Inducible Oxide Research Articles

Regenerative and Anti-Senescence Potential of Extracts from Different Parts of Black Persimmon in an In Vitro Model of Vascular Endothelium

Antioxidants are essential for mitigating oxidative stress and maintaining vascular health. Endothelial colony-forming cells (ECFCs) are pivotal in endothelial regeneration and angiogenesis and serve as a model to study the diversity of endothelial cells across various organs. This study evaluated the effects of peel, pulp, and seed extracts from Diospyros digyna Jacq. fruit (black persimmon) on human cord blood-derived ECFCs (CB-ECFCs) to determine how the distinct antioxidant profiles of the fruit’s different parts influence cellular functions. The extracts did not affect endothelial marker expression, cell proliferation, or nitric oxide production, indicating no cytotoxic or inflammatory effects. However, functional assays revealed that the seed extract significantly enhanced tube formation, increasing closed tubular networks by 1.5-fold. All extracts promoted cell migration, with the seed extract demonstrating the most substantial effect, surpassing even vascular endothelial growth factor (VEGF). Additionally, the seed extract exhibited the strongest reduction in cellular senescence, both before and after oxidative stress induction with H2O2. These findings underscore the potential of black persimmon extracts, especially from the seed, to enhance the regenerative capabilities of CB-ECFCs and reduce cellular senescence without affecting the normal endothelial phenotype. This positions them as promising candidates for developing endothelial cell therapies and advancing vascular regeneration.

Investigating antioxidant effects of hamamelitannin-conjugated zinc oxide nanoparticles on oxidative stress-Induced neurotoxicity in zebrafish larvae model.

An excessive amount of reactive oxygen species triggers oxidative stress, leading to an imbalance in cellular homeostasis. Antioxidant therapy is an effective tool for lowering the oxidative stress and associated ailments. Recently, green nano-based drug formulations have demonstrated promising antioxidant activity and neutralizing oxidative stress. In this study, a tannin molecule Hamamelitannin (HAM), was utilized to synthesize zinc oxide nanoparticles HAM-ZnO NPs, to mitigate oxidative stress and associated ailments . The HAM-ZnO NPs were synthesized and characterized by XRD, SEM, and FTIR. The antioxidant potentials of HAM-ZnO NPs were analyzed by in vitro antioxidant assays. Zebrafish embryos and larvae were used as in-vivo models to assess the toxicity and antioxidant protective mechanism. Hydrogen peroxide (1mM) was employed to induce oxidative stress and treated with HAM-ZnO NPs to study the cognitive impairment and antioxidant enzyme levels. Levels of reactive oxygen species and cell death due to oxidative stress induction were studied by 2',7'-dichlorodihydrofluorescein diacetate and Acridine orange staining methods. Additionally, expression of Antioxidant genes such as SOD, CAT, GPx, and GSR were studied. . HAM-ZnO NPs exhibited a spherical morphology and size ranges between 48 and 53nm. In vitro antioxidant studies revealed the antioxidant properties of HAM-ZnO NPs. Furthermore, in vivo studies indicated that HAM-ZnO NPs don't possess any cytotoxic effects in zebrafish larvae at concentrations between (5-25µg/ml), The study also observed that HAM-ZnO NPs significantly reduced Hydrogen Peroxide-induced stress and increased antioxidant activity in zebrafish larvae. Also, the antioxidant gene expression was upregulated in the HAM-ZnO NPs zebrafish larvae. Findings in this study showed that HAM-ZnO NPs might be a potential intervention for diseases linked to oxidative stress.

Evaluation of the tribological performance and oxidative stability of a bi-functional lubricating oil additive prepared from corn cob extract

To meet the requirements of a circular economy, a class of sulfur- and phosphorus-free green bifunctional lubricating oil additives was developed based on corn cob extract as a naturally renewable biomass material. These additives can significantly enhance the friction-reducing, anti-wear properties, and oxidative stability of base oils. Results indicate that at an addition level of 4000 ppm, ternary polymer additive reduced the wear volume and surface roughness of steel friction pairs by 98.17 % and 97.63 %, respectively, and increased the oxidation induction period by 40.52 %. The improvement in tribological performance is attributed to the rigid ring structure preventing direct contact between friction pairs, and the chemical adsorption of carboxylic acid and anhydride groups with the metal, forming a dense friction film.

