Threshold effects of nitric oxide-induced toxicity and cellular responses in wild-type and p53-null human lymphoblastoid cells

NOS2 and COX-2 Co-Expression Promotes Cancer Progression: A Potential Target for Developing Agents to Prevent or Treat Highly Aggressive Breast Cancer

Nitric oxide (NO) and reactive nitrogen species (RNS) exert profound biological impacts dictated by their chemistry. Understanding their spatial distribution is essential for deciphering their roles in diverse biological processes. This review establishes a framework for the chemical biology of NO and RNS, exploring their dynamic reactions within the context of cancer. Concentration-dependent signaling reveals distinctive processes in cancer, with three levels of NO influencing oncogenic properties. In this context, NO plays a crucial role in cancer cell proliferation, metastasis, chemotherapy resistance, and immune suppression. Increased NOS2 expression correlates with poor survival across different tumors, including breast cancer. Additionally, NOS2 can crosstalk with the proinflammatory enzyme cyclooxygenase-2 (COX-2) to promote cancer progression. NOS2 and COX-2 co-expression establishes a positive feed-forward loop, driving immunosuppression and metastasis in estrogen receptor-negative (ER-) breast cancer. Spatial evaluation of NOS2 and COX-2 reveals orthogonal expression, suggesting the unique roles of these niches in the tumor microenvironment (TME). NOS2 and COX2 niche formation requires IFN-γ and cytokine-releasing cells. These niches contribute to poor clinical outcomes, emphasizing their role in cancer progression. Strategies to target these markers include direct inhibition, involving pan-inhibitors and selective inhibitors, as well as indirect approaches targeting their induction or downstream effectors. Compounds from cruciferous vegetables are potential candidates for NOS2 and COX-2 inhibition offering therapeutic applications. Thus, understanding the chemical biology of NO and RNS, their spatial distribution, and their implications in cancer progression provides valuable insights for developing targeted therapies and preventive strategies.

S-Glutathionylation and S-Nitrosylation as Modulators of Redox-Dependent Processes in Cancer Cell

Development of oxidative/nitrosative stress associated with the activation of oncogenic pathways results from the increase in the generation of reactive oxygen and nitrogen species (ROS/RNS) in tumor cells, where they can have a dual effect. At high concentrations, ROS/RNS cause cell death and limit tumor growth at certain phases of its development, while their low amounts promote oxidative/nitrosative modifications of key redox-dependent residues in regulatory proteins. The reversibility of such modifications as S-glutathionylation and S-nitrosylation that proceed through the electrophilic attack of ROS/RNS on nucleophilic Cys residues ensures the redox-dependent switch in the activity of signaling proteins, as well as the ability of these compounds to control cell proliferation and programmed cell death. The content of S-glutathionylated and S-nitrosylated proteins is controlled by the balance between S-glutathionylation/deglutathionylation and S-nitrosylation/denitrosylation, respectively, and depends on the cellular redox status. The extent of S-glutathionylation and S-nitrosylation of protein targets and their ratio largely determine the status and direction of signaling pathways in cancer cells. The review discusses the features of S-glutathionylation and S-nitrosylation reactions and systems that control them in cancer cells, as well as their relationship with redox-dependent processes and tumor growth.

New Nanostructured Materials Based on Mesoporous Silica Loaded with Ru(II)/Ru(III) Complexes with Anticancer and Antimicrobial Properties

A new series of nanostructured materials was obtained by functionalization of SBA-15 mesoporous silica with Ru(II) and Ru(III) complexes bearing Schiff base ligands derived from salicylaldehyde and various amines (1,2-diaminocyclohexane, 1,2-phenylenediamine, ethylenediamine, 1,3-diamino-2-propanol, N,N-dimethylethylenediamine, 2-aminomethyl-pyridine, and 2-(2-aminoethyl)-pyridine). The incorporation of ruthenium complexes into the porous structure of SBA-15 and the structural, morphological, and textural features of the resulting nanostructured materials were investigated by FTIR, XPS, TG/DTA, zeta potential, SEM, and N₂ physisorption. The ruthenium complex-loaded SBA-15 silica samples were tested against A549 lung tumor cells and MRC-5 normal lung fibroblasts. A dose-dependent effect was observed, with the highest antitumoral efficiency being recorded for the material containing [Ru(Salen)(PPh₃)Cl] (50%/90% decrease in the A549 cells' viability at a concentration of 70 μg/mL/200 μg/mL after 24 h incubation). The other hybrid materials have also shown good cytotoxicity against cancer cells, depending on the ligand included in the ruthenium complex. The antibacterial assay revealed an inhibitory effect for all samples, the most active being those containing [Ru(Salen)(PPh₃)Cl], [Ru(Saldiam)(PPh₃)Cl], and [Ru(Salaepy)(PPh₃)Cl], especially against Staphylococcus aureus and Enterococcus faecalis Gram-positive strains. In conclusion, these nanostructured hybrid materials could represent valuable tools for the development of multi-pharmacologically active compounds with antiproliferative, antibacterial, and antibiofilm activity.

Occupational exposure to gasoline in gasoline station male attendants promotes M1 polarization in macrophages

Several studies have reported the toxicological implications of exposure to petroleum hydrocarbon fumes in animal models. There is little documentation on the effect of such exposure on oxidative stress levels and immune response. To our knowledge, no documentation of M1 polarization in macrophages in gasoline station male attendants. Therefore, this study aimed to evaluate the harmful effects of gasoline vapors in 62 male attendants (16-70 years) compared to 29 age- and sex-matched-unexposed controls. The attendants were recruited from Damietta governorate gasoline stations. Gasoline exposure induced a significant increase in tumor necrosis factor-α (TNF-α) level (p < 0.05) as well as a slight but non-significant increase in the activity of acidic mammalian chitinase (AMCase) (p > 0.05). Further TNF-α/AMCase ratio was significantly increased (p < 0.01) in sera of the attendants when compared to those of the healthy controls. Also, the total leucocytic and lymphocytic counts were significantly increased (p < 0.01 and p < 0.001, respectively). On contrary, neutrophils to lymphocytes ratio (NLR) and platelets to lymphocytes ratio (PLR) were significantly decreased (p < 0.05 and p < 0.001, respectively). In addition, significant reduction in hemoglobin (Hb) concentration, plasma glutathione reduced form (GSH), and catalase, as well as superoxide dismutase (SOD) activities in red blood cells were observed in the exposed attendants. As a result, malondialdehyde (MDA), nitric oxide (NO) levels, and NO/AMCase ratio were significantly increased (p < 0.05). In conclusion, this study inferred that prolonged gasoline exposure can mediate immune activation, especially M1 macrophages polarization, possibly via oxidative stress-mediated mechanism.

The Role of the BH4 Cofactor in Nitric Oxide Synthase Activity and Cancer Progression: Two Sides of the Same Coin

Cancer development is associated with abnormal proliferation, genetic instability, cell death resistance, metabolic reprogramming, immunity evasion, and metastasis. These alterations are triggered by genetic and epigenetic alterations in genes that control cell homeostasis. Increased reactive oxygen and nitrogen species (ROS, RNS) induced by different enzymes and reactions with distinct molecules contribute to malignant transformation and tumor progression by modifying DNA, proteins, and lipids, altering their activities. Nitric oxide synthase plays a central role in oncogenic signaling modulation and redox landscape. Overexpression of the three NOS isoforms has been found in innumerous types of cancer contributing to tumor growth and development. Although the main function of NOS is the production of nitric oxide (NO), it can be a source of ROS in some pathological conditions. Decreased tetrahydrobiopterin (BH4) cofactor availability is involved in NOS dysfunction, leading to ROS production and reduced levels of NO. The regulation of NOSs by BH4 in cancer is controversial since BH4 has been reported as a pro-tumoral or an antitumoral molecule. Therefore, in this review, the role of BH4 in the control of NOS activity and its involvement in the capabilities acquired along tumor progression of different cancers was described.

