Se-methylselenocysteine inhibits the progression of non-small cell lung cancer via ROS-mediated NF-κB signaling pathway.

Se-methylselenocysteine (MSC) is recognized for its potential in cancer prevention, yet the specific effects and underlying processes it initiates within non-small cell lung cancer (NSCLC) remain to be fully delineated. Employing a comprehensive array of assays, including CCK-8, colony formation, flow cytometry, MitoSOX Red staining, wound healing, transwell, and TUNEL staining, we evaluated MSC's effects on A549 and 95D cell lines. Our investigation extended to the ROS-mediated NF-κB signaling pathway, utilizing Western blot analysis, P65 overexpression, and the application of IκB-α inhibitor (BAY11-7082) or N-acetyl-cysteine (NAC) to elucidate MSC's mechanism of action. In vivo studies involving subcutaneous xenografts in mice further confirmed MSC's inhibitory effect on tumor growth. Our findings indicated that MSC inhibited the proliferation of A549 and 95D cells, arresting cell cycle G0/G1 phase and reducing migration and invasion, while also inducing apoptosis and increasing intracellular ROS levels. This was accompanied by modulation of key proteins, including the upregulation of p21, p53, E-cadherin, Bax, cleaved caspase-3, cleaved-PARP, and downregulation of CDK4, SOD2, GPX-1. MSC was found to inhibit the NF-κB pathway, as evidenced by decreased levels of P-P65 and P-IκBα. Notably, overexpression of P65 and modulation of ROS levels with NAC could attenuate MSC's effects on cellular proliferation and metastasis. Moreover, MSC significantly curtailed tumor growth in vivo and disrupted the NF-κB signaling pathway. In conclusion, our research demonstrates that MSC exhibits anticancer effects against NSCLC by modulating the ROS/NF-κB signaling pathway, suggesting its potential as a therapeutic agent in NSCLC treatment.

[Experimental study on promotion of peripheral nerve regeneration by selenium-methylselenocysteine].

Objective: To investigate the feasibility of selenium-methylselenocysteine (SMC) to promote peripheral nerve regeneration and its mechanism of action. Methods: Rat Schwann cells RSC96 cells were randomly divided into 5 groups, which were group A (without any treatment, control group), group B (adding 100 µmol/L H 2O 2), group C (adding 100 µmol/L H 2O 2+100 µmol/L SMC), group D (adding 100 µmol/L H 2O 2+200 µmol/L SMC), group E (adding 100 µmol/L H 2O 2+400 µmol/L SMC); the effect of SMC on cell proliferation was detected by MTT method, and the level of oxidative stress was detected by immunofluorescence for free radicals [reactive oxygen species (ROS)] after determining the appropriate dose group. Thirty-six 4-week-old male Sprague Dawley rats were randomly divided into 3 groups, namely, the sham operation group (Sham group), the sciatic nerve injury group (PNI group), and the SMC treatment group (SMC group), with 12 rats in each group; the rats in the PNI group were fed with food and water normally after modelling operation, and the rats in the SMC group were added 0.75 mg/kg SMC to the drinking water every day. At 4 weeks after operation, the sciatic nerves of rats in each group were sampled for neuroelectrophysiological detection of highest potential of compound muscle action potential (CMAP). The levels of inflammatory factors [interleukin 17 (IL-17), IL-6, IL-10 and oxidative stress factors catalase (CAT), superoxide dismutase (SOD), and malondialdehyde (MDA)] were detected by ELISA assay. The luxol fast blue (LFB) staining was used to observe the myelin density, fluorescence intensity of glial fibrillary acidic protein (GFAP) and myelin basic protein (MBP) was observed by immunofluorescence staining, and myelin morphology was observed by transmission electron microscopy with measurement of axon diameter. Western blot was used to detect the protein expressions of p38 mitogen-activated protein kinases (p38MAPK), phosphorylated p38MAPK (p-p38MAPK), heme oxygenase 1 (HO-1), and nuclear factor erythroid 2-related factor 2 (Nrf2). Results: MTT assay showed that the addition of SMC significantly promoted the proliferation of RSC96 cells, and the low concentration could achieve an effective effect, so the treatment method of group C was selected for the subsequent experiments; ROS immunofluorescence test showed that group B showed a significant increase in the intensity of ROS fluorescence compared with that of group A, and group C showed a significant decrease in the intensity of ROS fluorescence compared with that of group B ( P<0.05). Neuroelectrophysiological tests showed that the highest potential of CMAP in SMC group was significantly higher than that in PNI and Sham groups ( P<0.05). ELISA assay showed that the levels of IL-6, IL-17, and MDA in PNI group were significantly higher than those in Sham group, and the levels of IL-10, SOD, and CAT were significantly lower; the levels of IL-6, IL-17, and MDA in SMC group were significantly lower than those in PNI group, and the levels of IL-10, SOD, and CAT were significantly higher ( P<0.05). LFB staining and transmission electron microscopy showed that the myelin density and the diameter of axons in the SMC group were significantly higher than those of the PNI group and the Sham group ( P<0.05). Immunofluorescence staining showed that the fluorescence intensity of GFAP and MBP in the SMC group were significantly stronger than those in the PNI group and Sham group ( P<0.05). Western blot showed that the relative expressions of Nrf2 and HO-1 proteins in the SMC group were significantly higher than those in the PNI group and Sham group, and the ratio of p-p38MAPK/p38MAPK proteins was significantly higher in the PNI group than that in the SMC group and Sham group ( P<0.05). Conclusion: SMC may inhibit oxidative stress and inflammation after nerve injury by up-regulating the Nrf2/HO-1 pathway, and then inhibit the phosphorylation of p38MAPK pathway to promote the proliferation of Schwann cells, which ultimately promotes the formation of myelin sheaths and accelerates the regeneration of peripheral nerves.