On-demand imidazolidinyl urea-based tissue-like, self-healable, and antibacterial hydrogels for infectious wound care

Bacterial wound infections are a growing challenge in healthcare, posing severe risks like systemic infection, organ failure, and sepsis, with projections predicting over 10 million deaths annually by 2050. Antibacterial hydrogels, with adaptable extracellular matrix-like features, are emerging as promising solutions for treating infectious wounds. However, the antibacterial properties of most of these hydrogels are largely attributed to extrinsic agents, and their mechanisms of action remain poorly understood. Herein we introduce for the first time, modified imidazolidinyl urea (IU) as the polymeric backbone for developing tissue-like antibacterial hydrogels. As-designed hydrogels behave tissue-like mechanical features, outstanding antifreeze behavior, and rapid self-healing capabilities. Molecular dynamics (MD) simulation and density functional theory (DFT) calculation were employed to well-understand the extent of H-bonding and metal-ligand coordination to finetune hydrogels’ properties. In vitro studies suggest good biocompatibility of hydrogels against mouse fibroblasts & human skin, lung, and red blood cells, with potential wound healing capacity. Additionally, the hydrogels exhibit good 3D printability and remarkable antibacterial activity, attributed to concentration dependent ROS generation, oxidative stress induction, and subsequent disruption of bacterial membrane. On top of that, in vitro biofilm studies confirmed that developed hydrogels are effective in preventing biofilm formation. Therefore, these tissue-mimetic hydrogels present a promising and effective platform for accelerating wound healing while simultaneously controlling bacterial infections, offering hope for the future of wound care.

Microencapsulation of a Flaxseed and Avocado Oil Blend: Influence of Octenyl Succinic Anhydride (OSA)-Modified Starch and Rice and Pea Proteins on Powder Characterization and Oxidative Stability

This work investigated the influence of the OSA-modified starch, pea protein, and rice protein combination in the microencapsulation process of a blend of avocado and flaxseed oil (25–75%, w/w) by freeze-drying, focusing on emulsions and powders characteristics and oxidative stability. Four different ratios between the mixture of vegetable proteins (1:1) and the OSA-modified starch were analyzed, using a fixed ratio between the oils blend and the combined encapsulant agents of 1:3. Based on the creaming index, the separation of hydrophilic and hydrophobic phases was not observed. The results demonstrated a tendency to increase the droplet mean diameter with increased protein content (4.71–19.36 μm). An increase in the encapsulation efficiency was verified with the increase in the OSA-modified starch content (51.33–60.32%). Powders presented low moisture content and hygroscopicity, and an oxidative induction time value varying from 0.86 to 1.18 h. The increase in the vegetable protein content increased the powders’ oxidative stability, which could be associated with the antioxidant capacity of rice and pea proteins.

Silver Nanoparticles in Therapeutics and Beyond: A Review of Mechanism Insights and Applications.

Silver nanoparticles (NPs) have become highly promising agents in the field of biomedical science, offering wide therapeutic potential due to their unique physicochemical properties. The unique characteristics of silver NPs, such as their higher surface-area-to-volume ratio, make them ideal for a variety of biological applications. They are easily processed thanks to their large surface area, strong surface plasmon resonance (SPR), stable nature, and multifunctionality. With an emphasis on the mechanisms of action, efficacy, and prospective advantages of silver NPs, this review attempts to give a thorough overview of the numerous biological applications of these particles. The utilization of silver NPs in diagnostics, such as bioimaging and biosensing, as well as their functions in therapeutic interventions such as antimicrobial therapies, cancer therapy, diabetes treatment, bone repair, and wound healing, are investigated. The underlying processes by which silver NPs exercise their effects, such as oxidative stress induction, apoptosis, and microbial cell membrane rupture, are explored. Furthermore, toxicological concerns and regulatory issues are discussed, as well as the present difficulties and restrictions related to the application of silver NPs in medicine.

Which is the current knowledge on man-made endocrine- disrupting chemicals in follicular fluid? An overview of effects on ovarian function and reproductive health.

The increase in female reproductive disorders, such as polycystic ovary syndrome, endometriosis, and diminished ovarian reserve that lead to subfertility and infertility, has encouraged researchers to search and discover their underlying causes and risk factors. One of the crucial factors that may influence the increasing number of reproductive issues is environmental pollution, particularly exposure to man-made endocrine-disrupting chemicals (EDCs). EDCs can interfere with the ovarian microenvironment, impacting not only granulosa cell function but also other surrounding ovarian cells and follicular fluid (FF), which all play essential roles for oocyte development, maturation, and overall reproductive function. FF surrounds developing oocytes within an ovarian follicle and represents a dynamic milieu. EDCs are usually found in biological fluids, and FF is therefore of interest in this respect. This narrative review examines the current knowledge on specific classes of EDCs, including industrial chemicals, pesticides, and plasticizers, and their known effects on hormonal signaling pathways, gene expression, mitochondrial function, oxidative stress induction, and inflammation in FF. We describe the impact of EDCs on the development of reproductive disorders, oocyte quality, menstrual cycle regulation, and their effect on assisted reproductive technique outcomes. The potential transgenerational effects of EDCs on offspring through animal and first-human studies has been considered also. While significant progress has been made, the current understanding of EDCs' effects on ovarian function, particularly in humans, remains limited, underscoring the need for further research to clarify actions and effects of EDCs in the ovary.

