Formation Of Nitrogen Species Research Articles

The interplay of exercise and polyphenols in cancer treatment: A focus on oxidative stress and antioxidant mechanisms.

Exercise has been demonstrated to induce an elevated production of free radicals, leading to the onset of oxidative stress. Numerous studies highlight the positive impacts of aerobic exercise, primarily attributed to the increase in overall antioxidant capacity. The evidence suggests that engaging in aerobic exercise contributes to a reduction in the likelihood of advanced cancer and mortality. Oxidative stress occurs when there is an imbalance between the generation of free radicals and the collective antioxidant defense system, encompassing both enzymatic and nonenzymatic antioxidants. Typically, oxidative stress triggers the formation of reactive oxygen or nitrogen species, instigating or advancing various issues in cancers and other diseases. The pro-oxidant-antioxidant balance serves as a direct measure of this imbalance in oxidative stress. Polyphenols contain a variety of bioactive compounds, including flavonoids, flavanols, and phenolic acids, conferring antioxidant properties. Previous research highlights the potential of polyphenols as antioxidants, with documented effects on reducing cancer risk by influencing processes such as proliferation, angiogenesis, and metastasis. This is primarily attributed to their recognized antioxidant capabilities. Considering the extensive array of signaling pathways associated with exercise and polyphenols, this overview will specifically focus on oxidative stress, the antioxidant efficacy of polyphenols and exercise, and their intricate interplay in cancer treatment.

A Nonclinical Safety Evaluation of Cold Atmospheric Plasma for Medical Applications: The Role of Genotoxicity and Mutagenicity Studies.

Atmospheric nonthermal plasma (ANTP) has rapidly evolved as an innovative tool in biomedicine with various applications, especially in treating skin diseases. In particular, the formation of reactive oxygen species (ROS) and nitrogen species (RNS), which are generated by ANTP, plays an important role in the biological signaling pathways of human cells. Unfortunately, excessive amounts of these reactive species significantly result in cellular damage and cell death induction. To ensure the safe application of ANTP, preclinical in vitro studies must be conducted before proceeding to in vivo or clinical trials involving humans. Our study aimed to investigate adverse effects on genetic substances in murine fibroblast cells exposed to ANTP. Cell viability and proliferation were markedly reduced after exposing the cells with plasma. Both extracellular and intracellular reactive species, especially RNS, were significantly increased upon plasma exposure in the culture medium and the cells. Notably, significant DNA damage in the cells was observed in the cells exposed to plasma. However, plasma was not classified as a mutagen in the Ames test. This suggested that plasma led to the generation of both extracellular and intracellular reactive species, particularly nitrogen species, which affect cell proliferation and are also known to induce genetic damage in fibroblast cells. These results highlight the genotoxic and mutagenic effects of ANTP, emphasizing the need for the cautious selection of plasma intensity in specific applications to avoid adverse side effects resulting from reactive species production.

Rv2231c, a unique histidinol phosphate aminotransferase from Mycobacterium tuberculosis, supports virulence by inhibiting host-directed defense

Nitrogen metabolism of M. tuberculosis is critical for its survival in infected host cells. M. tuberculosis has evolved sophisticated strategies to switch between de novo synthesis and uptake of various amino acids from host cells for metabolic demands. Pyridoxal phosphate-dependent histidinol phosphate aminotransferase-HspAT enzyme is critically required for histidine biosynthesis. HspAT is involved in metabolic synthesis of histidine, phenylalanine, tyrosine, tryptophan, and novobiocin. We showed that M. tuberculosis Rv2231c is a conserved enzyme with HspAT activity. Rv2231c is a monomeric globular protein that contains α-helices and β-sheets. It is a secretory and cell wall-localized protein that regulates critical pathogenic attributes. Rv2231c enhances the survival and virulence of recombinant M. smegmatis in infected RAW264.7 macrophage cells. Rv2231c is recognized by the TLR4 innate immune receptor and modulates the host immune response by suppressing the secretion of the antibacterial pro-inflammatory cytokines TNF, IL-12, and IL-6. It also inhibits the expression of co-stimulatory molecules CD80 and CD86 along with antigen presenting molecule MHC-I on macrophage and suppresses reactive nitrogen species formation, thereby promoting M2 macrophage polarization. Recombinant M. smegmatis expressing Rv2231c inhibited apoptosis in macrophages, promoting efficient bacterial survival and proliferation, thereby increasing virulence. Our results indicate that Rv2231c is a moonlighting protein that regulates multiple functions of M. tuberculosis pathophysiology to increase its virulence. These mechanistic insights can be used to better understand the pathogenesis of M. tuberculosis and to design strategies for tuberculosis mitigation.

