Intracellular Glutathione Content Research Articles

Evaluation of the Anticancer Activity and Mechanism Studies of Glycyrrhetic Acid Derivatives toward HeLa Cells.

In this paper, a series of glycyrrhetic acid derivatives 3a-3f were synthesized via the esterification reaction. The cytotoxicity of these compounds against five tumor cells (SGC-7901, BEL-7402, A549, HeLa and B16) and normal LO2 cells was investigated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. The results showed that compound 3a exhibited high antiproliferative activity against HeLa cells (IC50 = 11.4 ± 0.2 μM). The anticancer activity was studied through apoptosis, cloning, and scratching; the levels of the intracellular ROS, GSH, and Ca2+; and the change in the mitochondrial membrane potential, cell cycle arrest and RNA sequencing. Furthermore, the effects of compound 3a on gene expression levels and metabolic pathways in HeLa cells were investigated via transcriptomics. The experimental results showed that this compound can block the cell cycle in the S phase and inhibit cell migration by downregulating Focal adhesion kinase (FAK) expression. Moreover, the compound can reduce the intracellular glutathione (GSH) content, increase the Ca2+ level and the intracellular ROS content, and induce a decrease in the mitochondrial membrane potential, further leading to cell death. In addition, it was also found that the mechanism of compounds inducing apoptosis was related to the regulation of the expression of mitochondria-related proteins B-cell lymphoma-2 (Bcl-2), Bcl-2-Associated X (Bax), and the activation of the caspase proteins. Taken together, this work provides a help for the development of glycyrrhetinic acid compounds as potential anticancer molecules.

Turning carbon dots into selenium bearing nanoplatforms with in vitro GPx-like activity and pro-oxidant activity

Selenium (Se) has been defined as the “Janus element”, with one face showing antioxidant activity and the other pro-oxidant activity. The biological effect of Se depends on both dose and speciation. Se nanoparticles are attracting major interest, although their large-scale preparation for biomedical applications is not trivial. We hypothesize that acid anhydride-coated carbon dots (AA-CD) are an attractive platform for preparing nanoparticles containing chemically defined Se. The reaction of AA-CD with 3-selenocyanatopropan-1-amine yields carbon dots bearing selenocyanate and carboxylate groups (CD-SeCN) that allow for tuning the hydrosolubility. CD-SeCN has a Se content of 0.36 µmol per mg of nanoparticles, and they show the typical photoluminescence of carbon dots. The selenocyanate groups (SeCN) exhibited glutathione peroxidase-like activity and cytotoxicity. Data show that antioxidant behavior differs between normal and tumor cells, and the evaluation on HEK293 and A549 cells reveals that the toxicity of CD-SeCN depends on dose, time, and intracellular glutathione (GSH) content. The toxicity of CD-SeCN decreases with the time of incubation and the cell death mechanism switches from necrosis to apoptosis, indicating that CD-SeCN is neutralized. Additionally, high levels of intracellular GSH exert a protective effect. These results support a pharmacological potential in cancers with low levels of intracellular GSH. The use of AA-CD as nanoplatforms is a general strategy that paves the way for the engineering of advanced nanosystems.

Dairy Proteins Protect against Dimethylhydrazine-Induced Intestinal Cancers in Rats

The impact of different dietary protein sources (whey, casein, soybean, red meat) on the incidence, burden and mass index of intestinal tumors induced by dimethylhydrazine in male Sprague-Dawley rats was assessed. A purified diet (based on AIN-76A) with a fat concentration of 20 g/100 g and other proteins substituted for casein (20 g/100 g) was used. Whey and casein diets were more protective against the development of intestinal tumors than were the red meat or soybean diets, as evidenced by a reduced incidence of rats affected (P = 0.15), fewer tumors per treatment group (burden, P < 0.005), and a reduced pooled area of tumors (tumor mass index) that formed (P = 0.39). Intracellular concentration of glutathione, an antioxidant and anticarcinogenic tripeptide, measured in liver, was greatest in whey protein- and casein-fed rats and lowest in soybean-fed animals (P < 0.001). For other tissues (spleen, colon, tumor) the differences were not significant, although the whey-fed animals had the highest concentrations of glutathione (P = 0.8). Whey is a source of precursors (cysteine-rich proteins) for glutathione synthesis and may be important in providing protection to the host by stimulating glutathione synthesis. A positive correlation was observed between mean fecal fat concentrations for rats in each treatment group and large intestinal tumor burden (r2 = 0.898, P = 0.05). Fecal fat could be involved in aiding initiation and/or promotion of carcinogenesis. Whatever the mechanism(s), dairy proteins, and whey proteins in particular, offer considerable protection to the host against dimethylhydrazine-induced tumors relative to the other protein sources examined.