In vivo assessment of oxidative stress, neurotoxicity and histological alterations induction in the marine gastropod Stramonita haemastoma exposed to Cr2O3 and Al2O3 nanoparticles

The increased use of nanoparticles (NPs) is expected to raise their presence in the marine ecosystem, which is considered as the final destination of released NPs. This study investigated the toxicity of Cr2O3 (42 nm) and Al2O3 (38 nm) NPs (1, 2.5, and 5 mg/L) on the digestive glands of Stramonita haemastoma for 7, 14, and 28 days by oxidative stress biomarkers, neurotoxicity indicator assessment, and histological study. Results revealed an imbalance in antioxidants at all periods. Following 7 days, both NPs caused GSH depletion with marked impacts from Al2O3. GPx, CAT, and AChE were also decreased with the highest changes induced by Cr2O3. Both NPs inducted GSH and GST levels on days 14 and 28, with more effects from Cr2O3 exposure. GPx, AChE, and MDA induction were observed on day 28, while MT varied through NPs and time, with imbalanced levels at all periods noticed, SOD was mostly not affected. Histology revealed alterations including necrosis and interstitial deteriorations; quantitative analysis through the histological condition index revealed dose-dependent impacts, with the highest values attributed to Cr2O3 exposure. While PCA revealed the co-response of GSH, GST, GPx, CAT, and AchE with separated MT responses. This study reported oxidative stress induction through a multi-biomarkers investigation, neurotoxicity, and histological damages in the digestive gland of S. haemastoma following Cr2O3 and Al2O3 NPs exposure.

Oncogenic Mutant p53 Sensitizes Non-Small Cell Lung Cancer Cells to Proteasome Inhibition via Oxidative Stress-Dependent Induction of Mitochondrial Apoptosis.

NSCLC is the leading cause of cancer death due, in part, to a lack of active therapies in advanced disease. We demonstrate that combination therapy with a proteasome inhibitor, BH3-mimetic, and chemotherapy is an active precision therapy in NSCLC cells and tumors expressing Onc-p53 alleles.

Phytotoxic Activity of Sesquiterpene Lactones-Enriched Fractions from Cynara cardunculus L. Leaves on Pre-Emergent and Post-Emergent Weed Species and Putative Mode of Action

Sesquiterpene lactones (SLs) are compounds that are highly produced in Cynara cardunculus leaves, known for their phytotoxic activity. This study aims to assess SL-enriched fractions’ (cynaropicrin, aguerin B, and grosheimin) phytotoxic potentials and putative modes of action, compared to an initial extract, using two approaches: first, against a panel of nine weed species in pre-emergence, and then on Portulaca oleracea L.’s post-emergency stage. The SL-enriched fractions demonstrated greater phytotoxic activity when compared with the C. cardunculus leaf initial extract. The SL-enriched fractions had higher activity at root growth inhibition over the panel tested, doubling the activity in five of them at 800 ppm. Regarding the post-emergence bioassay, the SL-enriched fractions had a higher influence on the plants’ growth inhibition (67% at 800 ppm). The SL-effects on the plants’ metabolisms were evidenced. The total chlorophyll content was reduced by 65% at 800 ppm. Oxidative stress induction was observed because of the enhancement in MDA levels at 800 ppm compared to control (52%) and the decrease in SOD-specific activity from 4.20 U/mg protein (400 ppm) to 1.74 U/mg protein (800 ppm). The phytotoxic effects of the SL-enriched fractions suggest that they could be used for a future bioherbicide development.

Exploring the potential of coal derived graphite as next generation lubricant additive for multifunctional applications

In the present study, the friction and wear characteristics of steel/steel contact under reciprocating sliding conditions were investigated using composite mixtures made from Polyalphaolefin 4 (PAO4) as base oil lubricant and North Dakota lignite-derived graphite (LG) as high-value carbon additive. The results show that addition of 1 wt% LG to PAO4 led to a reduction in the friction coefficient and wear volume by ∼15 % and ∼13 %, respectively. In addition, the oxidation induction time (OIT) at 160 °C was increased by ∼29 %, which further indicates good stability of the formulated composite lubricant against oxidative degradation. The primary wear mechanism on AISI 52100 steel flat and counter-body was found to be abrasive wear under high-contact stress reciprocating sliding conditions, where tribo-oxide films of 100–200 nm were observed on the wear tracks of 52100 steel surfaces using focused ion beam scanning transmission electron microscopy (FIB-STEM). Furthermore, cross-sectional analysis of the wear track of AISI 52100 steel revealed that 1 wt% of LG additive reduced the thickness of the sub-surface deformation zone by 44 %, which indicates higher load-bearing capacity and improved wear resistance.