Embedded metal inducing electron accumulation of multi-mesoporous pyridinic-N doped carbon for enhancing *COOH adsorption in electrochemical CO2 reduction

Nitrogen-doped carbon (NC) for carbon dioxide reduction reaction (CO2RR) are promising candidates. However, its selectivity and activity are limited by the undeveloped pore and limited electronic effect. Herein, we propose a strategy of three birds with one stone to utilize the embedded nickel for inducing electron-rich pyridinic-NC with multimodal porous structure based on the hard template assisted sacrificial template method. Nickel acts as sacrificial agent and inducer to facilitate the formation of mesoporous and reactive nitrogen species for capturing and activating reactants, respectively. Besides, we find that nickel as electron donor endows the NC with electron accumulation for participating actively in PCET reaction. The resultant Ni0.87-NC-1-AE exhibits an eminent FECO of 97.6 % with excellent activity and stability. In-situ Raman spectroscopy and the projected crystal orbital Hamilton populations (pCOHP) confirm the accumulation of *COOH and the stable adsorption of *COOH on the surface. What’s more, the well-designed experiments and DFT calculations accurately locate pyridinic-N as the active site, where the aggregated electrons donated by nickel significantly reduce the energy barrier of rate-determining step and promote the desorption of CO. This work provides an instructive perspective to construct advanced NC electrocatalysts with high mass transfer efficiency and high catalytic activity.

High-temperature adsorption of nitrogen dioxide for stable, efficient, and scalable doping of carbon nanotubes

This work is devoted to a novel efficient strategy for single-walled carbon nanotube doping employing heat treatment with nitrogen dioxide (NO2). Unlike numerous reports of unstable NO2 doping at room temperature, our method combines high efficiency and stability, enabled by its temperature-dependent adsorption on the nanotube surface. We reveal that doping stability increases with the treatment temperature reaching maxima at 300 °C avoiding any detrimental effect on nanotube structure and optical transmittance. As a result, we demonstrate doped carbon nanotube transparent conductive films exhibiting competitive performance (in respect to films treated with other dopants) with a less than 50% drop in conductive characteristics for over a year. Thermo-programmed desorption analysis and X-ray photoelectron spectroscopy confirm the preferential formation of long-living adsorbed nitrogen species, such as NO3-groups, as a result of high-temperature treatment. We believe the current work provides a basis for the robust and technologically efficient doping of single-walled carbon nanotubes and related structures at industrial scales, as the developed method could be easily coupled with a continuous technology of carbon nano materials production.

Structure evolution characteristic of hydrochar and nitrogen transformation mechanism during co-hydrothermal carbonization process of microalgae and biomass

Co-hydrothermal carbonization (co-HTC) of microalgae and lignocellulosic biomass has high potential for producing nitrogen-rich carbon materials (hydrochar) with relatively high yield. The synergistic effect, hydrochar structure evolution and nitrogen transformation mechanism during the co-HTC process were depicted in depth. The results of the co-HTC process showed that the positive synergy between biomass and microalgae could improve the hydrochar yield and facilitate incorporation of nitrogen into the hydrochar aromatic heterocycles structures. Moderate reaction conditions were beneficial for co-HTC hydrochar nitrogen enrichment and porosity increment, and the optimal nitrogen content and specific surface area reached 3.50% and 5.91 m2/g in co-HTC hydrochars at 240 °C and 1 h. Severe reaction conditions could enhance the formation of stable heterocyclic nitrogen species (reaching 54% at 300 °C). The hydrochar structure evolution and nitrogen transformation mechanism during co-HTC process could be generally divided into two stages. The first stage took place from 180 to 260 °C, and the nitrogen-rich secondary chars could be formed by the interaction of the hydrolysis intermediates. The second stage occurred from 260 to 300 °C, and the previously formed secondary char would be gradually decomposed. This study provides theoretical guidance for regulating the co-HTC process to produce nitrogen-rich carbon materials.

