Total Intracellular Glutathione Research Articles

Mechanistic Insights into the Neurotoxicity of 2,5-Dimethoxyphenethylamines (2C) and Corresponding N-(2-methoxybenzyl)phenethylamine (NBOMe) Drugs.

Substituted phenethylamines including 2C (2,5-dimethoxyphenethylamines) and NBOMe (N-(2-methoxybenzyl)phenethylamines) drugs are potent psychoactive substances with little to no knowledge available on their toxicity. In the present in vitro study, we explored the mechanisms underlying the neurotoxicity of six substituted phenethylamines: 2C-T-2, 2C-T-4, 2C-T-7 and their corresponding NBOMes. These drugs were synthesized and chemically characterized, and their cytotoxicity (0-1000 μM) was evaluated in differentiated SH-SY5Y cells and primary rat cortical cultures, by the NR uptake and MTT reduction assays. In differentiated SH-SY5Y cells, mitochondrial membrane potential, intracellular ATP and calcium levels, reactive oxygen species production, and intracellular total glutathione levels were also evaluated. All the tested drugs exhibited concentration-dependent cytotoxic effects towards differentiated SH-SY5Y cells and primary rat cortical cultures. The NBOMe drugs presented higher cytotoxicity than their counterparts, which correlates with the drug's lipophilicity. These cytotoxic effects were associated with mitochondrial dysfunction, evident through mitochondrial membrane depolarization and lowered intracellular ATP levels. Intracellular calcium imbalance was observed for 2C-T-7 and 25T7-NBOMe, implying a disrupted calcium regulation. Although reactive species levels remained unchanged, a reduction in intracellular total GSH content was observed. Overall, these findings contribute to a deeper understanding of these drugs, shedding light on the mechanisms underpinning their neurotoxicity.

CircAMN1-Mediated Ferroptosis Regulates the Expulsion of Placenta in Trophoblast Cells.

After delivery, the death of trophoblast cells can promote the expulsion of the placenta. Ferroptosis, an iron-dependent programmed cell death, is involved in mammalian development. Circular RNAs are associated with placental development; however, it is unclear whether circular RNAs regulate the expulsion of fetal membranes through ferroptosis. The gene expression profiles in the tail vein blood of Holstein cows with normal and retained placentas were investigated using RNA sequencing and a GSE214588 dataset. circAMN1 and SLC39A8 expression was significantly downregulated in the blood of cows with a retained placenta, whereas miR-205_R-1 expression was significantly upregulated. We validated erastin-induced ferroptosis in trophoblast cells. Transfection with si-circAMN1 and miR-205_R-1 mimic reduced intracellular total iron, Fe2+, and glutathione disulfide levels; increased intracellular glutathione levels and glutathione/glutathione disulfide; and enhanced cell viability in these cells. In contrast, transfection with pcDNA3.1 circAMN1 and an miR-205_R-1 inhibitor promoted ferroptosis. As an miR-205_R-1 sponge, circAMN1 regulated the expression of SLC39A8 to control erastin-induced ferroptosis and regulated the proliferation, invasion, and migration of trophoblast cells. Our findings provide a theoretical basis for studying the mechanism by which programmed cell death regulates fetal membrane expulsion and indicate its potential as a therapeutic target for placenta retention.

In vitro effects of European and Latin-American medicinal plants in CYP3A4 gene expression, glutathione levels, and P-glycoprotein activity.

