Molecular cross-talk between members of distinct families of selenium containing proteins

Abstract

Dietary intake of selenium has been associated with reduced risk of several cancer types, and this is likely due to its role as a specific constituent of selenium containing proteins. One of these, selenium-binding protein 1 (SBP1), is a protein of unknown function that has been shown to be reduced in tumors of diverse tissue types as compared to the corresponding normal tissue. More importantly, SBP1 has also been reported to be a predictor of clinical outcome. Levels of SBP1 are inversely associated with the levels of another protein representative of a different class of selenoproteins, glutathione peroxidase1 (GPx-1). GPx-1 is an anti-oxidant, selenocysteine containing enzyme implicated in several diseases, including cancer, due to the association of specific alleles with disease risk. The relationship between SBP1 and GPx-1 represents a unique example of a molecular interaction between selenium containing proteins with a likely significant impact on human health and disease.

Keywords: Cancer; Clinical outcome; Glutathione peroxidase; Selenium-binding protein 1.

Figure 1

Reduced levels of SBP1 in colorectal cancer are associated with poor clinical outcome. The expression of SBP1 was determined by immunohistochemistry of tissue microarrays and classified at “tumor-high SBP1” or “tumor-low SBP-1” based on the number of positively stained epithelial cells compared to all of the epithelial cells observed in the core, using a mean level of 22.5% as the discriminator. The graphs are Kaplan-Meier estimates of the association between SBP1 levels and either disease free survival (panel A) or overall survival (panel B). These data were obtained from [22].