Glutathione Peroxidase Family Research Articles

Viral Infections and the Glutathione Peroxidase Family: Mechanisms of Disease Development.

Significance: The glutathione peroxidase (GPx) family is recognized for its essential function in maintaining cellular redox balance and countering the overproduction of reactive oxygen species (ROS), a process intricately linked to the progression of various diseases including those spurred by viral infections. The modulation of GPx activity by viruses presents a critical juncture in disease pathogenesis, influencing cellular responses and the trajectory of infection-induced diseases. Recent Advances: Cutting-edge research has unveiled the GPx family's dynamic role in modulating viral pathogenesis. Notably, GPX4's pivotal function in regulating ferroptosis presents a novel avenue for the antiviral therapy. The discovery that selenium, an essential micronutrient for GPx activity, possesses antiviral properties has propelled us toward rethinking traditional treatment modalities. Critical Issues: Deciphering the intricate relationship between viral infections and GPx family members is paramount. Viral invasion can precipitate significant alterations in GPx function, influencing disease outcomes. The multifaceted nature of GPx activity during viral infections suggests that a deeper understanding of these interactions could yield novel insights into disease mechanisms, diagnostics, prognostics, and even chemotherapeutic resistance. Future Directions: This review aims to synthesize current knowledge on the impact of viral infections on GPx activity and expression and identify key advances. By elucidating the mechanisms through which GPx family members intersect with viral pathogenesis, we propose to uncover innovative therapeutic strategies that leverage the antioxidant properties of GPx to combat viral infections. The exploration of GPx as a therapeutic target and biomarker holds promise for the development of next-generation antiviral therapies. Antioxid. Redox Signal. 00, 000-000.

Glutathione peroxidase 3 is a potential biomarker for konzo

Konzo is a neglected paralytic neurological disease associated with food (cassava) poisoning that affects the world’s poorest children and women of childbearing ages across regions of sub-Saharan Africa. Despite understanding the dietary factors that lead to konzo, the molecular markers and mechanisms that trigger this disease remain unknown. To identify potential protein biomarkers associated with a disease status, plasma was collected from two independent Congolese cohorts, a discovery cohort (n = 60) and validation cohort (n = 204), sampled 10 years apart and subjected to multiple high-throughput assays. We identified that Glutathione Peroxidase 3 (GPx3), a critical plasma-based antioxidant enzyme, was the sole protein examined that was both significantly and differentially abundant between affected and non-affected participants in both cohorts, with large reductions observed in those affected with konzo. Our findings raise the notion that reductions in key antioxidant mechanisms may be the biological risk factor for the development of konzo, particularly those mediated through pathways involving the glutathione peroxidase family.

Exploring genes within the glutathione peroxidase family as potential predictors of prognosis in papillary renal cell carcinoma

Abstract Objectives This research aims to explore the relationship between glutathione peroxidase (GPX) expression variations in papillary renal cell carcinoma (pRCC) and patient survival, while also developing and evaluating a customized survival prediction model based on GPX. Methods The transcriptomic dataset, including clinical parameters and GPX expression levels, is sourced from The Cancer Genome Atlas (TCGA) database, comprising 290 individuals diagnosed with pRCC. We utilized a univariate Cox regression model to select differentially expressed genes. Subsequently, we calculated risk scores through the least absolute shrinkage and selection operator (LASSO) regression. Based on the median risk score, patients were categorized into high and low-risk groups, establishing a prognostic risk model. Following this, the relationship between the risk model and the survival of pRCC patients was revealed through Kaplan–Meier survival curve analysis. The sensitivity and specificity of the predictive model were evaluated using receiver operating characteristic (ROC) curve analysis. Furthermore, chemotherapy drug sensitivity analysis was conducted on patients in the high and low-risk groups. Results A risk-scoring model was built by selecting GPX7 and GPX8. Compared to the low-risk group, individuals in the high-risk category showed significantly reduced overall survival rates (p=0.018). Additionally, validation results demonstrated the model’s good predictive accuracy. Conclusions The risk-scoring model constructed based on GPX family genes provides an innovative biomarker for forecasting the prognosis of pRCC and serves as a reference for individualized therapy in pRCC.

