Thioredoxin reductase (TrxR) is one class of the most important antioxidant selenoproteins and is involved in regulating tumor genesis and progression. It has been reported that naphthoquinones can target and inhibit TrxR1 activity therefore produce reactive oxygen species (ROS) mediated by TrxR1, resulting into cellular redox imbalance and making the naphthoquinone compounds to become potential antitumor chemotherapy drugs. The purpose of this work is to explore the interaction between TrxR1 and menadione using biochemical and mass-spectrometric (MS) analyses, to further reveal the detailed mechanisms of TrxR1-mediated naphthoquinone reduction and inhibition of TrxR1 by naphthoquinone compounds. Using the site-directed mutagenesis and recombinantly expressed TrxR1 variants, we measured the steady-state kinetic parameters of menadione reduction mediated by TrxR1 and its variants, performed the inhibition analysis of menadione on TrxR1 activity, and eventually identified the interaction between menadione and TrxR1 through MS analysis. We found that Sec-to-Cys mutation at residue of 498 significantly enhanced the efficiency of TrxR1-mediated menadione reduction, though the Sec⁴⁹⁸ is capable to catalyze the menadione reduction, indicating that TrxR1-mediated menadione reduction is dominantly in a Se-independent manner. Mutation experiments showed that Cys⁴⁹⁸ is mainly responsible for menadione catalysis in comparison to Cys⁴⁹⁷, while the N-terminal Cys⁶⁴ is slightly stronger than Cys⁵⁹ regarding the menadione reduction. LC-MS results detected that TrxR1 was arylated with one molecule of menadione, suggesting that menadione irreversibly modified the hyper-reactive Sec residue at the C-terminus of selenoprotein TrxR1. This study revealed that TrxR1 catalyzes the reduction of menadione in a Se-independent manner meanwhile its activity is irreversibly inhibited by menadione. Hereby it will be useful for the research and development of naphthoquinone anticancer drugs targeting TrxR1.
Catalysis ; Drug Development ; Oxidation-Reduction ; Thioredoxin Reductase 1/metabolism* ; Vitamin K 3/metabolism*

The thioredoxin system plays a role in a variety of physiological functions, including cell growth, differentiation, apoptosis, tumorigenesis, and immunity. We previously confirmed that butaselen (BS), a novel thioredoxin reductase inhibitor, can inhibit the growth of various human cancer cell lines, yet the underlying mechanism remains elusive. In this study, we investigated the anti-tumor effect of BS in vivo through regulating the immune system of KM mice. We found that BS inhibits tumor proliferation by promoting the activation of splenic lymphocytes in mice. BS can elevate the percentage of CD₄^-CD₈⁺ T lymphocytes and the secretion of downstream cytokines in mice via down-regulating the expression of programmed death-ligand 1 (PD-L1) on the tumor cells' surface in vivo. Further study in HepG2 and BEL-7402 cells showed that decrease of PD-L1 level after BS treatment was achieved by inhibiting signal transducer and activator of transcription 3 (STAT3) phosphorylation. Taken together, our results suggest that BS has a role in promoting the immune response by reducing PD-L1 expression via the STAT3 pathway, and subsequently suppresses tumorigenesis.
Animals ; Antineoplastic Agents/pharmacology* ; B7-H1 Antigen/antagonists & inhibitors* ; Benzene Derivatives/therapeutic use* ; CD8-Positive T-Lymphocytes/drug effects* ; Hep G2 Cells ; Humans ; Liver Neoplasms/pathology* ; Male ; Mice ; Organoselenium Compounds/therapeutic use* ; STAT3 Transcription Factor/physiology* ; Thioredoxin-Disulfide Reductase/antagonists & inhibitors* ; Tumor Burden/drug effects*

Carcinoma, Hepatocellular ; enzymology ; pathology ; Glutathione Peroxidase ; Humans ; Liver Neoplasms ; enzymology ; pathology ; Thioredoxin-Disulfide Reductase

OBJECTIVETo explore the effect of nuclear factor erythroid-2 related factor 2 (Nrf2) and thioredoxin reductase (TrxR) gene on proliferation of chronic myeloid leukemia (CML) line cells and its mechanism.