Safety Assessment of the Modified Lactoperoxidase System-In Vitro Studies on Human Gingival Fibroblasts.

One strategy in caries prevention is to inhibit the formation of cariogenic biofilms. Attempts are being made to develop oral hygiene products enriched with various antimicrobial agents. One of them is lactoperoxidase-an enzyme that can oxidise (pseudo)halide ions to reactive products with antimicrobial activity. Currently, commercially available products utilise thiocyanate as a substrate; however, several alternatives that are oxidised to products with greater antimicrobial potential have been found. In this study, toxicity against human gingival fibroblasts of the lactoperoxidase system was evaluated using four different (pseudo)halide substrate systems-thiocyanate, iodide, selenocyanate, and a mixture of thiocyanate and iodide. For this purpose, cells were treated with the systems and then apoptosis, cell cycle, intracellular glutathione concentration, and mitochondrial superoxide production were assessed. The results showed that each system, after generating 250 µM of the product, inhibited cell divisions, increased apoptosis, and increased the percentage of dead cells. It was concluded that the mechanism of the observed phenomena was not related to increased superoxide production or the depletion of glutathione concentration. These findings emphasised the need for the further in vitro and in vivo toxicity investigation of the modified lactoperoxidase system to assess its safety and the possibility of use in oral hygiene products.

Sulfasalazine, a potent cystine-glutamate transporter inhibitor, enhances osteogenic differentiation of canine adipose-derived stem cells.

Cystine-glutamate transporter (xCT) is a plasma membrane transporter that imports cystine and indirectly contributes to the oxidative stress resistance associated with increased intracellular glutathione levels. Canine adipose-derived stem cells (CADSCs) include an xCT-positive subpopulation and show relatively low expression of osteogenic markers during in vitro osteogenic differentiation. Sulfasalazine (SSZ), a drug used to treat rheumatoid arthritis, suppresses xCT expression in cancer cells. In this study, we found that the SSZ treatment at 100 µM significantly suppressed xCT mRNA expression in CADSCs but did not significantly affect cell proliferation under the same conditions. Additionally, this treatment decreased the intracellular glutathione concentration. During in vitro osteogenic differentiation, the SSZ treatment at 50 µM and 100 µM significantly increased alizarin red staining and its quantification, as well as the concentration-dependent osteogenic differentiation markers (BMP1 and SPP) mRNA expression. Our results suggested that SSZ enhances the osteogenic differentiation potential of CADSCs and can potentially exhibit a superior therapeutic profile in canine bone regenerative medicine.

CD70-Targeted Micelles Enhance HIF2α siRNA Delivery and Inhibit Oncogenic Functions in Patient-Derived Clear Cell Renal Carcinoma Cells.

The majority of clear cell renal cell carcinomas (ccRCCs) are characterized by mutations in the Von Hippel−Lindau (VHL) tumor suppressor gene, which leads to the stabilization and accumulation of the HIF2α transcription factor that upregulates key oncogenic pathways that promote glucose metabolism, cell cycle progression, angiogenesis, and cell migration. Although FDA-approved HIF2α inhibitors for treating VHL disease-related ccRCC are available, these therapies are associated with significant toxicities such as anemia and hypoxia. To improve ccRCC-specific drug delivery, peptide amphiphile micelles (PAMs) were synthesized incorporating peptides targeted to the CD70 marker expressed by ccRCs and anti-HIF2α siRNA, and the ability of HIF2α-CD27 PAMs to modulate HIF2α and its downstream targets was evaluated in human ccRCC patient-derived cells. Cell cultures were derived from eight human ccRCC tumors and the baseline mRNA expression of HIF2A and CD70, as well as the HIF2α target genes SLC2A1, CCND1, VEGFA, CXCR4, and CXCL12 were first determined. As expected, each gene was overexpressed by at least 63% of all samples compared to normal kidney proximal tubule cells. Upon incubation with HIF2α-CD27 PAMs, a 50% increase in ccRCC-binding was observed upon incorporation of a CD70-targeting peptide into the PAMs, and gel shift assays demonstrated the rapid release of siRNA (>80% in 1 h) under intracellular glutathione concentrations, which contributed to ~70% gene knockdown of HIF2α and its downstream genes. Further studies demonstrated that knockdown of the HIF2α target genes SLC2A1, CCND1, VEGFA, CXCR4, and CXCL12 led to inhibition of their oncogenic functions of glucose transport, cell proliferation, angiogenic factor release, and cell migration by 50−80%. Herein, the development of a nanotherapeutic strategy for ccRCC-specific siRNA delivery and its potential to interfere with key oncogenic pathways is presented.

