Using Information from Public Databases to Critically Evaluate Studies Linking the Antioxidant Enzyme Selenium-Dependent Glutathione Peroxidase 2 (GPX2) to Cancer

Abstract

Recent research on selenium-dependent glutathione peroxidase 2 (GPX2) tends to focus on possible roles in tumorigenesis. This is based on the idea that normally generated hydroperoxide species can damage DNA to produce mutations and react with protein sulfhydryl groups to perturb normal regulation of cancer-related pathways. GPX2 is one of many peroxidases available to control hydroperoxide levels. Altered GPX2 expression levels from normal to cancer or with cancer stages seems to be the main feature in bringing it to the attention of investigators. In this commentary, we examine this premise as a basis for cancer studies, largely by trying to place GPX2 within the larger context of antioxidant enzyme gene expression. We make use of public databases and illustrate their possible role in approaching this issue. Since use of such databases is new to us, we looked to sources in the literature to evaluate expression level data, finding general agreement with some discrepancies over the range of expression and relative expression levels among some samples. Using the database information, we critically evaluate methods used to study GPX2 in the current literature for a variety of cancers. Second, groups are now trying to compare enzymatic properties of GPX1 and GPX2 using proteins from bacterial cultures. We weigh in on these recent findings and discuss the impact on the relative GPX2 and GPX1 functions.