Se-methylselenocysteine ameliorates mitochondrial function by targeting both mitophagy and autophagy in the mouse model of Alzheimer's disease.

Background: Alzheimer's disease (AD) exerts tremendous pressure on families and society due to its unknown etiology and lack of effective treatment options. Our previous study had shown that Se-methylselenocysteine (SMC) improved the cognition and synaptic plasticity of triple-transgenic AD (3 × Tg-AD) mice and alleviated the related pathological indicators. We are dedicated to investigating the therapeutic effects and molecular mechanisms of SMC on mitochondrial function in 3 × Tg-AD mice. Methods: Transmission electron microscopy (TEM), western blotting (WB), mitochondrial membrane potential (ΔΨm), mitochondrial swelling test, and mitochondrial oxygen consumption test were used to evaluate the mitochondrial morphology and function. Mitophagy flux and autophagy flux were assessed with immunofluorescence, TEM and WB. The Morris water maze test was applied to detect the behavioral ability of mice. Results: The destroyed mitochondrial morphology and function were repaired by SMC through ameliorating mitochondrial energy metabolism, mitochondrial biogenesis and mitochondrial fusion/fission balance in 3 × Tg-AD mice. In addition, SMC ameliorated mitochondria by activating mitophagy flux via the BNIP3/NIX pathway and triggering autophagy flux by suppressing the Ras/Raf/MEK/ERK/mTOR pathway. SMC remarkably increased the cognitive ability of AD mice. Conclusions: This research indicated that SMC might exert its therapeutic effect by protecting mitochondria in 3 × Tg-AD mice.

Se-(Methyl)-selenocysteine ameliorates blood-brain barrier disruption of focal cerebral ischemia mice via ferroptosis inhibition and tight junction upregulation in an Akt/GSK3ß-dependent manner.