Cytotoxic effects of crystalline silica in form of micro and nanoparticles on the human lung cell line A549.

Airborne crystalline silica (SiO2) particles are one of the most common pollutants in stone industries. Limited studies have investigated the health effects of crystalline SiO2 nanoparticles. Hence, the objective of this study was to study the cytotoxicity of SiO2 in nano and micron sizes. A mineral quartz sample in the range of 0.2-0.8mm sizes was purchased. These particles were ground at about 5 and 0.1 microns. Human cell line A549 was exposed to micro and nanometer particles at concentrations of 10, 50, 100, and 250μg/ml for 24 and 72 h. Subsequently, the cytotoxicity of exposed cells was investigated by measuring cell survival, ROS generation, mitochondrial permeability, and intracellular glutathione content. The results showed that crystalline SiO2 nano and microparticles decreased cell survival, increased ROS generation, damaged the mitochondrial membrane, and lowered the antioxidant content of these cells in a concentration- and time-dependent manner. The toxicity of crystalline SiO2 microparticles at concentrations ≤50μg/mL was greater than for nanoparticles, which was the opposite at concentrations ≥100μg/mL. Exposure time and concentration were crucial factors for the cytotoxicity of exposed A549 cells to crystalline SiO2 particles, which can affect the severity of the effect of particle size. Due to the limitation of exposure concentration and test durations in this study, further studies on the parameters of nanoparticle toxicity and underlying mechanisms could advance our knowledge.

A cancer cell membrane coated nanoparticles-based gene delivery system for enhancing cancer therapy

Gene therapy is a superior therapeutic means in cancer therapy. However, the instability of nucleic acid and the lack of suitable delivery carrier greatly restricts its further development and application. Herein, we coupled low molecular weight polyethyleneimine (LMW PEI) through disulfide bonds, then modified it with manganese dioxide (MnO2) nanosheets and nuclear localization signal peptide (NLS), as a p53 gene carrier, and finally coated it with B16F10 cell membrane to construct a novel gene-carrier system CM@MnO2-PEI-NLS-ss/p53 (M@MPNs/p53). Tumor cell membrane coating endows nanoparticles with homotypic targeting and immune escape capabilities, disulfide-crosslinked LMW-PEI has high transfection efficiency and low toxicity, and NLS peptides enhance nuclear delivery and improve p53 gene delivery efficiency; meanwhile, MnO2 nanosheets oxidize high intracellular concentration of glutathione (GSH), sensitizing p53 gene-mediated antitumor therapy. The results showed that the novel biofilm-camouflaged M@MPNs/p53 nanoparticles had a highly specific targeting effect on homologous cancer cells and could effectively inhibit tumor growth in vitro and in vivo. Besides, MnO2 loading improved p53-mediated tumor regression. This novel gene delivery platform is of great significance in improving gene delivery efficiency and enhancing anti-tumor therapy.

Cadmium–Zinc Interaction in Mus musculus Fibroblasts

This work aimed to evaluate the effects of zinc (Zn) relating to cadmium (Cd)-induced toxicity and the role played by MTF-1. This transcription factor regulates the expression of genes encoding metallothioneins (MTs), some Zn transporters and the heavy chain of γ-glutamylcysteine synthetase. For this reason, two cell lines of mouse fibroblasts were used: a wild-type strain and a knockout strain to study the effects. Cells were exposed to complete medium containing: (1) 50 μM ZnSO4 (Zn), (2) 1 μM CdCl2 (Cd 1), (3) 2 μM CdCl2 (Cd 2), (4) 50 μM ZnSO4 + 1 μM CdCl2 (ZnCd 1) and (5) 50 μM ZnSO4 + 2 μM CdCl2 (ZnCd 2) for 4, 18 and 24 h. Following exposure, cell viability, the intracellular content of metals, glutathione (GSH) and MT and the gene expression of the two isoforms of MT was evaluated. The results obtained suggest that a lower Cd content in the co-treatments is responsible for the protection offered by Zn due to the probable competition for a common transporter. Furthermore, Zn determines an increase in GSH in co-treatments compared to treatments with Cd alone. Finally, the MTF-1 factor is essential for the expression of MT-1 but not of MT-2 nor probably for the heavy chain of γ-glutamylcysteine synthetase.

