Hydrogen peroxide inhibits cell cycle progression by inhibition of the spreading of mitotic CHO cells

Hydrogen peroxide (H2O2) induces a number of events, which are also induced by mitogens. Since the progression through the G1 phase of the cell cycle is dependent on mitogen stimulation, we were interested to study the effect of H2O2 on the cell cycle progression. This study demonstrates that H2O2 inhibits DNA synthesis in a dose-dependent manner when given to cells in mitosis or at different points in the G1 phase. Interestingly, mitotic cells treated immediately after synchronization are significantly more sensitive to H2O2 than cells treated in the G1, and this is due to the inhibition of the cell spreading after mitosis by H2O2. H2O2 reversibly inhibits focal adhesion activation and stress fiber formation of mitotic cells, but not those of G1 cells. The phosphorylation of MAPK is also reversibly inhibited in both mitotic and G1 cells. Taken together, H2O2 is probably responsible for the inhibition of the expression of cyclin D1 and cyclin A observed in cells in both phases. In conclusion, H2O2 inhibits cell cycle progression by inhibition of the spreading of mitotic CHO cells. This may play a role in pathological processes in which H2O2 is generated.