Abstract: Objective To investigate the effects of iron overload induced oxidative stress on the expression of c-MYC protein in human breast cancer cells. Methods The human breast cancer MCF-7 cells were treated by 0, 50 and 500 μmol/L ferrous sulfate respectively. After 24 hours, immunocytochemistry stain and western blot methods were used to investigate the changes of reactive oxygen species and the expression of IRP1、IRP2、c-MYC、P-ERK、GSK、PP2A protein. The changes of ROS activity and c-MYC protein were further examed by blocking NADPH oxidase pathway using Diphenyliodonium iodide (DPI). Result With the increase of ferrous sulfate, both ROS activity of and IRP2 protein expression of MCF-7 cell were increased significantly (P<0.05), but IRP1 was not. Iron overload also increased c-MYC protein expression, and enhanced the levels of phosphorylation of ERK1/2 and reduced the expressions of GSK and PP2A proteins (P<0.05). NADPH oxidase inhibitor (DPI) could significantly inhibit the enhancement of ROS activity and the expression of c-MYC protein (P<0.05). Conclusion Iron overload may enhance the expression of c-MYC protein by upregulated ROS activity.

Key words: Breast cancer cell, ROS, IRPs, c-MYC.