Development of Novel Amphotericin B-Immobilized Nitric Oxide-Releasing Platform for the Prevention of Broad-Spectrum Infections and Thrombosis

Indwelling medical devices currently used to diagnose, monitor, and treat patients invariably suffer from two common clinical complications: broad-spectrum infections and device-induced thrombosis. Currently, infections are managed through antibiotic or antifungal treatment, but the emergence of antibiotic resistance, the formation of recalcitrant biofilms, and difficulty identifying culprit pathogens have made treatment increasingly challenging. Additionally, systemic anticoagulation has been used to manage device-induced thrombosis, but subsequent life-threatening bleeding events associated with all available therapies necessitates alternative solutions. In this study, a broad-spectrum antimicrobial, antithrombotic surface combining the incorporation of the nitric oxide (NO) donor S-nitroso-N-acetylpenicillamine (SNAP) with the immobilization of the antifungal Amphotericin B (AmB) on polydimethylsiloxane (PDMS) was developed in a two-step process. This novel strategy combines the key advantages of NO, a bactericidal agent and platelet inhibitor, with AmB, a potent antifungal agent. We demonstrated that SNAP-AmB surfaces significantly reduced the viability of adhered Staphylococcus aureus (99.0 ± 0.2%), Escherichia coli (89.7 ± 1.0%), and Candida albicans (93.5 ± 4.2%) compared to controls after 24 h of in vitro exposure. Moreover, SNAP-AmB surfaces reduced the number of platelets adhered by 74.6 ± 3.9% compared to controls after 2 h of in vitro porcine plasma exposure. Finally, a cytotoxicity assay validated that the materials did not present any cytotoxic side effects toward human fibroblast cells. This novel approach is the first to combine antifungal surface functionalization with NO-releasing technology, providing a promising step toward reducing the rate of broad-spectrum infection and thrombosis associated with indwelling medical devices.

Cardiotoxicity induced by Cochinchina momordica seed extract in zebrafish

Momordica cochinchinensis (Lour.) Spreng is an indigenous South Asian edible fruit, and seeds of Momordica cochinchinensis have been used therapeutically in traditional Chinese medicine. Previous studies have shown that M. cochinchinensis seed (Momordicae Semen) has various pharmaceutical properties such as antioxidant and anti-ulcer effects as well as contains secondary metabolites with potential anticancer activities such as triterpenoids and saponins. Recent studies reported that water extract and ethanol extract of M. cochinchinensi seed were tested on mammals using an acute toxic classic method as OECD guidelines 420. No matter injected intravenously or intramuscularly, animals died within several days. In this study, zebrafish embryos were exposed to various doses of Cochinchina momordica seed extract (CMSE) from 2 dpf (days post fertilization, dpf) to 3 dpf. CMSE-induced cardiotoxicity such as pericardial edema, cardiac apoptosis, increased ROS production, cardiac neutrophil infiltration, decreased blood flow velocity, and reduced expression of three marker genes of cardiac functions were found in zebrafish roughly in a dose-dependent manner. These results suggest that CMSE may induce cardiotoxicity through pathways involved in inflammation, oxidative stress, and apoptosis.

Genome-Wide Comparison of the Target Genes of the Reactive Oxygen Species and Non-Reactive Oxygen Species Constituents of Cold Atmospheric Plasma in Cancer Cells

Simple Summary

Cold atmospheric plasma is being applied to treat cancer by virtue of its preferential anti-proliferative effect on cancer cells over normal cells. This study aimed to systemically determine the distribution of target genes regulated by the reactive oxygen species and non-reactive oxygen species constituents of the plasma. After analyzing genome-wide expression data for a leukemia and a melanoma cancer cell line from a public database followed by experimental approaches, PTGER3 and HSPA6 genes were found regulated by the non-reactive oxygen species and non-reactive nitrogen species constituents of the plasma in the cancer cells. This study could contribute to elucidate the molecular mechanism how each physicochemical constituent of the plasma induces the specific molecular changes in cancer cells.

Abstract

Cold atmospheric plasma (CAP) can induce cancer cell death. The majority of gene regulation studies have been biased towards reactive oxygen species (ROS) among the physicochemical components of CAP. The current study aimed to systemically determine the distribution of target genes regulated by the ROS and non-ROS constituents of CAP. Genome-wide expression data from a public database, which were obtained after treating U937 leukemia and SK-mel-147 melanoma cells with CAP or H₂O₂, were analyzed, and gene sets regulated by either or both of them were identified. The results showed 252 and 762 genes in H₂O₂-treated U937 and SK-mel-147 cells, respectively, and 112 and 843 genes in CAP-treated U937 and SK-mel-147 cells, respectively, with expression changes higher than two-fold. Notably, only four and two genes were regulated by H₂O₂ and CAP in common, respectively, indicating that non-ROS constituents were responsible for the regulation of the majority of CAP-regulated genes. Experiments using ROS and nitrogen oxide synthase (NOS) inhibitors demonstrated the ROS- and reactive nitrogen species (RNS)-independent regulation of PTGER3 and HSPA6 when U937 cancer cells were treated with CAP. Taken together, this study identified CAP-specific genes regulated by constituents other than ROS or RNS and could contribute to the annotation of the target genes of specific constituents in CAP.

Ponatinib-induced ischemic stroke in larval zebrafish for drug screening

Conventional mammalian ischemic stroke models for drug screening are technically challenging, laborious and time-consuming. In this study, using Ponatinib as an inducer, we developed and characterized a zebrafish ischemic stroke model. This zebrafish ischemic stroke had the cerebral vascular endothelial injury, thrombosis, reduced blood flow, inflammation and apoptosis as well as the reduced motility. The zebrafish ischemic stroke model was validated with 6 known human therapeutic drugs of ischemic stroke (Aspirin, Clopidogrel, Naoxintong capsules, Edaravone, Xingnaojing injection, Shuxuening injection). The mRNA levels of the neovascularization-related gene (vegfaa) and vascular endothelial growth factor receptor gene (VEGFR), neurodevelopment related genes (mbp and α1-tubulin), brain-derived neurotrophic factor (BDNF) and glial cell derived neurotrophic factor (GDNF) were significantly downregulated; whereas apoptosis-related genes (caspase-3, caspase-7, caspase-9 and bax/bcl-2), and inflammatory factor genes (IL-1β, IL-6, IL-10, TNF-α and NF-κB) were remarkably upregulated in the model. These results suggest that the pathophysiology of Ponatinib-induced zebrafish ischemic stroke is similar to that of human ischemic stroke patients and this whole animal model could be used to study the complex cellular and molecular pathogenesis of ischemic stroke and to rapidly identify therapeutic agents.

Fenobucarb-induced developmental neurotoxicity and mechanisms in zebrafish

Fenobucarb (2-sec-butylphenyl methylcarbamate, BPMC) is an extensively used carbamate insecticide. Its developmental neurotoxicity and the underlying mechanisms have not been well investigated. In this study, zebrafish embryos were exposed to various concentrations of BPMC from 6 hpf (hours post fertilization, hpf) to 120 hpf. BPMC induced developmental toxicity with reduced motility in larval zebrafish. The spinal cord neutrophil infiltration, increased ROS production, caspase 3 and 9 activation, central nerve and peripheral motor neuron damage, axon and myelin degeneration were observed in zebrafish treated with BPMC generally in a dose-dependent manner. The expression of eight marker genes for nervous system function or development, namely, a1-tubulin, shha, elavl3, gap43, syn2a, gfap, mbp and manf, was significantly downregulated following BPMC exposure. AChE activity reduction and ache gene expression suppression was also found significantly in BPMC-treated zebrafish. These results indicate that BPMC is highly toxic to zebrafish and that BPMC induces zebrafish developmental neurotoxicity through pathways involved in inflammation, oxidative stress, degeneration and apoptosis.

