GPX1 Localizes to the Nucleus in Prostate Epithelium and its Levels are not Associated with Prostate Cancer Recurrence

Glutathione Peroxidase GPX1 and Its Dichotomous Roles in Cancer

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.

Assessment of Glutathione Peroxidase-1 (GPX1) Gene Expression as a Specific Diagnostic and Prognostic Biomarker in Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a malignant tumor of the mesothelial lining of the thorax. It has been related to frequent exposure to asbestos. Diagnosis of malignant pleural mesothelioma is considered a criticizing problem for clinicians. Early diagnosis and sufficient surgical excision of MPM are considered the cornerstone success factors for the management of early MPM. Glutathione peroxidase-1 (GPX1) is an intracellular protein found to be extensively distributed in all cells, and it belongs to the GPX group. In the current study, we included ninety-eight patients with MPM that underwent surgery at the Zagazig University Hospital in Egypt. We assessed GPX1 gene expression level as it was thought to be related to pathogenicity of cancer in a variety of malignant tumors. We observed a significant elevation in GPX1-mRNA levels in MPM relative to the nearby normal pleural tissues. It was found to be of important diagnostic specificity in the differentiation of MPM from normal tissues. Moreover, we studied the survival of patients in correlation to the GPX1 expression levels and we reported that median overall survival was about 16 months in patients with high GPX1 expression levels, while it was found to be about 40 months in low GPX1 levels.

Expression and prognostic potential of GPX1 in human cancers based on data mining

BACKGROUND

Glutathione peroxidase-1 (GPX1) is a member of the GPX family, which considered an enzyme that interacts with oxidative stress. GPX1 differential expression is closely correlated with carcinogenesis and disease progression. In this study, we used bioinformatics analysis to investigate GPX1 expression level and explore the prognostic information in different human cancers.

METHODS

Expression was analyzed via the Oncomine database and Gene Expression Profiling Interactive Analysis tool, and potential prognostic analysis was evaluated using the UALCAN, GEPIA, and DriverDBv3 databases. Then, the UALCAN database was used to find the promoter methylation of GPX1 in defied cancer types. While GPX1 related functional networks were found within the GeneMANIA interactive tool and Cytoscape software. Moreover, Metascape online website was used to analyze Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways.

RESULTS

We found that GPX1 was commonly overexpressed in most human cancers. High expression of GPX1 could lead to poor outcomes in Brain Lower Grade Glioma, while GPX1 over expression was correlated with better prognosis in Kidney renal papillary cell carcinoma (KIPP). High GPX1 expression was marginally associated with poor prognosis in acute myeloid leukemia (AML). Gene regulation network suggested that GPX1 mainly involved in pathways including the glutathione metabolism, ferroptosis, TP53 regulates metabolic genes, reactive oxygen species (ROS) metabolic process, and several other signaling pathways.

CONCLUSIONS

Our findings revealed that GPX1 showed significant expression differences among cancers and served as a prognostic biomarker for defined cancer types. The data mining effectively revealed useful information about GPX1 expression, prognostic values, and potential functional networks in cancers, thus providing researchers with an available way to further explore the mechanism underlying carcinogenesis of genes of interest in different cancers.

Selenoproteins of the Human Prostate: Unusual Properties and Role in Cancer Etiology

The prostate is an important organ for the maintenance of sperm health with prostate cancer being a common disease for which there is a critical need to distinguish indolent from aggressive disease. Several selenium-containing proteins have been implicated in prostate cancer risk or outcome due to either enzyme function, the reduced levels of these proteins being associated with cancer recurrence after prostatectomy or their corresponding genes containing single-nucleotide polymorphisms associated with increased risk. Moreover, experimental data obtained from the manipulation of either cultured cells or animal models have indicated that some of these proteins are contributing mechanistically to prostate cancer incidence or progression. Among these are selenocysteine-containing proteins selenoprotein P (SELENOP), glutathione peroxidase (GPX1), and selenoprotein 15 (SELENOF); and the selenium-associated protein selenium-binding protein 1 (SBP1). Genotyping of some of the genes for these proteins has identified functional single-nucleotide polymorphisms that are associated with prostate cancer risk and the direct quantification of these proteins in human prostate tissues has not only revealed associations to clinical outcomes but have also identified unique properties that are different from what is observed in other tissue types. The location of GPX1 in the nucleus and SELENOF in the plasma membrane of prostate epithelial cells indicates that these proteins may have functions in normal prostate tissue that are distinct from that of the other tissue types.