Many medicinal plants species from European -such as Artemisia absinthium, Equisetum arvense, Lamium album, Malva sylvestris, Morus nigra, Passiflora incarnata, Frangula purshiana, and Salix alba- as well as Latin American traditions -such as Libidibia ferrea, Bidens pilosa, Casearia sylvestris, Costus spicatus, Monteverdia ilicifolia, Persea americana, Schinus terebinthifolia, Solidago chilensis, Syzygium cumini, Handroanthus impetiginosus, and Vernonanthura phosphorica- are shortlisted by the Brazilian National Health System for future clinical use. However, they lack many data on their action upon some key ADME targets. In this study, we assess non-toxic concentrations (up to100 μg/ml) of their infusions for in vitro ability to modulate CYP3A4 mRNA gene expression and intracellular glutathione levels in HepG2 cells, as well as P-glycoprotein (P-gp) activity in vincristine-resistant Caco-2 cells (Caco-2 VCR). We further investigated the activation of human pregnane X receptor (hPXR) in transiently co-transfected HeLa cells and the inhibition of Gamma-glutamyl transferase (GGT) in HepG2 cells. Our results demonstrate L. ferrea, C. sylvestris , M. ilicifolia, P. americana, S. terebinthifolia, S. cumini, V. phosphorica, E. arvense, P. incarnata, F. purshiana, and S. alba can significantly increase CYP3A4 mRNA gene expression in HepG2 cells. Only F. purshiana shown to do so likely via hPXR activation. P-gp activity was affected by L. ferrea, F. purshiana, S. terebinthifolia, and S. cumini. Total intracellular glutathione levels were significantly depleted by exposure to all extracts except S. alba and S. cumini This was accompanied by a lower GGT activity in the case of C. spicatus, P. americana, S. alba, and S. terebinthifolia, whilst L. ferrea, P. incarnata and F. purshiana increased it. Surprisingly, S. cumini aqueous extract drastically decreased GGT activity (−48%, p < 0.01). In conclusion, this preclinical study shows that the administration of some of these herbal medicines causes in vitro disturbances to key drug metabolism mechanisms. We recommend active pharmacovigilance for Libidibia ferrea (Mart.) L. P. Queiroz, Frangula purshiana Cooper, Schinus terebinthifolia Raddi, and Salix alba L. which were able to alter all targets in our preclinical study.

Exploitation of High Tumour GSH Levels for Targeted siRNA Delivery in Rhabdomyosarcoma Cells.

Metastatic alveolar rhabdomyosarcoma (aRMS) is an aggressive paediatric cancer with a poor prognosis. Downregulation of critical tumour genes using targeted siRNA remains an obstacle, but association with nanoparticles could help to deliver, protect, target, and enhance penetration. siRNA towards two genes was investigated: (i) Human αB-crystallin (CRYAB) and Heat Shock Protein Family B (Small) Member 2 (HSPB2), and (ii) Keratin 17 (KRT17). A mesoporous silica based nanosystem was linked to siRNA via disulfide bonds and loaded with IR820 dye. Transfection efficiency and signalling was evaluated, and the metabolic effects and cell proliferation were monitored in 2D culture and 3D spheroid models. The bound siRNA was protected from degradation with RNase I for at least 24 h. The delivered siRNA showed significant suppression of viability; 53.21 ± 23.40% for CRYAB and HSPB2 siRNA, and 88.06 ± 17.28% for KRT17 siRNA. After 72 h this increased to >50% cell apoptosis and necrosis. Intracellular total glutathione (GSH) levels were also compared with fibroblasts, and the RMS cell lines showed a several-fold increase. IR820 cellular uptake rate and penetration depth was significantly improved by nanoparticle delivery. Targetted siRNA delivery may pave the way for less invasive and more effective treatments of aRMS.

Homeostasis of the ER redox state subsequent to proteasome inhibition

Endoplasmic reticulum (ER) maintains within, an oxidative redox state suitable for disulfide bond formation. We monitored the ER redox dynamics subsequent to proteasome inhibition using an ER redox probe ERroGFP S4. Proteasomal inhibition initially led to oxidation of the ER, but gradually the normal redox state was recovered that further led to a reductive state. These events were found to be concomitant with the increase in the both oxidized and reduced glutathione in the microsomal fraction, with a decrease of total intracellular glutathione. The ER reduction was suppressed by pretreatment of a glutathione synthesis inhibitor or by knockdown of ATF4, which induces glutathione-related genes. These results suggested cellular adaptation of ER redox homeostasis: (1) inhibition of proteasome led to accumulation of misfolded proteins and oxidative state in the ER, and (2) the oxidative ER was then reduced by ATF4 activation, followed by influx of glutathione into the ER.

