Expanding beyond ICP-MS to better understand selenium biochemistry.

Selenium is an essential trace element in human health and therefore its concentration in biological samples (biofluids and tissues) is used as an indicator of health and nutritional status. In humans, selenium's biological activity occurs through the 25 identified selenoproteins. As total selenium concentration encompasses both functional selenoproteins, small selenocompounds and other selenium-binding proteins, selenium speciation, rather than total concentration, is critical in order to assess functional selenium. Previously, quantitative analysis of selenoproteins required laborious techniques that were often slow and costly. However, more recent advancements in tandem mass spectrometry have facilitated the qualitative and quantitative identification of these proteins. In light of the current alternatives for understanding selenium biochemistry, we aim to provide a review of the modern applications of electrospray ionisation mass spectrometry (ESI-MS) as an alternative to inductively coupled plasma mass spectrometry (ICP-MS) for qualitative and quantitative selenium speciation.

Selenium-binding protein 1 in head and neck cancer is low-expression and associates with the prognosis of nasopharyngeal carcinoma.

BACKGROUND: Selenium-binding protein 1 (SELENBP1) expression is reduced markedly in many types of cancers and low SELENBP1 expression levels are associated with poor patient prognosis. METHODS: SELENBP1 gene expression in head and neck squamous cell carcinoma (HNSCC) was analyzed with GEO dataset and characteristics of SELENBP1 expression in paraffin embedded tissue were summarized. Expression of SELENBP1 in nasopharyngeal carcinoma (NPC), laryngeal cancer, oral cancer, tonsil cancer, hypopharyngeal cancer and normal tissues were detected using immunohistochemistry, at last, 99 NPC patients were followed up more than 5 years and were analyzed the prognostic significance of SELENBP1. RESULTS: Analysis of GEO dataset concluded that SELENBP1 gene expression in HNSCC was lower than that in normal tissue (P < 0.01), but there was no significant difference of SELENBP1 gene expression in different T-stage and N-stage (P > 0.05). Analysis of pathological section concluded that SELENBP1 in the majority of HNSCC is low expression and in cancer nests is lower expression than surrounding normal tissue, even associated with the malignant degree of tumor. Further study indicated the low SELENBP1 expression group of patients with NPC accompanied by poor overall survival and has significantly different comparing with the high expression group. CONCLUSION: SELENBP1 expression was down-regulated in HNSCC, but has no associated with T-stage and N-stage of tumor. Low expression of SELENBP1 in patients with NPC has poor over survival, so SELENBP1 could be a novel biomarker for predicting prognosis.

A Comprehensive Analysis of Selenium-Binding Proteins in the Brain Using Its Reactive Metabolite.

The intracellular metabolism of selenium in the brain currently remains unknown, although the antioxidant activity of this element is widely acknowledged to be important in maintaining brain functions. In this study, a comprehensive method for identifying the selenium-binding proteins using PenSSeSPen as a model of the selenium metabolite, selenotrisulfide (RSSeSR, STS), was applied to a complex cell lysate generated from the rat brain. Most of the selenium from L-penicillamine selenotrisulfide (PenSSeSPen) was captured by the cytosolic protein thiols in the form of STS through the thiol-exchange reaction (R-SH+PenSSeSPen→R-SSeSPen+PenSH). The cytosolic protein species, which reacted with the PenSSeSPen mainly had a molecular mass of less than 20 kDa. A thiol-containing protein at m/z 15155 in the brain cell lysate was identified as the cystatin-12 precursor (CST12) from a rat protein database search and a tryptic fragmentation experiment. CST12 belongs to the cysteine proteinase inhibitors of the cystatin superfamily that are of interest in mechanisms regulating the protein turnover and polypeptide production in the central nervous system and other tissues. Consequently, CST12 is suggested to be one of the cytosolic proteins responsible for the selenium metabolism in the brain.

SELENBP1 expression in the prefrontal cortex of subjects with schizophrenia.

Selenium binding protein 1 (SELENBP1) messenger RNA (mRNA) has previously been shown to be upregulated in the brain and blood from subjects with schizophrenia. We aimed to validate these findings in a new cohort using real-time PCR in Brodmann's Area (BA) 9, and to determine the disease specificity of increased SELENBP1 expression by measuring SELENBP1 mRNA in subjects with major depressive disorder and bipolar disorder. We then extended the study to include other cortical regions such as BA8 and BA44. SELENBP1 mRNA was higher in BA9 (P = 0.001), BA8 (P = 0.003) and BA44 (P = 0.0007) from subjects with schizophrenia. Conversely, in affective disorders, there was no significant difference in SELENBP1 mRNA in BA9 (P = 0.67), suggesting that the upregulation may be diagnosis specific. Measurement of SELENBP1 protein levels showed that changes in mRNA did not translate to changes in protein. In addition, chronic treatment of rats with antipsychotics did not significantly affect the expression of Selenbp1 in the cortex (P = 0.24). Our data show that elevated SELENBP1 transcript expression is widespread throughout the prefrontal cortex in schizophrenia, and confirm that this change is a consistent feature of schizophrenia and not a simple drug effect.

