Signalling apoptosis: a radical approach

Nanoparticles and Cell Longevity

The field of engineering has made substantial strides in nanotechnology, in the realm of materials science and construction of nanoscale devices. Nanomedicine encompasses application of cutting edge engineered nanostructures to biological systems and development of novel strategies for disease intervention. In the current review, we discuss the pharmacological application of nanoparticles as free radical scavengers and the capacity of nanoparticles to promote cell and organismal longevity.

Induction of intrinsic and extrinsic apoptosis through oxidative stress in drug-resistant cancer by a newly synthesized Schiff base copper chelate

Multidrug resistance (MDR) in cancer represents a variety of strategies employed by tumor cells to evade the beneficial cytotoxic effects of structurally different anticancer drugs and thus confers impediments to the successful treatment of cancers. Efflux of drugs by MDR protein-1, functional P-glycoprotein and elevated level of reduced glutathione confer resistance to cell death or apoptosis and thus provide a possible therapeutic target for overcoming MDR in cancer. Previously, we reported that a Schiff base ligand, potassium-N-(2-hydroxy 3-methoxy-benzaldehyde)-alaninate (PHMBA) overcomes MDR in both in vivo and in vitro by targeting intrinsic apoptotic/necrotic pathway through induction of reactive oxygen species (ROS). The present study describes the synthesis and spectroscopic characterization of a copper chelate of Schiff base, viz., copper (II)-N-(2-hydroxy-3-methoxy-benzaldehyde)-alaninate (CuPHMBA) and the underlying mechanism of cell death induced by CuPHMBA in vitro. CuPHMBA kills both the drug-resistant and sensitive cell types irrespective of their drug resistance phenotype. The cell death induced by CuPHMBA follows apoptotic pathway and moreover, the cell death is associated with intrinsic mitochondrial and extrinsic receptor-mediated pathways. Oxidative stress plays a pivotal role in the process as proved by the fact that antioxidant enzyme; polyethylene glycol conjugated-catalase completely blocked CuPHMBA-induced ROS generation and abrogated cell death. To summarize, the present work provides a compelling rationale for the future clinical use of CuPHMBA, a redox active copper chelate in the treatment of cancer patients, irrespective of their drug-resistance status.

Antitumor effects of the benzophenanthridine alkaloid sanguinarine: Evidence and perspectives

Historically, natural products have represented a significant source of anticancer agents, with plant-derived drugs becoming increasingly explored. In particular, sanguinarine is a benzophenanthridine alkaloid obtained from the root of Sanguinaria canadensis, and from other poppy Fumaria species, with recognized anti-microbial, anti-oxidant and anti-inflammatory properties. Recently, increasing evidence that sanguinarine exibits anticancer potential through its capability of inducing apoptosis and/or antiproliferative effects on tumor cells, has been proved. Moreover, its antitumor seems to be due not only to its pro-apoptotic and inhibitory effects on tumor growth, but also to its antiangiogenic and anti-invasive properties. Although the precise mechanisms underlying the antitumor activity of this compound remain not fully understood, in this review we will focus on the most recent findings about the cellular and molecular pathways affected by sanguinarine, together with the rationale of its potential application in clinic. The complex of data currently available suggest the potential application of sanguinarine as an adjuvant in the therapy of cancer, but further pre-clinical studies are needed before such an antitumor strategy can be effectively translated in the clinical practice.

Comparison on the molecular response profiles between nano zinc oxide (ZnO) particles and free zinc ion using a genome-wide toxicogenomics approach

Increasing production and applications of nano zinc oxide particles (nano-ZnO) enhances the probability of its exposure in occupational and environmental settings, but toxicity studies are still limited. Taking the free Zn ion (Zn(2+)) as a control, cytotoxicity of a commercially available nano-ZnO was assessed with a 6-h exposure in Escherichia coli (E. coli). The fitted dose-cytotoxicity curve for ZnCl2 was significantly sharper than that from nano-ZnO. Then, a genome-wide gene expression profile following exposure to nano-ZnO was conducted by use of a live cell reporter assay system with library of 1820 modified green fluorescent protein (GFP)-expressing promoter reporter vectors constructed from E. coli K12 strains, which resulted in 387 significantly altered genes in bacterial (p < 0.001). These altered genes were enriched into ten biological processing and two cell components (p < 0.05) terms through statistical hypergeometric testing, strongly suggesting that exposure to nano-ZnO would result a great disturbance on the functional gene product synthesis processing, such as translation, gene expression, RNA modification, and structural constituent of ribosome. The pattern of expression of 37 genes altered by nano-ZnO (fold change>2) was different from the profile following exposure to 6 mg/L of free zinc ion. The result indicates that these two Zn forms might cause toxicity to bacterial in different modes of action. Our results underscore the importance of understanding the adverse effects elicited by nano-ZnO after entering aquatic environment.

