Evaluation of the antioxidant and anti-inflammatory effect of sublingual glutathione on COPD patients

Glutathione (GSH) is a potent antioxidant and anti-inflammatory, proven effective in reducing treatment duration, prescribed doses, and hospitalization for several diseases. This study assessed the therapeutic response of chronic obstructive pulmonary disease (COPD) patients by measuring oxidative superoxide dismutase (SOD3), glutathione peroxidase 1 (GPX1), and inflammatory biomarkers such as tumor necrosis factor-alpha (TNF-α) and Interleukin-8 (IL-8) after sublingual administration of glutathione supplements. A cohort of 50 COPD individuals was involved and divided into two groups of 25 each. The first group received conventional therapy involving the administration of formoterol fumarate (12 µg inhaler) twice daily. The second group received the conventional treatment alongside sublingual glutathione (300 mg twice daily) for two months. The levels of serum IL-8, TNF-α, SOD3, and GPX1 were assessed before therapy, as well as at one and two months after treatment, in both cohorts. Both groups exhibited a notable reduction in the inflammatory mediators IL-8 and TNF-α when compared to their respective pre-treatment levels (P value <0.05). However, it is worth noting that the observed difference between the groups was not statistically significant (P value >0.05). The levels of SOD3 and GPX1 exhibited a substantial rise in both groups; however, they were found to be greater in group 2 compared to group 1 (P value >0.05). The administration of glutathione resulted in enhanced levels of antioxidant biomarkers among individuals diagnosed with COPD, accompanied by a minor and statistically insignificant decrease in the levels of the anti-inflammatory mediators IL-8 and TNF-alpha.

Selenium-dependent glutathione peroxidase 1 regulates transcription of elongase 3 in murine tissues

We have previously shown dysregulated lipid metabolism in tissues of glutathione peroxidase 1 (GPX1) overexpressing (OE) or deficient (KO) mice. This study explored underlying mechanisms of GPX1 in regulating tissue fatty acid (FA) biosynthesis. GPX1 OE, KO, and wild-type (WT) mice (n = 5, male, 3-6 months old) were fed a Se-adequate diet (0.3 mg/kg) and assayed for liver and adipose tissue FA profiles and mRNA levels of key enzymes of FA biosynthesis and redox-responsive transcriptional factors (TFs). These three genotypes of mice (n = 5) were injected intraperitoneally with diquat, ebselen, and N-acetylcysteine (NAC) at 10, 50, and 50 mg/kg of body weight, respectively, and killed at 0 and 12 h after the injections to detect mRNA levels of FA elongases and desaturases and the TFs in the liver and adipose tissue. A luciferase reporter assay with targeted deletions of mouse Elovl3 promoter was performed to determine transcriptional regulations of the gene by GPX1 mimic ebselen in HEK293T cells. Compared with WT, GPX1 OE and KO mice had 9-42% lower (p < 0.05) and 36-161% higher (p < 0.05) concentrations of C20:0, C22:0, and C24:0 in these two tissues, respectively, along with reciprocal increases and decreases (p < 0.05) of Elovl3 transcripts. Ebselen and NAC decreased (p < 0.05), whereas diquat decreased (p < 0.05), Elovl3 transcripts in the two tissues. Overexpression and knockout of GPX1 decreased (p < 0.05) and increased (p < 0.05) ELOVL3 levels in the two tissues, respectively. Three TFs (GABP, SP1, and DBP) were identified to bind the Elovl3 promoter (-1164/+33 base pairs). Deletion of DBP (-98/-86 base pairs) binding domain in the promoter attenuated (13%, p < 0.05) inhibition of ebselen on Elovl3 promoter activation. In summary, GPX1 overexpression down-regulated very long-chain FA biosynthesis via transcriptional inhibition of the Elovl3 promoter activation.