The influence of dibenzocyclooctadiene lignans on macrophage glutathione and lipid metabolism associated with Chlamydia pneumoniae-induced foam cell formation

Triggered by changes in macrophage redox status and lipid metabolism, foam cells represent a hallmark of atherosclerosis. Induction of macrophage foam cell formation by Chlamydia pneumoniae, a gram-negative human pathogen, has been established in various earlier studies in vitro and in vivo. Oxidation of low-density lipoprotein (LDL) by C. pneumoniae and alterations in macrophage lipid metabolism do not require chlamydial replication, making conventional antibiotics useless in the intervention of the process. In this work, we report on the ability of schisandrin B and schisandrin C, two dibenzocyclooctadiene lignans, to suppress the C. pneumoniae -induced foam cell formation in RAW264.7 macrophages. This effect was accompanied with the upregulation of PPARγ, a nuclear receptor acting as a major transcriptional regulator of lipid metabolism and inflammatory responses. Schisandrin B and schisandrin C also increased the total intracellular glutathione content of the macrophages. In the case of schisandrin B, this was accompanied with the upregulation of GSH biosynthetic genes glutamate cysteine ligase (both the catalytic and the modifier subunits GCLc and GCLm) as well as gamma-glutamyl transpeptidase GGT1. In addition, schisandrin B and schisandrin C upregulated the expression of a lipid transport protein ABCA1 gene mediating cholesterol efflux from macrophages translating into a reduction in total cholesterol concentration in the schisandrin B -treated cells. Collectively, these data indicate that both schisandrin B and schisandrin C are able to alleviate the pathogenic consequences of C. pneumoniae infection in macrophages by altering the cellular redox balance and lipid trafficking.

Novel Antioxidant Therapy with the Immediate Precursor to Glutathione, γ-Glutamylcysteine (GGC), Ameliorates LPS-Induced Cellular Stress in In Vitro 3D-Differentiated Airway Model from Primary Cystic Fibrosis Human Bronchial Cells.

Systemic glutathione deficiency, inflammation, and oxidative stress are hallmarks of cystic fibrosis (CF), an inherited disease that causes persistent lung infections and severe damage to the respiratory system and many of the body organs. Improvements to current antioxidant therapeutic strategies are needed. The dietary supplement, γ-glutamylcysteine (GGC), which is the immediate precursor to glutathione, rapidly boosts cellular glutathione levels following a single dose in healthy individuals. Efficacy of GGC against oxidative stress induced by Pseudomonas aeruginosa, which is a common and chronic pathogen infecting lungs of CF patients, remains unassessed. Primary mucocilliary differentiated airway (bronchial and/or nasal) epithelial cells were created from four individuals with CF. Airway oxidative stress and inflammation was induced by P. aeruginosa lipopolysaccharide (LPS). Parameters including global proteomics alterations, cell redox state (glutathione, oxidative stress), pro-inflammatory mediators (IL-8, IDO-1), and cellular health (membrane integrity, stress granule formation, cell metabolic viability) were assayed under six experimental conditions: (1) Mock, (2) LPS-challenged (3) therapeutic, (4) prophylactic (5) therapeutic and prophylactic and (6) GGC alone. Proteomic analysis identified perturbation of several pathways related to cellular respiration and stress responses upon LPS challenge. Most of these were resolved when cells were treated with GGC. While GGC did not resolve LPS-induced IL-8 and IDO-1 activity, it effectively attenuated LPS-induced oxidative stress and stress granule formation, while significantly increasing total intracellular glutathione levels, metabolic viability and improving epithelial cell barrier integrity. Both therapeutic and prophylactic treatments were successful. Together, these findings indicate that GGC has therapeutic potential for treatment and prevention of oxidative stress-related damage to airways in cystic fibrosis.

Comparison of three oral selenium compounds in cancer patients: Evaluation of differential pharmacodynamic effects in normal and malignant cells