Sodium Fluoride Induces Apoptosis in H9c2 Cardiomyocytes by Altering Mitochondrial Membrane Potential and Intracellular ROS Level

Chronic excessive fluoride intake is known to be toxic, and effects of long-term fluorosis on different organ systems have been examined. However, there are few studies about the effects of fluorosis on cardiovascular systems. Here, we studied the fluoride-induced apoptosis in H9c2 cells and determined the underlying molecular mechanisms including the cell viability, intracellular reactive oxygen species (ROS) level, the changes of mitochondrial membrane potential (ΔΨm), and the cell apoptosis. Sodium fluoride (NaF) at concentrations of 0, 2, 4, 8, and 16 mg/L was administered to cultured H9c2 cells for up to 48 h. After the treatment, H9c2 cells were collected and the associated parameters were measured by flow cytometry. Our study found that fluoride not only inhibited H9c2 cell proliferation but also induced cell apoptosis. With the increment of NaF concentration, the apoptotic rates and ROS generation were increased, while the ΔΨm was decreased. In summary, these data suggested that NaF-induced H9c2 cell apoptosis is mediated by direct increased intracellular ROS and downregulated ΔΨm.

Disruptive chemicals, senescence and immortality

Carcinogenesis is thought to be a multistep process, with clonal evolution playing a central role in the process. Clonal evolution involves the repeated 'selection and succession' of rare variant cells that acquire a growth advantage over the remaining cell population through the acquisition of 'driver mutations' enabling a selective advantage in a particular micro-environment. Clonal selection is the driving force behind tumorigenesis and possesses three basic requirements: (i) effective competitive proliferation of the variant clone when compared with its neighboring cells, (ii) acquisition of an indefinite capacity for self-renewal, and (iii) establishment of sufficiently high levels of genetic and epigenetic variability to permit the emergence of rare variants. However, several questions regarding the process of clonal evolution remain. Which cellular processes initiate carcinogenesis in the first place? To what extent are environmental carcinogens responsible for the initiation of clonal evolution? What are the roles of genotoxic and non-genotoxic carcinogens in carcinogenesis? What are the underlying mechanisms responsible for chemical carcinogen-induced cellular immortality? Here, we explore the possible mechanisms of cellular immortalization, the contribution of immortalization to tumorigenesis and the mechanisms by which chemical carcinogens may contribute to these processes.

Aryl Hydrocarbon Receptor Ligand 5F 203 Induces Oxidative Stress That Triggers DNA Damage in Human Breast Cancer Cells

Breast tumors often show profound sensitivity to exogenous oxidative stress. Investigational agent 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203) induces aryl hydrocarbon receptor (AhR)-mediated DNA damage in certain breast cancer cells. Since AhR agonists often elevate intracellular oxidative stress, we hypothesize that 5F 203 increases reactive oxygen species (ROS) to induce DNA damage, which thwarts breast cancer cell growth. We found that 5F 203 induced single-strand break formation. 5F 203 enhanced oxidative DNA damage that was specific to breast cancer cells sensitive to its cytotoxic actions, as it did not increase oxidative DNA damage or ROS formation in nontumorigenic MCF-10A breast epithelial cells. In contrast, AhR agonist and procarcinogen benzo[a]pyrene and its metabolite, 1,6-benzo[a]pyrene quinone, induced oxidative DNA damage and ROS formation, respectively, in MCF-10A cells. In sensitive breast cancer cells, 5F 203 activated ROS-responsive kinases: c-Jun-N-terminal kinase (JNK) and p38 mitogen activated protein kinase (p38). AhR antagonists (alpha-naphthoflavone, CH223191) or antioxidants (N-acetyl-l-cysteine, EUK-134) attenuated 5F 203-mediated JNK and p38 activation, depending on the cell type. Pharmacological inhibition of AhR, JNK, or p38 attenuated 5F 203-mediated increases in intracellular ROS, apoptosis, and single-strand break formation. 5F 203 induced the expression of cytoglobin, an oxidative stress-responsive gene and a putative tumor suppressor, which was diminished with AhR, JNK, or p38 inhibition. Additionally, 5F 203-mediated increases in ROS production and cytoglobin were suppressed in AHR100 cells (AhR ligand-unresponsive MCF-7 breast cancer cells). Our data demonstrate 5F 203 induces ROS-mediated DNA damage at least in part via AhR, JNK, or p38 activation and modulates the expression of oxidative stress-responsive genes such as cytoglobin to confer its anticancer action.

The role of nitric oxide synthase in an early phase Cd-induced acute cytotoxicity in MCF-7 cells

Literature to date has confirmed that cadmium (Cd) can accomplish its toxic effects via the free radical-induced damage, but Cd itself cannot generate free radicals directly. Nitric oxide (NO) is a fundamental molecule that interplays with reactive oxygen species (ROS), which may be associated with the Cd-induced cytotoxicity. However, the role of nitric oxide synthase (NOS) in an early phase Cd-induced acute cytotoxicity and its interaction has not been studied. In this report, we provide data showing that CdCl2 (10 μM, 100 μM, 1 mM) could modulate NOS activity in terms of NO production which was first suppressed with the release of Ca(2+) and Zn(2+), then induced with the transcriptional and translational activation of the three NOS isoforms in a possible feedback manner. The ROS level in cells was increased after CdCl2 exposure. By using the free radical scavenger N-acetyl-L-cysteine (LNAC) or the NOS activity inhibitor N(G)-methyl-L-arginine (LNMMA), it was demonstrated that NOS played a critical role on the Cd-induced ROS generation. The Cd-induced cytotoxicity was associated with the NOS-mediated oxidative stress in MCF-7 cells.

