Combined action of FOXO1 and superoxide dismutase 3 promotes MDA-MB-231 cell migration

Abstract

Superoxide dismutase 3 (SOD3), one of SOD isozymes, maintains extracellular redox homeostasis through the dismutation reaction of superoxide. Loss of SOD3 in tumor cells induces oxidative stress and exacerbates tumor progression; however, interestingly, overexpression of SOD3 also promotes cell proliferation through the production of hydrogen peroxide. In this study, we investigated the functional role of SOD3 in human breast cancer MDA-MB-231 cell migration and the molecular mechanisms involved in high expression of SOD3 in MDA-MB-231 cells and human monocytic THP-1 cells. The level of histone H3 trimethylation at lysine 27 (H3K27me3), a marker of gene silencing, was decreased in 12-O-tetra-decanoylphorbol-13-acetate (TPA)-treated THP-1 cells. Also, that reduction was observed within the SOD3 promoter region. We then investigated the involvement of H3K27 demethylase JMJD3 in SOD3 induction. The induction of SOD3 and the reduction of H3K27me3 were inhibited in the presence of JMJD3 inhibitor, GSK-J4. Additionally, it was first determined that the knockdown of the transcription factor forkhead box O1 (FOXO1) significantly suppressed TPA-elicited SOD3 induction. FOXO1-mediated SOD3 downregulation was also observed in MDA-MB-231 cells, and knockdown of FOXO1 and SOD3 suppressed cell migration. Our results provide a novel insight into epigenetic regulation of SOD3 expression in tumor-associated cells, and high expression of FOXO1 and SOD3 would participate in the migration of MDA-MB-231 cells.