Considerations of the importance of redox state for reactive nitrogen species action

Nitric oxide (NO) and other reactive nitrogen species (RNS) are immensely important signalling molecules in plants, being involved in a range of physiological responses. However, the exact way in which NO fits into signal transduction pathways is not always easy to understand. Here, some of the issues that should be considered are discussed. This includes how NO may interact directly with other reactive signals, such as reactive oxygen and sulfur species, how NO metabolism is almost certainly compartmentalized, that threshold levels of RNS may need to be reached to have effects, and how the intracellular redox environment may impact on NO signalling. Until better tools are available to understand how NO is generated in cells, where it accumulates, and to what levels it reaches, it will be hard to get a full understanding of NO signalling. The interaction of RNS metabolism with the intracellular redox environment needs further investigation. A changing redox poise will impact on whether RNS species can thrive in or around cells. Such mechanisms will determine whether specific RNS can indeed control the responses needed by a cell.

Quantum dot therapeutics: a new class of radical therapies

Traditional therapeutics and vaccines represent the bedrock of modern medicine, where isolated biochemical molecules or designed proteins have led to success in treating and preventing diseases. However, several adaptive pathogens, such as multidrug-resistant (MDR) superbugs, and rapidly evolving diseases, such as cancer, can evade such molecules very effectively. This poses an important problem since the rapid emergence of multidrug-resistance among microbes is one of the most pressing public health crises of our time-one that could claim more than 10 million lives and 100 trillion dollars annually by 2050. Several non-traditional antibiotics are now being developed that can survive in the face of adaptive drug resistance. One such versatile strategy is redox perturbation using quantum dot (QD) therapeutics. While redox molecules are nominally used by cells for intracellular signaling and other functions, specific generation of such species exogenously, using an electromagnetic stimulus (light, sound, magnetic field), can specifically kill the cells most vulnerable to such species. For example, recently QD therapeutics have shown tremendous promise by specifically generating superoxide intracellularly (using light as a trigger) to selectively eliminate a wide range of MDR pathogens. While the efficacy of such QD therapeutics was shown using in vitro studies, several apparent contradictions exist regarding QD safety and potential for clinical applications. In this review, we outline the design rules for creating specific QD therapies for redox perturbation; summarize the parameters for choosing appropriate materials, size, and capping ligands to ensure their facile clearance; and highlight a potential path forward towards developing this new class of radical QD therapeutics.

Fenobucarb induces heart failure and cerebral hemorrhage in zebrafish

The potential risk and toxic mechanisms of fenobucarb (2-sec-butylphenyl methylcarbamate, BPMC) to animals and humans have not been fully elucidated. In this study, zebrafish embryos were exposed to various concentrations of BPMC from 48 hpf (hour post fertilization, hpf) to 72 hpf. We found that BPMC induced severe heart failure with bradycardia, reduced heart contractions, cardiac output and blood flow dynamics；and myocardial apoptosis. BPMC also induced cerebral hemorrhages and blood erythrocyte reduction in a dose-dependent manner. Also observed were increased ROS production and capase 9 and 3/7 activation. The mRNA levels of the ATPase-related gene (atp2a1l), calcium channel-related gene (cacna1ab), sodium channel-related gene (scn5Lab), potassium channel-related gene (kcnq1), the regulatory gene (tnnc1a) for cardiac troponin C, and several apoptosis-related genes were significantly downregulated in zebrafish following BPMC exposure. These results suggest that exposure to BPMC is a possible risk factor to cardiovascular and cerebrovascular systems in animals.

Sensitization and synergistic anti-cancer effects of Furanodiene identified in zebrafish models

Furanodiene is a natural terpenoid isolated from Rhizoma Curcumae, a well-known Chinese medicinal herb that presents anticancer effects in various types of cancer cell lines. In this study, we have successfully established zebrafish xenografts with 5 various human cancer cell lines; and validated these models with anti-cancer drugs used clinically for treating human cancer patients. We found that Furanodiene was therapeutically effective for human JF 305 pancreatic cancer cells and MCF-7 breast cancer cells xenotranplanted into zebrafish. Furanodiene showed a markedly synergistic anti-cancer effect when used in combination with 5-FU (5-Fluorouracil) for both human breast cancer MDA-MB-231 cells and human liver cancer BEL-7402 cells xenotransplanted into zebrafish. Unexpectedly, Furanodiene reversed multiple drug resistance in the zebrafish xenotransplanted with cis-Platinum-resistant human non-small cell lung cancer cells and Adriamycin-resistant human breast cancer cells. Furanodiene played its anti-cancer effects through anti-angiogenesis and inducing ROS production, DNA strand breaks and apoptosis. Furanodiene suppresseed efflux transporter Pgp (P-glycoprotein) function and reduced Pgp protein level, but no effect on Pgp related gene (MDR1) expression. These results suggest sensitizition and synergistic anti-cancer effects of Furanodiene that is worthy of a further investigation.

Molecular Mechanisms of Nitric Oxide in Cancer Progression, Signal Transduction, and Metabolism

SIGNIFICANCE

Cancer is a complex disease, which not only involves the tumor but its microenvironment comprising different immune cells as well. Nitric oxide (NO) plays specific roles within tumor cells and the microenvironment and determines the rate of cancer progression, therapy efficacy, and patient prognosis. Recent Advances: Key understanding of the processes leading to dysregulated NO flux within the tumor microenvironment over the past decade has provided better understanding of the dichotomous role of NO in cancer and its importance in shaping the immune landscape. It is becoming increasingly evident that nitric oxide synthase 2 (NOS2)-mediated NO/reactive nitrogen oxide species (RNS) are heavily involved in cancer progression and metastasis in different types of tumor. More recent studies have found that NO from NOS2+ macrophages is required for cancer immunotherapy to be effective.

CRITICAL ISSUES

NO/RNS, unlike other molecules, are unique in their ability to target a plethora of oncogenic pathways during cancer progression. In this review, we subcategorize the different levels of NO produced by cells and shed light on the context-dependent temporal effects on cancer signaling and metabolic shift in the tumor microenvironment.

FUTURE DIRECTIONS

Understanding the source of NO and its spaciotemporal profile within the tumor microenvironment could help improve efficacy of cancer immunotherapies by improving tumor infiltration of immune cells for better tumor clearance.

Alkaloids from Tetrastigma hemsleyanum and Their Anti-Inflammatory Effects on LPS-Induced RAW264.7 Cells

Alkaloids 1–10 were isolated from the aerial parts of Tetrastigma hemsleyanum (APTH) and obtained from species of the genus Tetrastigma for the first time. The chemical structures of the isolated compounds were identified by NMR, UV, and MS analyses. Their anti-inflammatory activities were investigated by measuring nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW264.7 macrophages. Among all the isolates, compounds 6, 7 and 10 showed potent inhibitory activity against LPS-stimulated NO production in RAW264.7 cells (IC₅₀: 31.9, 25.2 and 6.3 μM, respectively). Furthermore, APTH and S-(−)-trolline (10) inhibited induction of inflammatory cytokines or mediators such as interleukin-1β (IL-1β) and inducible nitric oxide synthase (iNOS) via suppression of nuclear factor κB (NF-κB) translocation into the nucleus. In addition, 10 suppressed extracellular signal-regulated protein kinase 1/2 (ERK1/2) mitogen-activated protein kinase (MAPK) phosphorylation in a dose-dependent manner. These results conclusively demonstrated that compound 10 displays anti-inflammatory activity via suppression of NF-κB activation and the ERK-MAPK signaling pathway in LPS-stimulated RAW264.7 cells.