Lipid peroxidation-derived modification and its effect on the activity of glutathione peroxidase 1

Oxidative stress and the resulting lipid peroxidation are associated with various pathological states, including neurodegenerative diseases and cancer. The end products of lipid peroxidation, such as 4-oxo-2(E)-nonenal (ONE), 4-hydroxy-2(E)-nonenal (HNE), and methylglyoxal (MG), exert several biological effects through modification of various cellular components, including DNA and proteins. Glutathione peroxidase 1 (GPx1) is an intracellular antioxidant enzyme that uses glutathione (GSH) to reduce a variety of peroxides, thereby modulating cellular oxidative stress and redox-mediated responses. GPx1 contains nucleophilic amino acids at its active (one Sec) and GSH-binding (four Arg and one Lys) sites. We found that lipid peroxidation-derived reactive aldehydes (ONE, HNE, and MG) modified the GSH-binding site, resulting in the inhibition of GPx1 activity. Mass spectrometry-based proteomic analysis identified the sites modified by each aldehyde (ONE, 14 sites; HNE, 7 sites; MG, 9 sites). The GSH-binding sites modified were as follows: ONE, Arg57, 103, 184, and 185; HNE, Lys91; MG, Arg103. Upon incubation of GPx1 with each aldehyde, ONE reduced GPx1 activity more significantly than did HNE or MG in a dose- and time-dependent manner. The addition of GSH to GPx1 3 h after incubation with ONE prevented further inhibition by trapping ONE as a ONE-GSH adduct. However, the activity of GPx1 was not restored to the initial level, indicating that ONE modified GPx1 irreversibly. This study suggests that oxidative damage to lipids, resulting in the formation of reactive aldehydes, can amplify cellular oxidative stress via direct inactivation of GPx1, which increases the production of intracellular peroxides.

Cellular and exosomal GPx1 are essential for controlling hydrogen peroxide balance and alleviating oxidative stress in hypoxic glioblastoma

Tumor hypoxia promotes malignant progression and therapeutic resistance in glioblastoma partly by increasing the production of hydrogen peroxide (H2O2), a type of reactive oxygen species critical for cell metabolic responses due to its additional role as a second messenger. However, the catabolic pathways that prevent H2O2 overload and subsequent tumor cell damage in hypoxic glioblastoma remain unclear. Herein, we present a hypoxia-coordinated H2O2 regulatory mechanism whereby excess H2O2 in glioblastoma induced by hypoxia is diminished by glutathione peroxidase 1 (GPx1), an antioxidant enzyme detoxifying H2O2, via the binding of hypoxia-inducible factor-1α (HIF-1α) to GPx1 promoter. Depletion of GPx1 results in H2O2 overload and apoptosis in glioblastoma cells, as well as growth inhibition in glioblastoma xenografts. Moreover, tumor hypoxia increases exosomal GPx1 expression, which assists glioblastoma and endothelial cells in countering H2O2 or radiation-induced apoptosis in vitro and in vivo. Clinical data explorations further demonstrate that GPx1 expression was positively correlated with tumor grade and expression of HIF-1α, HIF-1α target genes, and exosomal marker genes; by contrast, it was inversely correlated with the overall survival outcome in human glioblastoma specimens. Our analyses validate that the redox balance of H2O2 within hypoxic glioblastoma is clinically relevant and could be maintained by HIF-1α-promoted or exosome-related GPx1.

Growth differentiation factor-15 and circulating biomarkers as predictors of periodontal treatment effects in patients with periodontitis: a randomized-controlled clinical trial

BACKGROUND

During the last decades, in patients with periodontitis, periodontal treatment has been shown to reduce the potential release of local and systemic biomarkers linked to an early risk of systemic inflammatory disorders. This study evaluated the efficacy of non-surgical-periodontal treatment (NSPT) on growth differentiation factor 15 (GDF-15) and related circulating biomarkers such as glutathione peroxidase 1 (GPx-1), c-reactive protein (hs-CRP), and surfactant protein D (SP-D) in periodontal patients and explored whether subjects who had high GDF-15 levels at baseline showed increased clinical benefits following NSPT at 6-months follow-up.

METHODS

For this two-arm, parallel randomized clinical trial, patients with periodontitis were randomly allocated to receive quadrant scaling and root-planing (Q-SRP, n = 23, median age 51 years old) or full-mouth disinfection (FMD, n = 23, median age 50 years old) treatment. Clinical and periodontal parameters were recorded in all enrolled patients. The primary outcome was to analyse serum concentrations changes of GDF-15 and of GPx-1, hs-CRP, and SP-D at baseline and at 30, 90, and 180-days follow-up after NSPT through enzyme-linked immunosorbent assay (ELISA) and nephelometric assay techniques.