Downregulation of GPX8 in hepatocellular carcinoma: impact on tumor stemness and migration

PurposeGPX8, which is found in the endoplasmic reticulum lumen, is a member of the Glutathione Peroxidases (GPXs) family. Its role in hepatocellular carcinoma (HCC) is unknown.MethodsImmunohistochemical staining was used to detect the protein levels of GPX8 in HCC tissue microarrays. A short hairpin RNA lentivirus was used to knock down GPX8, and the main signaling pathways were investigated using transcriptome sequencing and a phosphorylated kinase array. The sphere formation assays, cloning-formation assays and cell migration assays were used to evaluate the stemness and migration ability of HCC cells. Identifying the GPX8-interacting proteins was accomplished through immunoprecipitation and protein mass spectrometry.ResultsThe GPX8 protein levels were downregulated in HCC patients. Low expression of GPX8 protein was related to early recurrence and poor prognosis in HCC patients. GPX8 knockdown could enhance the stemness and migration ability of HCC cells. Consistently, Based on transcriptome analysis, multiple signaling pathways that include the PI3K-AKT and signaling pathways that regulate the pluripotency of stem cells, were activated after GPX8 knockdown. The downregulation of GPX8 could increase the expression of the tumor stemness markers KLF4, OCT4, and CD133. The in vivo downregulation of GPX8 could also promote the subcutaneous tumor-forming and migration ability of HCC cells. MK-2206, which is a small-molecule inhibitor of AKT, could reverse the tumor-promoting effects both in vivo and in vitro. We discovered that GPX8 and the 71-kDa heat shock cognate protein (Hsc70) have a direct interaction. The phosphorylation of AKT encouraged the translocation of Hsc70 into the nucleus and the expression of the PI3K p110 subunit, thereby increasing the downregulation of GPX8.ConclusionThe findings from this study demonstrate the anticancer activity of GPX8 in HCC by inactivating the Hsc70/AKT pathway. The results suggest a possible therapeutic target for HCC.

Surufatinib combined with photodynamic therapy induces ferroptosis to inhibit cholangiocarcinoma in vitro and in tumor models.

The curative effect of single therapy for advanced cholangiocarcinoma (CCA) is poor, thus investigating combined treatment strategies holds promise for improving prognosis. Surufatinib (SUR) is a novel multikinase inhibitor that has been confirmed to prolong survival of patients with advanced CCA. Photodynamic therapy (PDT) can also ablate advanced CCA and relieve biliary obstruction. In this study, we explored the anti-CCA effect of SUR combined with PDT, and explored the underlying mechanism. We found that SUR could effectively inhibit the abilities of proliferation, migration and metastasis in CCA cells (HUCCT-1, RBE). The ability of SUR to inhibit CCA was also confirmed by the HUCCT-1 cell xenograft model in Balb/c nude mice and CCA patient-derived organoids. SUR combined with PDT can significantly enhance the inhibitory effect on CCA, and can be alleviated by two ferroptosis inhibitors (Ferrostatin-1, Deferoxamine). By detecting the level of reactive oxygen species, lipid peroxides, malondialdehyde and glutathione, we further confirmed that SUR combined with PDT can inhibit CCA cells by inducing ferroptosis. Glutathione peroxidase 4 (GPX4) belongs to the glutathione peroxidase family and is mainly responsible for the metabolism of intracellular hydrogen peroxide. GPX4 inhibits ferroptosis by reducing cytotoxic lipid peroxides (L-OOH) to the corresponding alcohols (L-OH). Acyl-CoA synthetase long-chain family member 4 (ACSL4) is a member of the long-chain fatty acid coenzyme a synthetase family and is mainly involved in the biosynthesis and catabolism of fatty acids. ACSL4 induces ferroptosis by promoting the accumulation of lipid peroxides. Both SUR and PDT can induce ferroptosis by promoting ACSL4 and inhibiting GPX4. The regulation effect is found to be more significant in combined treatment group. In conclusion, SUR combined with PDT exerted an anti-CCA effect by inducing ferroptosis. Combination therapy provides a new idea for the clinical treatment of CCA.

Se Alleviated Pb-Caused Neurotoxicity in Chickens: SPS2-GPx1-GSH-IL-2/IL-17-NO Pathway, Selenoprotein Suppression, Oxidative Stress, and Inflammatory Injury.