Winner of the society for biomaterials young investigator award for the annual meeting of the society for biomaterials, April 11-14, 2018, Atlanta, GA: S-nitrosated poly(propylene sulfide) nanoparticles for enhanced nitric oxide delivery to lymphatic tissues

Nitric oxide (NO) is a therapeutic implicated for the treatment of diseases afflicting lymphatic tissues, which range from infectious and cardiovascular diseases to cancer. Existing technologies available for NO therapy, however, provide poor bioactivity within lymphatic tissues. In this work, we address this technology gap with a NO encapsulation and delivery strategy leveraging the formation of S-nitrosothiols on lymphatic-targeting pluronic-stabilized, poly(propylene sulfide)-core nanoparticles (SNO-NP). We evaluated in vivo the lymphatic versus systemic delivery of NO resulting from intradermal administration of SNO-NP benchmarked against a commonly used, commercially available small molecule S-nitrosothiol NO donor, examined signs of toxicity systemically as well as localized to the site of injection, and investigated SNO effects on lymphatic transport and NP uptake by lymph node (LN)-resident cells. Donation of NO from SNO-NP, which scaled in proportion to the total administered dose, enhanced LN accumulation by two orders of magnitude without substantially reducing lymphatic transport of NP or the viability and extent of NP uptake by LN-resident cells. Additionally, NO delivery by SNO-NP was accompanied by low-to-negligible NO accumulation in systemic tissues with no apparent inflammation. These results suggest the utility and selectivity of SNO-NP for the targeted treatment of NO-regulated diseases that afflict lymphatic tissues. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1463-1475, 2018.

Wound healing activity of Streptocaulon juventas root ethanolic extract

Streptocaulon juventas is a well-known plant that has antimicrobial activity, in vitro antiplasmodial activity, anti-proliferative activity, and antioxidant activity. In this study, we showed experimental evidence that proved that S. juventas root ethanolic extract has wound healing activities. First, in a mouse excision wound model, S. juventas root ethanolic extract at a dose of 100 mg/kg/day significantly reduced the wound closure time. After 7 days, the wound granulation tissue in mice treated with the extract exhibited a 2.3-fold decrease in inflammatory cells, a 1.7-fold increase in fibroblasts and enhanced angiogenesis. Molecular analysis also revealed that after wounds were treated with S. juventas root ethanolic extract, TNF-α and NF-κB1 gene expression were down-regulated by 4.7 and 3.7 times, respectively. In contrast, TGF-β1 and VEGF gene expression were up-regulated by 1.9 and 6.5 times, respectively. Taken together, our experimental data strongly show that the ethanolic extract from S. juventas root displays remarkable wound healing activity.

Intracellular and extracellular factors influencing the genotoxicity of nitric oxide and reactive oxygen species

A number of factors affect cellular responses to nitric oxide (NO^•) and reactive oxygen species (ROS), including their source, concentration, cumulative dose, target gene and biological milieu. This limits the extrapolation of data to in vivo pathological states in which NO^• and ROS may be important. The present study investigated lethality and mutagenesis in the HPRT and TK1 genes of human lymphoblastoid TK6 cells exposed to NO^• and ROS derived from two delivery methods: A reactor system and a Transwell™ co-culture. The delivery of NO^• into the medium at controlled steady-state concentrations (given in µM/min) and the production of NO^• and ROS by activated macrophages, resulted in a time-dependent decrease in total cell numbers, and an increase in mutation frequency (MF), compared with untreated controls. This increase in MF was effectively suppressed by N-methyl-L-arginine monoacetate. Single base substitutions were the most common type of spontaneous and NO^• induced mutations in HPRT, followed by exon exclusions and small deletions in both delivery systems. Among the single base pair substitutions, an equal frequency of four types of single base substitutions were identified in TK6 cells exposed to NO^• delivered by the reactor system, whereas G:C to T:A transversions and A:T to G:C transitions were more frequent in the co-culture system. Taken together, these results demonstrate that both the delivery method of NO^• and ROS, and the target genes are determinants of observed cytotoxic and mutagenic responses, indicating that these parameters need to be considered in assessing the potential effects of NO^• and ROS in vivo.

Modulating and Measuring Intracellular H2O2 Using Genetically Encoded Tools to Study Its Toxicity to Human Cells

Reactive oxygen species (ROS) such as H₂O₂ play paradoxical roles in mammalian physiology. It is hypothesized that low, baseline levels of H₂O₂ are necessary for growth and differentiation, while increased intracellular H₂O₂ concentrations are associated with pathological phenotypes and genetic instability, eventually reaching a toxic threshold that causes cell death. However, the quantities of intracellular H₂O₂ that lead to these different responses remain an unanswered question in the field. To address this question, we used genetically encoded constructs that both generate and quantify H₂O₂ in a dose-response study of H₂O₂-mediated toxicity. We found that, rather than a simple concentration-response relationship, a combination of intracellular concentration and the cumulative metric of H₂O₂ concentration multiplied by time (i.e., the area under the curve) determined the occurrence and level of cell death. Establishing the quantitative relationship between H₂O₂ and cell toxicity promotes a deeper understanding of the intracellular effects of H₂O₂ specifically as an individual reactive oxygen species, and it contributes to an understanding of its role in various redox-related diseases.

Bioactivity-guided isolation of anti-inflammatory triterpenoids from the sclerotia of Poria cocos using LPS-stimulated Raw264.7 cells

Poria cocos Wolf (Polyporaceae) has been used as a medicinal fungus to treat various diseases since ancient times. This study aimed to investigate the anti-inflammatory chemical constituents of the sclerotia of P. cocos. Based on bioassay-guided fractionation using lipopolysaccharide (LPS)-stimulated Raw264.7 cells, chemical investigation of the EtOH extract of the sclerotia of P. cocos resulted in the isolation and identification of eight compounds including six triterpenoids, namely poricoic acid A (1), 3-O-acetyl-16α-hydroxydehydrotrametenolic acid (2), polyporenic acid C (3), 3β-hydroxylanosta-7,9(11),24-trien-21-oic acid (4), trametenolic acid (5), and dehydroeburicoic acid (6), as well as (-)-pinoresinol (7) and protocatechualdehyde (8). The structures of the isolated compounds were determined by spectroscopic analysis, including ¹H and ¹³C NMR spectra, and LC/MS analysis. The anti-inflammatory activities of the isolates were evaluated by estimating their effect on the production of nitric oxide (NO) and prostaglandin E₂ (PGE₂) in LPS-stimulated Raw264.7 as well as on the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Compounds 1-5 inhibited NO production and iNOS expression in LPS-stimulated Raw264.7 cells. Among them, compound 1 exerted the highest anti-inhibitory activity and reduced PGE₂ levels via downregulation of COX-2 protein expression. The findings of this study provide experimental evidence that the sclerotia of P. cocos are a potential source of natural anti-inflammatory agents for use in pharmaceuticals and functional foods. Furthermore, the most active compound 1, seco-lanostane triterpenoid, could be a promising lead compound for the development of novel anti-inflammatory agents.