RESULTS

In comparison with FMD, patients of the Q-SRP group showed a significant improvement in clinical periodontal parameters (p < 0.05) and a reduction in the mean levels of GDF-15 (p = 0.005), hs-CRP (p < 0.001), and SP-D (p = 0.042) and an increase of GPx-1 (p = 0.025) concentrations after 6 months of treatment. At 6 months of treatment, there was a significant association between several periodontal parameters and the mean concentrations of GDF-15, GPx-1, hs-CRP, and SP-D (p < 0.05 for all parameters). Finally, the ANOVA analysis revealed that, at 6 months after treatment, the Q-SRP treatment significantly impacted the reduction of GDF-15 (p = 0.015), SP-D (p = 0.026) and the upregulation of GPx-1 (p = 0.045).

CONCLUSION

The results evidenced that, after 6 months of treatment, both NSPT protocols improved the periodontal parameters and analyzed biomarkers, but Q-SRP was more efficacious than the FMD approach. Moreover, patients who presented high baseline GDF-15 and SP-D levels benefited more from NSPT at 6-month follow-up.

TRIAL REGISTRATION

NCT05720481.

Polyalanine polymorphism in the signal peptide of Glutathione peroxidase 1 (GPX1) gene & its association with osteoporosis

Background & objectives

Osteoporosis is a systemic skeletal disease, characterized by a low bone mass leading to increased bone fragility and hence, a greater susceptibility to the risk of fracture. Since age-related oxidative stress is one of the factors that has been implicated in developing low bone mineral density (BMD), leading to osteoporosis, this study wanted to explore the expression of antioxidant enzymes in individuals with osteoporosis. The present study focused on mapping polymorphism in an important antioxidant enzyme glutathione peroxidase 1 (GPx1) among osteoporosis and healthy Asian Indians.

Methods

Dual-energy X-ray absorptiometry was used to assess BMD of individuals and was classified into normal (n=96) and osteoporotic (n=88) groups. Biochemical parameters such as vitamin D, total oxidant status (TOS), and GPx1 enzyme activity were estimated from plasma samples of recruited individuals. Quantitative real-time qRT-PCR was carried out using GAPDH as an endogenous control. Genomic DNA was isolated from whole blood, and polymorphisms were evaluated by sequencing.

Results

The BMD was lower in osteoporotic individuals, and further analysis of biochemical parameters indicated significantly low 25-hydroxy vitamin D and GPx1 with higher TOS levels in osteoporotic as compared to healthy individuals. Furthermore, qRT-PCR revealed low expression of GPX1 in osteoporotic individuals. GPX1 sequence analysis of the promoter and two exons revealed the lower frequency of five alanine repeats in the osteoporotic individuals.

Interpretation & conclusions

In this study, the in silico analysis revealed the lower frequency of five alanine repeats in exon 1 of GPX1 and high TOS to be associated with osteoporosis. However, no polymorphism was found in exon 2 of GPX1 among the two study groups.

The role of glutathione peroxidase-1 in health and disease

Glutathione peroxidase 1 (GPx1) is an important cellular antioxidant enzyme that is found in the cytoplasm and mitochondria of mammalian cells. Like most selenoenzymes, it has a single redox-sensitive selenocysteine amino acid that is important for the enzymatic reduction of hydrogen peroxide and soluble lipid hydroperoxides. Glutathione provides the source of reducing equivalents for its function. As an antioxidant enzyme, GPx1 modulates the balance between necessary and harmful levels of reactive oxygen species. In this review, we discuss how selenium availability and modifiers of selenocysteine incorporation alter GPx1 expression to promote disease states. We review the role of GPx1 in cardiovascular and metabolic health, provide examples of how GPx1 modulates stroke and provides neuroprotection, and consider how GPx1 may contribute to cancer risk. Overall, GPx1 is protective against the development and progression of many chronic diseases; however, there are some situations in which increased expression of GPx1 may promote cellular dysfunction and disease owing to its removal of essential reactive oxygen species.

Contribution of glutathione peroxidase 1 (Pro200Leu) single nucleotide polymorphism and serum homocysteine levels in the risk of acute myocardial infarction in Egyptians

Background

Oxidative stress is among the most common risk factors in the pathogenesis of acute myocardial infarction (AMI). Glutathione peroxidase 1 enzyme coded by the GPX1 gene plays an essential role in reducing oxidative stress. Previous studies correlated the GPX1 (Pro200Leu) single nucleotide polymorphism (SNP) with AMI incidence. Elevated homocysteine (Hcy) levels induce oxidative stress and are considered an independent risk factor for AMI. Evidence showed a complex relationship between Hcy and GPx-1 activity. This study examined the association of the common (Pro200Leu) SNP in GPX1 with AMI incidence in an Egyptian population. This study is the first to check this association in an Egyptian population. Moreover, the association between serum Hcy and the incidence of AMI was checked, and the novelty was to statistically correlate GPX1 Pro200Leu genotypes with serum Hcy levels in patients and control subjects. Hundred control subjects and hundred and twenty AMI patients were genotyped using PCR-RFLP analysis. An ELISA was used to measure serum Hcy levels.

