Copper deprivation potentiates oxidative stress in HL-60 cell mitochondria

The Role of Zinc and Copper in Gynecological Malignancies

Zinc (Zn) and copper (Cu) are essential microelements, which take part in cellular metabolism, feature in enzymatic systems, and regulate enzyme activity. Homeostasis of these micronutrients is tightly regulated by multiple compensatory mechanisms that balance their concentrations including transporters, importers, and metallothioneins. An altered intake of only one of these trace elements may cause an imbalance in their levels and result in their competition for absorption. Relatively low levels of zinc and increased levels of copper may result in an increased level of oxidative stress and impair the antioxidant properties of multiple enzymes. Altered levels of trace elements were discovered in various pathologies including immunological, degenerative, and inflammatory diseases. Moreover, due to the role of Zn and Cu in oxidative stress and chronic inflammation, they were found to influence cancerogenesis. We review the roles of zinc and copper and their mechanisms in tumor growth, metastasis potential, microenvironment remodeling, and drug resistance. We highlight their role as potential biomarkers for cancer diagnosis, treatment, and prognosis, concentrating on their impact on gynecological malignancies.

Effects of copper sulphate concentrations during in vitro maturation of bovine oocytes

THE OBJECTIVES WERE TO EVALUATE: 1) copper (Cu) concentrations in plasma and follicular fluid (FF) from cattle ovaries; 2) the effects of supplemental Cu during in vitro maturation (IVM) on DNA damage of cumulus cells and glutathione (GSH) content in oocytes and cumulus cells; and 3) supplementary Cu during IVM on subsequent embryo development. Copper concentrations in heifer plasma (116 ± 27.1 μg/dL Cu) were similar (P > 0.05) to concentrations in FF from large (90 ± 20.4 μg/dL Cu) and small (82 ± 22.1 μg/dL Cu) ovarian follicles in these heifers. The DNA damage in cumulus cells decreased with supplemental Cu concentrations of 4 and 6 μg/mL (P < 0.01) in the IVM medium (mean ± SEM index of DNA damage was: 200.0 ± 27.6, 127.6 ± 6.0, 46.4 ± 4.8, and 51.1 ± 6.0 for supplementation with 0, 2, 4, and 6 μg/mL Cu respectively). Total GSH concentrations increased following supplementation with 4 μg/mL Cu (4.7 ± 0.4 pmol in oocytes and 0.4 ± 0.04 nmol/10(6) cumulus cells) and 6 μg/mL Cu (5.0 ± 0.5 pmol in oocytes and 0.5 ± 0.05 nmol/10(6) cumulus cells, P < 0.01) compared with the other classes. Cleavage rates were similar (P ≥ 0.05) when Cu was added to the IVM medium at any concentration (65.1 ± 2.0, 66.6 ± 1.6, 72.0 ± 2.1, and 70.7 ± 2.1 for Cu concentrations of 0, 2, 4, and 6 μg/mL). Percentages of matured oocytes that developed to the blastocyst stage were 18.7 ± 0.6, 26.4 ± 0.03, and 29.0 ± 1.7% for 0, 2, and 4 μg/mL Cu, and was highest (33.2 ± 1.6 %) in oocytes matured with 6 μg/mL Cu (P > 0.01). There was an increase (P > 0.05) in mean cell number per blastocyst obtained from oocytes matured with 4 and 6 μg/mL Cu relative to 0 Cu (IVM alone) and 2 μg/mL Cu. In conclusion, Cu concentrations in the FF and plasma of heifers were similar. Adding copper during oocyte maturation significantly increased both intracellular GSH content and DNA integrity of cumulus cells. Since embryo development was responsive to copper supplementation, we inferred that optimal embryo development to the blastocyst stage was partially dependent on the presence of adequate Cu concentrations during IVM.

Frataxin, iron-sulfur clusters, heme, ROS, and aging

A deficiency in mitochondrial frataxin causes an increased generation of mitochondrial reactive oxygen species (ROS), which may contribute to the cell degenerative features of Friedreich's ataxia. In this work the authors demonstrate mitochondrial iron-sulfur cluster (ISC) defects and mitochondrial heme defects, and suggest how both may contribute to increased mitochondrial ROS in lymphoblasts from human patients. Mutant cells are deficient in the ISC-requiring mitochondrial enzymes aconitase and succinate dehydrogenase, but not in the non-ISC mitochondrial enzyme citrate synthase; also, the mitochondrial iron-sulfur scaffold protein IscU2 co-immunoprecipitates with frataxin in vivo. Presumably as a consequence of the iron-sulfur cluster defect, cytochrome c heme is deficient in mutants, as well as heme-dependent Complex IV. Mitochondrial superoxide is elevated in mutants, which may be a consequence of cytochrome c deficiency. Hydrogen peroxide, glutathione peroxidase activity, and oxidized glutathione (GSSG) are each elevated in mutants, consistent with activation of the glutathione peroxidase pathway. Mutant status blunted the effects of Complex III and IV inhibitors, but not a Complex I inhibitor, on superoxide production. This suggests that heme defects late in the electron transport chain of mutants are responsible for increased mutant superoxide. The impact of ISC and heme defects on ROS production with age are discussed.

Effect of copper deficiency on oxidative DNA damage in Jurkat T-lymphocytes

The micronutrient copper is a catalytic cofactor for copper, zinc superoxide dismutase and ceruloplasmin, which are two important antioxidant enzymes. As such, a lack of copper may promote oxidative stress and damage. The purpose of this study was to determine the effect of copper deficiency on oxidative damage to DNA in Jurkat T-lymphocytes. To induce copper deficiency, cells were incubated for 48 h with 5-20 microM 2,3,2-tetraamine (2,3,2-tet), a high affinity copper chelator. Such treatment did not affect cell proliferation/viability, as assessed by measuring mitochondrial reduction of WST-1 reagent (4-[3-(4-Iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-ben zen e disulfonate). Furthermore, the induction of copper deficiency did not promote oxidative DNA damage as evaluated by the comet assay. Comet scores were 15 +/- 0 and 16 +/- 1 for control and copper-deficient cells, respectively. However, the copper-deficient cells sustained greater oxidative DNA damage than the control cells (comet scores of 175 +/- 15 and 50 +/- 10, respectively) when both were oxidatively challenged with 50 microM hydrogen peroxide (H(2)O(2)). Supplemental copper but not zinc or iron prevented the potentiation of the H(2)O(2)-induced oxidative DNA damage caused by 2,3,2-tet. These data suggest that copper deficiency compromises the antioxidant defense system of cells, thereby increasing their susceptibility to oxidative DNA damage.