Neuroprotective Effects of a New Derivative of Chlojaponilactone B against Oxidative Damaged Induced by Hydrogen Peroxide in PC12 Cells.

A new sesquiterpenoid (1) was obtained by hydrogenating Chlojaponilactone B. The structure of 1 was elucidated according to a combination of NMR, HRESIMS, and NOE diffraction data. The treatment of H2O2 in a PC12 cell model was used to evaluate the antioxidant activity of 1. An MMT assay showed that 1 had no cytotoxicity to the PC12 cell and rescued cell viability from the oxidative damage caused by H2O2. The treatment of 1 stabilized the mitochondria membrane potential (MMP), which decreased the intracellular ROS level and reduced cell apoptosis in the oxidative stress model. The activities of antioxidant enzyme superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and the content of intracellular glutathione (GSH) were significantly enhanced after the treatment of 1. In addition, the results of qRT-PCR showed that 1 treatment minimized the cell injury by H2O2 via the up-regulation of the expression of nuclear factor erythroid 2 (Nrf2) and its downstream enzymes Heme oxygenase 1 (HO-1), glutamate cysteine ligase-modifier subunit (GCLm), and NAD(P)H quinone dehydrogenase 1 (Nqo1). Based on the antioxidant activity of 1, we speculated its potential as a therapeutic agent for some diseases induced by oxidative damage.

Acute and mutigenerational effects of environmental concentration of the antifouling agent dichlofluanid on the mysid model, Neomysis awatschensis

A broad-spectrum fungicide, dichlofluanid is widely used in antifouling paints and agricultural pesticides. In this study, the acute and chronic effects of sublethal concentrations, namely, no observable effect concentration (NOEC) and 50% lethal concentration (LC50) of dichlofluanid (1/10 NOEC, NOEC, 1/10 LC50, and LC50) were evaluated on the marine mysid, Neomysis awatschensis. Acute toxicity test (96 h) showed higher sensitivity to dichlofluanid in juvenile mysids (LC50 3.1 μg L−1) than adults (LC50 24.5 μg L−1), with lower survival rate and reduction in food consumption. Exposure with dichlofluanid considerably induced oxidative imbalance, as NOEC (0.006 μg L−1 for juveniles and 0.074 μg L−1 for adults) and 1/10 LC50 values increased intracellular concentrations of malondialdehyde and glutathione, and the enzymatic activities of catalase and superoxide dismutase, whereas exposure to LC50 value decreased the values of oxidative parameters. Enzymatic activity of acetylcholinesterase decreased considerably when exposed to LC50 value. In the case of chronic effects, exposure to NOEC for 4 weeks markedly decreased the juvenile survival rate, while adults showed tolerance. Multigenerational monitoring in response to NOEC showed a significant growth retardation with an increase in intermolt duration as well as a decrease in the number of newborn mysids from females of the third generation. Consistent exposure to environmentally relevant sublethal concentrations of dichlofluanid would be detrimental to mysid individuals and the survival of the mysid population.

Metabolic engineering of the l-serine biosynthetic pathway improves glutathione production in Saccharomyces cerevisiae

BackgroundGlutathione is a valuable tri-peptide that is industrially produced by fermentation using the yeast Saccharomyces cerevisiae, and is widely used in the pharmaceutical, food, and cosmetic industries. It has been reported that addition of l-serine (l-Ser) is effective at increasing the intracellular glutathione content because l-Ser is the common precursor of l-cysteine (l-Cys) and glycine (Gly) which are substrates for glutathione biosynthesis. Therefore, we tried to enhance the l-Ser biosynthetic pathway in S. cerevisiae for improved glutathione production.ResultsThe volumetric glutathione production of recombinant strains individually overexpressing SER2, SER1, SER3, and SER33 involved in l-Ser biosynthesis at 48 h cultivation was increased 1.3, 1.4, 1.9, and 1.9-fold, respectively, compared with that of the host GCI strain, which overexpresses genes involved in glutathione biosynthesis. We further examined simultaneous overexpression of SHM2 and/or CYS4 genes involved in Gly and l-Cys biosynthesis, respectively, using recombinant GCI strain overexpressing SER3 and SER33 as hosts. As a result, GCI overexpressing SER3, SHM2, and CYS4 showed the highest volumetric glutathione production (64.0 ± 4.9 mg/L) at 48 h cultivation, and this value is about 2.5-fold higher than that of the control strain.ConclusionsThis study first revealed that engineering of l-Ser and Gly biosynthetic pathway are useful strategies for fermentative glutathione production by S. cerevisiase.

