Thioredoxin reductase regulates angiogenesis by increasing endothelial cell-derived vascular endothelial growth factor

Low selenium (Se) status increases angiogenesis by inducing the production of vascular endothelial growth factor (VEGF); however, the mechanism responsible for VEGF up-regulation has yet to be characterized. Se's ability to control cellular oxidative state through its incorporation into selenoproteins such as thioredoxin reductase (TrxR) may explain previous studies that connect Se status to tumor angiogenesis. Therefore, the focus of this study was to determine if altered VEGF expression and angiogenesis due to decreased Se levels are influenced by reduced TrxR activity. We found that chemical inhibition of TrxR in Se-sufficient endothelial cells (ECs) was associated with increases in VEGF and VEGF receptor expression, cell migration, proliferation, and angiogenesis to levels similar to those seen in Se-deficient ECs. Specific inhibition of glutathione peroxidase did not affect pro-angiogenic responses, indicating a unique role of the TrxR system during low Se status. These data correlate changes in TrxR activity with changes in VEGF expression and angiogenic development in ECs, which is significant because minimal mechanistic data exist that explain the role of Se in cancer prevention. Understanding the importance of the tumor microenviromnent in contributing to angiogenic regulation has the potential to significantly impact breast cancer chemoprevention strategies by,focusing on maintaining proper EC function within the mammary gland.