BackgroundSelenium (Se) compounds have demonstrated therapeutic synergism in combination with anticancer treatments whilst reducing normal tissue toxicities in a range of experimental models. While reduction in some toxicities of chemotherapy and radiation has been confirmed in randomised clinical trials, they have not been powered to evaluate improved anticancer efficacy. A lack of data on the clinical potencies of the main nutritionally-relevant forms of Se and the relationship between their pharmacokinetic (PK) profiles and pharmacodynamic (PD) effects in cancer patients has hampered progress to date.The primary objective of this study was to determine the dose and form of Se that can be most safely and effectively used in clinical trials in combination with anti-cancer therapies. Study methodsIn a phase I randomised double-blinded study, the PD profile of sodium selenite (SS), Se-methylselenocysteine (MSC) and seleno-l-methionine (SLM) were compared in two cohorts of 12 patients, one cohort with chronic lymphocytic leukaemia (CLL) and the other with solid malignancies. All 24 patients were randomised to receive 400 μg of elemental Se as either SS, MSC or SLM, taken orally daily for 8 weeks. PD parameters were assessed before, during and 4 weeks after Se compound exposure in plasma and peripheral blood mononuclear cells (PBMCs). ResultsNo significant sustained changes were observed in plasma concentrations of vascular endothelial growth factor-α (VEGF-α), expression of proteins associated with endoplasmic reticulum stress (the unfolded protein response) or in intracellular total glutathione in PBMCs, in either disease cohort or when grouped by Se compound. ConclusionsAt the 400 μg dose level no substantial changes in PD parameters were noted. Extrapolating from pre-clinical data, the dose examined in this cohort was too low to achieve the Se plasma concentration (≥ 5 μM) expected to elicit significant PD effects. Recruitment of a subsequent cohort at higher doses to exceed this PK threshold is planned.

Experimental Human Root Canal Irrigant NaOCl Against Enterococcus Faecalis and 3T3, and Determination of Cytotoxicity Effect

The main aim of endodontic treatment is disinfection of root canal and to prevent chances of reinfection. The most commonly isolated species due to oral infections is Enterococcus faecalis. For nonsurgical endodontic procedures Sodium hypochlorite (NaOCl) has been the irrigant of choice. The mechanism by which endodontic irrigants induce cytotoxicity is still unclear. However, many studies clearly indicated that rapid expression of the reactive oxygen species (ROS) leads to free radicals formation which results in cytotoxicity and cell death. Hence this study was done to determine the viability of cells and oxidative stress mediated by NaOCl, an endodontic irrigant. The irrigants were tested for their effect against fibroblast isolated from human primary buccal mucosa and against 3T3 Cell line. Antibacterial activity was performed against Enterococcus faecalis. Cytotoxicity was determined by MTT. To determine the oxidative stress, total intracellular glutathione, superoxide radical scavenging activity, and catalase assays were performed. The MIC (Minimal Inhibitory Concentration) for the irrigants against Enterococcus faecalis was found to be 10 µl. 10 µl of NaOCl plain 5.2% produced the same effect as that of 10 μl of NaOCl plain 3%. The higher concentration of the irrigants decreased viability of the cells during dye exclusion assay. Enzyme based study showed there is a decrease in enzyme dehydrogenase when treat with irrigants. Glutathione, SOD level was increased gradually on 3T3 cells. But CAT level was increased when the irrigants concentration less. The results of this study indicated that endodontic irrigants were potentially controlling the Enterococcus faecalis and non-toxic/reduced viability of 3T3 cells by MTT which could be due to the oxidative stress and loss of cellular integrity probably due to the liberation of ROS evidenced by the alteration of antioxidant enzymes Glutathione, SOD and CAT.

Dendrimer-N-acetyl-L-cysteine modulates monophagocytic response in adrenoleukodystrophy.

X-linked adrenoleukodystrophy (ALD) is a neurodegenerative disorder due to mutations in the peroxisomal very long-chain fatty acyl-CoA transporter, ABCD1, with limited therapeutic options. ALD may manifest in a slowly progressive adrenomyeloneuropathy (AMN) phenotype, or switch to rapid inflammatory demyelinating cerebral disease (cALD), in which microglia have been shown to play a pathophysiological role. The aim of this study was to determine the role of patient phenotype in the immune response of ex vivo monophagocytic cells to stimulation, and to evaluate the efficacy of polyamidoamine dendrimer conjugated to the antioxidant precursor N-acetyl-cysteine (NAC) in modulating this immune response. Human monophagocytic cells were derived from fresh whole blood, from healthy (n = 4), heterozygote carrier (n = 4), AMN (n = 7), and cALD (n = 4) patients. Cells were exposed to very long-chain fatty acids (VLCFAs; C24:0 and C26:0) and treated with dendrimer-NAC (D-NAC). Ex vivo exposure to VLCFAs significantly increased tumor necrosis factor α (TNFα) and glutamate secretion from cALD patient macrophages. Additionally, a significant reduction in total intracellular glutathione was observed in cALD patient cells. D-NAC treatment dose-dependently reduced TNFα and glutamate secretion and replenished total intracellular glutathione levels in cALD patient macrophages, more efficiently than NAC. Similarly, D-NAC treatment decreased glutamate secretion in AMN patient cells. ALD phenotypes display unique inflammatory profiles in response to VLCFA stimulation, and therefore ex vivo monophagocytic cells may provide a novel test bed for therapeutic agents. Based on our findings, D-NAC may be a viable therapeutic strategy for the treatment of cALD. Ann Neurol 2018;84:452-462.

