Role of thioredoxin reductase 1 in dysplastic transformation of human breast epithelial cells triggered by chronic oxidative stress.

Thioredoxin reductase 1 (TrxR1) is a pivotal intracellular redox sensor and antioxidant enzyme. On the other hand, overexpression of TrxR1 is closely correlated with the initiation of various tumors including breast cancer, though the detailed mechanism remains unclear. Here we investigated the role of TrxR1 in dysplastic transformation of human breast epithelial cell line MCF-10A induced by chronic oxidative stress. Not surprisingly, sustained exposure to H2O2 significantly augmented the expression and activity of TrxR1 in MCF-10A cells. The dysplastically transformed MCF-10A (MCF-10AT) cells undergoing 8-week H2O2 treatment exhibited a certain degree of malignancy in tumorigenicity evaluation. Moreover, TrxR1 inhibitor ethaselen (BBSKE) could partially reverse some malignant phenotypes including epithelial to mesenchymal transition (EMT) of MCF-10AT as well as MCF-7 cells. Collectively, our results supported the considerable involvement of TrxR1 in the onset of breast cancer and BBSKE may be a promising agent against breast cancer.