Polycystic ovary syndrome and its management: In view of oxidative stress.

In the past two decades, oxidative stress (OS) has drawn a lot of interest due to the revelation that individuals with many persistent disorders including diabetes, polycystic ovarian syndrome (PCOS), cardiovascular, and other disorders often have aberrant oxidation statuses. OS has a close interplay with PCOS features such as insulin resistance, hyperandrogenism, and chronic inflammation; there is a belief that OS might contribute to the development of PCOS. PCOS is currently recognized as not only one of the most prevalent endocrine disorders but also a significant contributor to female infertility, affecting a considerable proportion of women globally. Therefore, the understanding of the relationship between OS and PCOS is crucial to the development of therapeutic and preventive strategies for PCOS. Moreover, the mechanistic study of intracellular reactive oxygen species/ reactive nitrogen species formation and its possible interaction with women's reproductive health is required, which includes complex enzymatic and non-enzymatic antioxidant systems. Apart from that, our current review includes possible regulation of the pathogenesis of OS. A change in lifestyle, including physical activity, various supplements that boost antioxidant levels, particularly vitamins, and the usage of medicinal herbs, is thought to be the best way to combat this occurrence of OS and improve the pathophysiologic conditions associated with PCOS.

Modeling nitrogen species from ammonia reciprocating engine combustion in temperature-equivalence ratio space

This paper explores nitrogen species formation in temperature (T)-equivalence ratio (ϕ) space under internal combustion engine-relevant conditions using zero-dimensional modeling. The analysis reveals that N2O and NO are formed in a much larger region of ϕ-T space than in hydrocarbon combustion due to fuel chemical pathways. N2O is formed over a large range of ϕ, primarily in low temperature regions that have significant levels of unburned NH3. NO is formed over a large, high temperature, lean region. Further analysis shows that even when mixing burned gas with unburned NH3 from engine crevices, N2O is reduced to low levels in the expansion stroke after initially increasing due to the thermal de-NOx mechanism. This indicates that N2O emissions measured from premixed engine combustion are likely from quenching near cold surfaces.

Exploring Energy-Efficient Techniques and Chemical Kinetics in Reactive Nitrogen Species Production with Ambient Air Plasma for Plasma-Activated Water

This study investigates the chemical kinetics of reactive nitrogen species (RNS) formation in plasma-activated water (PAW) using ambient air and evaluates its energy efficiency. A singular plasma/liquid reactor was used, with discharge power varying between 16.4 to 27.0 W and agitation speeds set at 0 and 750 rpm. The reactor operated across temperatures from 5.00 to 35.00 °C during a consistent 180 min plasma activation. Analysis encompassed ionic strength effects, hydronium activity, conductivity, and iodide as a redox indicator for PAW. Findings suggest reactive species predominantly originate in the gas phase and move to the liquid through the gas-liquid interface. HNO3 production in PAW demonstrated a zero-order, temperature-dependent reaction. From activation parameters and ionic strength effects, a determinant step for aqueous HNO3 production was proposed. The influence of discharge power and agitation on HNO3 and HNO2 production was associated with heightened rates due to increased mass transfer and electric field strength. The research highlighted a trade-off between energy efficiency and nitrate production rate, emphasizing an efficiency peak of 72.33 nmol J-1 in PAW, pivotal for cost and operational benefits.