Results

The GPX1 (Pro200Leu) genotype distribution and allele frequency were not significantly different between patients and control subjects (P = 0.60 and P = 0.62, respectively). Serum levels of Hcy were significantly elevated in patients compared to control subjects (P ≤ 0.0001). However, no significant difference was observed in serum Hcy levels among different GPX1 genotypes in neither patients nor control subjects.

Conclusions

The minor T allele of GPX1 Pro200Leu is not associated with AMI risk in this Egyptian population. However, high homocysteine serum levels might contribute independently to the risk of AMI. Finally, Hcy levels were not significantly different in homozygous minor TT compared to homozygous wild CC.

Association of GSTO1, GSTO2, GSTP1, GPX1 and SOD2 polymorphism with primary open angle glaucoma

It is becoming increasingly evident that oxidative stress has a supporting role in pathophysiology and progression of primary open angle glaucoma (POAG). The aim of our study was to assess the association between polymorphisms in genes encoding enzymes involved in redox homeostasis, mitochondrial superoxide dismutase (SOD2), glutathione peroxidase (GPX1) and glutathione transferases (GSTs) with susceptibility to POAG. Single nucleotide polymorphisms in GST omega (GSTO1rs4925, GSTO2 rs156697), pi 1 (GSTP1 rs1695), as well as GPX1 (rs1050450) and SOD2 (rs4880) were determined by quantitative polymerase chain reaction (qPCR) in 102 POAG patients and 302 respective controls. The risk for POAG development was noted in carriers of both GSTO2*GG and GSTO1*AA variant genotypes (OR = 8.21, p = 0.002). Individuals who carried GPX1*TT and SOD2*CC genotypes had also an increased risk of POAG development but without significance after Bonferroni multiple test correction (OR = 6.66, p = 0.005). The present study supports the hypothesis that in combination, GSTO1/GSTO2, modulate the risk of primary open angle glaucoma.

hMTH1 and GPX1 expression in human thyroid tissue is interrelated to prevent oxidative DNA damage

Oxidative stress (OS) is recognized as disturbance of cellular equilibrium between reactive oxygen species (ROS) formation and their elimination by antioxidant defense systems. One example of ROS-mediated damage is generation of potentially mutagenic DNA precursor, 8-oxodGTP. In human cells genomic 8-oxodGTP incorporation is prevented by the MutT homologue 1 (MTH1 or hMTH1 for human MTH1) protein. It is well established that malignant cells, including thyroid cancer cells, require hMTH1 for maintaining proliferation and cancerous transformation phenotype. Above observations led to the development of hMTH1 inhibitors as novel anticancer therapeutics. In the current study we present extensive analysis of oxidative stress responses determining sensitivity to hMTH1 deficiency in cultured thyroid cells. We observe here that hMTH1 depletion results in downregulation of several glutathione-dependent OS defense system factors, including GPX1 and GCLM, making some of the tested thyroid cell lines highly dependent on glutathione levels. This is evidenced by the increased ROS burden and enhanced proliferation defect after combination of hMTH1 siRNA and glutathione synthesis inhibition. Moreover, due to the lack of data on hMTH1 expression in human thyroid tumor specimens we decided to perform detailed analysis of hMTH1 expression in thyroid tumor and peri-tumoral tissues from human patients. Our results allow us to propose here that anticancer activity of hMTH1 suppression may be boosted by combination with agents modulating glutathione pool, but further studies are necessary to precisely identify backgrounds susceptible to such combination treatment.