Gaseous mediators nitric oxide and hydrogen sulfide in the mechanism of gastrointestinal integrity, protection and ulcer healing

Nitric oxide (NO) and hydrogen sulfide (H2S) are known as biological messengers; they play an important role in human organism and contribute to many physiological and pathophysiological processes. NO is produced from l-arginine by constitutive NO synthase (NOS) and inducible NOS enzymatic pathways. This gaseous mediator inhibits platelet aggregation, leukocyte adhesion and contributes to the vessel homeostasis. NO is known as a vasodilatory molecule involved in control of the gastric blood flow (GBF) and the maintenance of gastric mucosal barrier integrity in either healthy gastric mucosa or that damaged by strong irritants. Biosynthesis of H2S in mammals depends upon two enzymes cystathionine-β-synthase and cystathionine γ-lyase. This gaseous mediator, similarly to NO and carbon monoxide, is involved in neuromodulation, vascular contractility and anti-inflammatory activities. For decades, H2S has been known to inhibit cytochrome c oxidase and reduce cell energy production. Nowadays it is generally considered to act through vascular smooth muscle ATP-dependent K+ channels, interacting with intracellular transcription factors and promote sulfhydration of protein cysteine moieties within the cell, but the mechanism of potential gastroprotective and ulcer healing properties of H2S has not been fully explained. The aim of this review is to compare current results of the studies concerning the role of H2S and NO in gastric mucosa protection and outline areas that may pose new opportunities for further development of novel therapeutic targets.

Chemistry meets biology in colitis-associated carcinogenesis

The intestine comprises an exceptional venue for a dynamic and complex interplay of numerous chemical and biological processes. Here, multiple chemical and biological systems, including the intestinal tissue itself, its associated immune system, the gut microbiota, xenobiotics, and metabolites meet and interact to form a sophisticated and tightly regulated state of tissue homoeostasis. Disturbance of this homeostasis can cause inflammatory bowel disease (IBD)-a chronic disease of multifactorial etiology that is strongly associated with increased risk for cancer development. This review addresses recent developments in research into chemical and biological mechanisms underlying the etiology of inflammation-induced colon cancer. Beginning with a general overview of reactive chemical species generated during colonic inflammation, the mechanistic interplay between chemical and biological mediators of inflammation, the role of genetic toxicology, and microbial pathogenesis in disease development are discussed. When possible, we systematically compare evidence from studies utilizing human IBD patients with experimental investigations in mice. The comparison reveals that many strong pathological and mechanistic correlates exist between mouse models of colitis-associated cancer, and the clinically relevant situation in humans. We also summarize several emerging issues in the field, such as the carcinogenic potential of novel inflammation-related DNA adducts and genotoxic microbial factors, the systemic dimension of inflammation-induced genotoxicity, and the complex role of genome maintenance mechanisms during these processes. Taken together, current evidence points to the induction of genetic and epigenetic alterations by chemical and biological inflammatory stimuli ultimately leading to cancer formation.

A kinetic platform to determine the fate of nitric oxide in Escherichia coli

Nitric oxide (NO•) is generated by the innate immune response to neutralize pathogens. NO• and its autoxidation products have an extensive biochemical reaction network that includes reactions with iron-sulfur clusters, DNA, and thiols. The fate of NO• inside a pathogen depends on a kinetic competition among its many targets, and is of critical importance to infection outcomes. Due to the complexity of the NO• biochemical network, where many intermediates are short-lived and at extremely low concentrations, several species can be measured, but stable products are non-unique, and damaged biomolecules are continually repaired or regenerated, kinetic models are required to understand and predict the outcome of NO• treatment. Here, we have constructed a comprehensive kinetic model that encompasses the broad reactivity of NO• in Escherichia coli. The incorporation of spontaneous and enzymatic reactions, as well as damage and repair of biomolecules, allowed for a detailed analysis of how NO• distributes in E. coli cultures. The model was informed with experimental measurements of NO• dynamics, and used to identify control parameters of the NO• distribution. Simulations predicted that NO• dioxygenase (Hmp) functions as a dominant NO• consumption pathway at O2 concentrations as low as 35 µM (microaerobic), and interestingly, loses utility as the NO• delivery rate increases. We confirmed these predictions experimentally by measuring NO• dynamics in wild-type and mutant cultures at different NO• delivery rates and O2 concentrations. These data suggest that the kinetics of NO• metabolism must be considered when assessing the importance of cellular components to NO• tolerance, and that models such as the one described here are necessary to rigorously investigate NO• stress in microbes. This model provides a platform to identify novel strategies to potentiate the effects of NO•, and will serve as a template from which analogous models can be generated for other organisms.

New inhibitors of ROS generation and T-cell proliferation from Myrtus communis

Phytochemical investigation on Myrtus communis Linn. afforded myrtucommuacetalone (1) with an unprecedented carbon skeleton and a new phloroglucinol-type compound, myrtucommulone M (2), along with four known constituents 3-6. Their structures were established by extensive analyses of NMR and mass spectral data as well as by single-crystal X-ray diffraction studies. These constituents were evaluated for their ability to modulate the immune response, based on their effects on various components of immune system. Compounds 1 and 5 exhibited significant inhibitory effect against nitric oxide (NO(•)) production. Compound 1 also exhibited significant antiproliferative activity (IC50 < 0.5 μg/mL) against T-cell proliferation. Myricetin (3) exerted a significant inhibition (IC50 = 1.6 μg/mL) on zymosan-stimulated whole blood phagocytes ROS production. Compounds 1 and 3 were active against PMA-stimulated ROS generation.

A system for exposing molecules and cells to biologically relevant and accurately controlled steady-state concentrations of nitric oxide and oxygen

Nitric oxide (NO) plays key roles in cell signaling and physiology, with diverse functions mediated by NO concentrations varying over three orders-of-magnitude. In spite of this critical concentration dependence, current approaches to NO delivery in vitro result in biologically irrelevant and poorly controlled levels, with hyperoxic conditions imposed by ambient air. To solve these problems, we developed a system for controlled delivery of NO and O(2) over large concentration ranges to mimic biological conditions. Here we describe the fabrication, operation and calibration of the delivery system. We then describe applications for delivery of NO and O(2) into cell culture media, with a comparison of experimental results and predictions from mass transfer models that predict the steady-state levels of various NO-derived reactive species. We also determined that components of culture media do not affect the steady-state levels of NO or O(2) in the device. This system provides critical control of NO delivery for in vitro models of NO biology and chemistry.

Delivery method, target gene structure, and growth properties of target cells impact mutagenic responses to reactive nitrogen and oxygen species

Dysregulated production of nitric oxide (NO•) and reactive oxygen species (ROS) by inflammatory cells in vivo may contribute to mutagenesis and carcinogenesis. Here, we compare cytotoxicity and mutagenicity induced by NO• and ROS in TK6 and AS52 cells, delivered by two methods: a well-characterized delivery system and a novel adaptation of a system for coculture. When exposed to preformed NO•, a cumulative dose of 620 μM min reduced the viability of TK6 cells at 24 h to 36% and increased mutation frequencies in the HPRT and TK1 genes to 7.7 × 10⁻⁶ (p < 0.05) and 24.8 × 10⁻⁶ (p < 0.01), 2.7- and 3.7-fold higher than background, respectively. In AS52 cells, cumulative doses of 1700 and 3700 μM min reduced viability to 49 and 22%, respectively, and increased the mutation frequency 10.2- and 14.6-fold higher than the argon control (132 × 10⁻⁶ and 190 × 10⁻⁶, respectively). These data show that TK6 cells were more sensitive than AS52 cells to killing by NO•. However, the two cell lines were very similar in relative susceptibility to mutagenesis; on the basis of fold increases in MF, average relative sensitivity values [(MF(exp)/MF(control))/cumulative NO• dose] were 5.16 × 10⁻³ and 4.97 × 10⁻³ μM⁻¹ min⁻¹ for TK6 cells and AS52 cells, respectively. When AS52 cells were exposed to reactive species generated by activated macrophages in the coculture system, cell killing was greatly reduced by the addition of NMA to the culture medium and was completely abrogated by combined additions of NMA and the superoxide scavenger Tiron, indicating the relative importance of NO• to loss of viability. Exposure in the coculture system for 48 h increased mutation frequency in the gpt gene by more than 9-fold, and NMA plus Tiron again completely prevented the response. Molecular analysis of gpt mutants induced by preformed NO• or by activated macrophages revealed that both doubled the frequency of gene inactivation (40% in induced vs 20% in spontaneous mutants). Sequencing showed that base-substitution mutations dominated the spectra, with transversions (30-40%) outnumbering transitions (10-20%). Virtually all mutations took place at guanine sites in the gene. G:C to T:A transversions accounted for about 30% of both spontaneous and induced mutations; G:C to A:T transitions amounted to 10-20% of mutants; insertions, small deletions, and multiple mutations were present at frequencies of 0-10%. Taken together, these results indicate that cell type and proximity to generator cells are critical determinants of cytotoxic and genotoxic responses induced by NO• and reactive species produced by activated macrophages.