Cytotoxic effects of biosynthesized zinc oxide nanoparticles on murine cell lines

The aim of this study is to evaluate the in vitro cytotoxic activity and cellular effects of previously prepared ZnO-NPs on murine cancer cell lines using brown seaweed (Sargassum muticum) aqueous extract. Treated cancer cells with ZnO-NPs for 72 hours demonstrated various levels of cytotoxicity based on calculated IC50 values using MTT assay as follows: 21.7 ± 1.3 μg/mL (4T1), 17.45 ± 1.1 μg/mL (CRL-1451), 11.75 ± 0.8 μg/mL (CT-26), and 5.6 ± 0.55 μg/mL (WEHI-3B), respectively. On the other hand, ZnO-NPs treatments for 72 hours showed no toxicity against normal mouse fibroblast (3T3) cell line. On the other hand, paclitaxel, which imposed an inhibitory effect on WEHI-3B cells with IC50 of 2.25 ± 0.4, 1.17 ± 0.5, and 1.6 ± 0.09 μg/mL after 24, 48, and 72 hours treatment, respectively, was used as positive control. Furthermore, distinct morphological changes were found by utilizing fluorescent dyes; apoptotic population was increased via flowcytometry, while a cell cycle block and stimulation of apoptotic proteins were also observed. Additionally, the present study showed that the caspase activations contributed to ZnO-NPs triggered apoptotic death in WEHI-3 cells. Thus, the nature of biosynthesis and the therapeutic potential of ZnO-NPs could prepare the way for further research on the design of green synthesis therapeutic agents, particularly in nanomedicine, for the treatment of cancer.

Phosphonomethyl iminodiacetic acid-conjugated cobalt oxide nanoparticles liberate Co(++) ion-induced stress associated activation of TNF-α/p38 MAPK/caspase 8-caspase 3 signaling in human leukemia cells

The aim of this work is to understand the potential health effects of metal nanoparticles by exposing human leukemic cell lines (jurkat, K562 and KG1A cells) to nanosize phosphonomethyl iminodiacetic acid coated cobalt oxide (PMIDA-CoO) NPs. The synthesized PMIDA-CoO NPs were characterized by XRD, dynamic light scattering, transmission electron microscopy and scanning electron microscopy. Our results showed that exposure of leukemic cell lines to PMIDA-CoO NPs caused reactive oxygen species (ROS) generation by increasing the concentration of free Co(++) ions in cancer microenvironment. But at physiological pH, PMIDA-CoO liberates little amount of Co(++) ions into media and exerts lower toxicity to normal cells up to a certain dose. PMIDA-CoO NPs caused DNA damage in leukemic cell lines, which was reflected by an increase in apoptosis of jurkat, KG-1A and K562 cells. PMIDA-CoO NPs induced apoptosis by increasing pro-inflammatory cytokines, primarily TNF-α. The in vivo study shows that PMIDA-CoO NPs were efficiently killed DLA cells. These findings have important implications for understanding the potential anticancer property induced by surface-modified cobalt oxide nanoparticles.

Toxicity of cobalt oxide nanoparticles to normal cells; an in vitro and in vivo study

The aim of this study was to find out the intracellular signaling transduction pathways involved in cobalt oxide nanoparticles (CoO NPs) mediated oxidative stress in vitro and in vivo system. Cobalt oxide nanoparticles released excess Co++ ions which could activated the NADPH oxidase and helps in generating the reactive oxygen species (ROS). Our results showed that CoO NPs elicited a significant (p<0.05) amount of ROS in lymphocytes. In vitro pretreatment with N-acetylene cystine had a protective role on lymphocytes death induced by CoO NPs. In vitro and in vivo results showed the elevated level of TNF-α after CoO NPs treatment. This TNF-α phosphorylated the p38 mitogen-activated protein kinase followed by activation of caspase 8 and caspase 3 which could induce cell death. This study showed that CoO NPs induced oxidative stress and activated the signaling pathway of TNF-α-caspase-8-p38-caspase-3 to primary immune cells. This study suggested that bare CoO NPs are a toxic for primary human immune cells that deals directly with human health. Surface modification or surface functionalization may open the gateway for further use of CoO NPs in different industrial use or in biomedical sciences.

The role of nitric oxide synthase signaling pathway in the Zn-induced cellular responses in MCF-7 cells

Trace amount zinc plays key roles in biological systems, while in excessive amount it causes toxic effects. Evidence shows that there exists a crosstalk between NO and Zn apoptotic signal transduction pathway. However, the potential mechanism of Zn-induced cellular responses through the NOS signaling pathway has not been determined yet. In this research, trace amount ZnCl2 (1nM) could induce the NO production, however it appears that this influence does not extend to genetic level in MCF-7 cells. Whereas, excess ZnCl2 (100μM, 1mM) could lead to a decreased NO production first with the release of Ca(2+), and then induce the NO production with the transcriptional and translational activation of NOSs. The ROS generation was also induced by excess ZnCl2, causing the elF2α phosphorylation. The alleviation effect of N-acetyl-l-cysteine or l-arginine on the Zn-induced ROS generation and apoptosis suggested that Zn-induced apoptosis was associated with the NOS-mediated oxidative stress.