METHODSFour interfering sequences of Nrf2 and one negative control sequence were designed and synthesised based on the principle of target sequence of siRNA, then constructed lentivirus vectors, which were transfected into K562 cell lines. The transfection effect was observed by laser scanning confocal microscope (LSCM) and flow cytometer (FCM); The depressing effect of siRNA was analyzed by real-time PCR. The cell proliferation inhibiting rate was measured with CCK-8 assay, the apoptotic rate by Annexin V-PE/PI with FCM and the apoptotic morphology of cells by LSCM.

RESULTSThe transfection efficiency of lentivirus was 65%. One cell line K562-C3 which significantly inhibited Nrf2 mRNA was obtained by real-time PCR, Nrf2 relative quantitation (RQ) expressions were 1.003±0.093 and 0.344±0.032 in the control group and K562-C3 respectively; TrxR expression also decreased with RQ as 1.090±0.549 and 0.395±0.029 respectively. The cellular proliferation inhibition rates of K562-C3 were (4.74±0.39)%, (6.13±1.78)% and (25.36±3.77)%, respectively at 24, 48 and 72 h. The apoptotic rate induced by K562-C3 (29.9%) at 72 hours was obviously higher than in the control group (7.9%). The Annexin V-PE positive K562-C3 cells presented the following apoptotic characteristics, such as karyopyknosis, nuclear fragmentation and apoptotic bodies observed by LSCM.

CONCLUSIONNrf2 specific siRNA could repress its expression at the cellular level and down-regulate the expression of its downstream antioxidant enzyme, such as TrxR, which lead to increased apoptotic rate and decreased cell proliferation.

Apoptosis ; Cell Proliferation ; Down-Regulation ; Genetic Vectors ; Humans ; K562 Cells ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; metabolism ; pathology ; NF-E2-Related Factor 2 ; metabolism ; RNA, Messenger ; genetics ; RNA, Small Interfering ; genetics ; Thioredoxin-Disulfide Reductase ; metabolism

OBJECTIVETo investigate the in vitro protective effect of Pinus massoniana bark extracts (PMBE) against cisplatin-induced nephrotoxicity in human embryonic kidney cells (HEK293), and preliminarily study its mechanism.

METHODHuman embryonic kidney cells (HEK293) were cultured in vitro. The MTT assay was adopted to test the effect of PMBE and cisplatin on growth of HEK293 cells, and the protective effect of PMBE on cisplatin-induced nephrotoxicity of HEK293, and then detect the intracellular reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH) content, catalase (CAT), superoxide dismutase (SOD) and activity of thioredoxin reductase (TrxR).

RESULTPMBE could promote growth of HEK293 cells at low concentrations, but generate slight nephrotoxicity at high concentration. Cisplatin could inhibit growth of HEK293 cells, increase ROS and MDA content, while reducing SOD, CAT and TrxR. The pre-protective PMBE was added to reduce cisplatin's injury to HEK293 cells, ROS, MDA and GSH content, SOD, CAT and TrxR within certain range.

CONCLUSIONPMBE at specific concentration has the protective effect in cisplatin-induced nephrotoxicity in HEK293 cells. Its mechanism may be related to PMBE's antioxidant activity.

Animals ; Antioxidants ; metabolism ; Cisplatin ; toxicity ; Epithelial Cells ; drug effects ; enzymology ; metabolism ; Glutathione ; metabolism ; Glutathione Peroxidase ; metabolism ; HEK293 Cells ; Humans ; Kidney ; drug effects ; enzymology ; metabolism ; Malondialdehyde ; metabolism ; Mice ; Pinus ; chemistry ; Plant Bark ; chemistry ; Plant Extracts ; pharmacology ; Protective Agents ; pharmacology ; Reactive Oxygen Species ; metabolism ; Superoxide Dismutase ; metabolism ; Thioredoxin-Disulfide Reductase ; metabolism

