Glutathione Peroxidase GPX1 and Its Dichotomous Roles in Cancer

SIMPLE SUMMARY: Glutathione peroxidase 1 (GPX1), as one of the most important antioxidant enzymes, maintains cellular redox balance by regulating reactive oxygen species levels. In this review, we summarize and discuss the relationship between GPX1 genetic polymorphisms and cancer susceptibility, as well as the dichotomous roles of GPX1 aberrant expressions in the occurrence and development of human malignancies via various biological mechanisms. Our work may deepen the understanding of the critical clinical values and future directions of GPX1 as a potential prognostic biomarker and novel cancer therapeutic target. ABSTRACT: As the first identified selenoprotein, glutathione peroxidase 1 (GPX1) is a widely and abundantly expressed antioxidant enzyme. GPX1 utilizes glutathione as a substrate to catalyze hydrogen peroxide, lipid peroxide, and peroxynitrite, thereby reducing intracellular oxidative stress. The GPX1 gene is regulated at transcriptional, post-transcriptional, and translational levels. Numerous case-control studies and meta-analyses have assessed the association between a functional genetic polymorphism of the GPX1 gene, named Pro198Leu (rs1050450 C>T), and cancer susceptibility in different populations. GPX1 polymorphism has type-specific effects as a candidate marker for cancer risk, but the association between GPX1 variants and cancer susceptibility remains controversial in different studies. GPX1 is abnormally elevated in most types of cancer but has complex dichotomous roles as tumor suppressor and promoter in different cancers. GPX1 can participate in various signaling pathways to regulate tumor biological behaviors, including cell proliferation, apoptosis, invasion, immune response, and chemoresistance. In this review, we comprehensively summarize the controversial associations between GPX1 polymorphism and cancer risks and further discuss the relationships between the aberrant expressions of GPX1 and tumorigenesis. Further studies are needed to elucidate the clinical significance of GPX1 as a potential prognostic biomarker and novel therapeutic target in various malignancies.