BACKGROUND: Ischemic stroke still ranks as the most fatal disease worldwide. Blood-brain barrier (BBB) is a promising therapeutic target for protection. Brain microvascular endothelial cell is a core component of BBB, the barrier function maintenance of which can ameliorate ischemic injury and improve neurological deficit. Se-methyl L-selenocysteine (SeMC) has been shown to exert cardiovascular protection. However, the protection of SeMC against ischemic stroke remains to be elucidated. This research was designed to explore the protection of SeMC from the perspective of BBB protection. METHODS: To simulate cerebral ischemic injury, C57BL/6J mice were subjected to middle cerebral artery occlusion/reperfusion (MCAO/R), and bEnd.3 was exposed to oxygen-glucose deprivation/reoxygenation (OGD/R). After the intervention of SeMC, the barrier function and the expression of tight junction and ferroptosis-associated proteins were determined. For mechanism exploration, LY294002 (Akt inhibitor) was introduced both in vivo and in vitro. RESULTS: SeMC lessened the brain infarct volume and attenuated the leakage of BBB in mice. In vitro, SeMC improved cell viability and maintained the barrier function of bEnd.3 cells. The protection of SeMC was accompanied with ferroptosis inhibition and tight junction protein upregulation. Mechanism studies revealed that the effect of SeMC was reversed by LY294002, indicating that the protection of SeMC against ischemic stroke was mediated by the Akt signal pathway. CONCLUSION: These results suggested that SeMC exerted protection against ischemic stroke, which might be attributed to activating the Akt/GSK3ß signaling pathway and increasing the nuclear translocation of Nrf2 and ß-catenin, subsequently maintaining the integrity of BBB.

Optimized methyl donor and reduced precursor degradation pathway for seleno-methylselenocysteine production in Bacillus subtilis.

BACKGROUND: Seleno-methylselenocysteine (SeMCys) is an effective component of selenium supplementation with anti-carcinogenic potential that can ameliorate neuropathology and cognitive deficits. In a previous study, a SeMCys producing strain of Bacillus subtilis GBACB was generated by releasing feedback inhibition by overexpression of cysteine-insensitive serine O-acetyltransferase, enhancing the synthesis of S-adenosylmethionine as methyl donor by overexpression of S-adenosylmethionine synthetase, and expressing heterologous selenocysteine methyltransferase. In this study, we aimed to improve GBACB SeMCys production by synthesizing methylmethionine as a donor to methylate selenocysteine and by inhibiting the precursor degradation pathway. RESULTS: First, the performance of three methionine S-methyltransferases that provide methylmethionine as a methyl donor for SeMCys production was determined. Integration of the NmMmt gene into GBACB improved SeMCys production from 20.7 to 687.4 µg/L. Next, the major routes for the degradation of selenocysteine, which is the precursor of SeMCys, were revealed by comparing selenocysteine hyper-accumulating and non-producing strains at the transcriptional level. The iscSB knockout strain doubled SeMCys production. Moreover, deleting sdaA, which is responsible for the degradation of serine as a precursor of selenocysteine, enhanced SeMCys production to 4120.3 µg/L. Finally, the culture conditions in the flasks were optimized. The strain was tolerant to higher selenite content in the liquid medium and the titer of SeMCys reached 7.5 mg/L. CONCLUSIONS: The significance of methylmethionine as a methyl donor for SeMCys production in B. subtilis is reported, and enhanced precursor supply facilitates SeMCys synthesis. The results represent the highest SeMCys production to date and provide insight into Se metabolism.

Molecular Mechanisms of the Cytotoxic Effect of Recombinant Selenoprotein SELENOM on Human Glioblastoma Cells.

Currently, selenobiology is an actively developing area, primarily due to the study of the role of the trace element selenium and its organic and inorganic compounds in the regulation of vital processes occurring in the cell. In particular, the study of the functions of selenium nanoparticles has gained great popularity in recent years. However, a weak point in this area of biology is the study of the functions of selenoproteins, of which 25 have been identified in mammals to date. First of all, this is due to the difficulties in obtaining native forms of selenoproteins in preparative quantities, due to the fact that the amino acid selenocysteine is encoded by one of the three stop codons of the TGA universal genetic code. A complex system for recognizing a given codon as a selenocysteine codon has a number of features in pro- and eukaryotes. The selenoprotein SELENOM is one of the least studied mammalian selenoproteins. In this work, for the first time, studies of the molecular mechanisms of regulation of the cytotoxic effect of this protein on human glioblastoma cells were carried out. The cytotoxicity of cancer cells in our experiments was already observed when cells were exposed to 50 µg of SELENOM and increased in proportion to the increase in protein concentration. Apoptosis of human glioblastoma cells was accompanied by an increase in mRNA expression of a number of pro-apoptotic genes, an increase in endoplasmic reticulum stress, and activation of the UPR IRE1α signaling pathway. The results obtained also demonstrate a dose-dependent depletion of the Ca2+ pool under the action of SELENOM, which proves the important role of this protein in the regulation of calcium homeostasis in the cell.