Sodium selenite protects from 3-nitropropionic acid-induced oxidative stress in cultured primary cortical neurons

Selenium (Se) is an essential trace element for humans; its intake is needed to allow the proper synthesis of 25 different selenoproteins that are necessary to the normal functioning of several organs, including the brain. Accordingly, decreased Se levels have been associated with neurological disorders. In the present study, we investigated the potential beneficial effects of Se, as sodium selenite, against 3-nitropropionic acid (3-NP)-induced oxidative stress in primary cultures of mouse cortical neurons. 3-NP treatment caused a significant decrease in cellular viability, which was accompanied by decreases in mitochondrial complex II activity and reduced glutathione (GSH) content, as well as increases in reactive oxygen species (ROS) generation and oxidized glutathione (GSSG) levels. Sodium selenite pretreatment (6 days) attenuated 3-NP-induced decrease in cell viability. In addition, sodium selenite pretreatment significantly protected against 3-NP-induced increase in ROS generation and decrease in GSH/GSSG ratio. Of note, sodium selenite pretreatment did not change 3-NP-induced decrease of mitochondrial complex II activity, suggesting that Se modulates secondary events resultant from 3-NP-induced mitochondrial dyshomeostasis. In addition, sodium selenite pretreatment significantly increased glutathione peroxidase (GPx) activity. Our data provide insights into the mechanism of protection by sodium selenite, which is related, at least in part, to GPx induction.

Role of glutathione peroxidase 1 in glucose and lipid metabolism-related diseases

Glutathione peroxidase 1 (GPX1) is a selenium-dependent enzyme that reduces intracellular hydrogen peroxide and lipid peroxides. While past research explored regulations of gene expression and biochemical function of this selenoperoxidase, GPX1 has recently been implicated in the onset and development of chronic diseases. Clinical data have shown associations of human GPX1 gene variants with elevated risks of diabetes. Knockout and overexpression of Gpx1 in mice may induce types 1 and 2 diabetes-like phenotypes, respectively. This review assembles the latest advances in this new field of selenium biology, and attempts to postulate signal and molecular mechanisms mediating the role of GPX1 in glucose and lipid metabolism-related diseases. Potential therapies by harnessing the beneficial effects of this ubiquitous redox-modulating enzyme are briefly discussed.

Comparison of analytical methods using enzymatic activity, immunoaffinity and selenium-specific mass spectrometric detection for the quantitation of glutathione peroxidase 1

Glutathione peroxidase 1 (Gpx1), one of the most responsive selenoproteins to the variation of selenium concentration, is often used to evaluate "selenium status" at a cellular or organismal level. The four major types of analytical methodologies to quantify Gpx1 were revisited. They include (i) an enzymatic assay, (ii, iii) polyacrylamide gel electrophoresis (PAGE) with (ii) western blot detection of protein or (iii) inductively coupled plasma mass spectrometry (ICP MS) detection of selenium, and (iv) size-exclusion chromatography with ICP MS detection. Each of the four methods was optimized for the quantification of Gpx1 with maximum sensitivity. The methods based on the enzymatic and immunodetection offer a much higher sensitivity but their accuracy is compromised by the limited selectivity and limited dynamic range. The advantages, drawbacks and sources of error of each technique are critically discussed and the need for the cross-validation of the results using the different techniques to assure the quality assurance of quantitative analysis is emphasized.

Identification and characterization of two selenium-dependent glutathione peroxidase 1 isoforms from Larimichthys crocea

Glutathione peroxidases, a vital family of antioxidant enzymes in oxybiotic organisms, are involved in anti-pathogen immune response. In this study, two complete selenium-dependent glutathione peroxidase 1 cDNAs (designated as LcGPx1a and LcGPx1b) were obtained from the large yellow croaker Larimichthys crocea by rapid amplification of cDNA ends. The full-length sequence of LcGPx1a was 917 bp with a 5'-untranslated region (UTR) of 52 bp, a 3'-UTR of 289 bp, and an open reading frame of 576 bp encoding 191 amino acid (aa) polypeptides. The cDNA of LcGPx1b was composed of 884 bp with a 5'-UTR of 59 bp, a 3'-UTR of 258 bp, and an open reading frame of 567 bp encoding 188 aa polypeptides. The conserved selenocysteine insertion sequence was detected in the 3'-UTR of both isoforms, which can classify types I and II. Protein sequence analysis revealed that both isoforms included a selenocysteine encoded by an opal codon (TGA) and formed the functioning tetrad site with glutamine, tryptophan, and asparagine. Three conservative motifs, including one active site motif ("GKVVLIENVASLUGTT") and two signature site motifs ("LVILGVPCNQFGHQENC" and "V(A/S)WNFEKFLI"), were conserved both in sequence and location. Multiple alignments revealed that they exhibited a high level of identities with GPx1 from other organisms, especially in the abovementioned conserved amino acid sequence motifs. Tissue expression analysis indicated that LcGPx1a and LcGPx1b had a wide distribution in nine tissues with various abundances. The transcript level of LcGPx1a was not significantly different among the nine tissues, whereas that of LcGPx1b was higher in the kidney and head kidney than in the other tissues. After Vibrio parahaemolyticus stimulation, the expression levels of LcGPx1a and LcGPx1b were unanimously altered in the liver, spleen, kidney, and head kidney but with different magnitudes and response time. LcGPx1a and LcGPx1b showed distinct expression trends in the liver, where LcGPx1b was induced and LcGPx1a was depressed in response to pathogen infection. These results indicate that LcGPx1a and LcGPx1b display functional diversities and play crucial roles in mediating the immune response of fish.