Quantitative proteomic analysis reveals that anti-cancer effects of selenium-binding protein 1 in vivo are associated with metabolic pathways.

Previous studies have shown the tumor-suppressive role of selenium-binding protein 1 (SBP1), but the underlying mechanisms are unclear. In this study, we found that induction of SBP1 showed significant inhibition of colorectal cancer cell growth and metastasis in mice. We further employed isobaric tags for relative and absolute quantitation (iTRAQ) to identify proteins that were involved in SBP1-mediated anti-cancer effects in tumor tissues. We identified 132 differentially expressed proteins, among them, 53 proteins were upregulated and 79 proteins were downregulated. Importantly, many of the differentially altered proteins were associated with lipid/glucose metabolism, which were also linked to Glycolysis, MAPK, Wnt, NF-kB, NOTCH and epithelial-mesenchymal transition (EMT) signaling pathways. These results have revealed a novel mechanism that SBP1-mediated cancer inhibition is through altering lipid/glucose metabolic signaling pathways.

Predicting dedifferentiation in liposarcoma: a proteomic approach.

There are no known morphologic characteristics, cytogenetic aberrations, or molecular alterations predictive of dedifferentiation in liposarcomas. Identification of such a prognostic marker could potentially affect surgical and adjuvant therapy and/or follow-up surveillance for these patients. Two-dimensional difference gel electrophoresis was utilized to characterize protein expression patterns in lipoma, atypical lipomatous tumor (ALT), and the well-differentiated components of dedifferentiated liposarcoma (DDL). Protein spots were identified by peptide mapping/fingerprinting using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. No significant differences in protein expression were identified between lipoma and ALT or DDL. Proteins that were significantly down-regulated in the well-differentiated component of DDL compared to ALT included mitochondrial aldehyde dehydrogenase 2 (ALDH2, >3-fold reduction) and selenium-binding protein-1 (SELENBP1, >4-fold reduction). Subsequent validation studies were performed by immunohistochemistry (IHC) on a separate series of ALT (n = 30) and the well-differentiated components of DDL (n = 28). IHC stains were evaluated in a semi-quantitative manner, and the results were analyzed using the Mann-Whitney test and receiver-operator curve analysis. Decreased IHC staining for SELENBP1 in the well-differentiated component of DDL was confirmed. Cytoplasmic ALDH2 levels determined by IHC were not significantly different in ALT and DDL; no nuclear staining for ALDH2 was observed. Expression of SELENBP1 is decreased in the well-differentiated component of DDL compared to ALT. However, variability in the staining patterns in liposarcoma precludes its use as a predictive marker for dedifferentiation.

The expression of selenium-binding protein 1 is decreased in uterine leiomyoma.

BACKGROUND: Selenium has been shown to inhibit cancer development and growth through the mediation of selenium-binding proteins. Decreased expression of selenium-binding protein 1 has been reported in cancers of the prostate, stomach, colon, and lungs. No information, however, is available concerning the roles of selenium-binding protein 1 in uterine leiomyoma. METHODS: Using Western Blot analysis and immunohistochemistry, we examined the expression of selenium-binding protein 1 in uterine leiomyoma and normal myometrium in 20 patients who had undergone hysterectomy for uterine leiomyoma. RESULTS AND DISCUSSION: The patient age ranged from 34 to 58 years with a mean of 44.3 years. Proliferative endometrium was seen in 8 patients, secretory endometrium in 7 patients, and atrophic endometrium in 5 patients. Two patients showed solitary leiomyoma, and eighteen patients revealed 2 to 5 tumors. Tumor size ranged from 1 to 15.5 cm with a mean of 4.3 cm. Both Western blot analysis and immunohistochemistry showed a significant lower level of selenium-binding protein 1 in leiomyoma than in normal myometrium. Larger tumors had a tendency to show a lower level of selenium-binding protein 1 than smaller ones, but the difference did not reach a statistical significance. The expression of selenium-binding protein 1 was the same among patients with proliferative, secretory, and atrophic endometrium in either leiomyoma or normal myometrium. Also, we did not find a difference of selenium-binding protein 1 level between patients younger than 45 years and older patients in either leiomyoma or normal myometrium. CONCLUSIONS: Decreased expression of selenium-binding protein 1 in uterine leiomyoma may indicate a role of the protein in tumorigenesis. Our findings may provide a basis for future studies concerning the molecular mechanisms of selenium-binding protein 1 in tumorigenesis as well as the possible use of selenium in prevention and treatment of uterine leiomyoma.