Lead (Pb), a heavy metal environmental pollutant, poses a threat to the health of humans and birds. Inflammation is one of the most common pathological phenomena in the case of illness and poisoning. However, the underlying mechanisms of inflammation remain unclear. The cerebellum and the thalamus are important parts of the nervous system. To date, there have been no reports of Pb inducing inflammation in animal cerebellums or thalami. Selenium (Se) can relieve Pb poisoning. Therefore, we aimed to explore the mechanism by which Se alleviates Pb toxicity to the cerebellums and thalami of chickens by establishing a chicken Pb or/and Se treatment model. Our results demonstrated that exposure to Pb caused inflammatory damage in cerebellums and thalami, evidenced by the characteristics of inflammation, the decrease in anti-inflammatory factors (interleukin (IL)-2 and interferon-γ (INF-γ)), and the increase in pro-inflammatory factors (IL-4, IL-6, IL-12β, IL-17, and nitric oxide (NO)). Moreover, we found that the IL-2/IL-17-NO pathway took part in Pb-caused inflammatory injury. The above findings were reversed by the supplementation of dietary Se, meaning that Se relieved inflammatory damage caused by Pb via the IL-2/IL-17-NO pathway. In addition, an up-regulated oxidative index malondialdehyde (MDA) and two down-regulated antioxidant indices (glutathione (GSH) and total antioxidant capacity (TAC)) were recorded after the chickens received Pb stimulation, indicating that excess Pb caused an oxidant/antioxidant imbalance and oxidative stress, and the oxidative stress mediated inflammatory damage via the GSH-IL-2 axis. Interestingly, exposure to Pb inhibited four glutathione peroxidase (GPx) family members (GPx1, GPx2, GPx3, and GPx4), three deiodinase (Dio) family members (Dio1, Dio2, and Dio3), and fifteen other selenoproteins (selenophosphate synthetase 2 (SPS2), selenoprotein (Sel)H, SelI, SelK, SelM, SelO, SelP1, SelPb, SelS, SelT, SelU, and selenoprotein (Sep)n1, Sepw1, Sepx1, and Sep15), suggesting that Pb reduced antioxidant capacity and resulted in oxidative stress involving the SPS2-GPx1-GSH pathway. Se supplementation, as expected, reversed the changes mentioned above, indicating that Se supplementation improved antioxidant capacity and mitigated oxidative stress in chickens. For the first time, we discovered that the SPS2-GPx1-GSH-IL-2/IL-17-NO pathway is involved in the complex inflammatory damage mechanism caused by Pb in chickens. In conclusion, this study demonstrated that Se relieved Pb-induced oxidative stress and inflammatory damage via the SPS2-GPx1-GSH-IL-2/IL-17-NO pathway in the chicken nervous system. This study offers novel insights into environmental pollutant-caused animal poisoning and provides a novel theoretical basis for the detoxification effect of Se against oxidative stress and inflammation caused by toxic pollutants.

The selenium-independent phospholipid hydroperoxide glutathione peroxidase from Theobroma cacao (TcPHGPX) protects plant cells against damages and cell death

Proteins from the glutathione peroxidase (GPX) family, such as GPX4 or PHGPX in animals, are extensively studied for their antioxidant functions and apoptosis inhibition. GPXs can be selenium-independent or selenium-dependent, with selenium acting as a potential cofactor for GPX activity. However, the relationship of plant GPXs to these functions remains unclear. Recent research indicated an upregulation of Theobroma cacao phospholipid hydroperoxide glutathione peroxidase gene (TcPHGPX) expression during early witches' broom disease stages, suggesting the use of antioxidant mechanisms as a plant defense strategy to reduce disease progression. Witches' broom disease, caused by the hemibiotrophic fungus Moniliophthora perniciosa, induces cell death through elicitors like MpNEP2 in advanced infection stages. In this context, in silico and in vitro analyses of TcPHGPX's physicochemical and functional characteristics may elucidate its antioxidant potential and effects against cell death, enhancing understanding of plant GPXs and informing strategies to control witches' broom disease. Results indicated TcPHGPX interaction with selenium compounds, mainly sodium selenite, but without improving the protein function. Protein-protein interaction network suggested cacao GPXs association with glutathione and thioredoxin metabolism, engaging in pathways like signaling, peroxide detection for ABA pathway components, and anthocyanin transport. Tests on tobacco cells revealed that TcPHGPX reduced cell death, associated with decreased membrane damage and H2O2 production induced by MpNEP2. This study is the first functional analysis of TcPHGPX, contributing to knowledge about plant GPXs and supporting studies for witches' broom disease control.

Genome-wide identification of Glutathione peroxidase (GPX) family genes and silencing TaGPX3.2A reduced disease resistance in wheat