404 Novel glycerin compounds improve skin health

Novel glycerin compounds (NGCs) were developed which generated new reaction products, endoperoxide derivatives. NGCs have been reported to exhibit various biological effects. In addition to their deodorizing, disinfecting and antiviral effects, NGCs were found to promote wound healing in the skin by stimulating epithelial growth and regeneration with the synthesis of extracellular matrix such as hyaluronic acid. In this study, in order to clarify the effects of NGCs on normal human skin, we quantified the mRNA gene expression of heme oxygenase-1 (HO-1) and DAD(P)H quinone dehydrogenase 1 (NQO-1) as antioxidant factors by PR-PCR and the protein content of intracellular glutathione (GSH) using a culture system of normal human epidermal keratinocyte. Moreover, gene expression of factors related to skin barrier functions (involucrin (INV), filaggrin (FLG), and serine palmitoyl transferase (SPT)) was examined to clarify the effects of NGCs on epidermal cell differentiation. Our results showed that NGCs enhanced expression of HO-1, NQO-1 mRNA and GSH protein in a concentration-dependent manner from 20 ppm after 24 h of stimulation. These results suggest that the oxidative property of NGCs activates Nrf2 (NF-E2-related factor 2) transcription factor, which is a biological defense sensor, and induces the expression of antioxidant factors. Since their expression was caused by oxidative stimulation at low concentrations of NGCs, it was strongly suggested that their hormesis effect would be working protectively for the skin. Consistent with this, the expression of INV, FLG, and SPT genes also increased at low concentrations of NGCs: FLG showed a threefold increase compared to the control group. These results suggest that NGCs promote epidermal cell differentiation and have positive effects on skin barrier functions. Mild oxidative stimulation of NGC may lead to healthy skin through hormesis effect. We are currently conducting detailed analysis of the effects of NGCs using three-dimensional cultures of human epidermis.

Self-assembled hydrogel nanocube for stimuli responsive drug delivery and tumor ablation by phototherapy against breast cancer

The shape and responsiveness of nanoengineered delivery carriers are crucial characteristics for the rapid and efficient delivery of therapeutics. We report on a novel type of micrometer-sized hydrogel particles of controlled shape with dual pH and redox sensitivity for intracellular delivery of anticancer drugs and phototherapy. The cubical HA-DOP-CS-PEG networks with disulfide links are obtained by cross-linking HA-DOP-CS-PEG with cystamine. The pH-triggered hydrogel swelling/shrinkage was not only affords effective doxorubicin release. It also actively provides the endosomal/lysosomal escape, redox-triggered drug release. The hydrogels degrade rapidly to low molecular weight chains in the presence of the typical intracellular concentration of glutathione. Drug-loaded cube particles found to be 12% more cytotoxic. ICG and DOX-loaded hydrogel cubes demonstrate 90% cytotoxicity when incubated with MCF-7 cancer cells for 24 and 48 h, respectively. This approach integrates the advantages of pH sensitivity, enzymatic degradation, and shape-regulated internalization for novel types of “intelligent” three-dimensional networks with programmable behavior for controlled delivery of therapeutics.

Dual Responsive poly(vinyl caprolactam)-Based Nanogels for Tunable Intracellular Doxorubicin Delivery in Cancer Cells.

In this work, doxorubicin (Dox)-encapsulated poly(vinyl caprolactam) (PVCL)-based three-dimensional nanogel networks were developed and were crosslinked with disulfide linkages. The nanogels degrade rapidly to low molecular weight chains in the presence of the typical intracellular concentration of glutathione. Doxorubicin (Dox) was successfully encapsulated into these nanogels. The nanogels have a high drug loading of 49% and can be tailored to 182 nm to deliver themselves to the targeted cells and release Dox under dual stimuli conditions, such as redox and temperature. By evaluating cell viability in the HepG2 cell line, we observed that Dox-loaded nanogels effectively killed the cancer cell. Fluorescence microscopy results show that the nanogels could easily be internalized with HepG2 cells. The results confirm that the nanogels destabilized in intracellular cytosol via degradation of disulfide bonds in nanogels networks and release of the Dox nearby the nucleus. These carriers could be promising for cancer drug delivery.