Ammonia Toxicity and Associated Protein Oxidation: A Single-Cell Surface Enhanced Raman Spectroscopy Study.

Ammonia (NH3) is a commonly used industrial chemical to which exposure at high concentrations can result in severe skin damage. Moreover, high levels of ammonia in the human body can lead to hyperammonemia conditions and enhanced cancer metabolism. In this work, the toxicity mechanism of NH3 has been studied against human dermal fibroblast (HDF) cells using surface-enhanced Raman spectroscopy (SERS). For this purpose, gold nanoparticles of size 50 nm have been prepared and used as probes for Raman signal enhancement, after being internalized inside HDF cells. Following the exposure to ammonia, HDF cells showed a significant variation in the protein ternary structure's signals, demonstrating their denaturation and oxidation process, together with early signs of apoptosis. Meaningful changes were observed especially in the Raman vibrations of sulfur-containing amino acids (cysteine and methionine) together with aromatic residues. Fluorescence microscopy revealed the formation of reactive oxygen and nitrogen species in cells, which confirmed their stressed condition and to whom the causes of protein degradation can be attributed. These findings can provide new insights into the mechanism of ammonia toxicity and protein oxidation at a single-cell level, demonstrating the high potential of the SERS technique in investigating the cellular response to toxic compounds.

Toluenin Nitrik Oksit Üretimine Etkisinin ve Resveratrolün Koruyucu Özelliklerinin Araştırılması

Amaç: Organik çözücü olarak en çok tercih edilen Toluendir. Toluene uzun süre maruz kalmak ciddi sağlık sorunlarına neden olur. Uluslararası Kanser Araştırmaları Birliği (IACR), tolüeni "insanlar için muhtemelen kanserojen" (Grup 2B) olarak sınıflandırmıştır. Bu sınıflandırma, toluenin potansiyel kanserojen etkilere sahip olabileceğini belirtir. Toluene maruz kalma, reaktif nitrojen türlerinin ve reaktif oksijen türlerinin oluşumuyla bağlantılı olup, doğrudan doku hasarına ve çeşitli antioksidan sistemlerin değişmesine neden olur. Polifenol yapısında olan resveratrol, bitkilerde önemli etkilere sahip bir moleküldür. İnsanlarda da olumlu etkilere sahip olduğu bilinmektedir. Bu çalışmada, kardiyovasküler, nörolojik, immünolojik ve diğer birçok sistemde biyolojik düzenleyici olarak önemli bir role sahip olan nitrik oksit üretimine toluene maruz kalmanın etkisi ve resveratrolün koruyucu özellikleri araştırılmıştır.
 
 Yöntem: Tolüenin 900mg/kg dozu erkek sıçanlara (250-350gr Wistar-Albino) intraperitoneal yolla uygulanırken resveratrol 5, 10 ve 20mg/kg dozları aynı yolla altı gün boyunca uygulanmıştır. Karaciğer dokusunda ve serumda nitrik oksit seviyeleri ve nitrik oksit sentaz aktiviteleri araştırılmıştır.
 
 Bulgular: Veriler, karaciğer dokusunda ve serumda nitrik oksit seviyesinin arttığını ve toluen uygulamasını takiben yüksek nitrik oksit sentaz aktivitesini gösterdi. Resveratrolün çeşitli dozlarının uygulanmasından sonra karaciğerde nitrik oksit seviyelerinde ve nitrik oksit sentaz aktivitesinde önemli azalmalar gözlendi.
 
 Sonuçlar: Sonuçlarımız yüksek dozda toluenin nitrik oksit üretimini tetiklediğini, resveratrolün ise koruyucu özelliklere sahip olduğunu gösterdi.