Comparative study of different pretreatment methods on peanut oil quality characteristics, anti-oxidation attributes, and phenolic compound compositions

The peanuts heat pretreatment is a crucial step for the following oil extraction, influencing both efficiency and oil quality. The present study investigated the effects of oven roasting (OR, 150 °C, 25 min), infrared ray roasting (IRR, 150 °C, 25 min), and microwave roasting (MR, 700 W, 5 min) on the quality characteristics, anti-oxidation attributes, and phenolic compound compositions of peanut oil. All pretreatment methods changed the physicochemical properties and bioactive compounds of peanut oil. Notably, IRR resulted in the highest oxidation induction index (9.25 h) and enhanced free radical scavenging activity, with increases of 55 % (2,2-diphenyl-1-picrylhydrazyl (DPPH)) and 121 % (2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS)) compared with the control. Furthermore, the free phenolics content (Free-P) increased significantly, particularly with IRR, which was increased 6.00 times. Correlation analysis indicated that Free-P was the primary contributor to the anti-oxidation attributes of peanut oil. The results can provide valuable insights for optimizing peanut oil processing technologies.

Effect of thermal pretreatments on the quality attributes and irradiation markers of sesame oil extracted from sesame seeds without and with gamma irradiation

This study comparatively studied the effects of three thermal pretreatment methods, i.e., wet-heat (WT), roasting (RT) and microwave (MT), on the quality attributes and irradiation markers of sesame oil obtained from sesame seeds without and with gamma irradiation. Results showed that gamma irradiation had negligible effect on the quality of sesame seeds and their extracted oils. The effects of thermal pretreatments on irradiated and non-irradiated sesame seeds and their oils were similar, little synergistic effects were observed. The RT-treated oils had more carotenoids, chlorophyll, total phenols, tocopherols, and heterocyclic volatiles content, as well as longer oxidation induction time, but darker color compared with their WT- and MT-treated counterparts. All oil samples had identical FTIR spectra. Eight radiolytic hydrocarbons were identified in the irradiated sesame oils. Thermal pretreatments reduced the content of radiolytic hydrocarbons, but did not significantly change their composition. Our study helps to identify products from irradiated sesame seeds.

Abstract C037: Characterization of cysteine dependency implicates glutathione metabolism as a critical adaptation axis in pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a deadly cancer that is highly malignant and lethal. The treatment options are limited, contributing to its high mortality rate. PDAC is known to have profound metabolic alterations that enable its growth and survival. Here, we screened for amino acid dependency in PDAC cell lines and found that the cells cluster into cysteine highly dependent, moderately dependent, and independent cells. In the highly dependent cells, cysteine deprivation reduces viability by ∼90%, which could be rescued by glutathione (GSH) supplementation. Metabolomics revealed that cysteine deprivation led to GSH depletion, suggesting an impairment in the GSH pathway machinery in these cells. Consistently, most metabolite intermediates in the GSH pathway are downregulated in the cysteine-reliant PDAC cell lines compared to cell lines that resist cysteine deprivation, and those cells showed higher sensitivity to oxidative stress induction. Bioinformatics analysis of multiple PDAC tumor gene expression datasets indicated that the GSH pathway is strongly upregulated in PDAC and correlates with proliferation, metastasis, and oncogenic KRAS upregulation. Using CRISPR/Cas9, we found that the knockout of GSH genes enhanced sensitivity to oxidative stress. Our data implicate the GSH pathway as a critical nexus to be targeted to overcome metabolic adaptation in PDAC. Citation Format: Chiamaka J Ezeh, Matthew H Ward, Chesta Jain, Verodia Charlestin, Daeho D Kim, Andrew Yang, Maya Nassif, Nneka Mbah, Peter Sajjakulnukit, Anthony Andren, Li Zhang, Marina Pasca di Magliano, Costas A Lyssiotis, Zeribe C Nwosu. Characterization of cysteine dependency implicates glutathione metabolism as a critical adaptation axis in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr C037.