Berberine-induced apoptosis in human breast cancer cells is mediated by reactive oxygen species generation and mitochondrial-related apoptotic pathway

Berberine has drawn extensive attention toward their wide range of biochemical and pharmacological effects, including antineoplastic effect in recent years, but the precise mechanisms remain unclear. Treatment of human breast cancer cells (MCF-7 and MDA-MB-231 cells) with berberine induced inhibition of cell viability in concentration- and time-dependent manner irrespective of their estrogen receptor (ER) expression. Hoechst33342 staining confirmed berberine induced breast cancer cell apoptosis in time-dependent manner. Because apoptosis induction is considered to be a crucial strategy for cancer prevention and therapy, berberine may be an effective chemotherapeutic agent against breast cancer. To explore the precise mechanism, berberine-induced oxidative stress and mitochondrial-related apoptotic pathway in human breast cancer cells were investigated in this study. In both MCF-7 and MDA-MB-231 cells, berberine increased the production of reactive oxygen species (ROS), which activated the pro-apoptotic JNK signaling. Phosphorylated JNK triggered mitochondria membrane potential (ΔΨm) depolarization and downregulation expression of anti-apoptotic protein Bcl-2 concomitant with the upregulation expression of pro-apoptotic protein Bax. Downregulation of anti-apoptotic Bcl-2 family protein in parallel with loss of ΔΨm, leading to increased the release of cytochrome c and apoptosis-inducing factor (AIF) from mitochondria, and eventually triggered the caspase-dependent and caspase-independent apoptosis. Taken together, our study reveled that berberine exerted an antitumor activity in breast cancer cells by reactive oxygen species generation and mitochondrial-related apoptotic pathway. These finding provide an insight into the potential of berberine for breast cancer therapy.

Photodynamic therapy mediated antiproliferative activity of some metal-doped ZnO nanoparticles in human liver adenocarcinoma HepG2 cells under UV irradiation

Photodynamic therapy (PDT) is a promising new modality for the treatment of cancer through generation of reactive oxygen species (ROS). In this work, human liver adenocarcinoma cells HepG2 were treated with zinc oxide nanoparticles (ZnO-NPs), metal-doped-ZnO-NPs: Fe-ZnO-NPs Ag-ZnO-NPs, Pb-ZnO-NPs, and Co-ZnO-NPs, Silica-coated ZnO-NPs, titanium dioxide nanoparticles (TiO2-NPs), titanium dioxide nano-tubes (TiO2-NTs) and ZnO-NPs/TiO2-NTs nanocomposite under UV irradiation. Doxorubicin was used as a standard drug. The results demonstrated that the ZnO-NPs, Fe-ZnO-NPs, Ag-ZnO-NPs, Pb-ZnO-NPs, and Co-ZnO-NPs showed cytotoxicity against HepG2 cells, with the median growth inhibitory concentrations (IC50) 42.60, 37.20, 45.10, 77.20 and 56.50 μg/ml, respectively, as compared to doxorubicin (IC50: 20.10 μg/ml). Treatment of the cancer cells with ZnO-NPs, Fe-ZnO-NPs, Ag-ZnO-NPs, Pb-ZnO-NPs, and Co-ZnO-NPs resulted in a significant increase in the activity of SOD and the levels of H2O2 and NO than those of control, accompanied with a significant decrease in the activity of CAT and GSH-Px. Also, depletion of reduced GSH, total protein and nucleic acids levels was observed. In conclusion, metal-doped ZnO-NPs may induce antiproliferative effect on HepG2 cells under UV-irradiation due to generation of ROS. Therefore, they could be included in modern clinical trials after in vivo more investigations, using photodynamic therapy technique.

Chitosan-modified cobalt oxide nanoparticles stimulate TNF-α-mediated apoptosis in human leukemic cells

The objective of this study was to develop chitosan-based delivery of cobalt oxide nanoparticles to human leukemic cells and investigate their specific induction of apoptosis. The physicochemical properties of the chitosan-coated cobalt oxide nanoparticles were characterized using transmission electron microscopy, dynamic light scattering, X-ray diffraction, and Fourier transform infrared spectroscopy. The solubility of chitosan-coated cobalt oxide nanoparticles was higher at acidic pH, which helps to release more cobalt ions into the medium. Chitosan-coated cobalt oxide nanoparticles showed good compatibility with normal cells. However, our results showed that exposure of leukemic cells (Jurkat cells) to chitosan-coated cobalt oxide nanoparticles caused an increase in reactive oxygen species generation that was abolished by pretreatment of cells with the reactive oxygen species scavenger N-acetyl-L-cysteine. The apoptosis of Jurkat cells was confirmed by flow-cytometric analysis. Induction of TNF-α secretion was observed from stimulation of Jurkat cells with chitosan-coated cobalt oxide nanoparticles. We also tested the role of TNF-α in the induction of Jurkat cell death in the presence of TNF-α and caspase inhibitors. Treatment of leukemic cells with a blocker had a greater effect on cancer cell viability. From our findings, oxidative stress and caspase activation are involved in cancer cell death induced by chitosan-coated cobalt oxide nanoparticles.