L-Selenocysteine induced HepG-2 cells apoptosis through reactive oxygen species-mediated signaling pathway.

BACKGROUND: Currently, Liver cancer is the fifth most common tumor and the second most important reason for cancer-related death in the world. However, there are still many limitations of the clinical treatment of liver cancer, and new treatment options are clearly needed. Fortunately, studies have shown that L-Selenocysteine has a certain effect on cancer. This study was to investigate the effects of L-Selenocysteine on the inhibition of cell proliferation and the promotion of apoptosis of HepG-2 cells through ROS mediated fine signaling pathway. MATERIALS AND METHODS: CCK-8 assay was applied to evaluating the cytotoxic effect of L-Selenocysteine on HepG-2 cells. Electron microscopy, flow cytometry and Western Blot was utilization in further researching cells signaling pathways. RESULTS: The growth of HepG-2 cells was inhibited by L-selenocysteine ​​treatment in a dose-dependent manner. The cell viability decreased to 52.20%, 43.20% and 30.83% under the treatment of 4, 8, 16 µM L-selenocysteine, respectively. L-Selenocysteine had higher cytotoxicity towards HepG-2 cells than normal cells. L-Selenocysteine can induce the apoptosis of HepG-2 cells by increasing the DNA fragmentation, and activating the Caspase-3. In addition, it was found that the mechanism of the induction to HepG-2 cell apoptosis by L-Selenocysteine was closely related to the overproduction of ROS and promoted apoptosis through the Bcl-2 signaling pathway. CONCLUSIONS: Our data suggest that L-selenocysteine ​​may cause mitochondrial damage and subsequently stimulate ROS production. ROS can damage cellular DNA and mediate the production of Casapase-8, Bid, Bcl-2 and other proteins, affecting downstream signaling pathways, and ultimately induced apoptosis.

Effect of Dietary Methylseleninic Acid and Se-Methylselenocysteine on Carcinogen-Induced, Androgen-Promoted Prostate Carcinogenesis in Rats.

Selenomethionine (SeMet) did not prevent prostate cancer in the SELECT trial and in two hormone-driven rat models. However, we have shown that daily oral bolus administration of next-generation selenium forms, methylseleninic acid (MSeA) and Se-methylselenocysteine (MSeC) at 3 mg Se/kg body weight, inhibits prostate carcinogenesis in the TRAMP and pten-deficient mouse models and In Vivo growth of human prostate cancer cells. Here, we determined whether these Se forms prevent prostate cancer in a chemically induced-androgen promoted carcinogenesis rat model in which SeMet was not preventive. WU rats were treated with methylnitrosourea, and one week later, slow-release testosterone implants when they were randomized to groups fed AIN-93M diet supplemented with 3 ppm selenium as MSeA or MSeC or control diet. Mean survival, tumor incidence in all accessory sex glands combined (dorsolateral and anterior prostate plus seminal vesicle) and the incidence of tumors confined to dorsolateral and/or anterior prostate were not statistically significantly different among the groups. Thus, MSeA and MSeC feeding was not preventive in this model. The contrast with the inhibitory effects of MSeA and MSeC in mouse models may be due to differences in carcinogenic mechanisms, selenium dosage, delivery mode, and pharmacokinetics or fundamental rat-mouse differences in selenium metabolism.

Immunomodulatory and Anti-Inflammatory Properties of Selenium-Containing Agents: Their Role in the Regulation of Defense Mechanisms against COVID-19.