STAT3 mediates multidrug resistance of Burkitt lymphoma cells by promoting antioxidant feedback

Burkitt lymphoma (BL) is a highly aggressive B-cell neoplasm. Although BL is relatively sensitive to chemotherapy, some patients do not respond to initial therapy or relapse after standard therapy, which leads to poor prognosis. The mechanisms underlying BL chemoresistance remain poorly defined. Here, we report a mechanism for the relationship between the phosphorylation of STAT3 on Tyr705 and BL chemoresistance. In chemoresistant BL cells, STAT3 was activated and phosphorylated on Tyr705 in response to the generation of the reactive oxygen species (ROS), which induced Src Tyr416 phosphorylation after multi-chemotherapeutics treatment. As a transcription factor, the elevated phosphorylation level of STAT3^Y705 increased the expression of GPx1 and SOD2, both of which protected cells against oxidative damage. Our findings revealed that the ROS-Src-STAT3-antioxidation pathway mediated negative feedback inhibition of apoptosis induced by chemotherapy. Thus, the phosphorylation of STAT3 on Tyr705 might be a target for the chemo-sensitization of BL.

Reduction of selenium-binding protein 1 sensitizes cancer cells to selenite via elevating extracellular glutathione: a novel mechanism of cancer-specific cytotoxicity of selenite

Selenium is an essential trace element and has been extensively studied for preventive effects on cancers. Recent emerging evidence has also shown that selenium at supranutritional dosage has a preferential cytotoxicity in cancer cells and chemotherapeutic drug-resistant cells, but the underlying mechanisms remain largely unknown. This study was to investigate the roles of two distinct representatives of selenium-containing proteins, selenium-binding protein 1 (SBP1) and glutathione peroxidase 1 (GPX1), in selenite-mediated cancer-specific cytotoxicity. We found that there was a significantly inverse correlation between SBP1 and GPX1 protein level in human breast cancers and adjacent matched nontumor tissues (Pearson r=-0.4347, P=0.0338). Ectopic expression of GPX1 enhanced selenite cytotoxicity through down-regulation of SBP1, and SBP1 was likely to be a crucial determinant for selenite-mediated cytotoxicity. Reduction of SBP1 in cancer cells and epirubicin-resistant cells on selenite exposure resulted in a dramatic increase in the generation of hydrogen peroxide and superoxide anion, which in turn caused oxidative stress and triggered apoptosis. Furthermore, knockdown SBP1 by small interfering RNA increased selenite sensitivity by elevating extracellular glutathione (GSH), which spontaneously reacted with selenite and led to the rapid depletion of selenium (IV) in growth medium and the high-affinity uptake of selenite. In conclusion, these findings would improve our understanding of the roles of selenium-containing proteins in selenite-mediated cytotoxicity, and revealed a potent mechanism of the selective cytotoxicity of selenite in cancer cells and drug-resistant cells, in which SBP1 was likely to play an important role in modulating the extracellular microenvironment by regulating the levels of extracellular GSH.

Selenium-binding protein 1 as a tumor suppressor and a prognostic indicator of clinical outcome

Selenium is a trace element that plays a critical role in physiological processes and cancer prevention, whose functions may be through its effects on selenium-containing proteins. Selenium-binding protein 1 (SBP1) is a member of an unusual class of selenium-containing proteins that may function as a tumor suppressor in multiple cancer types and whose levels have been shown to be lower in cancers as compared to corresponding normal tissues. This review is intended to summarize recent advances in gaining an understanding of the significance of SBP1 in carcinogenesis, and suggest that SBP1 could be developed as a potential biomarker for cancer progression and prognosis.