Direct oxidative modifications of signalling proteins in mammalian cells and their effects on apoptosis

The production of ROS is an inevitable consequence of metabolism. However, high levels of ROS within a cell can be lethal and so the cell has a number of defences against oxidative cell stress. Occasionally the cell's antioxidant mechanisms fail and oxidative stress occurs. High levels of ROS within a cell have a number of direct and indirect consequences on cell signalling pathways and may result in apoptosis or necrosis. Although some of the indirect effects of ROS are well known, limitations in technology mean that the direct effects of the cell's redox environment upon proteins are less understood. Recent work by a number of groups has demonstrated that ROS can directly modify signalling proteins through different modifications, for example by nitrosylation, carbonylation, di-sulphide bond formation and glutathionylation. These modifications modulate a protein's activity and several recent papers have demonstrated their importance in cell signalling events, especially those involved in cell death/survival. Redox modification of proteins allows for further regulation of cell signalling pathways in response to the cellular environment. Understanding them may be critical for us to modulate cell pathways for our own means, such as in cytotoxic drug treatments of cancer cells. Protein modifications mediated by oxidative stress can modulate apoptosis, either through specific protein modifications resulting in regulation of signalling pathways, or through a general increase in oxidised proteins resulting in reduced cellular function. This review discusses direct oxidative protein modifications and their effects on apoptosis.

Ascorbic acid protects against colistin sulfate-induced neurotoxicity in PC12 cells

This study aimed to examine the protective effect of ascorbic acid against colistin-induced neurotoxicity mediated by oxidative stress, a potential mechanism. An in vitro neurotoxicity model was established with PC12 cells exposed to 125 µg/mL colistin sulfate for 24 h. PC12 cells were treated with colistin (125 µg/mL) in the absence and presence of ascorbic acid (0.1, 1.0 and 10 µM/mL) for 24 h. Both 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay and lactate dehydrogenase (LDH) assay were carried out to evaluate cell viability. The levels of intracellular reactive oxygen species (ROS), superoxide dismutase (SOD) and glutathione (GSH) levels were assessed. Moreover, we tested the level of DNA fragmentation, the release of cytochrome-c and the expressions of caspase-9 and -3 mRNA. The results showed that 1 and 10 µM/mL ascorbic acid significantly increased the cell viability and the levels of SOD and GSH (both p<0.05), while 0.1, 1 and 10 µM/mL ascorbic acid significantly decreased the generation of ROS, the release of cytochrome-c, formation of DNA fragmentation and the expressions of caspase-9 and -3 mRNA in colistin-treated PC12 cells, compared with the colistin model group. These results suggest that ascorbic acid could reduce colistin sulfate-induced neurotoxicity through the resistance of oxidative stress and the prevention of apoptosis mediated via mitochondria pathway. They also highlight the potential of coadministering ascorbic acid to widen the therapeutic dose of colistin.

Sanguinarine induces apoptosis in human colorectal cancer HCT-116 cells through ROS-mediated Egr-1 activation and mitochondrial dysfunction

We examined the effects of sanguinarine, a benzophenanthridine alkaloid, on reactive oxygen species (ROS) production and the association of these effects with apoptotic cell death in a human colorectal cancer HCT-116 cell line. Sanguinarine generated ROS, which was followed by a decrease in the mitochondrial membrane potential (MMP), the activation of caspase-9 and -3, and the down-regulation of anti-apoptotic proteins, such as Bcl2, XIAP and cIAP-1. Sanguinarine also promoted the activation of caspase-8 and truncation of Bid (tBid). However, the quenching of ROS generation by N-acetyl-l-cysteine, a scavenger of ROS, reversed the sanguinarine-induced apoptosis effects via inhibition of the MMP collapse, tBid expression, and activation of caspases. Sanguinarine also markedly induced the expression of the early growth response gene-1 (Egr-1) during the early period, after which expression level was decreased. In addition, HCT-116 cells transfected with Egr-1 siRNA displayed significant blockage of sanguinarine-induced apoptotic activity in a ROS-dependent manner. These observations clearly indicate that ROS, which are key mediators of Egr-1 activation and MMP collapse, are involved in the early molecular events in the sanguinarine-induced apoptotic pathway acting in HCT-116 cells.

Ent-11α-Hydroxy-15-oxo-kaur-16-en-19-oic-acid Inhibits Growth of Human Lung Cancer A549 Cells by Arresting Cell Cycle and Triggering Apoptosis

OBJECTIVE

To examine the apoptotic effect of ent-11α-hydroxy-15-oxo-kaur-16-en-19-oic-acid (5F), a compound isolated from Pteris semipinnata L (PsL), in human lung cancer A549 cells.

METHODS

A549 cells were treated with 5F (0-80 μg/ml) for different time periods. Cytotoxicity was examined using a MTT method. Cell cycle was examined using propidium iodide staining. Apoptosis was examined using Hoechst 33258 staining, enzyme-linked immunosorbent assay (ELISA) and caspase-3 activity analysis. Expression of representative apoptosis-related proteins was evaluated by Western blot analysis. Reactive oxygen species (ROS) level was measured using standard protocols. Potential interaction of 5F with cisplatin was also examined.