The review presents the latest data on the role of selenium-containing agents in the regulation of diseases of the immune system. We mainly considered the contributions of selenium-containing compounds such as sodium selenite, methylseleninic acid, selenomethionine, and methylselenocysteine, as well as selenoproteins and selenium nanoparticles in the regulation of defense mechanisms against various viral infections, including coronavirus infection (COVID-19). A complete description of the available data for each of the above selenium compounds and the mechanisms underlying the regulation of immune processes with the active participation of these selenium agents, as well as their therapeutic and pharmacological potential, is presented. The main purpose of this review is to systematize the available information, supplemented by data obtained in our laboratory, on the important role of selenium compounds in all of these processes. In addition, the presented information makes it possible to understand the key differences in the mechanisms of action of these compounds, depending on their chemical and physical properties, which is important for obtaining a holistic picture and prospects for creating drugs based on them.

In vitro cytotoxic data on Se-methylselenocysteine conjugated to dendritic poly(glycerol) against human squamous carcinoma cells.

Polymeric nanoparticles acting as sources of selenium (Se) are currently an interesting topic in cancer chemotherapy. In this study, polyglycerol dendrimer (DPGLy) was functionalized with seleno-methyl-selenocysteine (SeMeCys) by means of Steglich esterification with 4-dimethylaminopyridine/(l-ethyl-3-(3-dimethylaminopropyl)carbodiimide) (EDC/DMAP) and cerium chloride as cocatalyst in acetonitrile at quantitative yields of 98 ± 1%. The SeMeCys coupling DPGLy efficiency vs. time were determined by Fourier Transform infrared spectroscopy (FTIR) and ultraviolet-visible (UV-Vis) spectroscopy. The cytotoxic effects of SeMeCys-DPGLy on the Chinese Hamster ovary cell line (CHO-K1) and head and neck squamous cell carcinoma (HNSCC) cells line were assessed by MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. No signs of general toxicity of SeMeCys-DPGLy against CHO-K1 cells were detectable at which cell viability was greater than 98%. MTS assays revealed that SeMeCys-DPGLy reduced HNSCC cell viability and proliferation at higher doses and long incubation times.

Thioredoxin reductase as a pharmacological target.

Thioredoxin reductases (TrxRs) belong to the pyridine nucleotide disulfide oxidoreductase family enzymes that reduce thioredoxin (Trx). The couple TrxR and Trx is one of the major antioxidant systems that control the redox homeostasis in cells. The thioredoxin system, comprised of TrxR, Trx and NADPH, exerts its activities via a disulfide-dithiol exchange reaction. Inhibition of TrxR is an important clinical goal in all conditions in which the redox state is perturbed. The present review focuses on the most critical aspects of the cellular functions of TrxRs and their inhibition mechanisms by metal ions or chemicals, through direct targeting of TrxRs or their substrates or protein interactors. To update the involvement of overactivation/dysfunction of TrxRs in various pathological conditions, human diseases associated with TrxRs genes were critically summarized by publicly available genome-wide association study (GWAS) catalogs and literature. The pieces of evidence presented here justify why TrxR is recognized as one of the most critical clinical targets and the growing current interest in developing molecules capable of interfering with the functions of TrxR enzymes.

Se-Methylselenocysteine Alleviates Liver Injury in Diethylnitrosamine (DEN)-Induced Hepatocellular Carcinoma Rat Model by Reducing Liver Enzymes, Inhibiting Angiogenesis, and Suppressing Nitric Oxide (NO)/Nitric Oxide Synthase (NOS) Signaling Pathway.

