioxidant enzymes and cell growth.

Pancreatic cancer has a dismal prognosis due to the fact that patients present late when metastatic disease is already present. Previous studies have demonstrated that pancreatic cancer cells have decreased levels of MnSOD, which correlates well with increased rates of tumor cell proliferation. Recently, we have found that nude mice injected with MIA PaCa-2 human pancreatic cancer cells in the flank occasionally develop ascites and intra-abdominal metastatic deposits.

Suppression of the malignant phenotype in pancreatic cancer by overexpression of phospholipid hydroperoxide glutathione peroxidase.

Phospholipid glutathione peroxidase (PhGPx) reduces lipid hydroperoxides generated in biomembranes and also uses a wide range of reducing cofactors in addition to glutathione. PhGPx is synthesized as a mitochondrial PhGPx form (L-form) and as a nonmitochondrial PhGPx form (S-form). Our aims were to determine whether overexpression of PhGPx altered pancreatic tumor cell behavior.