We compared changes in the redox status and intensity of oxidative modification of proteins in intact Jurkat tumor cells and cells cultured with buthionine sulfoximine, an inhibitor of the key enzyme of glutathione synthesis γ-glutamylcysteine synthetase. The glutathione system components play a role in modulation of the content of protein-bound glutathione, protein carbonyl derivatives, bityrosine, and oxidized tryptophan, and in dysregulation of apoptosis in Jurkat tumor cells. Inhibition of de novo synthesis of glutathione in Jurkat tumor cells was followed by accumulation of hydroxyl radical, a reduction in the level of protein-bound glutathione and oxidized tryptophan, and a rise in the concentration of protein carbonyl derivatives. These changes were accompanied by activation of programmed cell death.
MCF-7 breast cancer cells and HBL-100 breast epithelial cells were cultured with N-ethylmaleimide, a blocker of SH groups. Changes in redox potential of the glutathione system, activities of glutathione reductase, glutathione peroxidase, and intensity of apoptotic cell death were evaluated. The results indicate that incubation with N-ethylmaleimide led to glutathione system imbalance, reduced tumor cell redox potential, and induced their programmed death, which seemed useful for prospective target therapy of tumor diseases.
Spontaneous lipolysis was found to be increased in adipocytes of rats with alloxan-induced diabetes. In addition, isoproterenol-stimulated hydrolysis of triacylglycerols was inhibited against the background of oxidative stress and decreased redox-status of cells. A decrease in the ability of insulin to inhibit isoproterenol-stimulated lipolysis in adipocytes that were isolated from adipose tissue of rats with experimental diabetes was found, which shows a disorder in regulation of lipolysis in adipocytes by the hormone in alloxan-induced diabetes. Based on these findings, we concluded that there is an influence of reactive oxygen species, superoxide anion radical in particular, and redox potential of the glutathione system on molecular mechanisms of change in lipolysis intensity in rat adipocytes in alloxan-induced oxidative stress. Activation of spontaneous lipolysis under conditions of oxidative stress might be a reason for the high concentration of free fatty acids in blood plasma in experimental diabetes, and this may play a significant role in development of insulin resistance and appearance of complications of diabetes.
Reaction of the glutathione system of Jurkat tumor cells and blood lymphocytes was evaluated under conditions of culturing with 5-(5-ethyl-2-hydroxy-4-methoxyphenyl)-4-(4-methoxyphenyl) isoxazole (KRIBB3), a selective inhibitor of heat shock protein Hsp27. The results indicated the regulatory role of Hsp27 in the maintenance of the functional activities of glutathione reductase, glutathione peroxidase, and realization of apoptotic death of Jurkat cells and blood lymphocytes. Inhibition of Hsp27 in Jurkat tumor cells led to imbalance of the glutathione system and increase of the share of annexin-positive cells.
Background: Breast tumors are number one cause of cancer morbidity and mortality among women around the world, and Russia is not an exception. Many proteins that control proliferation of immortalized cells are redox-regulated, which is essential for modulating cellular proliferative activity, especially during tumor growth. Studying the role of glutaredoxin and glutathione in cell cycle phase distribution will allow not only to identify the molecular targets regulating cell proliferation, but also to develop methods of diagnosis and targeted therapy of socially sensitive diseases, including breast cancer, in the future.Aims: To evaluate the role of glutathione and glutaredoxin in the molecular mechanisms regulating MCF-7 breast cancer cell proliferation under the effects of roscovitine, a cyclin-dependent protein kinase inhibitor.Materials and methods: The MCF-7 cell line (human breast adenocarcinoma) was used in the study. The cell culture was incubated in the presence and absence of roscovitine in the final concentration of 20 µmol for 18 h. The production of reactive oxygen species, the distribution of cells between cell cycle phases and the amount of Annexin V positive cells were determined using flow cytometry. The concentrations of total, reduced and oxidized glutathione, protein SH groups and protein-bound glutathione were measured by spectrophotometry. The levels of glutaredoxin, cyclin E and cyclin-dependent protein kinases were estimated by Western blotting with monoclonal antibodies.Results: The effects of roscovitine in the MCF-7 cells resulted in cell cycle arrest in G2/М phases with the decreased levels of cyclin E and cyclin-dependent protein kinase 2. It was accompanied by activation of programmed cell death. In tumor cells incubated in the presence of roscovitine, oxidative stress was triggered, which was accompanied by the elevated generation of reactive oxygen species, the decrease in the concentration of reduced glutathione, and the rise in the level of glutaredoxin. It contributed to the increase in protein glutathionylation against the backdrop of the decreased SH group concentration.Conclusions: Breast cancer cell proliferation under the effects of roscovitine is reduced following not only the decrease in the cyclin level and cyclin-dependent protein kinase activity, but also the shift in the intracellular oxidant/antioxidant ratio. Roscovitine-induced oxidative stress in the MCF-7 cells contributed to protein glutathionylation with the changes in the protein structure and functions. It results in impaired cell cycle progression, indicating a possibility to regulate cellular proliferation through modulating functional properties of redox-dependent proteins using the glutathione/glutaredoxin system.
Heat shock proteins Hsp) act as molecular chaperones, protecting enzymes and other proteins against reactive oxygen species. The objective of the study was to investigate the role of Hsp27 in maintaining the balance of the glutathione system and Hsp70 concentrations as well as in implementing Jurkat tumor cell apoptosis. Addition of the Hsp27 inhibitor KRIBB3 (5-(5-ethyl-2-hydroxy-4-methoxyphenyl)-4-(4-methoxyphenyl)-isoxazol) to Jurkat cells resulted in glutathione redox imbalance (increased GSSG and increased glutathione reductase activity), a decrease in Hsp70 concentrations, and also increased cell apoptosis as compared with to the intact cell culture. The proposed selective regulation of chaperone activity is a promising direction in regulating apoptosis at the cellular level.
The effects of the SH-group blocker N-ethylmaleimide (NEM) and thiol group protector 1,4-dithioerythritol (DTE) on the redox status of cells HBL-100 cells, oxidative modification of their proteins and the state of glutathione and thioredoxin systems have been investigated. Breast epithelial cells cultivated in the presence of NEM were characterized by decreased redox status, increased glutathione reductase activity, and increased concentrations of products of irreversible oxidative modification of protein and amino acids. Cultivation of HBL-100 cells in the presence of DTE resulted in a shift of the redox status towards reduction processes and increased reversible protein modification by glutathionylation. The proposed model of intracellular redox modulation may be used in the development of new therapeutic approaches to treat diseases accompanied by impaired redox homeostasis (e.g. oncologic, inflammatory, cardiovascular and neurodegenerative disease).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.