Measurement of argon excimers, Ar2*, in a cold atmospheric plasma jet using cavity ringdown spectroscopy

The argon excimer (Ar2*) species is considered to play an important role in the chemistry of cold atmospheric plasma jets, notably in the formation of reactive oxygen and nitrogen species. In the present work, we demonstrate that cavity ringdown spectroscopy can be used to detect and quantitatively measure Ar2* in the effluent of a cold atmospheric plasma jet, the so-called kINPen-Sci. The spectroscopic features of the 5p π3Πg ← a3Σu+Δν = 0 and 7p σ3Σg+ ← a3Σu+ (ν′ - ν″) systems were clearly identified allowing unambiguous assignment to the Ar2* species. A predominant absorption feature at 512 nm was used to determine the integrated density along the axis perpendicular to the gas flow. Assuming a homogeneous density distribution in the kINPen-Sci effluent, Ar2* densities from 1.8 × 1011 molecule · cm−3 at 0 mm to 1.3 × 1010 molecule · cm−3 at 4.2 mm below the nozzle tip were determined.

Perioperative redox changes in patients undergoing hepato-pancreatico-biliary cancer surgery

BackgroundTissue injury induces inflammation and the surgical stress response, which are thought to be central to the orchestration of recovery or deterioration after surgery. Enhanced formation of reactive oxygen and nitrogen species accompanies the inflammatory response and triggers separate but integrated reduction/oxidation (redox) pathways that lead to oxidative and/or nitrosative stress (ONS). Quantitative information on ONS in the perioperative period is scarce. This single-centre exploratory study investigated the effects of major surgery on ONS and systemic redox status and their potential associations with postoperative morbidity.MethodsBlood was collected from 56 patients at baseline, end of surgery (EoS) and the first postoperative day (day-1). Postoperative morbidity was recorded using the Clavien-Dindo classification and further categorised into minor, moderate and severe. Plasma/serum measures included markers of lipid oxidation (thiobarbituric acid-reactive substances; TBARS, 4-hydroxynonenal; 4-HNE, 8-iso-prostaglandin F2⍺; 8-isoprostanes). Total reducing capacity was measured using total free thiols (TFTs) and ferric-reducing ability of plasma (FRAP). Nitric oxide (NO) formation/metabolism was measured using cyclic guanosine monophosphate (cGMP), nitrite, nitrate and total nitroso-species (RxNO). Interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF-⍺) were measured to evaluate inflammation.ResultsBoth oxidative stress (TBARS) and nitrosative stress (total nitroso-species) increased from baseline to EoS (+14%, P = 0.003 and +138%, P < 0.001, respectively), along with an increase in overall reducing capacity (+9%, P = 0.03) at EoS and protein-adjusted total free thiols (+12%, P = 0.001) at day-1 after surgery. Nitrite, nitrate and cGMP concentrations declined concomitantly from baseline to day-1. Baseline nitrate was 60% higher in the minor morbidity group compared to severe (P = 0.003). The increase in intraoperative TBARS was greater in severe compared to minor morbidity (P = 0.01). The decline in intraoperative nitrate was more marked in the minor morbidity group compared to severe (P < 0.001), whereas the cGMP decline was greatest in the severe morbidity group (P = 0.006).ConclusionIn patients undergoing major HPB surgery, intraoperative oxidative and nitrosative stress increased, with a concomitant increase in reductive capacity. Baseline nitrate was inversely associated with postoperative morbidity, and the hallmarks of poor postoperative outcome include changes in both oxidative stress and NO metabolism.

Generation of Reactive Nitrogen Species in UV Photolysis of Dichloramine and Their Incorporation into Nitrogenous Byproducts.

Dichloramine (NHCl2) often coexists with monochloramine (NH2Cl) in reverse osmosis (RO) permeate in potable reuse scenarios when NH2Cl is added upstream of RO for membrane fouling control such that UV photolysis of NHCl2 occurs during the downstream UV/chloramine process. However, the formation of reactive nitrogen species (RNS) and their incorporation into byproducts during the UV/NHCl2 process are largely unknown. This study quantitatively evaluated the generation of RNS in the UV/NHCl2 process and investigated the role of RNS in micropollutant transformation. UV photolysis of NHCl2 produced comparable RNS concentration to that of NH2Cl at the same oxidant dosage (100 μM) at pH 5.5. Under the experimental conditions, the RNS contributed greatly (40.6%) to N,N-diethyl-3-methylbenzamide (DEET) degradation. By using 15N-labeling and mass spectrometry methods, seven nitrogenous byproducts of DEET degradation with the incorporation of nitrogen originating from the RNS were detected. Among these seven byproducts, six were identified to contain a nitro group (-NO2). While the UV/NHCl2 process formed comparable intensities of -NO-containing products to those in the UV/NH2Cl process, the later process formed 3-91% higher intensities of -NO2-containing products. These findings are essential in furthering our understanding of the contribution of the UV/NHCl2 process in potable reuse scenarios.