Modulatory Effects of Chrysanyhemi Flos Pharmacopuncture on Nitric-oxide (NO) Production in Murin Macrophagy Cells

Objectives:

Much evidence exists that herbs have effective immunomodulatory activities. Chrysanthemi Flos (CF) is effective in clearing heat, reducing inflammation, dropping blood pressure and treating headache and is used as a pharmaceutical raw material for an immune enhancer. The purpose of this study was to investigate the modulatory effect of Chrysanthemi Flos pharmacopuncture on nitric-oxide (NO) production in activating macrophages.

Methods:

After a murine macrophage cell line, RAW 264.7, was cultured in the presence of lipopolysaccharide (LPS), immune-modulating abilities of CF were evaluated by using NO, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) production and phagocytic activity of macrophages.

Results:

CF enhanced the activities of macrophages by increasing the phagocytic activity and decreasing NO production. Especially, both LPS and CF, 200 ㎍/ml, treatment could significantly reduce the NO production, but did not change the production of IL-6 and TNF-α.

Conclusion:

The results of this study indicate that CF may be of immunomodulatory value, especially for adverse diseases due to increased NO production. It may have potential for use as immunoenhancing pharmacopuncture.

XRCC1 and base excision repair balance in response to nitric oxide

Inflammation associated reactive oxygen and nitrogen species (RONs), including peroxynitrite (ONOO(-)) and nitric oxide (NO), create base lesions that potentially play a role in the toxicity and large genomic rearrangements associated with many malignancies. Little is known about the role of base excision repair (BER) in removing these endogenous DNA lesions. Here, we explore the role of X-ray repair cross-complementing group 1 (XRCC1) in attenuating RONs-induced genotoxicity. XRCC1 is a scaffold protein critical for BER for which polymorphisms modulate the risk of cancer. We exploited CHO and human glioblastoma cell lines engineered to express varied levels of BER proteins to study XRCC1. Cytotoxicity and the levels of DNA repair intermediates (single-strand breaks; SSB) were evaluated following exposure of the cells to the ONOO(-) donor, SIN-1, and to gaseous NO. XRCC1 null cells were slightly more sensitive to SIN-1 than wild-type cells. We used small-scale bioreactors to expose cells to NO and found that XRCC1-deficient CHO cells were not sensitive. However, using a molecular beacon assay to test lesion removal in vitro, we found that XRCC1 facilitates AAG-initiated excision of two key NO-induced DNA lesions: 1,N(6)-ethenoadenine and hypoxanthine. Furthermore, overexpression of AAG rendered XRCC1-deficient cells sensitive to NO-induced DNA damage. These results show that AAG is a key glycosylase for BER of NO-induced DNA damage and that XRCC1's role in modulating sensitivity to RONs is dependent upon the cellular level of AAG. This demonstrates the importance of considering the expression of other components of the BER pathway when evaluating the impact of XRCC1 polymorphisms on cancer risk.

p53 null fluorescent yellow direct repeat (FYDR) mice have normal levels of homologous recombination

The tumor suppressor p53 is a transcription factor whose function is critical for maintaining genomic stability in mammalian cells. In response to DNA damage, p53 initiates a signaling cascade that results in cell cycle arrest, DNA repair or, if the damage is severe, programmed cell death. In addition, p53 interacts with repair proteins involved in homologous recombination. Mitotic homologous recombination (HR) plays an essential role in the repair of double-strand breaks (DSBs) and broken replication forks. Loss of function of either p53 or HR leads to an increased risk of cancer. Given the importance of both p53 and HR in maintaining genomic integrity, we analyzed the effect of p53 on HR in vivo using Fluorescent Yellow Direct Repeat (FYDR) mice as well as with the sister chromatid exchange (SCE) assay. FYDR mice carry a direct repeat substrate in which an HR event can yield a fluorescent phenotype. Here, we show that p53 status does not significantly affect spontaneous HR in adult pancreatic cells in vivo or in primary fibroblasts in vitro when assessed using the FYDR substrate and SCEs. In addition, primary fibroblasts from p53 null mice do not show increased susceptibility to DNA damage-induced HR when challenged with mitomycin C. Taken together, the FYDR assay and SCE analysis indicate that, for some tissues and cell types, p53 status does not greatly impact HR.

Mutagenic analysis of six disinfection by-products in the Tk gene of mouse lymphoma cells

Drinking water must be disinfected prior to its distribution for human consumption. This water treatment process generates disinfection by-products (DBPs), formed by the interaction of the disinfectant with organic matter, anthropogenic contaminants and inorganic (bromide/iodide) matter naturally present in source water. Due to the potential genotoxic/carcinogenic risk of these DBPs, we have investigated the mutagenic potential of six of such compounds on the thymidine kinase (Tk) gene in the well-validated mouse lymphoma assay (MLA). The MLA quantifies a wide range of genetic alterations affecting the expression of this gene in L5178Y/Tk(+/-)-3.7.2C cells. In this study we selected six emerging DBPs, corresponding to three different chemical classes: halonitromethanes (bromonitromethane and trichloronitromethane), halogenated acetaldehydes (tribromoacetaldehyde and chloral hydrate) and hydroxyfuranones (mucobromic and mucochloric acids), each class including one chlorinated and one brominated form. The results showed that after 4h of treatment, only mucobromic acid increased the frequency of mutant colonies, with a higher proportion of small colonies, which would indicate a clastogenic potential. This is the first study reporting mutagenicity data in mammalian cells for the six selected DBPs.

Nitric oxide delivery system for biological media

Developing an understanding of how chronically elevated levels of nitric oxide at sites of inflammation or infection can lead to cancer and other diseases requires ways to expose cells and biomolecules to controlled concentrations of NO for hours to days. To achieve this, a small (65ml) stirred reactor was fabricated that included a flat, porous poly(tetrafluoroethylene) membrane and a loop of poly(dimethylsiloxane) tubing for NO and O(2) delivery, respectively. It was equipped with probes for continuous monitoring of NO and O(2) concentrations. Transport through the membrane and tubing was characterized using separate O(2) depletion experiments. In experiments using only a 10% NO mixture and a buffer that was initially air-equilibrated, constant rates of accumulation were observed for NO(2)(-) (53±2μM/h; n=8), the end product of NO oxidation, as expected. Simultaneous delivery of NO and O(2) yielded steady NO concentrations of 0.7-2.3μM, depending on the tubing length and gas compositions. A model was developed that allows the steady NO and O(2) concentrations and the duration of the transients to be predicted to within a few percent. This system should be useful for exposing cells and biomolecules to concentrations of NO that mimic those in vivo.