Glutathione peroxidase (GPX) is a crucial enzyme that scavenges reactive oxygen species in plants, playing a vital role in enhancing plant stress resistance. In this study, we identified 14 glutathione peroxidase genes (TaGPXs) from common hexaploid wheat (Triticum aestivum L.). These genes were subsequently categorized into three distinct groups based on their phylogenetic relationships. Simultaneously, a preliminarily analysis was conducted on the protein characteristics, chromosome localization, gene structure, cis-regulatory elements and transcriptome. Using reverse transcription quantitative PCR to analyze the expression patterns of five GPX genes that were investigated under various exogenous hormone treatments. According to the qRT-PCR analysis, it indicated that TaGPX genes have the distinct expression patterns. The enzyme activities in transiently overexpressed Nicotiana benthamiana (TaGPX3.2A and TaGPX3.4A) leaves were measured under salt and drought stresses, showed that peroxidase (POD) exhibited higher enzyme activity under stresses. Silencing TaGPX3.2A by virus-induced gene silencing (VIGS) led to reduced resistance of wheat to Fusarium graminearum, indicating that TaGPX3.2A plays a crucial role in enhancing wheat resistance against F. graminearum. This research provides a foundational basis for further investigations on the functional characterization of TaGPXs family members. And in the future it is provides valuable resources for genetic improvement of wheat resistance.

A PPIX-binding probe facilitates discovery of PPIX-induced cell death modulation by peroxiredoxin

While heme synthesis requires the formation of a potentially lethal intermediate, protoporphyrin IX (PPIX), surprisingly little is known about the mechanism of its toxicity, aside from its phototoxicity. The cellular protein interactions of PPIX might provide insight into modulators of PPIX-induced cell death. Here we report the development of PPB, a biotin-conjugated, PPIX-probe that captures proteins capable of interacting with PPIX. Quantitative proteomics in a diverse panel of mammalian cell lines reveal a high degree of concordance for PPB-interacting proteins identified for each cell line. Most differences are quantitative, despite marked differences in PPIX formation and sensitivity. Pathway and quantitative difference analysis indicate that iron and heme metabolism proteins are prominent among PPB-bound proteins in fibroblasts, which undergo PPIX-mediated death determined to occur through ferroptosis. PPB proteomic data (available at PRIDE ProteomeXchange # PXD042631) reveal that redox proteins from PRDX family of glutathione peroxidases interact with PPIX. Targeted gene knockdown of the mitochondrial PRDX3, but not PRDX1 or 2, enhance PPIX-induced death in fibroblasts, an effect blocked by the radical-trapping antioxidant, ferrostatin-1. Increased PPIX formation and death was also observed in a T-lymphoblastoid ferrochelatase-deficient leukemia cell line, suggesting that PPIX elevation might serve as a potential strategy for killing certain leukemias.

Ferric chloride induces ferroptosis in Pseudomonas aeruginosa and heals wound infection in a mouse model

As one of the most common pathogens leading to fatal human infection, Pseudomonas aeruginosa has been evolving complex drug resistance, posing significant challenges to the current antibiotic-dependent healthcare system. New therapeutic approaches are urgently required to treat infections caused by P. aeruginosa. Inspired by ferroptosis, we investigated the antibacterial effects of iron compounds on P. aeruginosa via direct exposure, and developed thermal-responsive hydrogels to carry FeCl3 as a wound dressing to treat P. aeruginosa-induced wound infection in mice model. The results showed that 200 μM FeCl3 killed more than 99.9% P. aeruginosa cells. The FeCl3-mediated cell death in P. aeruginosa was associated with ferroptosis hallmarks of mammal cells, e.g., reactive oxygen species (ROS) burst, lipid peroxidation, and DNA damage. Either catalase or Fe2+ chelator alleviated the FeCl3-mediated cell death, indicating that H2O2 and labile Fe2+ facilitated the Fenton reaction leading to the cell death. Further proteomics analysis showed that proteins related to glutathione (GSH) synthesis and glutathione peroxidase (GPX) family were significantly down-regulated after FeCl3 treatment, equivalent to GPX4 inactivation in ferroptosis-occurring mammal cells. We further evaluated the therapeutic effect of FeCl3 on P. aeruginosa in a mouse wound infection model using polyvinyl alcohol-boric acid (PB) hydrogels as the carrier of FeCl3. Strikingly, FeCl3-PB hydrogels completely cleared pus on wounds and promoted the healing of wounds. These results indicated that FeCl3 facilitates microbial ferroptosis in the gram-negative pathogen P. aeruginosa and has high therapeutic potential in P. aeruginosa wound infection.

Research progress of glutathione peroxidase family (GPX) in redoxidation.