Degradation and toxicity of bisphenol A and S during cold atmospheric pressure plasma treatment

Bisphenols are widely recognised as toxic compounds that potentially threaten the environment and public health. Here we report the use of cold atmospheric pressure plasma (CAP) to remove bisphenol A (BPA) and bisphenol S (BPS) from aqueous systems. Additionally, methanol was added as a radical scavenger to simulate environmental conditions. After 480 s of plasma treatment, 15–25 % of BPA remained, compared to > 80 % of BPS, with BPA being removed faster (-kt = 3.4 ms−1, half-life = 210 s) than BPS (-kt = 0.15 ms−1, half-life 4700 s). The characterisation of plasma species showed that adding a radical scavenger affects the formation of reactive oxygen and nitrogen species, resulting in a lower amount of ˙OH, H2O2, and NO2- but a similar amount of NO3-. In addition, a non-target approach enabled the elucidation of 11 BPA and five BPS transformation products. From this data, transformation pathways were proposed for both compounds, indicating nitrification with further cleavage, demethylation, and carboxylation, and the coupling of smaller bisphenol intermediates. The toxicological characterisation of the in vitro HepG2 cell model has shown that the mixture of transformation products formed during CAP is less toxic than BPA and BPS, indicating that CAP is effective in safely degrading bisphenols.

Pathogenesis of nitrosative stress and approaches to modulation of NO levels in organs and tissues

The pathogenesis of nitrosative stress and approaches to the modulation of NO levels in organs and tissues are considered. Nitrosative stress occurs with the participation of the NO molecule in situations where the formation of reactive nitrogen species exceeds the ability of the biological system to neutralize and eliminate them. Nitrosative stress can lead to nitrosation, and, accordingly, changes in the structures of various proteins and inhibition of their biological functions.

Increased Levels of Circulating Iron-Albumin Complexes in Peripheral Arterial Disease Patients.

Under physiological conditions, extracellular iron circulates in the blood bound to transferrin. As a consequence of several pathologies, the circulating level of a Non-Transferrin Bound pool of Iron (NTBI) increases. The NTBI pool is biologically heterogeneous and represented by iron chelated either by small metabolites (citrate, amino acids, or cofactors) or by serum proteins. By promoting reactive oxygen species (ROS) and reactive nitrogen species (RNS) formation, NTBI causes oxidative stress and alteration of membrane lipids, seriously compromising the healthy state of organs and tissues. While NTBI involvement in several pathologies has been clarified, its contribution to vascular diseases remains to be investigated. Here we measure and analyze the pool of NTBI in the serum of a small group of peripheral arterial disease (PAD) patients. We show that: (i) the NTBI pool shifts from low molecular complexes to high-molecular ones in PAD patients compared to healthy controls; (ii) most of this NTBI is bound to the serum protein Albumin; (iii) this NTBI-Albumin complex can be isolated and quantitated following a simple immunoisolation procedure amenable to automation and suitable for clinical screening purposes.