The role of oxidative stress in antipsychotics induced ovarian toxicity

This study tested the hypothesis that oxidative stress could be an underlying mechanism for APs-induced ovarian cytotoxicity and reproductive dysfunction. Rat ovarian theca interstitial cells (TICs) were isolated and treated with four APs [chlorpromazine (CPZ), haloperidol (HAL), risperidone (RIS) and clozapine (CLZ)]. MTT assay was used to test the effects of these antipsychotics on TICs viability and to estimate their 50% inhibitory concentrations (IC50s). The effects of APs (IC50s and 1μM concentrations) on the activities of caspases-3, -8 and -9, reactive oxygen species (ROS) production, total intracellular glutathione and lipid peroxidation (LPO) in TICs were assessed. The effect of antioxidants (reduced glutathione (GSH) and quercetin) on the APs-induced cytotoxicity on TICs was investigated. MTT assay showed all APs to reduce TICs viability. CPZ, HAL and CLZ significantly increased the activity of caspases-3, -8 and -9 (P<0.0001, <0.0001 and <0.01, respectively). All APs at IC50s significantly (P<0.0001) increased ROS production, decreased total intracellular glutathione and increased LPO. MTT assay in the presence of antioxidants (reduced GSH (5mM) or quercetin (50mM)) showed each antioxidant to significantly inhibit the effects of APs at their IC50s on TICs viability. In conclusion, oxidative stress seems to be a possible mechanism for APs-induced ovarian and reproductive toxicity.

Influence of the PDE5 inhibitor tadalafil on redox status and antioxidant defense system in C2C12 skeletal muscle cells.

Phosphodiesterase type 5 inhibitors (PDE5Is), widely known for their beneficial effects onto male erectile dysfunction, seem to exert favorable effects onto metabolism as well. Tadalafil exposure increases oxidative metabolism of C2C12 skeletal muscle cells. A rise in fatty acid (FA) metabolism, requiring more oxygen, could induce a larger reactive oxygen species (ROS) release as a byproduct thus leading to a redox imbalance. The aim of this study was to determine how PDE5I tadalafil influences redox status in skeletal muscle cells to match the increasing oxidative metabolism. To this purpose, differentiated C2C12 skeletal muscle cells were treated with tadalafil and analyzed for total antioxidant capacity (TAC) and glutathione levels as marker of redox status; enzyme activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) engaged in antioxidant defense; and lipid peroxidation (TBARS) and protein carbonyls (PrCar) as markers of oxidative damage. Tadalafil increased total intracellular glutathione (tGSH), CAT, SOD, and GPx enzymatic activities while no changes were found in TAC. A perturbation of redox status, as showed by the decrease in the ratio between reduced/oxidized glutathione (GSH/GSSG), was observed. Nevertheless, it did not cause any change in TBARS and PrCar levels probably due to the enhancement in the antioxidant enzymatic network. Taken together, these data indicate that tadalafil, besides improving oxidative metabolism, may be beneficial to skeletal muscle cells by enhancing the enzymatic antioxidant system capacity.