Maintaining the balance of a cell's redox function is key to determining cell fate. In the critical redox system of mammalian cells, glutathione peroxidase (GPX) is the most prominent family of proteins with a multifaceted function that affects almost all cellular processes. A total of eight members of the GPX family are currently found, namely GPX1-GPX8. They have long been used as antioxidant enzymes to play an important role in combating oxidative stress and maintaining redox balance. However, each member of the GPX family has a different mechanism of action and site of action in maintaining redox balance. GPX1-4 and GPX6 use selenocysteine as the active center to catalyze the reduction of H2O2 or organic hydroperoxides to water or corresponding alcohols, thereby reducing their toxicity and maintaining redox balance. In addition to reducing H2O2 and small molecule hydroperoxides, GPX4 is also capable of reducing complex lipid compounds. It is the only enzyme in the GPX family that directly reduces and destroys lipid hydroperoxides. The active sites of GPX5 and GPX7-GPX8 do not contain selenium cysteine (Secys), but instead, have cysteine residues (Cys) as their active sites. GPX5 is mainly expressed in epididymal tissue and plays a role in protecting sperm from oxidative stress. Both enzymes, GPX7 and GPX8, are located in the endoplasmic reticulum and are necessary enzymes involved in the oxidative folding of endoplasmic reticulum proteins, and GPX8 also plays an important role in the regulation of Ca2+ in the endoplasmic reticulum. With an in-depth understanding of the role of the GPX family members in health and disease development, redox balance has become the functional core of GPX family, in order to further clarify the expression and regulatory mechanism of each member in the redox process, we reviewed GPX family members separately.

Detection of selenoprotein transcriptome in chondrocytes of patients with Kashin-Beck disease.

Background: Kashin-Beck disease (KBD) is a deformed osteochondral disease with a chronic progression that is restrictively distributed in eastern Siberia, North Korea, and some areas of China, and selenium deficiency has been identified as an important factor in the pathogenesis of this disease in recent years. Objective: The aim of this study is to investigate the selenoprotein transcriptome in chondrocytes and define the contribution of selenoprotein to KBD pathogenesis. Methods: Three cartilage samples were collected from the lateral tibial plateau of adult KBD patients and normal controls paired by age and sex for real-time quantitative polymerase chain reaction (RT-qPCR) to detect the mRNA expression of 25 selenoprotein genes in chondrocytes. Six other samples were collected from adult KBD patients and normal controls. In addition, immunohistochemistry was used on four adolescent KBD samples and seven normal controls (IHC) to determine the expression of proteins screened by RT-qPCR results that had different gene levels. Results: Increased mRNA expression of GPX1 and GPX3 was observed in chondrocytes, and stronger positive staining was displayed in the cartilage from both adult and adolescent patients. The mRNA levels of DIO1, DIO2, and DIO3 were increased in KBD chondrocytes; however, the percentage of positive staining decreased in the KBD cartilage of adults. Conclusion: The selenoprotein transcriptome, mainly the glutathione peroxidase (GPX) and deiodinase (DIO) families were altered in KBD and might play a vital role in the pathogenesis of KBD.

The presence of glutathione peroxidase 8 (GPx8) in rat male genital organs.

The aim of our work was to determine the presence of GPx8, the latest discovered member of glutathione peroxidase family, in rat male genital organs. The oxidative stress is considered as one of the most important causalities of male infertility. To defend itself, the organism comprises many different antioxidants. We assessed the GPx8 presence in tissues of genital organs from adult rat Sprague-Dawley males by mRNA expression, Western Blot analysis, and immunohistochemistry. The highest mRNA and protein levels were detected in the testis, followed by seminal vesicle. Within testis the enzyme was observed predominantly in the Leydig and Sertoli cells, residual and Hermes bodies. In other organs, such as epididymis, seminal vesicle and prostate gland, the GPx8 was seen in the cytoplasm of epithelial cells. The enzyme was also observed in the muscular layer of hollow organs, in blood plasma and extracellular matrix. The antioxidant enzyme GPx8 was detected in all examined male genital organs. The fact, that the enzyme was released into lumen of genital organs probably means, that GPx8 is also a component of the semen. To our knowledge, this is the first paper describing GPx8 presence in male genital organs of mammals (Fig. 8, Ref. 63).

Bioinformatics analysis on the expression of GPX family in gastric cancer and its correlation with the prognosis of gastric cancer

BackgroundGastric cancer (GC) is one of the most common cancers of the digestive tract, with the fifth-highest incidence and third highest mortality rate in the world. MethodsIn this study, the Kaplan-Meier Plotter database was used to analyze the correlation between the expression of the glutathione peroxidase (GPX) family and the clinical prognosis of gastric cancer (GC). The prognostic value of increased GPX family mRNA expression in GC patients in different clinical stages, with different differentiation degrees, in different genders and human epidermal growth factor receptor-2 (HER2) status, and treated with different therapeutic regimens was also studied. ResultsThe results showed that with the increase of GPX1 and GPX2 mRNA low expression levels, the overall survival (OS) of gastric cancer patients was longer. However, when the high expression levels of GPX3, GPX5 and GPX6 mRNA increased, gastric cancer patients presented good OS, while the increase of GPX4 mRNA expression level had no significant correlation with OS in gastric cancer patients. ConclusionThe results of this study are expected to provide a reliable basis for the clinical treatment of GC and lay a foundation for the development of a novel GC treatment approach.