Protective effect of isopsoralen on UVB-induced injury in HaCaT cells via the ER and p38MAPK signaling pathways.

This study investigated the protective effect of isopsoralen on UVB-induced damage in HaCaT cells and its molecular mechanism. The cytotoxicity of isopsoralen and its effects on the viability of HaCaT cells were examined using the MTT assay. The effects of UVB irradiation and isopsoralen on the intracellular glutathione (GSH-PX), superoxide dismutase (SOD), malondialdehyde (MDA), and reactive oxygen species (ROS) content were examined using commercially available assay kits. Further, the effects of UVB irradiation and isopsoralen on the levels of the inflammatory cytokines TNF-α, IL-6, and IL-1α were examined using enzyme-linked immunosorbent assay. Finally, we examined the effect of adding the estrogen receptor (ER) antagonist ICI182780,780 and the p38MAPK antagonist SB203580 on the changes in inflammatory cytokines induced by isopsoralen treatment and UVB irradiation. Isopsoralen pretreatment markedly inhibited UVB-induced reduction in the viability and proliferation of HaCaT cells. Isopsoralen also reduced UVB-induced increase in the expression of the inflammatory cytokines and the level of free radicals (ROS and MDA), and reversed the UVB-induced suppression of antioxidant activity. Additionally, inhibition of ER and p38MAPK via the addition of their respective antagonists reversed the observed anti-inflammatory effects of Isopsoralen. Isopsoralen can efficiently provide protection against UVB-induced damage in HaCaT cells brought about via oxidation and inflammatory reactions, and the underlying mechanisms involve the ER and p38MAPK pathways. Therefore, Isopsoralen could be used in therapeutic solutions for UVB-induced skin conditions. PRACTICAL APPLICATIONS: Isopsoralen shows antioxidant and anti-inflammatory effects. As natural, healthy, and effective additives, isopsoralen has been widely used in cosmetics and botanical medicine products. The results of this study reveal the molecular mechanisms underlying isopsoralen effects, showing that isopsoralen reverses the effects of UVB irradiation regulating ER and p38MAPK signaling pathways. Consequently, isopsoralen regulates the expression of ER and p38MAPK signaling pathways, thereby reducing the activation of antioxidant and anti-inflammatory activity. These findings suggest that isopsoralen can be used as the base ingredient for antiphotoaging cosmetics and botanical medicine products. This study provides both theoretical and experimental background for isopsoralen deep processing and utilization.

A Yellow Fluorescence Probe for the Detection of Oxidized Glutathione and Biological Imaging.

It is well-known that the ratio of reduced l-glutathione (GSH) to oxidized l-glutathione (GSSG) is a vital biomarker for monitoring overall cellular health, thus detecting the intracellular concentration of glutathione is of great significance. Recently, an increasing number of reports have published various methods for GSH detection, but studies on the detection of GSSG are still rare. Here, we report a kind of new yellow fluorescent carbon dots (CDs) for the detection of GSSG through a fluorescence "off-on" process. Because the surface is rich in amino groups, the CDs show a positive potential. When the concentration of GSSG was continuously increased, the CDs' fluorescence dropped sharply, while the fluorescence gradually recovered after the addition of sodium sulfide. The phenomenon of fluorescence quenching is linear with the concentration of the quencher (GSSG)(0-200 μM), and 0.18 μM is calculated as the detection limit. More interestingly, as a fluorescent probe, the CDs can be further used for fluorescence imaging in living cells and zebrafish.

NIR Activated Upper Critical Solution Temperature Polymeric Micelles for Trimodal Combinational Cancer Therapy.