RESULTS

5F inhibited the proliferation of A549 cells in a concentration- and time-dependent manner. 5F increased the accumulation of cells in sub-G1 phase and arrested the cells in the G2 phase. Exposure to 5F induced morphological changes and DNA fragmentation that are characteristic of apoptosis. The expression of p21 was increased. 5F exposure also increased Bax expression, release of cytochrome c and apoptosis inducing factor (AIF), and activation of caspase-3. 5F significantly sensitized the cells to cisplatin toxicity. Interestingly, treatment with 5F did not increase ROS, but reduced ROS production induced by cisplatin.

CONCLUSION

5F could inhibit the proliferation of A549 cells by arresting the cells in G2 phase and by inducing mitochondrial-mediated apoptosis.

Curcumin protects against iron induced neurotoxicity in primary cortical neurons by attenuating necroptosis

Necroptosis was reported as one backup way of programmed cell death when apoptosis was blocked, and the receptor interacting protein 1 was considered as the key necroptosis regulator protein. Here, we report the neuroprotective effects of curcumin which attenuates necroptosis. Primary cortical neurons were cultured and were injured by ferrous chloride, z.vad.fmk was applied to block apoptosis, curcumin was administrated to protect neurons, necrostatin-1 was applied to inhibit necroptosis if needed. Cell viability was measured by detecting lactate dehydrogenase activity in lysates of surviving cells, and assessed by cell counting kit-8. The expression of receptor interacting protein 1 was detected by immunoblot and immunofluorescence. Results showed that necroptosis mainly occurred in the concentrations of ferrous chloride ranging from 100 to 200μM, curcumin attenuated necroptosis in a dose-dependent manner. Furthermore, curcumin decreased expression of receptor interacting protein 1 in a dose- and time-dependent manner. Taken together, these findings suggest that curcumin protects against iron induced neurotoxicity in primary cortical neurons by attenuating necroptosis.

The oxidant/antioxidant status and cell death mode in oral squamous cell carcinoma

OBJECTIVE

Oxidative stress and imbalance in the oxidant/antioxidant system have a critical role in carcinogenesis by affecting necrosis and apoptosis. The aim of this study is to evaluate the oxidant/antioxidant status and cell death modes in patients with oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

Twenty-nine patients with OSCC and 29 control subjects were included in the study. The levels of malondialdehyde (MDA), advanced oxidation protein products (AOPP) and ferric reducing antioxidant power (FRAP) were determined in plasma samples of all subjects. The necrotic and apoptotic cell death modes were evaluated with M65 ELISA and M30 ELISA, respectively.

RESULTS

MDA and AOPP values as oxidative stress markers were higher in patients with OSCC than in the control group. FRAP values evaluating plasma antioxidant status increased in OSCC patients. M65 and M30 levels indicating necrosis and apoptosis were significantly higher in OSCC patients compared to controls. There were significant correlations between MDA, AOPP and FRAP; M65 and M30 values.

CONCLUSIONS

The elevated levels of oxidative stress markers together with the increase of antioxidant capacity and the presence of a strong correlation between MDA, AOPP and FRAP suggest an activation of antioxidant defense against accentuated oxidative stress determined in OSCC. Enhanced oxidation of lipids and proteins may cause decomposition of cell membranes with subsequent leakage of cytoskeletal cytokeratins as CK18 and caspase-cleaved CK18 (evaluated as M65 and M30, respectively) in the circulation, suggesting that both cell death modes are affected in OSCC.

Phytoglycoprotein (38 kDa) induces cell cycle (G₀/G₁) arrest and apoptosis in HepG2 cells

Styrax japonica Siebold et al Zuccarini (SJSZ) has been used to heal inflammation and bronchitis as folk medicine in Korea. Firstly, glycoprotein isolated from SJSZ (SJSZ glycoprotein) has a molecular weight with 38  kDa and consists of carbohydrate (57.64%) and protein (42.35%). In the composition of SJSZ glycoprotein, carbohydrate mostly consists of glucose (28.17%), galactose (21.85%), and mannose (2.62%) out of 52.64%, respectively. The protein consists of Trp (W, 7.01%), Pro (P, 6.72%), and Ile (I, 5.42%) out of 42.35% as three major amino acids, while total amount of other amino acids is 23.20%. The purpose of this study is to know whether the SJSZ glycoprotein (38  kDa) induces the cell cycle arrest and apoptosis in HepG2 cells. Cytotoxicity was evaluated using MTT and lactate dehydrogenase assay and amount of intracellular reactive oxygen species (iROS) and nitric oxide (NO) was measured using fluorescence microplate reader. Activities of cell cycle-related proteins [p53, p21, p27, Cyclin D1, and cyclin-dependent kinase (CDK)4] and apoptosis-related factors [iNOS, Bid, Bcl-2/bax, cytochrome c, caspase-9, caspase-3, and poly-(ADP-ribose) polymerase (PARP)] were assessed by Western blot and fluorescence-activated cell sorter (FACS) analysis. In the cell cycle-related proteins, SJSZ glycoprotein (50  µg/ml) significantly enhances the expression of p53, p21, and p27, whereas it suppressed the activity of cyclin D1/CDK4. In the apoptosis-related factors, SJSZ glycoprotein (50  µg/ml) stimulates to increase iROS, and NO, to activate iNOS, Bid, Bcl-2/bax, cytochrome c, caspase-9, caspase-3, and PARP. SJSZ glycoprotein (50  µg/ml) has potent effect to arrest cell cycle from G(0) /G(1) to S and to induce apoptosis in HepG2 cells.