BACKGROUND Hepatocellular carcinoma is the third leading cause of cancer-associated mortality. This study aimed to investigate the effects of se-methylselenocysteine (MSC) on oncogenesis of diethylnitrosamine (DEN)-induced hepatocellular carcinoma. MATERIAL AND METHODS A hepatocellular carcinoma rat model was established by administering DEN. Rat models were divided into Model (0.1 mg/kg MSC), Model+0.3 mg/kg MSC, Model+1 mg/kg MSC, and Model+3 mg/kg MSC groups. A Normal control group consisted of mice not administered MSC. Hematoxylin and eosin staining was used to determine liver injury. Immunohistochemical analysis was conducted to identify CD34 and vascular endothelial growth factor (VEGF) expression. VEGF gene transcription was detected with RT-PCR. Biochemical analyses were performed to determine alanine aminotransferase, aspartate aminotransferase, total bilirubin, γ-glutamyl transpeptidase, alkaline phosphatase, and albumin levels in serum, and nitric oxide (NO)/nitric oxide synthase (NOS) levels in liver tissues. Transmission electron microscopy was used to observe the ultra-microstructures of hepatocytes. RESULTS MSC treatment markedly alleviated liver injury and nuclear lesions in the treatment groups compared to the Model group. MSC treatment significantly improved liver functions in the treatment groups compared to the Model group (P<0.05). MSC treatment significantly decreased CD34 expression and NO and NOS levels in liver tissues and suppressed VEGF expression compared to the Model group (all P<0.05). CONCLUSIONS MSC administration alleviated liver injury in a DEN-induced hepatocellular carcinoma rat model through reducing liver enzymes, inhibiting angiogenesis, and suppressing the NO/NOS signaling pathway.

L-Se-methylselenocysteine sensitizes lung carcinoma to chemotherapy.

OBJECTIVES: Organic Selenium (Se) compounds such as L-Se-methylselenocysteine (L-SeMC/SeMC) have been employed as a class of anti-oxidant to protect normal tissues and organs from chemotherapy-induced systemic toxicity. However, their comprehensive effects on cancer cell proliferation and tumour progression remain elusive. MATERIALS AND METHODS: CCK-8 assays were conducted to determine the viabilities of cancer cells after exposure to SeMC, chemotherapeutics or combined treatment. Intracellular reactive oxygen species (ROS) levels and lipid peroxidation levels were assessed via fluorescence staining. The efficacy of free drugs or drug-loaded hydrogel against tumour growth was evaluated in a xenograft mouse model. RESULTS: Among tested cancer cells and normal cells, the A549 lung adenocarcinoma cells showed higher sensitivity to SeMC exposure. In addition, combined treatments with several types of chemotherapeutics induced synergistic lethality. SeMC promoted lipid peroxidation in A549 cells and thereby increased ROS generation. Significantly, the in vivo efficacy of combination therapy was largely potentiated by hydrogel-mediate drug delivery. CONCLUSIONS: Our study reveals the selectivity of SeMC in the inhibition of cancer cell proliferation and develops an efficient strategy for local combination therapy.

Suppression of lipopolysaccharide-induced activation of RAW 264.7 macrophages by Se-methylseleno-l-cysteine.

Se-methylseleno-l-cysteine (l-SeMC) is a natural source of organic selenium for humans. Although it has a structure similar to that of l-Cysteine (l-Cys), its anti-inflammatory properties and possible underlying mechanisms have not been explored. Here, we compared the anti-inflammatory activities of inorganic selenium (selenite), l-Cys, and l-SeMC in lipopolysaccharide (LPS)-activated RAW 264.7 murine macrophages and focused on the related molecular and biochemical events. The results showed that, anti-inflammatory activity of l-SeMC was much stronger compared to both individual l-Cys treatment and l-Cys/selenite combinations. The organic form of selenium may play a crucial role in the effects of l-SeMC. Further study confirmed that l-SeMC suppressed the RNA expression of iNOS, TNF-α, IL-1ß, IL-6, COX-2, and MMP-9, as well as the release of NO, TNF-α, IL-6, IL-12p70, COX-2, and PGE2 from LPS-activated RAW264.7 macrophages in a concentration-dependent manner. Moreover, l-SeMC prevented LPS-induced changes in cell morphology. l-SeMC concentrations between 50 and 200 µM exhibited an anti-inflammatory effect closed to that exhibited by 20 µM dexamethasone. Our results demonstrated that l-SeMC effectively inhibited the activation of RAW 264.7 macrophages induced by LPS, and suggested that l-SeMC could be a potential functional food component for the prevention or treatment of inflammatory diseases.

The Effects of Selenium on Wheat Fusarium Head Blight and DON Accumulation Were Selenium Compound-Dependent.