Glutathione peroxidase family and survival prognosis in patients with renal cell carcinoma.

Renal cell carcinoma (RCC) is a renal cortical tumor with high clinical incidence. The effect of glutathione peroxidases (GPXs) on RCC and the possible mechanism are still unclear. This study aims to explore the expression level of GPXs gene in RCC and its effect on the clinical prognosis of patients with RCC via bioinformatics analysis. The mRNA expressions of GPXs family genes were obtained from the public data of The Cancer Genome Atlas (TCGA) database. The Kruskal-Wails test was used to analyze the differences in mRNA expression of GPXs family genes between samples from patients with RCC and the normal population. UALAN databases were used to analyze the differences in protein expression of GPXs family genes between samples from patients with renal clear cell carcinoma and the normal population, and to evaluate the role of GPXs family genes in RCC. The Kaplan-Meier Plotter was used to analyze the correlation between different types of RCC and overall survival (OS), disease-free survival (DFS), disease-specific survival (DSS), and progression-free survival (PFS). Kaplan-Meier survival curve was drawn based on the GPX8 gene expression to study the relationship between GPX8 gene expression and prognosis of RCC patients. Based on the results of multivariate Cox regression analysis, a Nomogram scoring model for RCC prediction was established by introducing GPX8 gene. The mRNA expressions of GPX1 and GPX4 were higher in the sample of renal chromophobe cell carcinoma, renal clear cell carcinoma, and renal papillary cell carcinoma than those in the normal population (all P<0.01), and GPX7 and GPX8 were significantly over-expressed in patients with renal papillary cell carcinoma and renal clear cell carcinoma (all P<0.01). Compared with the normal group, the protein expressions of GPX1, GPX2, GPX7, and GPX8 were increased significantly in renal clear cell carcinoma (all P<0.01), while GPX3 and GPX4 expressions were decreased significantly (both P<0.01). The protein expressions of GPX1, GPX2, GPX7, and GPX8 were increased significantly in patients with renal clear cell carcinoma at different tumor grades (all P<0.01), while GPX3 and GPX4 expressions were decreased significantly (both P<0.01). Survival analysis showed that OS, DFS, DSS, and PFS were all decreased in patients with clear cell carcinoma compared with patients with papillary cell carcinoma and chromophobe cell carcinoma. According to the GPX8 level, patients were assigned into the low, medium, and high expression groups. Compared with the low GPX8 level group, the OS (P<0.01), DFS (P=0.03), DSS (P<0.01), and PFS (P=3.18×10-7) were significantly decreased in the high level group. Univariate Cox proportional regression analysis showed that the high level of GPX8 was associated with poor OS of 3 different types of renal cancer. Multifactorial analysis showed that GPX8 was an independent factor affecting the OS of patients with renal papillary cell carcinoma. Race and post tumor node metastasis (pTNM) typing were independent factors influencing the OS of patients with renal clear cell carcinoma. GPX8 and pTMN were independent factors influencing the OS of patients with renal chromophobe cell carcinoma. Based on these variables, the Nomogram risk models of 3 types of cell carcinoma were established, and the discrimination and calibration of the models were evaluated using the Consistency index (C-index) and calibration curves. The C-index of the risk model of renal papillary cell carcinoma was 0.62 (95% CI 0.51 to 1.00, P=0.03). The results of receiver operating characteristic (ROC) curve showed that the area under the curve (AUC) was 0.88. The C-index of the risk model of renal clear cell carcinoma was 0.72 (95% CI 0.52 to 1.00, P=0.03). The results of ROC curve showed that the AUC was 0.90. The C-index of the risk model of chromophobe cell carcinoma of kidney was 0.90 (95% CI 0.85 to 1.00, P<0.01). The results of ROC curve showed that the AUC was 0.59. GPXs family genes, especially GPX8, are potential markers for poor prognosis of RCC, and the occurrence and development of RCC can be predicted in clinical practice based on the expressions of GPXs family genes.

Immunohistochemistry and Bioinformatics Identify GPX8 as a Potential Prognostic Biomarker and Target in Human Gastric Cancer.