In vitro Effects of Four Native Brazilian Medicinal Plants in CYP3A4 mRNA Gene Expression, Glutathione Levels, and P-Glycoprotein Activity

Erythrina mulungu Benth. (Fabaceae), Cordia verbenacea A. DC. (Boraginaceae), Solanum paniculatum L. (Solanaceae) and Lippia sidoides Cham. (Verbenaceae) are medicinal plant species native to Brazil shortlisted by the Brazilian National Health System for future clinical use. However, nothing is known about their effects in metabolic and transporter proteins, which could potentially lead to herb-drug interactions (HDI). In this work, we assess non-toxic concentrations (100 μg/mL) of the plant infusions for their in vitro ability to modulate CYP3A4 mRNA gene expression and intracellular glutathione levels in HepG2 cells, as well as P-glycoprotein (P-gp) activity in vincristine-resistant Caco-2 cells (Caco-2 VCR). Their mechanisms of action were further studied by measuring the activation of human pregnane X receptor (hPXR) in transiently co-transfected HeLa cells and the inhibition of γ-glutamyl transferase (GGT) in HepG2 cells. Our results show that P-gp activity was not affected in any case and that only Solanum paniculatum was able to significantly change CYP3A4 mRNA gene expression (twofold decrease, p < 0.05), this being correlated with an antagonist effect upon hPXR (EC50 = 0.38 mg/mL). Total intracellular glutathione levels were significantly depleted by exposure to Solanum paniculatum (-44%, p < 0.001), Lippia sidoides (-12%, p < 0.05) and Cordia verbenacea (-47%, p < 0.001). The latter plant extract was able to decrease GGT activity (-48%, p < 0.01). In conclusion, this preclinical study shows that the administration of some of these herbal medicines may be able to cause disturbances to metabolic mechanisms in vitro. Although Erythrina mulungu appears safe in our tests, active pharmacovigilance is recommended for the other three species, especially in the case of Solanum paniculatum.

L-carnitine exerts a cytoprotective effect against H2O2-induced oxidative stress in thefathead minnowmuscle cell line

This study was conducted to investigate the protective effect of L-carnitine (LC) against H2O2-induced oxidative stress in the fathead minnow muscle cell line (FHM). The FHM cells were stimulated with 1 mM H2O2 for 1 h after LC pre-treatment, and the cell viability and the activity and mRNA relative expression of antioxidant enzyme were measured to assess the antioxidant properties of LC. The results showed that the toxic effect of H2O2 on the viability of FHM cells was both dose- and time-dependent. Furthermore, the viability of the 0.01–1 LC mM groups was significantly higher than those of the 1 mM H2O2 group. L-carnitine protected the cells from H2O2-induced oxidative damage, which was demonstrated by a significant reduction in the malondialdehyde and reactive oxygen species levels and increases in the intracellular total glutathione levels and the activities of total superoxide dismutase, catalase, glutathione peroxidase (GPx) and gamma-glutamyl-cysteine synthetase (γ-GCS) in FHM cells pre-treated with LC for 6 h compared with the 1 mM H2O2 group. In addition, the mRNA relative expression levels of the γ-GCS catalytic subunit and nuclear factor nuclear factor erythroid 2-related factor 2 were significantly higher than those of the 1 mM H2O2 group. It could be concluded that LC exerts a beneficial antioxidant effect against oxidative stress induced by H2O2 in FHM cells and that the appropriate treatment is 0.1–1 mM for 6 h in this study.

S-Sulfocysteine simplifies fed-batch processes and increases the CHO specific productivity via anti-oxidant activity

Industrial fed-batch cultivation of mammalian cells is used for the production of therapeutic proteins such as monoclonal antibodies. Besides medium ensuring initial growth, feeding is necessary to improve growth, viability and antibody production. Established processes include a slight acidic main feed and a separate alkaline feed containing l-tyrosine and l-cysteine. Since l-cysteine is not stable at neutral pH, a new derivative, S-sulfocysteine, was tested in neutral pH feeds. In small scale fed-batch processes, the S-sulfocysteine process yielded a comparable maximum viable cell density, prolonged viability and increased titer compared to the two feed system. Bioreactor experiments confirmed the increase in specific productivity. In depth characterization of the monoclonal antibody indicated no change in the glycosylation, or charge variant pattern whereas peptide mapping experiments were not able to detect any integration of the modified amino acid in the sequence of the monoclonal antibody. Finally, the mechanism of action of S-sulfocysteine was investigated, and results pointed out the anti-oxidative potential of the molecule, mediated through an increase in superoxide dismutase enzyme levels and in the total intracellular glutathione pool. Finally, we propose that the increase in specific productivity obtained in the S-sulfocysteine process results from the anti-oxidative properties of the molecule.

