Long-Term Excessive Selenium Supplementation Affects Gene Expression in Esophageal Tissue of Rats

Abstract

Esophageal cancer is one of the leading causes of cancer death and the seventh most prevalent cancer worldwide. Considering the positive association of high selenium with the prevalence of esophageal cancer, we have investigated the effect of high doses of selenium on gene expression in the normal esophageal tissue of rats. Twenty male rats were randomly divided into four groups: control group, group 2 mg Se/L, 10 mg Se/L, and 20 mg Se/L rats fed with a basal basic diet and 2, 10, and 20 mg Se/L as sodium selenite in drinking water, respectively, for 20 weeks. Serum malondialdehyde and glutathione peroxidase activity were measured. Moreover, the expression and concentration of the cyclin D1, cyclin E, KRAS, p53, NF-kB, TGF-β, and MGMT in the esophageal tissue were analyzed and compared between the four groups. In normal esophageal tissue, selenium supplementations (2, 10, and 20 mg Se/L) increased the mRNA levels of cyclin D1, P53, KRAS, NF-κB p65, and MGMT and decreased the mRNA level of TGFß1. The concentrations of cyclin D1 and MGMT were also significantly increased by selenium supplementations. Selenium supplementations had no significant effect on serum MDA but significantly increased GPX activity. The present study suggests that selenium supplementation (2, 10, and 20 mg Se/L) affects gene expression related to inflammation, Cell proliferation, and apoptosis in the normal esophageal tissue. However, there were no observed abnormalities other than reduced growth with supplementation of 20 mg/L as Na2SeO3 in rats.

Keywords: Esophageal cancer; Reactive oxygen species; Selenium; Toxicity.