The balance between drug efficiency and its side effects on normal tissues is still a challenging problem to be solved in current cancer therapies. Among different strategies, cancer therapeutic methods based on nanomedicine delivery systems have received extensive attention due to their unique advantages such as improved circulation and reduced toxicity of drugs in the body. Herein, we constructed dual-responsive polymeric micelles DOX&ALS@MFM based on an upper critical solution temperature (UCST) polymer to simultaneously combine chemotherapy, photothermal therapy (PTT), and photodynamic therapy (PDT). Amphiphilic block copolymer P(AAm-co-AN)-b-PEI-ss-PEG-FA with a critical point of 42 °C was able to self-assemble into polymeric micelles under physiological conditions, which further encapsulated anticancer drug doxorubicin (DOX) and photosensitizer ALS to obtain drug-loaded micelles DOX&ALS@MFM. Micelles aggregated at tumor sites due to folate targeting and an enhanced permeability retention (EPR) effect. After that, the high intracellular concentration of glutathione (GSH) and near-infrared (NIR) light prompted disassembly of the polymer to release DOX and ALS. ALS not only plays a role in PTT but also produces singlet oxygen, therefore killing tumor cells by PDT. Both in vitro and in vivo studies demonstrated the photothermal conversion and reactive oxygen species generation ability of DOX&ALS@MFM micelles, at the same time as the excellent inhibitory effect on tumor growth with NIR light irradiation. Thus, our research substantiated a new strategy for the biomedical application of UCST polymers in the cited triple modal tumor therapy.

Influenza Virus Down-Modulates G6PD Expression and Activity to Induce Oxidative Stress and Promote Its Replication.

Influenza virus infection induces oxidative stress in host cells by decreasing the intracellular content of glutathione (GSH) and increasing reactive oxygen species (ROS) level. Glucose-6-phosphate dehydrogenase (G6PD) is responsible for the production of reducing equivalents of nicotinamide adenine dinucleotide phosphate (NADPH) that is used to regenerate the reduced form of GSH, thus restoring redox homeostasis. Cells deficient in G6PD display elevated levels of ROS and an increased susceptibility to viral infection, although the consequences of G6PD modulation during viral infection remain to be elucidated. In this study, we demonstrated that influenza virus infection decreases G6PD expression and activity, resulting in an increase in oxidative stress and virus replication. Moreover, the down regulation of G6PD correlated with a decrease in the expression of nuclear factor erythroid 2-related factor 2 (NRF2), a key transcription factor that regulates the expression of the antioxidant response gene network. Also down-regulated in influenza virus infected cells was sirtuin 2 (SIRT2), a NADPH-dependent deacetylase involved in the regulation of G6PD activity. Acetylation of G6PD increased during influenza virus infection in a manner that was strictly dependent on SIRT2 expression. Furthermore, the use of a pharmacological activator of SIRT2 rescued GSH production and NRF2 expression, leading to decreased influenza virus replication. Overall, these data identify a novel strategy used by influenza virus to induce oxidative stress and to favor its replication in host cells. These observations furthermore suggest that manipulation of metabolic and oxidative stress pathways could define new therapeutic strategies to interfere with influenza virus infection.

Protective Effect of Siegesbeckia orientalis on Pancreatic β-Cells under High Glucose-Induced Glucotoxicity

The glucotoxicity caused by long-term exposure of β-cells to high glucose (HG) conditions may lead to the generation of more reactive oxygen species (ROS), reduce the activity of antioxidant enzymes, cause cell damage and apoptosis, and induce insulin secretion dysfunction. Siegesbeckia orientalis linne is a traditional folk herbal medicine used to treat snake bites, rheumatoid arthritis, allergies, and immune deficiencies. In this study, we evaluated the protective effect of S. orientalis ethanol extract (SOE) on cell death and oxidative stress in RIN-m5f pancreatic β-cells stimulated by two HG concentrations (50–100 mM). In the cell viability assay, SOE could significantly increase the survival rate of pancreatic β-cells under HG-induced conditions. For the oxidative stress induced by HG condition, the treatment of SOE effectively reduced the ROS formation, increased the content of intracellular glutathione, and up-regulated the expression of antioxidant enzymes, catalase, superoxide dismutase, and glutathione peroxidase. As a result, the SOE treatment could decrease the glucotoxicity-mediated oxidative damage on RIN-m5F β-cells. Moreover, SOE had the function of regulating insulin secretion in pancreatic β-cells under different HG-mediated conditions. It could decrease the increasing intracellular insulin secretion under the low glucose concentration to normal level; while increase the decreasing intracellular insulin secretion under the relatively high glucose concentration to normal level. Taken together, this study suggests that SOE has a protective effect on pancreatic β-cells under the HG-stimulated glucotoxic environment.