Antitumor activity of a novel STAT3 inhibitor and redox modulator in non-small cell lung cancer cells

NSC-743380 is a novel STAT3 inhibitor that suppresses the growth of several NCI-60 cancer cell lines derived from different tissues and induces regression of xenograft tumors in vivo at various doses. To evaluate the antitumor activity of NSC-743380 in lung cancer cells, we analyzed the susceptibility of 50 NSCLC cell lines to this compound using cell viability assay. About 32% (16 of 50) of these cell lines were highly susceptible to this compound, with a 50% inhibitory concentration (IC₅₀) of < 1 μM. In mechanistic studies, the increased numbers of apoptotic cells as well as increased PARP cleavage showed that cytotoxic effects correlate with apoptosis induction. Treatment with NSC-743380 inhibited transcription factor STAT3 activation and induced ROS production in sensitive human lung cancer cell lines but not in resistant cells. Blocking ROS generation with the antioxidant NDGA dramatically abolished NSC-743380-induced growth suppression and apoptosis, but had minimal effect on NSC-743380-induced STAT3 inhibition, suggesting that STAT3 inhibition is not caused by ROS production. Interestingly, knockdown of STAT3 with use of shSTAT3 induced ROS generation and suppressed tumor cell growth. Moreover, scavenging ROS induced by STAT3 inhibition also diminished antitumor activity of STAT3 inhibition. In vivo administration of NSC-743380 suppressed tumor growth and p-STAT3 in lung tumors. Our results indicate that NSC-743380 is a potent anticancer agent for lung cancer and that its apoptotic effects in lung cancer cells are mediated by induction of ROS through STAT3 inhibition.

Effects of sesamol on apoptosis and steroidogenesis in MA-10 mouse Leydig tumor cells

Sesamol, a pure compound of sesame, has been reported to have antitumor effects. In the present study, the apoptotic and steroidogenic effects of sesamol on MA-10 cells, a mouse Leydig tumor cell line, was investigated by morphological observations, cell viability assay, flow cytometry analysis, radioimmunoassay, and immunoblotting assay. We found that the number of rounded-up cells increased as the treatment duration of sesamol increased from 3 to 24 h and that the plasma membrane blebbing phenomenon could be observed after 12 h of treatment. In the cell viability assay, the cell surviving rate significantly decreased as the dosage and duration of sesamol treatment increased (p<0.05). Moreover, cell cycle studies illustrated that the percentages of subG1 phase cells significantly increased after 1 mM sesamol treatments for 12 h, and 0.1 and 1 mM sesamol treatments for 24 h, respectively (p<0.05). Furthermore, 0.1 mM sesamol for 24 h and 1 mM sesamol for 12 and 24 h treatments, respectively, significantly induced the cleavage of caspase-3 (p<0.05). These results confirmed the apoptotic event of sesamol treatment on MA-10 cells. Meanwhile, we also found that sesamol at 1 mM for 24 h and 10 mM for 12 and 24 h significantly increased progesterone production (p<0.05), and 1 mM sesamol for 24 h treatment significantly activated the expression of steroidogenic acute regulatory (StAR) protein (p<0.05). However, the expression of P450scc enzyme remained no different among all treatments (p>0.05). In conclusion, sesamol could concurrently induce apoptosis through the activation of the caspase pathway and steroidogenesis through the induction of StAR protein expression in MA-10 mouse Leydig tumor cells.

Induction of apoptosis with diallyl disulfide in AGS gastric cancer cell line

Purpose

Diallyl disulfide (DADS) is a major organosulfur compound derived from garlic. It has been reported that DADS is able to inhibit the proliferation of several tumor cells. In this study, the effect of DADS was investigated in terms of the proliferation of AGS, gastric adenocarcinoma cell line at various concentrations.

Methods

The viability of cultured cells was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay. To detect the induction of apoptosis, Annexin V-FITC/propodium iodide (PI) staining assay was performed. Analysis of reactive oxygen species (ROS) and the distribution of cells in the cell cycle were measured by a flow cytometer. And using the Western blot analysis, the change of Fas, caspase-3, Bax, Bcl-2 activity was measured.

Results

The percentage of live AGS cells was decreased to 23% of that in the control group after 400 µM DADS treatment for 48 hours. The Annexin V positive/PI negative (apoptosis portion) area increased from low concentration of DADS to high concentration. When comparing among the DADS treatment groups, the amount of ROS production increased in a dose dependent manner. The percentage of sub-diploid DNA content increased from 8.71% at 50 µM to 25.74% at 400 µM DADS treatment group. The expressions of Fas, caspase-3, Bax were increased and that of Bcl-2 was decreased in a dose dependent manner.

Conclusion

DADS decreases the viability of AGS cell lines and induces apoptosis in a dose-dependent manner. But the relationship of the anti-proliferative effect of DADS and related molecular changes were not clearly proportional to the concentration of DADS.