PURPOSE: Drug-induced liver injury (DILI) is the most common adverse drug reaction; however, it is not easily predicted. We hypothesize that DILI has a common genetic basis. Based on the findings of previous animal studies on toxic hepatitis, we selected the thioredoxin reductase 1 gene (TXNRD1) as a candidate marker of DILI for this genetic association study. METHODS: Records from 118 patients with DILI were extracted from the database of the Adverse Drug Reaction Research Group in South Korea. Causative drugs included antituberculosis drugs (n=68, 57.6%), antibiotics (n=22, 18.6%), antiepileptic drugs (n=7, 5.9%), non-steroidal anti-inflammatory drugs (n=5, 4.2%), and others (n=16, 13.7%). Seven single nucleotide polymorphisms (SNPs) in TXNRD1 (rs10735393, rs4964287, rs4595619, rs10861201, rs11111997, rs4246270, and rs4246271) were scored in 118 DILI patients and in 120 drug-matched controls without liver injury. RESULTS: No differences were found between the frequencies of any of the 7 SNPs in the cases and controls; however, a significant association was found between a TTA haplotype composed of rs10735393, rs4964287, and rs4595619 and DILI using an allele model (odds ratio, 1.79; 95% confidence interval, 1.18-2.73; P=0.008; Bonferroni corrected P=0.024). CONCLUSIONS: These results suggest that genetic variations in TXNRD1 favor the development of DILI, although a larger confirmative study is needed.
Alleles ; Animals ; Anti-Bacterial Agents ; Anticonvulsants ; Drug Toxicity ; Drug-Induced Liver Injury ; Genetic Association Studies ; Genetic Variation ; Haplotypes ; Humans ; Liver ; Polymorphism, Genetic ; Polymorphism, Single Nucleotide ; Republic of Korea ; Thioredoxin Reductase 1

BACKGROUND AND OBJECTIVES: The redox system is an important anti-oxidative system composed of thioredoxin, thioredoxin reductase, and peroxiredoxin (PRx). The fine details of PRx expression and its protective effects in various cells in cardiovascular tissue under oxidative stress created by hydrogen peroxide have not been fully elucidated. SUBJECTS AND METHODS: Oxidative stress was induced by adding hydrogen peroxide at 0.25 mM for 2 hours to rat neonatal cardiomyocytes (rCMCs), rat vascular smooth muscle cells (rVSMCs), and human umbilical vein endothelial cells (HUVECs). Apoptosis was quantified by flow cytometry and the expression patterns of the six PRx isoforms were evaluated by western blotting in the three cell lines after hydrogen peroxide stimulation. Apoptosis and the cell survival signal pathway were evaluated by PRx1 gene delivery using lentiviral vector in hydrogen peroxide stimulated rCMCs versus green fluorescence protein gene delivery. RESULTS: Hydrogen peroxide induced 25% apoptosis in rCMCs. Furthermore, the PRx1 and 5 isoforms were found to be overexpressed in hydrogen peroxide treated rCMCs, and PRx1 overexpression by gene delivery was found to reduce hydrogen peroxide induced rCMCs apoptosis significantly. In addition, this effect was found to originate from cell survival pathway modification. CONCLUSION: Hydrogen peroxide induced significant oxidative stress in rCMCs, rVSMCs, and HUVECs, and PRx1 overexpression using a lentiviral vector system significantly reduced hydrogen peroxide induced rCMCs apoptosis by upregulation of cell survival signals and downregulation of apoptotic signals. These findings suggest that PRx1 could be used as a treatment strategy for myocardial salvage in conditions of oxidative stress.
Animals ; Apoptosis ; Blotting, Western ; Cell Line ; Cell Survival ; Down-Regulation ; Flow Cytometry ; Fluorescence ; Human Umbilical Vein Endothelial Cells ; Hydrogen ; Hydrogen Peroxide ; Muscle, Smooth, Vascular ; Myocytes, Cardiac ; Oxidation-Reduction ; Oxidative Stress ; Peroxiredoxins ; Protein Isoforms ; Rats ; Signal Transduction ; Thioredoxin-Disulfide Reductase ; Thioredoxins ; Up-Regulation