Nitric oxide, oxygen, and superoxide formation and consumption in macrophages and colonic epithelial cells

Knowledge of the rates at which macrophages and epithelial cells synthesize NO is critical for predicting the concentrations of NO and other reactive nitrogen species in colonic crypts during inflammation, and elucidating the linkage between inflammatory bowel disease, NO, and cancer. Macrophage-like RAW264.7 cells, primary bone marrow-derived macrophages (BMDM), and HCT116 colonic epithelial cells were subjected to simulated inflammatory conditions, and rates of formation and consumption were determined for NO, O(2), and O(2)(-). Production rates of NO were determined in either of two ways: continuous monitoring of NO concentrations in a closed chamber with corrections for autoxidation, or NO(2)(-) accumulation measurements in an open system with corrections for diffusional losses of NO. The results obtained using the two methods were in excellent agreement. Rates of NO synthesis (2.3 +/- 0.6 pmol s(-1) 10(6) cells(-1)), NO consumption (1.3 +/- 0.3 s(-1)), and O(2) consumption (59 +/- 17 pmol s(-1) 10(6) cells(-1) when NO is negligible) for activated BMDM were indistinguishable from those of activated RAW264.7 cells. NO production rates calculated from NO(2)(-) accumulation data for HCT116 cells infected with Helicobacter cinaedi (3.9 +/- 0.1 pmol s(-1) 10(6) cells(-1)) were somewhat greater than those of RAW264.7 macrophages infected under similar conditions (2.6 +/- 0.1 pmol s(-1) 10(6) cells(-1)). Thus, RAW264.7 cells have NO kinetics nearly identical to those of primary macrophages, and stimulated epithelial cells are capable of synthesizing NO at rates comparable to those of macrophages. Using these cellular kinetic parameters, simulations of NO diffusion and reaction in a colonic crypt during inflammation predict maximum NO concentrations of about 0.2 microM at the base of a crypt.

Nitric oxide activation of Keap1/Nrf2 signaling in human colon carcinoma cells

The transcription factor NF-E2-related nuclear factor 2 (Nrf2) regulates expression of genes that protect cells from oxidative damage. Here, we characterized nitric oxide (*NO)-induced Nrf2-Kelch-like ECH-associated protein 1 (Keap1) signaling and its role in counteracting *NO-induced apoptosis of human colon cancer HCT116 cells. Nrf2 was localized in the cytoplasm in control cells; *NO triggered its rapid nuclear accumulation, transcriptional activation, and up-regulation of HO-1, NQO1, and GCL, but not GST A4 and P1 subunits. Nrf2 accumulation in the nucleus was also associated with enhanced transcription and posttranscriptional modifications. (S)-nitrosation of Keap1 may contribute to nuclear accumulation of Nrf2 by facilitating its dissociation from Keap1, thus initiating *NO-mediated Nrf2-Keap1 signaling. *NO-mediated induction of ARE-dependent genes occurred well before apoptosis, as judged by caspase 3 activation. Collectively, these results show that the Nrf2-Keap1 signaling pathway mediates protective cellular responses to mitigate *NO-induced damage and may contribute to the relative resistance of HCT116 to *NO-induced cytotoxicity.

GSH-dependent iNOS and HO-1 mediated apoptosis of human Jurkat cells induced by nickel(II)

The molecular mechanisms by which nickel compounds cause immune cytotoxicity are far from understood. Our preliminary data suggested that nickel(II) induced apoptosis in Jurkat cells by mitochondrial pathway, specifically via mitochondrial membrane potential dissipation and antiapoptotic gene bcl-2 down-regulation. The main goal of this study was to further investigate the toxicity of nickel, especially the induction of reactive oxygen species (ROS) on immune cells, which finally induced apoptosis. Nickel was found to induce glutathione (GSH) depletion in a dose- and time-dependent manner. When Jurkat cells were preincubated with antioxidant N-acetylcysteine (NAC), apoptosis was inhibited distinctly, which suggested that ROS played an initial role in nickel immune toxicity. Heme oxygenase-1 (HO-1) and Nitric oxide (NO) which may play an important role in regulatory and protective processes in cells were assayed upon nickel treatment. A significant increase in HO-1 mRNA levels was detected in nickel treated cells. We confirmed that reduction of Nitrate levels in Jurkat cells was due to down-regulation of inducible nitric oxide synthase (iNOS), not endothelial nitric oxide synthase (eNOS). Expression changes of HO-1 and iNOS were markedly blocked when Jurkat cells were preincubated with NAC, suggesting that ROS resulted in HO-1 and iNOS dysfunction in Jurkat cells. We supposed that the immune toxicity of nickel(II) was mainly due to GSH depletion and finally led to apoptosis, probably via changing the expression levels of HO-1 and iNOS in human T lymphocytes.

Nitric oxide induces early viral transcription coincident with increased DNA damage and mutation rates in human papillomavirus-infected cells

High-risk human papillomavirus (HPV) infections are necessary but insufficient causes of cervical cancers. Other risk factors for cervical cancer (e.g., pregnancy, smoking, infections causing inflammation) can lead to high and sustained nitric oxide (NO) concentrations in the cervix, and high NO levels are related to carcinogenesis through DNA damage and mutation. However, the effects of NO exposure in HPV-infected cells have not been investigated. In this study, we used the NO donor DETA-NO to model NO exposure to cervical epithelium. In cell culture media, 24-hour exposure to 0.25 to 0.5 mmol/L DETA-NO yielded a pathologically relevant NO concentration. Exposure of cells maintaining episomal high-risk HPV genomes to NO increased HPV early transcript levels 2- to 4-fold but did not increase viral DNA replication. Accompanying increased E6 and E7 mRNA levels were significant decreases in p53 and pRb protein levels, lower apoptotic indices, increased DNA double-strand breaks, and higher mutation frequencies when compared with HPV-negative cells. We propose that NO is a molecular cofactor with HPV infection in cervical carcinogenesis, and that modifying local NO cervical concentrations may constitute a strategy whereby HPV-related cancer can be reduced.

Nitric oxide as a target of complementary and alternative medicines to prevent and treat inflammation and cancer

Nitric oxide (NO) and associated reactive nitrogen species (RNS) are involved in many physiological functions. There has been an ongoing debate to whether RNS can inhibit or perpetuate chronic inflammation and associated carcinogenesis. Although the final outcome depends on the genetic make-up of its target, the surrounding microenvironment, the activity and localization of nitric oxide synthase (NOS) isoforms, and overall levels of NO/RNS, evidence is accumulating that in general, RNS drive inflammation and cancers associated with inflammation. To this end, many complementary and alternative medicines (CAMs) that work in chemoprevention associated with chronic inflammation, are inhibitors of excessive NO observed in inflammatory conditions. Here, we review recent literature outlining a role of NO/RNS in chronic inflammation and cancer, and point toward NO as one of several targets for the success of CAMs in treating chronic inflammation and cancer associated with this inflammation.

Prediction of nitric oxide concentrations in colonic crypts during inflammation

Nitric oxide production in the colon has been linked to inflammatory bowel disease (IBD) and increased risk for colon cancer. However, measurements of NO concentration in the inflamed colon have not been available and it is not known what NO levels are pathophysiological. A computational model, based on anatomical length scales and rates of NO production measured in cell cultures, was used to predict spatially varying NO concentrations within a colonic crypt under inflammatory conditions. A variety of scenarios were considered, including different spatial distributions of macrophages and a range of possible macrophage and epithelial synthesis rates for NO. Activated macrophages arranged as a monolayer at the base of the crypt elicited maximum NO concentrations of approximately 0.3 microM. The epithelial contribution to NO synthesis was calculated to be negligible. Assuming a uniform macrophage layer, NO synthesis rates greater than 20 microM/s, or more than three times that measured in vitro, would be necessary to achieve maximum NO concentrations of 1 microM in the crypt. Thus, unless NO synthesis rates in macrophages and/or epithelial cells greatly exceed those measured in cell cultures, NO concentrations will remain submicromolar in the crypt during inflammation. Additionally, the results were used to predict the range of NO concentrations (<0.3 microM) and cumulative NO dose (560 microM min) experienced by a given epithelial cell migrating from the base to the top of the crypt. These estimates of NO concentrations in inflamed crypts should facilitate efforts to elucidate the molecular biological linkage between NO exposure and carcinogenesis in IBD.