Impact of anti-oxidant status and apoptosis on the induction phase of chemotherapy in childhood acute lymphoblastic leukemia

This study aimed to evaluate oxidative stress and apoptosis in childhood acute lymphoblastic leukemia (ALL) at diagnosis and their impact on outcome at the end of the induction phase. Our study included 50 newly diagnosed children with ALL. Evaluation of oxidative stresses (malondialdehyde and total anti-oxidant capacity) was made at diagnosis and at the end of the induction phase. Apoptosis level was determined by fluorometric terminal deoxynucleotidyl transferase dUTP nick end labeling system for patients at diagnosis and after 1 week of treatment. Our study showed that there was increased oxidative stress at diagnosis and after treatment with chemotherapy. Apoptosis index was higher after 1 week of treatment with chemotherapy when compared to its level at diagnosis.

Phagocytosis of melanized Aspergillus conidia by macrophages exerts cytoprotective effects by sustained PI3K/Akt signalling

Host cell death is a critical component of innate immunity and often determines the progression and outcome of infections. The opportunistic human pathogen Aspergillus fumigatus can manipulate the immune system either by inducing or by inhibiting host cell apoptosis dependent on its distinct morphological form. Here, we show that conidia of Aspergillus ssp. inhibit apoptosis of macrophages induced via the intrinsic (staurosporine) and extrinsic (Fas ligand) pathway. Hence, mitochondrial cytochrome c release and caspase activation were prevented. We further found that the anti-apoptotic effect depends on both host cell de novo protein synthesis and phagocytosis of conidia by macrophages. Moreover, sustained PI3K/Akt signalling in infected cells is an important determinant to resist apoptosis. We demonstrate that pigmentless pksP mutant conidia of A. fumigatus failed to trigger protection against apoptosis and provide evidence that the sustained survival of infected macrophages depends on the presence of the grey-green conidial pigment consisting of dihydroxynaphthalene-melanin. In conclusion, we revealed a novel potential function of melanin in the pathogenesis of A. fumigatus. For the first time, we show that melanin itself is a crucial component to inhibit macrophage apoptosis which may contribute to dissemination of the fungus within the host.

N-acetylcysteine counteracts oxidative stress and prevents hCG-induced apoptosis in rat Leydig cells through down regulation of caspase-8 and JNK

We have earlier reported that following persistent stimulation with hCG, oxidative stress-induced apoptosis in rat Leydig cells was mainly achieved through the extrinsic pathway. In the present study, the role of N-acetylcysteine (NAC) in counteracting the oxidative stress and the mechanisms of inhibition of apoptosis under such conditions were investigated. NAC (1 mM) intervention with repeated hCG stimulation (50 ng/ml, four times, each with 30 min challenge) prevented the decline in Leydig cell viability and the rise in lipid peroxidation and reactive oxygen species. Simultaneously, the activities of the enzymes glutathione-S-transferase, catalase, superoxide dismutase and the intracellular glutathione and antioxidant capacity of the treated cells improved significantly. Apoptotic markers Fas, FasL, and caspase-8, up-regulated following repeated hCG exposure, were significantly down-regulated following NAC co-incubation. While Bcl-2 expression was fully restored, Bax and caspase-9 remained unchanged. NAC treatment induced down-regulation of upstream JNK/pJNK and down-stream caspase-3 in the target cells. Taken together, the above findings indicate that NAC counteracted the oxidative stress in Leydig cells induced as a result of repeated hCG stimulation, and inhibited apoptosis by mainly regulating the extrinsic and JNK pathways of metazoan apoptosis.

Mutation of mitochondrial ATP8 gene improves hepatic energy status in a murine model of acute endotoxemic liver failure

AIMS

Mitochondria not only generate and modulate bioenergy but also serve as biosensors for oxidative stress, and eventually become effector organelles for cell viability. Therefore, the implications of mitochondrial (dys)function in the development of multiple organ failure are profound. We investigated whether a mutation in the ATPase subunit-8 gene affects the course of endotoxemic acute liver failure.

MAIN METHODS

C57BL/6J (ATP8 wild type) and C57BL/6J-mt(FVB/N) (ATP8 mutant) mice were challenged with d-galactosamine (GalN) and Escherichia coli lipopolysaccharide (LPS) for induction of acute liver failure, and studied 6 h thereafter. Control mice received physiological saline only. Analysis included in vivo fluorescence microscopy of hepatic microcirculation and levels of hepatocellular apoptosis, hepatic adenosine nucleotides and oxidative stress. Additionally, survival rates were assessed.

KEY FINDINGS

Induction of endotoxemic liver failure provoked marked liver damage, which was coexistent with a drop of total adenosine nucleotide levels and increased oxidative stress. Of interest, oxidative stress was higher in the GalN/LPS challenged ATP8 mutants compared to wild types. Concomitantly, adenosine triphosphate (ATP) levels in livers of mice carrying the ATP8 mutation remained higher than those in wild type mice. As net result, ATP8 mutants showed lower transaminase release and a tendency to better survival rate upon GalN/LPS exposure compared to wild types.

SIGNIFICANCE

Our findings demonstrate that mutation in the ATPase subunit-8 partially protects mice against endotoxemic stress, most probably due to better hepatic energy status despite elevated oxidative stress. Thus, modulating mitochondrial function to preserve bioenergetic status may be an effective strategy to protect against sepsis-induced multiorgan dysfunction.