BackgroundGlutathione peroxidase 8 (GPX8) is a type II transmembrane protein with rare structural features belonging to the glutathione peroxidase family. The function of GPX8 in stomach adenocarcinoma has not been discovered clearly.MethodsIn this study, we comprehensively analyzed the expression of GPX8 in stomach adenocarcinoma and discovered that it is a potential target in the treatment of stomach adenocarcinoma. The immunohistochemical staining of GPX8 and survival analysis were performed in carcinoma tissue and adjacent tissues of 83 gastric cancer patients. The Gene Expression Profiling Interactive Analysis (GEPIA) database and Kaplan–Meier plotter database were used to evaluate the prognostic survival of GPX8 in stomach adenocarcinoma. The Cancer Genome Atlas (TCGA) database was used to download the microarray mRNA data of GPX8 and clinical information for cancer patients. The TIMER database and GSEA database were used to systematically evaluate the association of GPX8 and tumor-infiltrating lymphocytes in adenocarcinoma carcinoma. The STRING database was used to analyze protein-to-protein interactions of GPX8. The ROC curve was used to analyze the diagnostic effect of GPX8 in distinguishing outcomes between different subgroups, and a nomogram was constructed based on GPX8. Top transcription factor binding sites were analyzed using the QIAGEN database in the GPX8 gene promoter, and the functional enrichment analysis of GPX8 was done by GO and KEGG pathway enrichment analyses.ResultBased on the GEPIA and TCGA databases, the mRNA expression of GPX8 was significantly higher in stomach adenocarcinoma compared with the adjacent normal tissues. The GEPIA and Kaplan–Meier plotter databases showed that a higher GPX8 expression level was correlated with poor prognosis of stomach adenocarcinoma, suggesting that GPX8 was a risk factor of poor prognosis in stomach adenocarcinoma. The TIMER database showed that the GPX8 expression level was positively correlated with infiltrating levels of CD8+ T cells, CD4+ T cells, macrophages, neutrophils, and dendritic cells in stomach adenocarcinoma. The GSEA database indicated that GPX8 was positively correlated with B cells, dendritic cells, CD4+ T cells, CD8+ T cells, macrophages, mast cells, monocytes, and natural killer cells. At last, GO analysis indicated that the biological processes were enriched in collagen fibril organization, endodermal cell differentiation, collagen metabolic process, extracellular matrix organization, etc. KEGG signaling pathway analysis showed that GPX8 was correlated with protein digestion and absorption, extracellular matrix receptor interaction, AGE/RAGE signaling pathway, etc. The GSEA database showed that GPX8 was positively associated with angiogenesis, epithelial mesenchymal transition, hedgehog signaling, etc. The immunohistochemical staining of GPX8 and survival analysis in 83 gastric cancer patients showed that the OS rate of patients with a high GPX8 expression was significantly lower than that of the low GPX8 expression group.ConclusionGPX8 is an important factor which might be a potential target in the treatment of stomach adenocarcinoma.

The Selenoprotein Glutathione Peroxidase 4: From Molecular Mechanisms to Novel Therapeutic Opportunities.

The selenoprotein glutathione peroxidase 4 (GPX4) is one of the main antioxidant mediators in the human body. Its central function involves the reduction of complex hydroperoxides into their respective alcohols often using reduced Glutathione (GSH) as a reducing agent. GPX4 has become a hotspot therapeutic target in biomedical research following its characterization as a chief regulator of ferroptosis, and its subsequent recognition as a specific pharmacological target for the treatment of an extensive variety of human diseases including cancers and neurodegenerative disorders. Several recent studies have provided insights into how GPX4 is distinguished from the rest of the glutathione peroxidase family, the unique biochemical properties of GPX4, how GPX4 is related to lipid peroxidation and ferroptosis, and how the enzyme may be modulated as a potential therapeutic target. This current report aims to review the literature underlying all these insights and present an up-to-date perspective on the current understanding of GPX4 as a potential therapeutic target.

