Oxidation-reduction reactions in Ehrlich cells treated with copper-neocuproine. Free Radic Biol Med 1992 Nov;13(5):469-78
Date
11/01/1992Pubmed ID
1334027DOI
10.1016/0891-5849(92)90141-3Scopus ID
2-s2.0-0026743289 (requires institutional sign-in at Scopus site) 30 CitationsAbstract
The interaction of 2,9-dimethyl-1,10-phenanthroline (neocuproine or NC) and its copper complex with Ehrlich ascites tumor cells was studied. NC is frequently used as a negative control in studies of in vitro DNA degradation by copper phenanthroline and has also found use as a potential inhibitor of damage from oxidative stress in biological systems. NC inhibited Ehrlich cell growth in monolayer culture over 48 h treatment by 50% at 0.05 nmol/10(5) cells. Addition of 5- to 100-fold ratios of CuCl2 to NC (at 0.035 nmol NC/10(5) cells) produced progressively more growth inhibition. Addition of 1:0.5 ratios of NC to CuCl2 over the range of NC concentrations 0.08-0.2 nmol/10(5) cells/mL resulted in DNA single-strand breakage during 1-h treatments as measured by DNA alkaline elution. Concomitant addition of catalase or dimethyl sulfoxide (DMSO) inhibited DNA strand scission, while superoxide dismutase enhanced breakage. Catalase and DMSO also inhibited induction of membrane permeability by the copper complex of NC. These cellular effects apparently result from the intracellular generation of hydroxyl radical from H2O2. NC facilitated the uptake of copper into cells, though it was initially bound as a copper-histidine-like complex. The internalized copper was reduced to Cu(I), bound mostly as (NC)2Cu(I). To explain the (NC)2Cu-dependent generation of hydroxyl radical, it is hypothesized that glutathione successfully competes for Cu(I), converting it to a redox-active form that can catalyze the reduction of molecular oxygen to .OH. Model studies support this view. Radical scavengers did not reverse growth inhibition produced by NC or NC + CuCl2.
Author List
Byrnes RW, Antholine WE, Petering DHMESH terms used to index this publication - Major topics in bold
AnimalsAntineoplastic Agents
Biological Transport
Carcinoma, Ehrlich Tumor
Cell Division
Cell Membrane Permeability
Copper
DNA Damage
DNA, Neoplasm
Dimethyl Sulfoxide
Electron Spin Resonance Spectroscopy
Glutathione
Mice
Organometallic Compounds
Oxidation-Reduction
Phenanthrolines
Superoxide Dismutase
Tumor Cells, Cultured