Fusarium head blight (FHB) caused by Fusarium graminearum not only results in severe yield losses, but also contaminates wheat grains with deoxynivalenol (DON) toxins. Prevention and control of FHB and DON contamination rely mainly on resistant varieties and fungicides. Selenium (Se) is an essential element for humans and animals, and also a beneficial element for plants. In this work, four Se compounds, i.e., sodium selenite (Na2SeO3), sodium selenate (Na2SeO4), selenomethionine (SeMet) and selenocysteine (SeCys2), were supplemented in a trichothecene biosynthesis induction (TBI) solid medium at different dosages in in vitro experiments. The four Se compounds at the dosage of 20 mg∙L-1 were sprayed onto wheat spikes immediately after inoculation at anthesis. All four of the Se compounds significantly inhibited the mycelial growth and DON production in the in vitro experiment; however, in planta, their effects on FHB severity and toxin accumulation in grains were compound-dependent. SeMet consistently negatively regulated fungal growth and DON accumulation both in vitro and in planta, which could be a novel and proconsumer strategy for reducing the detriment of wheat FHB disease and DON accumulation.

The Effect of Methylselenocysteine and Sodium Selenite Treatment on microRNA Expression in Liver Cancer Cell Lines.

The unique character of selenium compounds, including sodium selenite and Se-methylselenocysteine (MSC), is that they exert cytotoxic effects on neoplastic cells, providing a great potential for treating cancer cells being highly resistant to cytostatic drugs. However, selenium treatment may affect microRNA (miRNA) expression as the pattern of circulating miRNAs changed in a placebo-controlled selenium supplement study. This necessitates exploring possible changes in the expression profiles of miRNAs. For this, miRNAs being critical for liver function were selected and their expression was measured in hepatocellular carcinoma (HLE and HLF) and cholangiocarcinoma cell lines (TFK-1 and HuH-28) using individual TaqMan MicroRNA Assays following selenite or MSC treatments. For establishing tolerable concentrations, IC50 values were determined by performing SRB proliferation assays. The results revealed much lower IC50 values for selenite (from 2.7 to 11.3 µM) compared to MSC (from 79.5 to 322.6 µM). The treatments resulted in cell line-dependent miRNA expression patterns, with all miRNAs found to show fold change differences; however, only a few of these changes were statistically different in treated cells compared to untreated cells below IC50. Namely, miR-199a in HLF, miR-143 in TFK-1 upon MSC treatment, miR-210 in HLF and TFK-1, miR-22, -24, -122, -143 in HLF upon selenite treatment. Fold change differences revealed that miR-122 with both selenium compounds, miR-199a with MSC and miR-22 with selenite were affected. The miRNAs showing minimal alterations included miR-125b and miR-194. In conclusion, our results revealed moderately altered miRNA expression in the cell lines (less alterations following MSC treatment), being miR-122, -199a the most affected and miR-125b, -194 the least altered miRNAs upon selenium treatment.

Micronutrients Selenomethionine and Selenocysteine Modulate the Redox Status of MCF-7 Breast Cancer Cells.

Selenium is a micronutrient which is found in many foods, with redox status modulation activity. Our aim was to evaluate the effects of two chemical forms of selenoamino acids, Seleno-L-methionine and Seleno-L-cystine (a diselenide derived from selenocysteine), at different concentrations on cell viability, hydrogen peroxide production, antioxidant enzymes, UCP2 protein expression, as well as lipid and protein oxidative damage in MCF-7 breast cancer cells. Results showed that Seleno-L-methionine did not cause an increase in hydrogen peroxide production at relatively low concentrations, accompanied by a rise in the antioxidant enzymes catalase and MnSOD, and UCP2 protein expression levels. Furthermore, a decrease in protein and lipid oxidative damage was observed at 10 µM concentration. Otherwise, Seleno-L-cystine increased hydrogen peroxide production from relatively low concentrations (100 nM) to a large increase at high concentrations. Moreover, at 10 µM, Seleno-L-cystine decreased UCP2 and MnSOD protein expression. In conclusion, the chemical form of selenoamino acid and their incorporation to selenoproteins could affect the regulation of the breast cancer cell redox status. Taken together, the results obtained in this study imply that it is important to control the type of selenium-enriched nutrient consumption, taking into consideration their composition and concentration.