Oxidative stress and antioxidants in health and disease

Abstract The increase in the formation of reactive oxygen and reactive nitrogen species of endogenous or exogenous origin causes oxidative stress due to pro-oxidant and antioxidant imbalance that causes cellular damage in metabolism. This can increase inflammation of cells, apoptosis and necrosis, damage to DNA base damage, DNA and protein cross-links, lipid membrane peroxidation, and mitochondrial dysfunction. Antioxidants can be described as a system that protects biomolecules and the organism against the harmful effects of free radicals, reduces or repairs the damage done by reactive oxygen species (ROS) to the target molecule, and this is called antioxidant defense. It is known that the mechanisms caused by the increase in ROS resulting from oxidative stress are positively related to the pathology of many diseases such as cancer, metabolic syndrome, atherosclerosis, malaria, Alzheimer’s disease, rheumatoid arthritis, neurodegenerative diseases and preeclampsia.

A20 Restricts NOS2 Expression and Intestinal Tumorigenesis in a Mouse Model of Colitis-Associated Cancer.

Colon cancer can occur sporadically or in the setting of chronic inflammation, such as in patients with inflammatory bowel disease. We previously showed that A20, a critical negative regulator of tumor necrosis factor signal transduction, could regulate sporadic colon cancer development. In this report, we investigate whether A20 also acts as a tumor suppressor in a model of colitis-associated cancer. Colitis and colitis-associated tumors were induced in wild-type and A20 intestinal epithelial cell-specific knockout (A20dIEC) mice using dextran sodium sulfate and azoxymethane. Clinicopathologic markers of inflammation were assessed in conjunction with colonic tumor burden. Gene expression analyses and immunohistochemistry were performed on colonic tissue and intestinal enteroids. Nitric oxide (NO) production and activity were assessed in whole colonic lysates and mouse embryonic fibroblasts. A20dIEC mice develop larger tumors after treatment with dextran sodium sulfate and azoxymethane than wild-type mice. In addition to elevated markers of inflammation, A20dIEC mice have significantly enhanced expression of inducible nitric oxide synthase (iNOS), a well-known driver of neoplasia. Enhanced iNOS expression is associated with the formation of reactive nitrogen species and DNA damage. Loss of A20 also enhances NO-dependent cell death directly. Mechanistically, we propose that A20 normally restricts tumor necrosis factor-induced nuclear factor kappa B-dependent production of iNOS in intestinal epithelial cells, thereby protecting against colitis-associated tumorigenesis. We also propose that A20 plays a direct role in regulating NO-dependent cell death.

Gene Expression Profiling Elucidates Cellular Responses to NCX4040 in Human Ovarian Tumor Cells: Implications in the Mechanisms of Action of NCX4040.

The nitric oxide donor, NCX4040 is a non-steroidal anti-inflammatory-NO donor and has been shown to be extremely cytotoxic to a number of human tumors, including ovarian tumors cells. We have found that NCX4040 is cytotoxic against both OVCAR-8 and its adriamycin-selected OVCAR-8 variant (NCI/ADR-RES) tumor cell lines. While the mechanism of action of NCX4040 is not entirely clear, we as well as others have shown that NCX4040 generates reactive oxygen species (ROS) and induces DNA damage in tumor cells. Recently, we have reported that NCX4040 treatment resulted in a significant depletion of cellular glutathione, and formation of both reactive oxygen and nitrogen species (ROS/RNS), resulting in oxidative stress in these tumor cells. Furthermore, our results indicated that more ROS/RNS were generated in OVCAR-8 cells than in NCI/ADR-RES cells due to increased activities of superoxide dismutase (SOD), glutathione peroxidase and transferases expressed in NCI/ADR-RES cells. Further studies suggested that NCX4040-induced cell death may be mediated by peroxynitrite formed from NCX4040 in cells. In this study we used microarray analysis following NCX4040 treatment of both OVCAR-8 and its ADR-resistant variant to identify various molecular pathways involved in NCX4040-induced cell death. Here, we report that NCX4040 treatment resulted in the differential induction of oxidative stress genes, inflammatory response genes (TNF, IL-1, IL-6 and COX2), DNA damage response and MAP kinase response genes. A mechanism of tumor cell death is proposed based on our findings where oxidative stress is induced by NCX4040 from simultaneous induction of NOX4, TNF-α and CHAC1 in tumor cell death.