DOSE-DEPENDENT EFFECT OF HYDROGEN PEROXIDE ON THE LEVEL OF TRANSCRIPTION FACTOR NRF2 IN VITRO

Introduction. Nrf2 (NF-E2-related factor 2) is a redox-sensitive transcription factor whose synthesis is regulated by the ratio of reduced and oxidized SH groups in proteins. The aim of the study was to evaluate the dose-dependent effect of hydrogen peroxide on Nrf2 level in vitro. Materials and methods. The study was performed on the cell line Сасо-2. Hydrogen peroxide (H2O2) was added to the culture medium to concen-trations 0.1; 0.5; 1; 5; 10 and 50 µМ and cells ware incubated for 3, 24 and 72 hours. At the end of the experiment the level of protein and protein-free thiol (SH-) groups, as well as the level of Nrf2 were evaluated in the cells. Results. H2O2 during incubation with Cасо-2 cells for 3 hours did not significantly affect the concentration of protein and protein-free SH-groups and the level of Nrf2 in all concentrations. When the duration of exposure was increased to 24 hours H2O2 at concentrations 0.1–1 µМ caused a decrease in the level of reduced protein thiols, which led to an increase in the content of Nrf2, which in turn activated the antioxidant system of cells and restored the free radical status of cells after 3 days of incubation. Increased concentrations of H2O2 (10 and 50 µМ) induced oxidative stress, which was manifested by a depletion of reduced protein SH-groups not only after 24 hours, but also after 72 hours of the experiment. The level Nrf2 was elevated only after 3 days. Conclusion. Hydrogen peroxide stimulates the formation of Nrf2 in the time- and concentration-dependent manner.