Genome-wide analysis on Chlamydomonas reinhardtii reveals the impact of hydrogen peroxide on protein stress responses and overlap with other stress transcriptomes.

Reactive oxygen species (ROS) are produced by and have the potential to be damaging to all aerobic organisms. In photosynthetic organisms, they are an unavoidable byproduct of electron transfer in both the chloroplast and mitochondrion. Here, we employ the reference unicellular green alga Chlamydomonas reinhardtii to identify the effect of H2O2 on gene expression by monitoring the changes in the transcriptome in a time-course experiment. Comparison of transcriptomes from cells sampled immediately prior to the addition of H2O2 and 0.5 and 1 h subsequently revealed 1278 differentially abundant transcripts. Of those transcripts that increase in abundance, many encode proteins involved in ROS detoxification, protein degradation and stress responses, whereas among those that decrease are transcripts encoding proteins involved in photosynthesis and central carbon metabolism. In addition to these transcriptomic adjustments, we observe that addition of H2O2 is followed by an accumulation and oxidation of the total intracellular glutathione pool, and a decrease in photosynthetic O2 output. Additionally, we analyze our transcriptomes in the context of changes in transcript abundance in response to singlet O2 (O2*), and relate our H2O2 -induced transcripts to a diurnal transcriptome, where we demonstrate enrichments of H2O2 -induced transcripts early in the light phase, late in the light phase and 2 h prior to light. On this basis several genes that are highlighted in this work may be involved in previously undiscovered stress remediation pathways or acclimation responses.

2-deoxy-D-Glucose Synergizes with Doxorubicin or L-Buthionine Sulfoximine to Reduce Adhesion and Migration of Breast Cancer Cells.

Cancer metastasis depends on cell motility which is driven by cycles of actin polymerization and depolymerization. Reactive oxygen species (ROS) and metabolic oxidative stress have long been associated with cancer. ROS play a vital role in regulating actin dynamics that are sensitive to oxidative modification. The current work aimed at studying the effects of sub-lethal metabolic oxidative stress on actin cytoskeleton, focal adhesion and cell migration. T47D human breast cancer cells were treated with 2-deoxy- D-glucose (2DG), L-buthionine sulfoximine (BSO), or doxorubicin (DOX), individually or in combination, and changes in intracellular total glutathione and malondialdehyde (MDA) levels were measured. The expression of three major antioxidant enzymes was studied by immunoblotting, and cells were stained with fluorescent- phalloidin to evaluate changes in F-actin organization. In addition, cell adhesion and degradation ability were measured. Cell migration was studied using wound healing and transwell migration assays. Our results show that treating T47D human breast cancer cells with drug combinations (2DG/BSO, 2DG/DOX, or BSO/DOX) decreased intracellular total glutathione and increased oxidized glutathione, lipid peroxidation, and cytotoxicity. In addition, the drug combinations caused a reduction in cell area and mitotic index, prophase arrest and a decreased ability to form invadopodia. The formation of F-actin aggregates was increased in treated T47D cells. Moreover, combination therapy reduced cell adhesion and the rate of cell migration. Our results suggest that exposure of T47D breast cancer cells to combination therapy reduces cell migration via effects on metabolic oxidative stress.

In vitro neurotoxicity evaluation of piperazine designer drugs in differentiated human neuroblastoma SH‐SY5Y cells

