The Role of Redox Proteins in Arresting Proliferation of Breast Epithelial Cells Under Oxidative Stress

Background: Redox status imbalance against the backdrop of oxidative stress development underlies the pathogenesis of a whole range of diseases. Many intracellular proteins contain free thiol groups and undergo redox regulation which is one of the key processes in controlling cell proliferation. Thioredoxin and glutaredoxin are involved in maintaining intracellular redox homeostasis and act as candidates in regulating proliferation. This provides prospects for future development of methods for diagnosis and targeted therapy of socially sensitive diseases accompanied by oxidative stress. The aim of the study is to reveal the role of redox proteins in molecular mechanisms of regulating HBL-100 breast epithelial cell proliferation under the effect of roscovitine, a cell cycle inhibitor. Materials and methods: Two research groups were formed. They included HBL-100 human breast epithelial cells incubated in the presence and absence of 20 mcM roscovitine for 18 hours. The intracellular thioredoxin levels were determined using Western blot analysis with specific monoclonal antibodies. Distribution of the cells among cell cycle phases were evaluated by flow cytometry. The activity of glutathione reductase, glutathione peroxidase, and thioredoxin reductase were measured by spectrophotometry. Results: Under the effect of roscovitine in the HBL-100 cells, cell cycle arrest in the G₂/М phases occurred and oxidative stress developed. In the meantime, the decrease in the thioredoxin and glutaredoxin concentrations was registered along with the change in the functional activity of glutathione-dependent enzymes. Conclusions: Application of roscovitine, a cell cycle inhibitor, allowed creating a model of oxidative stress in the breast epithelial cells against the backdrop of inhibited cell proliferation. We identified that thioredoxin and glutaredoxin contributed to impairment of cell cycle progression. It points at a possibility to regulate cell proliferation by modulating the functional features of cellular redox-dependent proteins in different pathologies accompanied by oxidative stress.