Se-methylselenocysteine stimulates migration and antioxidant response in HaCaT keratinocytes: Implications for wound healing.

BACKGROUND: Se-methylselenocysteine (MSC), a natural organic selenium compound, is known for its anticancer effects. In the present study, we investigated the effects of MSC on cell migration, which is the most limiting step in the reepithelialization process of wound healing and the antioxidant response in HaCaT keratinocytes. METHODS: HaCaT cells were treated with various concentrations of MSC. Cell migration and proliferation, the expression of proteins that are involved in the epidermal-mesenchymal transition (EMT) process, the extent of oxidative stress and the antioxidant response, and the associated signaling pathways were analyzed. RESULTS: MSC (100-500 µM) increased HaCaT cell migration. MSC stimulated EMT, which was evidenced by a decrease in E-cadherin in the cells at the wound edge and increases in Snail, Twist, and matrix metalloproteinases. MSC increased the phosphorylation of Akt and glycogen synthase kinase 3ß, which led to the stabilization and nuclear accumulation of ß-catenin, a transcriptional coactivator involved in EMT. MSC caused a transient increase and then an eventual decrease in cellular reactive oxygen species, which appeared to be associated with the increase in nuclear factor erythroid 2-related factor 2, a key transcription factor for the antioxidant response. CONCLUSION: Our results suggest that MSC can promote skin wound healing by stimulating keratinocyte migration and, moreover, can protect cells from excessive oxidative stress that often accompanies and impairs the wound healing process, particularly in chronic wounds, by stimulating an antioxidant response.

Development and application of a HPLC-ICP-MS method to determine selenium speciation in muscle of pigs treated with different selenium supplements.

Dietary selenium deficiency is recognized as a global problem. Pork is the most widely consumed meat throughout the world and an important source of selenium for humans. In this study, a reliable approach was developed for analyzing selenium and its speciation in the muscles of pigs after different selenium treatments. The selenium source deposition efficiency was ranked as: selenomethionine > methylselenocysteine > selenite, and the muscle selenium content had a dose effect with selenomethionine supplementation. In total, four species of selenium were detected in the muscles of pigs and the distributions of these selenium species were greatly affected by the dietary selenium supplementation forms and levels. Selenomethionine (>70% of total selenium) and selenocystine (>11%) were the major selenium species, followed by methylselenocysteine and selenourea. Therefore, selenium-enriched pork produced from selenomethionine is a good source for improving human dietary selenium intake.

Treatment of Caenorhabditis elegans with Small Selenium Species Enhances Antioxidant Defense Systems.

SCOPE: Small selenium (Se) species play a key role in Se metabolism and act as dietary sources of the essential trace element. However, they are redox-active and trigger pro- and antioxidant responses. As health outcomes are strongly species-dependent, species-specific characteristics of Se compounds are tested in vivo. METHODS AND RESULTS: In the model organism Caenorhabditis elegans (C. elegans), immediate and sustained effects of selenite, selenomethionine (SeMet), and Se-methylselenocysteine (MeSeCys) are studied regarding their bioavailability, incorporation into proteins, as well as modulation of the cellular redox status. While all tested Se compounds are bioavailable, only SeMet persistently accumulates and is non-specifically incorporated into proteins. However, the protection toward chemically-induced formation of reactive species is independent of the applied Se compound. Increased thioredoxin reductase (TXNRD) activity and changes in mRNA expression levels of antioxidant proteins indicate the activation of cellular defense mechanisms. However, in txnrd-1 deletion mutants, no protective effects of the Se species are observed anymore, which is also reflected by differential gene expression data. CONCLUSION: Se species protect against chemically-induced reactive species formation. The identified immediate and sustained systemic effects of Se species give rise to speculations on possible benefits facing subsequent periods of inadequate Se intake.