Abuse of synthetic drugs is widespread worldwide. Studies indicate that piperazine designer drugs act as substrates at dopaminergic and serotonergic receptors and/or transporters in the brain. This work aimed to investigate the cytotoxicity of N-benzylpiperazine, 1-(3-trifluoromethylphenyl)piperazine, 1-(4-methoxyphenyl)piperazine and 1-(3,4-methylenedioxybenzyl)piperazine in the differentiated human neuroblastoma SH-SY5Y cell line. Cytotoxicity was evaluated after 24 h incubations through the MTT reduction and neutral red uptake assays. Oxidative stress (reactive oxygen and nitrogen species production and glutathione content) and energetic (ATP content) parameters, as well as intracellular Ca(2+), mitochondrial membrane potential, DNA damage (comet assay) and cell death mode were also evaluated. Complete cytotoxicity curves were obtained after 24 h incubations with each drug. A significant decrease in intracellular total glutathione content was noted for all the tested drugs. All drugs caused a significant increase of intracellular free Ca(2+) levels, accompanied by mitochondrial hyperpolarization. However, ATP levels remained unchanged. The investigation of cell death mode revealed a predominance of early apoptotic cells. No genotoxicity was found in the comet assay. Among the tested drugs, 1-(3-trifluoromethylphenyl)piperazine was the most cytotoxic. Overall, piperazine designer drugs are potentially neurotoxic, supporting concerns on risks associated with the abuse of these drugs.

3β-Acetyl tormentic acid reverts MRP1/ABCC1 mediated cancer resistance through modulation of intracellular levels of GSH and inhibition of GST activity

ABC transporter overexpression is an important mechanism of multidrug resistance (MDR) and one of the main obstacles to successful cancer treatment. As these proteins actively remove chemotherapeutics from the tumor cells, the pharmacological inhibition of their activity is a possible strategy to revert drug resistance. Moreover, the ability of MDR inhibitors to sensitize resistant cells to conventional drugs is important for their clinical use. Evidence has shown that the multidrug resistance protein 1 (MRP1/ABCC1) is a negative prognostic marker in patients with lung, gastric, or breast cancers or neuroblastoma. Previous data have shown that 3β-acetyl tormentic acid (3ATA) inhibits the transport activity of the protein MRP1/ABCC1. In this study, we evaluated the ability of 3ATA to sensitize an MDR cell line (GLC4/ADR), which overexpresses MRP1, and investigated the anti-MRP1 mechanisms activated by 3ATA. The results showed that 3ATA is able to reverse the resistance of the MDR cell line to doxorubicin and vincristine, two drugs that are commonly used in cancer chemotherapy. Regarding the sensitizing mechanism induced by 3ATA, this work shows that the triterpene does not modulate the expression of MRP1/ABCC1 but is able to reduce total intracellular glutathione (GSH) levels and decrease the activity of glutathione-s-transferase (GST), the enzyme responsible for the glutathione conjugation of xenobiotics. Together, these results show that 3ATA sensitizes the MDR cell line overexpressing MRP1/ABCC1 to antineoplastic drugs and that this effect is mediated by the modulation of intracellular levels of GSH and GST activity.

The role of reactive oxygen species in the genotoxicity of surface-modified magnetite nanoparticles

The generation of reactive oxygen species (ROS) has been proposed as the underlying mechanism involved in the genotoxicity of iron oxide nanoparticles. The data published to date are, however, inconsistent, and the mechanism underlying ROS formation has not been completely elucidated. Here, we investigated the capacity of several surface-modified magnetite nanoparticles (MNPs) to generate ROS in A549 human lung adenocarcinoma epithelial cells and HEL 12469 human embryonic lung fibroblasts. All MNPs, regardless of the coating, induced significant levels of DNA breakage in A549 cells but not in HEL 12469 cells. Under the same treatment conditions, variable low levels of intracellular ROS were detected in both A549 and HEL 12469 cells, but compared with control treatment, none of the coated MNPs produced any significant increase in oxidative damage to DNA in either of these cell lines. Indeed, no significant changes in the total antioxidant capacity and intracellular glutathione levels were observed in MNPs-treated human lung cell lines regardless of surface coating. In line with these results, none of the surface-modified MNPs increased significantly the GPx activity in A549 cells and the SOD activity in HEL 12469 cells. The GPx activity was significantly increased only in SO-Fe3O4-treated HEL 12469 cells. The SOD activity was significantly increased in SO-PEG-PLGA-Fe3O4-treated A549 cells but significantly decreased in SO-Fe3O4-treated A549 cells. Our data indicate that oxidative stress plays, at most, only a marginal role in the genotoxicity of surface-modified MNPs considered in this study in human lung cells.