GPX3 IS REQUIRED TO MEDIATE PROTECTIVE EFFECTS OF GPX1 LOSS IN COLITIS

Abstract Reactive oxygen species (ROS) have long been known to contribute to the development and severity of Inflammatory Bowel Disease. However, more recent data indicates ROS may not always be pathogenic, and in fact ROS may be necessary for intestinal homeostasis. Thus, the role of ROS in the intestine, and antioxidant proteins which regulate ROS, may be contextual and dose-dependent. Members of the glutathione peroxidase (GPx) family are antioxidants that reduce hydrogen peroxide to water. Previously, we determined that loss of GPx1, the most widely expressed GPx, protected against dextran sodium sulfate (DSS)-induced colitis and augmented intestinal proliferation. To better understand how a stepwise increase in ROS may affect intestinal phenotypes, Gpx1-/- mice were next crossed with Gpx3 null mice to yield double-knockout (DKO) mice. First, we assessed baseline proliferation, apoptosis, and DNA damage in the colon. Interestingly, while Gpx1-/- mice displayed increased proliferation compared to WT mice, this was not observed in the DKO mice. Furthermore, Gpx1-/- mice had no change in apoptosis or DNA damage, yet both were increased in DKO mice. Together, these data suggest DKO mice lose the survival benefits of GPx1 loss upon greater reduction of antioxidant capabilities. Next, we assessed the effects of combined GPx1 and GPx3 loss in the context of inflammation and colitis. At baseline, multiplex cytokine profiling identified higher levels of colitis-associated cytokines, including IL-12, CCL4, and CCL5, in DKO mice as compared to either Gpx1-/- or WT cohorts. Pro-inflammatory changes were more pronounced upon aging, as one-year-old DKO mice showed higher levels of TNF-α and IL-17, as well as histologic evidence of chronic inflammation which was absent in similarly aged WT mice. Next, we tested the effects of experimental DSS colitis. Here, while Gpx1-/- mice had less severe injury in the DSS colitis model, DKO mice showed more pronounced weight loss and a trend towards shortened colons as compared to WT mice. Finally, altered ROS-mediated signaling is known to impact interactions with the microbiota, and increased microbial diversity is associated with protection from colitis. To establish whether loss of GPx1 and GPx3 impacted the gut microbiome, stool was harvested from WT, Gpx1-/-, and DKO mice and bacterial DNA was assessed by 16S RNA sequencing. Interestingly, and in line with less severe colitis, Gpx1-/- mice had increased diversity and evenness compared to WT mice, whereas there was no change between WT and DKO mice. Taken together, these data indicate that GPx3 is required to mediate the anti-inflammatory effects of GPx1 loss. Furthermore, combinatorial GPx loss induces greater colonic inflammation at baseline and during DSS-induced colitis, highlighting dose-dependent effects of ROS and antioxidant capacity in the intestine.

GPX7 Is Targeted by miR-29b and GPX7 Knockdown Enhances Ferroptosis Induced by Erastin in Glioma.

BackgroundGlioma is a lethal primary tumor of central nervous system. Ferroptosis is a newly identified form of necrotic cell death. Triggering ferroptosis has shown potential to eliminate aggressive tumors. GPX7, a member of glutathione peroxidase family (GPXs), has been described to participate in oxidative stress and tumorigenesis. However, the biological functions of GPX7 in glioma are still unknown.MethodsBioinformatics method was used to assess the prognostic role of GPX7 in glioma. CCK8, wound healing, transwell and cell apoptosis assays were performed to explore the functions of GPX7 in glioma cells. In vivo experiment was also conducted to confirm in vitro findings. Ferroptosis-related assays were carried out to investigate the association between GPX7 and ferroptosis in glioma.ResultsGPX7 was aberrantly expressed in glioma and higher expression of GPX7 was correlated with adverse outcomes. GPX7 silencing enhanced ferroptosis-related oxidative stress in glioma cells and the loss of GXP7 sensitized glioma to ferroptosis induced by erastin. Furthermore, we found that miR-29b directly suppressed GPX7 expression post-transcriptionally. Reconstitution of miR-29b enhanced erastin sensitivity, partly via GPX7 suppression.ConclusionsOur study clarified the prognostic role of GPX7 in glioma and preliminarily revealed the role of GPX7 in ferroptosis, which may be conducive to the exploration of therapeutic targets of glioma.

Assay of selenol species in biological samples by the fluorescent probe Sel-green.

Selenium (Se) is an essential trace element for diverse cellular functions. The biological significance of Se is predominantly dependent on its incorporation into the selenocysteine (Sec) for synthesis of selenoproteins (SePs), such as thioredoxin reductase family enzymes and glutathione peroxidase family enzymes. In general, the hyperactivity of the selenol group in Sec confers the Sec residue critical for functions of SePs. The Sec is much less abundant than its sulfur analog cysteine (Cys), and it remains a high challenge to detect Sec, especially in complex biological samples. We recently reported a selective fluorescent probe Sel-green for selenols and summarized the principles for design of selenol (and thiophenol) probes. Sel-green discriminates selenols from other biological species, especially thiols, under physiological conditions, and has been applied to detect both endogenous and exogenous selenol species in live cells. In this chapter, we describe a protocol and guideline for the selective detection of Sec by applying the Sel-green. This protocol is also suitable for detection of other selenol species. This practical and convenient assay would assist scientists to better understand the pivotal roles of Sec as well as SePs.