The aim of the present study is to investigate the change of thioredoxin (Trx) system in myocardial tissue of type 2 diabetic rats after myocardial injury and the underlying mechanism. Adult Sprague Dawley rats were randomly divided into two groups: normal control (NC) group and diabetes (DM) group. Rats in DM group were subjected to high-sugar, high-fat diet and streptozotocin (STZ) injection. Rats in NC group were only given normal diet and equal amount of citric acid buffer injection. At week 1, 2, 4, 12, 21 after STZ injection, plasma glucose concentration and the concentrations of insulin, creatine kinase MB (CK-MB), cardiac troponin I (cTnI) in serum were measured. Myocardial Trx and thioredoxin reductase (TR) activities, as well as caspase-3 activity, were determined by respective assay methods. Protein and mRNA levels of Trx, TR, Trx interacting protein (TXNIP) were determined by Western blot and real time PCR, respectively. The results showed that type 2 diabetic rat model was successfully established at week 1 after STZ injection, and myocardial injury was induced from week 2. Moreover, caspase-3 activity was significantly increased at week 4, 12 in diabetic rats. The activities of myocardial Trx and TR in diabetic rats was decreased from week 2, and continually aggravated as the disease developed. Compared with those in NC group, the mRNA levels of Trx1, Trx2, TR1, TR2 in DM group decreased at week 4, and then increased in week 12. In DM group, the protein levels of Trx1, Trx2, TR1 and TR2 increased significantly at week 12. The mRNA expressions of myocardial TXNIP in diabetic rats were significantly increased at week 4, 12, 24 and protein expression was increased at week 12. These results suggest diabetes can decrease myocardial Trx, TR activity, inducing myocardial cell apoptosis and heart injury. The inhibitory effect of diabetes is mainly associated with TXNIP up-regulation and Trx nitration.
Animals ; Apoptosis ; Carrier Proteins ; metabolism ; Caspase 3 ; metabolism ; Creatine Kinase, MB Form ; blood ; Diabetes Mellitus, Experimental ; physiopathology ; Diet, High-Fat ; Insulin ; blood ; Myocardium ; pathology ; Rats ; Rats, Sprague-Dawley ; Streptozocin ; Thioredoxin-Disulfide Reductase ; metabolism ; Thioredoxins ; metabolism ; Troponin I ; blood ; Up-Regulation

OBJECTIVETo study the association between single nucleotide polymorphisms of thioredoxin reductase-2 (TrxR2) gene and the susceptibility to Kashin-Beck disease (KBD).

METHODSPolymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to analyze the genotype frequencies of rs5748469 in TrxR2 gene in 84 KBD patients and 109 healthy control subjects.

RESULTSThe genotype frequencies of A/A, A/C, and C/C in the KBD patients were 83.33%, 15.48% and 1.19%, as compared with the frequencies of 74.31%, 25.69%, and 0.00% in the healthy control, respectively, showing no significant difference in the single nucleotide polymorphisms of TrxR2 gene between the two groups (P=0.13).

CONCLUSIONNo obvious correlation can be found between rs5748469 polymorphisms in TrxR2 gene and the susceptibility to KBD.

Adult ; Alleles ; Female ; Genetic Predisposition to Disease ; Genotype ; Humans ; Kashin-Beck Disease ; genetics ; Male ; Middle Aged ; Polymorphism, Restriction Fragment Length ; Polymorphism, Single Nucleotide ; Thioredoxin Reductase 2 ; genetics

Space flight is known to produce a number of neurological disturbances. The etiology is unknown, but it may involve increased oxidative stress. A line of experimental evidence indicates that space flight may disrupt antioxidant defense system and result in increased oxidative stress. In vitro studies found that abundant of NO was produced in rat pheochromocytoma (PC12) cells, SHSY5Y neuroblastoma cells, and protein nitration was increased in PC12 cells within a simulated microgravity rotating wall bioreactor high aspect ratio vessel system or clinostat system. In the present study, we observed the change of redox status in SH-SY5Y cells after parabolic flight, and studied the effects of key redox molecule, thioredoxin (TRX), during the altered gravity. SH-SY5Y cells were divided into four groups: control cells, control cells transfected with TRX, flight cells and flight cells transfected with TRX. The expression levels of 3-nitrotyrosine (3-NT), inducible nitric oxide synthase (iNOS), TRX and thioredoxin reductase (TRXR) were observed by immunocytochemical method. It was shown that after parabolic flight, the staining of 3-NT and TRX were enhanced, while the expression level of TRXR was down-regulated compared with control. As for flight cells transfected with TRX, the staining of 3-NT and iNOS were weakened compared with flight cells. These results obtained suggest that altered gravity may increase protein nitration, down-regulate TRXR and elicit oxidative stress in SH-SY5Y cells, while TRX transfection could partly protect cells against oxidative stress induced by parabolic flight.
Animals ; Antioxidants ; Cell Line, Tumor ; Humans ; Hypogravity ; Nitric Oxide Synthase Type II ; physiology ; Oxidative Stress ; PC12 Cells ; Rats ; Space Flight ; Thioredoxin-Disulfide Reductase ; physiology ; Thioredoxins ; physiology ; Transfection ; Tyrosine ; analogs & derivatives ; physiology