Effects of oxygen on the antioxidant responses of normal and transformed cells.
Journal - Experimental cell research (United States )
Basal antioxidant defense levels are often aberrant in tumor cells; however, less attention has been given to differences in the way that normal and transformed cells respond to changes in oxidative stress. This study evaluated differences in the responses of various normal and transformed cell lines to different oxygen tensions. Exposure to hyperoxia generally failed to induce either the activity of GSH peroxidase (GPx) or the manganese-containing form of superoxide dismutase (MnSOD) after 48 h, although at 605 mm Hg oxygen, small inductions of MnSOD activity were observed in adult lung fibroblasts and amelanotic melanoma. Exposure to 605 mm Hg O2 for 48 h was inhibitory to GPx activity. MnSOD activity was strongly induced in virally transformed WI-38 cells by treatment with the herbicide paraquat or inhibition of GSH synthesis with BSO. In normal cells GSH concentration was proportional to ambient oxygen tension. Tumor cells exhibited greater GSH concentrations at low oxygen tensions than normal cells but were unable to increase GSH in response to elevation of oxygen tension. These results reveal differences in tumor and normal cell responses to changes in ambient oxygen tension and show that MnSOD activity is inducible when an appropriate stimulus is applied.
|ISSN : ||0014-4827|
|Mesh Heading : ||Anoxia Antioxidants Cell Line, Transformed Epithelial Cells Female Fibroblasts Glutathione Glutathione Peroxidase Humans Hyperoxia Male Neoplasms Oxidative Stress Oxygen Paraquat Superoxide Dismutase metabolism physiopathology drug effects metabolism drug effects metabolism drug effects metabolism metabolism metabolism drug therapy drug effects pharmacology metabolism|
|Mesh Heading Relevant : ||metabolism metabolism physiology pharmacology|
Oxygen-reactive species and antioxidant responses during development: the metabolic paradox of cellular differentiation.
Journal - Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.) (UNITED STATES )
Metabolic gradients are established during early phases of development and their existence influences subsequent developmental events. Variations in oxygen supply and oxygen metabolism associated with the gradation of metabolic rate in embryos appear to form one basis for the influence of metabolic gradients on development. The rate of oxygen metabolism affects the rate of oxidant generation by various cellular biochemical pathways. Cells contain antioxidant defenses that respond to variations in cellular oxidant production. Large changes in the activity of the antioxidant enzyme superoxide dismutase and changes in cellular redox state occur during the differentiation of many types of cells. These changes correspond to an increased rate of oxidant production; the cellular environment becomes more prooxidizing during differentiation. Evidence is presented that implicates oxidants as a factor that can stimulate alterations in gene expression. Possible mechanisms by which oxidants influence gene expression are also discussed.
|ISSN : ||0037-9727|
|Mesh Heading : ||Animals Antioxidants Cell Differentiation Gene Expression Regulation Glutathione Humans Oxygen Sulfhydryl Compounds Superoxide Dismutase metabolism metabolism physiology|
|Mesh Heading Relevant : ||physiology metabolism|
Developmental patterns in the antioxidant defenses of the housefly, Musca domestica.
Journal - Journal of cellular physiology (UNITED STATES )
The activities of superoxide dismutase (SOD), catalase, glutathione peroxidase, glutathione S-transferases, GSSG reductase, thiol transferases, gamma glutamylcysteine synthetase, and glucose-6-phosphate dehydrogenase, and the concentrations of H2O2 and reduced and oxidized glutathione were determined in the various developmental stages of houseflies. Housefly development was correlated with a progressive increase of cellular oxidizing equivalents and a loss of cellular reducing capacity. The loss of reducing equivalents appeared to result from a decrease in the activity of enzymes involved in glutathione and NADPH synthesis and a concomitant increase in glutathione-oxidizing enzymes. Relatively little change was observed in SOD activity during housefly development; however, the electrophoretic pattern of MnSOD varied in a manner specific to developmental stage. A striking increase in H2O2 concentration occurred prior to pupation possibly due to changes in substrate catabolism. These results support the hypothesis that the cellular environment becomes progressively more oxidizing during development.
|ISSN : ||0021-9541|
|Mesh Heading : ||Animals Catalase Glutathione Glutathione Reductase Houseflies Hydrogen Peroxide Larva Oxidoreductases Pupa Superoxide Dismutase metabolism physiology metabolism metabolism physiology growth & development metabolism enzymology metabolism enzymology metabolism physiology|
|Mesh Heading Relevant : ||enzymology physiology|
Oxidative influence on development and differentiation: an overview of a free radical theory of development.
Journal - Free radical biology & medicine (UNITED STATES )
Metabolic gradients exist in developing organisms and are believed to influence development. It has been postulated that the effects of these gradients on development result from differential oxygen supplies to tissues. Oxygen has been found to influence the course of development. Cells and tissues in various stages of differentiation exhibit discrete changes in their antioxidant defenses and in parameters of oxidation. Metabolically generated oxidants have been implicated as one factor that directs the initiation of certain developmental events. Also implicated as factors that modulate developmental processes are the cellular distribution of ions and the cytoskeleton both of which can be influenced by oxidants. The interaction of oxidants with ion balance and cytoskeleton is discussed.
|ISSN : ||0891-5849|
|Mesh Heading : ||Animals Catalase Glutathione Humans Oxidation-Reduction Superoxide Dismutase metabolism metabolism metabolism|
|Mesh Heading Relevant : ||Free Radicals Growth Models, Biological|
Superoxide dismutase induces differentiation in microplasmodia of the slime mold Physarum polycephalum.
Journal - Archives of biochemistry and biophysics (UNITED STATES )
Evidence is presented that supports a role for the enzyme superoxide dismutase (SOD) in the differentiation of the slime mold, Physarum polycephalum. SOD activity increases 46-fold during differentiation. A strain of Physarum that does not differentiate exhibits no change in SOD activity. Addition of SOD, via liposomes, to the nondifferentiating strain induces differentiation; this effect is enhanced by an inhibitor of glutathione synthesis. Other antioxidants selected for study failed to induce differentiation. Conversely, oxidative treatments including introduction of D-amino acid oxidase, via liposomes, induced differentiation. Cellular oxidation is the probable cause of the SOD effect.
|ISSN : ||0003-9861|
|Mesh Heading : ||Isoenzymes Kinetics Physarum Species Specificity Superoxide Dismutase metabolism cytology enzymology|
|Mesh Heading Relevant : ||growth & development metabolism|
Developmental changes in the superoxide dismutase activity of human skin fibroblasts are maintained in vitro and are not caused by oxygen.
Journal - The Journal of clinical investigation (UNITED STATES )
Confluent cultures of human skin fibroblast lines established from fetal and postnatal donors were exposed to a broad range of oxygen tensions (10-600 mmHg) for 1 wk; superoxide dismutase (SOD) activity was subsequently determined. Hyperoxia increased SOD activity slightly in postnatal lines but not in fetal lines. The magnitude of the increase in postnatal lines was not significant. Fetal lines exhibit only about one-fifth the SOD activity observed in postnatal lines. The results indicate that, while development-associated changes in SOD do occur in human cells, these alterations do not result from variations in ambient oxygen tension.
|ISSN : ||0021-9738|
|Mesh Heading : ||Adolescent Adult Aged Cells, Cultured Child Child, Preschool Fetus Fibroblasts Humans Middle Aged Oxygen Skin Skin Physiological Phenomena Superoxide Dismutase physiology cytology physiology|
|Mesh Heading Relevant : ||Aging enzymology physiology enzymology metabolism|