Effects of endogenous nitric oxide induced by 5-fluorouracil and L-Arg on liver carcinoma in nude mice

AIM: To study the effects of endogeous nitric oxide induced by 5-fluorouracil (5-FU) and L-arginine (L-Arg) on the human liver carcinoma model in nude mice.

METHODS: The human liver carcinoma model in nude mice was established with BEL-7402 cells and normal saline (NS), 5-FU and 5-FU + L-Arg injected intraperitoneally. The tumor size was measured. The necrotic degree and range were observed under microscope. The apoptosis of cancer cell was detected by turmina deoxynucleotidyl transferanse mediated dUTP nick end labeling (TUNEL) method. Immunohistochemical method was performed to determine the expression of iNOS, P16, BAX. The chemical colorimetry was used to test the activity and nitrate reductase method was adopted to test the concentration of nitric oxide (NO) in the tumor tissue. The BI2000 pathological image analyzer was used to analyze the result of immunohistochemistry.

RESULTS: 5-FU combined with L-Arg could inhibit the tumor growth apparently. In NS, 5-FU and 5-FU+L-Arg groups, the changes of tumor volumes were 257.978 ± 59.0, 172.232 ± 66.0 and 91.523 ± 26.7 mm³, respectively (P < 0.05 5-FU vs 5-FU + L-Arg group; P < 0.05 NS vs 5-FU + L-Arg group; P < 0.05, NS vs 5-FU group). The necrotic range and apoptosis index were significantly increased after the drug injection. The necrotic range was biggest in 5-FU + L-Arg group (χ² = 15.963, P < 0.05).

The apoptosis indexes were as follows: NS, 17.4% ± 6.19%; 5-FU, 31.3% ± 12.3%; and 5-FU + L-Arg, 46% ± 15.24% (P < 0.05, 5-FU vs 5-FU + L-Arg; P < 0.05, NS vs 5-FU + L-Arg; P < 0.05, NS vs 5-FU). The expression and activity of iNOS were increased in the tumor tissue. The concentration of NO was also increased. F of optical density of iNOS, iNOS activity and NO concentration are 31.693, 21.949, and 33.909, respectively, P < 0.05. The concentration of NO was related to the expression of P16 and BAX. The correlation coefficient was 0.764 and 0.554.

CONCLUSION: 5-FU combined with L-Arg can inhibit the growth of tumor in nude mice. The effect may be related to inducing the synthesis and increasing the activity of iNOS. The production of NO is increased, and it can enhance the expression of apoptosis-related gene and antioncogene.

GEA 3162, a peroxynitrite donor, induces Bcl-2-sensitive, p53-independent apoptosis in murine bone marrow cells

Apoptosis may be regulated by oxidants such as peroxynitrite (ONOO(-)). The tumour suppressor, p53, has been reported to play a crucial role in apoptosis induced by oxidants, therefore we assessed the ability of a ONOO(-) donor, GEA 3162, to activate caspases and induce mitochondrial permeability in a p53-deficient murine bone marrow cell line, Jaws II. Furthermore, these cells were stably transfected with Bcl-2, in order to investigate the impact of this survival protein on ONOO(-)-induced apoptosis. GEA 3162 activated caspases and induced loss of mitochondrial membrane potential in Jaws II cells. In particular, caspases 3 and 2 were activated, alongside minor activation of caspases 8 and 9, and apoptosis was partially dependent upon p38 MAP kinase activation, with little or no role for JNK. Overexpression of Bcl-2 abolished activation of all caspases and reduced the change in mitochondrial membrane potential. Thus, we have demonstrated that the ONOO(-) donor, GEA 3162, induces apoptosis in Jaws II murine myeloid cells despite lacking functional p53, via a pathway that principally involves caspases 2 and 3 and mitochondrial changes. This is blocked by overexpression of Bcl-2 via a mechanism that does not appear to merely reflect stabilisation of the mitochondrial membrane.

Nitric oxide induces apoptosis in cutaneous T cell lymphoma (HuT-78) by downregulating constitutive NF-κB

Constitutive active NF-kappaB have been shown to protect cutaneous T cell lymphoma (CTCL) cells from apoptosis. In the present study, we have studied the cytotoxic potential of nitric oxide generating compound, sodium nitroprusside (SNP) on CTCL cell line, HuT-78. Treatment of cells with SNP resulted in decrease in mitochondrial membrane potential, cytochrome c release, activation of caspase-3 and poly (ADP ribose) polymerase cleavage. SNP treatment inhibited activation of NF-kappaB in a concentration dependent manner. SNP increased the expression of IkappaBalpha without affecting the phosphorylation of IkappaBalpha. Downregulation of NF-kappaB by SNP decreased p65 nuclear translocation as evident by confocal fluorescence microscopy. Further it was found that SNP treatment caused downregulation of Bcl-2 family member (Bcl-xl) in HuT-78 cells. Thus, we have provided evidence that SNP induces apoptosis in CTCL cell line, HuT-78 by downregulating constitutive NF-kappaB and thereby Bcl-xl expression.

Neuronal apoptosis in neurodegeneration

Apoptosis mediates the precise and programmed natural death of neurons and is a physiologically important process in neurogenesis during maturation of the central nervous system. However, premature apoptosis and/or an aberration in apoptosis regulation is implicated in the pathogenesis of neurodegeneration, a multifaceted process that leads to various chronic disease states, such as Alzheimer's (AD), Parkinson's (PD), Huntington's (HD) diseases, amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), and diabetic encephalopathy. The current review focuses on two major areas (a) the fundamentals of apoptosis, which includes elements of the apoptotic machinery, apoptosis inducers, and emerging concepts in apoptosis research, and (b) apoptotic involvement in neurodegenerative disorders, neuroprotective treatment strategies/modalities, and the mechanisms of, and signaling in, neuronal apoptosis. Current and new experimental models for apoptosis research in neurodegenerative diseases are also discussed.

JS-K, a GST-activated nitric oxide generator, induces DNA double-strand breaks, activates DNA damage response pathways, and induces apoptosis in vitro and in vivo in human multiple myeloma cells

Here we investigated the cytotoxicity of JS-K, a prodrug designed to release nitric oxide (NO(*)) following reaction with glutathione S-transferases, in multiple myeloma (MM). JS-K showed significant cytotoxicity in both conventional therapy-sensitive and -resistant MM cell lines, as well as patient-derived MM cells. JS-K induced apoptosis in MM cells, which was associated with PARP, caspase-8, and caspase-9 cleavage; increased Fas/CD95 expression; Mcl-1 cleavage; and Bcl-2 phosphorylation, as well as cytochrome c, apoptosis-inducing factor (AIF), and endonuclease G (EndoG) release. Moreover, JS-K overcame the survival advantages conferred by interleukin-6 (IL-6) and insulin-like growth factor 1 (IGF-1), or by adherence of MM cells to bone marrow stromal cells. Mechanistic studies revealed that JS-K-induced cytotoxicity was mediated via NO(*) in MM cells. Furthermore, JS-K induced DNA double-strand breaks (DSBs) and activated DNA damage responses, as evidenced by neutral comet assay, as well as H2AX, Chk2 and p53 phosphorylation. JS-K also activated c-Jun NH(2)-terminal kinase (JNK) in MM cells; conversely, inhibition of JNK markedly decreased JS-K-induced cytotoxicity. Importantly, bortezomib significantly enhanced JS-K-induced cytotoxicity. Finally, JS-K is well tolerated, inhibits tumor growth, and prolongs survival in a human MM xenograft mouse model. Taken together, these data provide the preclinical rationale for the clinical evaluation of JS-K to improve patient outcome in MM.