Efeito da suplementação com diferentes níveis de selênio orgânico e inorgânico na produção e na composição do leite e no sangue de vacas em lactação / Effects of different sources and levels of selenium supplementation on milk yield and composition and selenium blood concentration in lactating cows

Avaliaram-se o efeito da suplementação de selênio, na dieta ofertada aos animais, sobre a concentração do mineral no sangue e no leite e as alterações nas características físico-químicas, contagem de células somáticas (CCS) e produção de leite. O experimento durou 63 dias, dos quais os primeiros 21 foram pré-experimental. Foram utilizadas 32 vacas em lactação da raça Jersey, as quais apresentavam, ao início, peso corporal de 402,5+58,4kg, escore de condição corporal de 3,19+0,31, produção de leite de 10,4+2,1kg e número de dias em lactação de 141,4+69,3. Os tratamentos foram: sem suplementação (grupo-controle); com suplementação de selênio inorgânico 0,3 (dieta-padrão + 0,3mg selenito de sódio/kg de concentrado - SI0,3); com suplementação com selênio orgânico 0,3 (dieta-padrão + 0,3mg seleniometionina/kg de concentrado - SO0,3) e com suplementação de selênio orgânico 0,6 (dieta-padrão + 0,6mg seleniometionina/kg de concentrado - SO0,6). As quantidades totais de selênio das dietas foram, respectivamente, 2,38; 4,18; 4,18 e 5,98mg/dia para os tratamentos controle, SI0,3, SO0,3 e SO0,6. O delineamento experimental foi o completamente ao acaso. O número de dias em lactação e os valores obtidos no início do experimento foram usados como covariáveis. Foram realizadas avaliações da produção de leite, do peso, da condição corporal, da composição do leite e do sangue nos dias 0, 14, 28 e 42 do período experimental. Entre os tratamentos, não foram detectadas alterações quanto à produção de leite, peso, condição corporal, características físico-químicas e microbiológicas do leite, e perfil bioquímico do sangue, exceto em relação à concentração de selênio no sangue entre o tratamento-controle e os tratamentos suplementados. Não houve diferenças quanto aos teores de selênio no sangue entre as fontes de selênio e as doses. Os teores de selênio no sangue evoluíram distintamente durante o experimento conforme a dose e a fonte. A suplementação com selênio ...

The effects of the dietary supplementation with selenium were evaluated on the concentration of the mineral in blood and milk, as well as changes in milk yield, physical and chemical characteristics, and somatic cells count (SCC). The trial lasted 63 days, the first 21 were designed to adaptation of animals to experimental conditions and standard diet. Thirty-two lactating Jersey cows were used and, at the beginning of the trial, they presented body weight of 402.5+58.4kg, body condition score of 3.19+0.31, milk yield of 10.4+2.1kg/day, and 141.4+69.3 days in milking. Treatments were: control (standard diet without added selenium), inorganic selenium (standard diet + 0.3mg sodium selenite/kg concentrate - SI0.3), organic selenium 0.3 (standard diet + 0.3mg selenomethionine/kg concentrate - SO0.3), and organic selenium 0.6 (standard diet + 0.6mg selenomethionine/kg concentrate - SO0.6). Total daily amounts of selenium were 2.38, 4.18, 4.18, and 5.98mg/cow, respectively, for control, SI0.3, SO0.3, and SO0.6 treatments. The trial was conducted as a completely randomized design. The number of days in milking and the values for all attributes measured at the end of the adaptation period were used as covariates. Measurements of body weight and condition score, milk yield and composition, and blood composition were performed on days 0, 14, 28, and 42 of the experimental period. No differences were detected among treatments for milk yield and composition, body weight and condition score, physical-chemical characteristics of milk, somatic cells count, and biochemical profile of the blood, except for Se contents of blood of control compared to supplemented. There were no differences caused by selenium sources or levels. Selenium supplementation did not alter neither milk nor blood components.

[Relationship between the expression of heat shock protein 25 and selenium binding protein 1 with ischemia/reperfusion lung injury in vivo: experiment with rats].

OBJECTIVE: To analyze the differential expression proteins of rat ischemia/reperfusion (I/R) lung tissues in vivo and normal lung tissues by comparative proteome analysis, and to study the mechanism of donor lung I/R injury. METHODS: Forty male SD rats were randomly divided into 2 equal groups: I/R group undergoing mimic orthotopic left lung auto-grafting and harvesting of the left lung five hours after the operation, and control group undergoing isolation of the left hilus of lung and then harvesting of the left lung. The differential proteins in the left ventricle of transplanted heart were separated by means of immobilized pH gradient-based two-dimensional gel electrophoresis (2-DE), identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), and searched through Matrix Science software system. Western blotting was used to verify part of the differentially expressed proteins. RESULTS: Well-resolved and reproducible 2-DE profile of rat I/R lung tissues and normal lung tissues were obtained. In the I/R lung tissue profile, the average spot number from 3 gels was 489 +/- 52 spots (P > 0.05) with an average matching rate of 89.28% (P > 0.05), and in the control group, the average spot number from 3 gels was 511 +/- 83 spots (P > 0.05) with an average matching rate of 91.22% (P > 0.05). Fourteen differential proteins were identified by peptide mass fingerprinting (PMF) searched in Matrix Science (P < 0.05). Western blotting confirmed that the protein expression of selenium binding protein 1 (SBP-1) and heat shock protein 25 (HSP25) increased at the early stage of I/R group. CONCLUSION: The protein expression of HSP25 and SBP-1 with stress protection function is upregulated in the early stage of lung I/R injury. Other differentially expressed proteins identified may have important functions in energy metabolism, tissue stress, cell apoptosis, and signal transduction.