Molecular Events in Response to Triclosan-Induced Oxidative Stress in CRISPR/Cas9-Mediated p53-Targeted Mutants in Daphnia magna.

Triclosan (TCS), a widely used antimicrobial agent, has been implicated in the oxidative stress induction and disruption of cellular processes in aquatic organisms. As TCS is ubiquitous in the aquatic environment, many previous studies have documented the effects of exposure to TCS on aquatic organisms. Nevertheless, most of the research has concentrated on the molecular and physiological responses of TCS, but there are still limited studies on the function of specific genes and the consequences of their absence. In this study, we focused on p53, a gene that is crucial for molecular responses such as autophagy and apoptosis as a result of TCS exposure. In order to ascertain the role and impact of the p53 gene in TCS-induced molecular responses, we examined the molecular responses to TCS-induced oxidative stress in wild-type (WT) and CRISPR/Cas9-mediated p53 mutant (MT) water fleas. The result has been accomplished by examining changes in molecular mechanisms, including in vivo end points, enzyme activities, adenosine triphosphate release rate, and apoptosis, to determine the role and impact of the p53 gene on TCS-induced molecular responses. The results indicated that the sensitivity of MT water fleas to TCS was greater than that of WT water fleas; however, the difference in sensitivity was significant at short exposures within 48 h and decreased toward 48 h. Accordingly, when we confirmed the oxidative stress after 24 h of exposure, the oxidative stress to TCS exposure was stronger in the MT group, with an imbalance of redox. To identify the mechanisms of tolerance to TCS in WT and MT Daphnia magna, we checked mitochondrial and ER-stress-related biomarkers and found an increase in apoptosis and greater sensitivity to TCS exposure in the MT group than in the WT. Our results suggest that the absence of p53 caused alterations in molecular processes in response to TCS exposure, resulting in increased sensitivity to TCS, and that p53 plays a critical role in response to TCS exposure.

Cellular toxicity of calcium propionate in human lymphocyte.

Calcium propionate is the chemical substance added to food in order to prolong the shelf-life of factory made foods by inhibiting the development of bacteria, fungi and other microorganisms. The objective of this study was to investigate the ability of calcium propionate to induce cytotoxic and genotoxic effects in lymphocytes. Oxidative stress induction by calcium propionate was also studied. Four concentrations of calcium propionate (0.5, 1.0, 1.5 and 2.0 mg/ml) were applied in lymphocytes for 24 and 48 h treatment. It studied cytotoxic and genotoxic effects by MTT assay, chromosome culture technique, and micronucleus assay. Oxidative stress induction was studied by superoxide dismutase (SOD) activity assay. The results showed that lymphocyte viability was decreased significantly by calcium propionate at 1.5 and 2.0 mg/ml (p < 0.05). Calcium propionate induced chromosome aberration at 1.0, 1.5 and 2.0 mg/ml and sister chromatid exchange at 1.5 and 2.0 mg/ml (p < 0.05). It induced micronucleus formation at 0.5, 1.0, 1.5 and 2.0 mg/ml (p < 0.05). The calcium propionate concentrations of 0.5 - 1.0 mg/ml and 1.5 - 2.0 mg/ml could reduce SOD activity inhibition (p < 0.05). Calcium propionate induced oxidative stress in lymphocytes. It can be concluded that calcium propionate induces genotoxic risk and oxidative stress in lymphocytes. Based on this study and the positive results, consumers should be made aware that calcium propionate should be considered a genotoxic compound. The awareness of food preservative usage and the educational program must take place frequently for good human health in the community.

P13-24 Exploring oxidative stress-mediated micronucleus induction by Acrylamide, Penitrem A and 3-acetyldeoxynivalenol in SH-SY5Y cells

P13-24 Exploring oxidative stress-mediated micronucleus induction by Acrylamide, Penitrem A and 3-acetyldeoxynivalenol in SH-SY5Y cells

Using the potential of Canadian goldenrod (Solidago canadensis) as a functional filler with antioxidant activity of low-density polyethylene composites as an example of sustainable development of an invasive plant

Novel bio-based low-density polyethylene (LDPE) composites have been manufactured using different Canadian goldenrod (CG) invasive plant parts. Fragmented and ground blossoms (CGB) and mixed leaves and stems (CGSL) were used as fillers introduced by melt mixing into an LDPE matrix at various concentrations (2, 5, 10, 20, 40 wt%). Moreover, the influence of a series of modified fillers based on stems and leaves saturated with an extract made of blossoms (CGSL+E) on LDPE has been verified. The oxidation resistance of composites was enhanced based on the oxidation induction time (OIT) assessment, which increased from 0.5 min for LDPE to 178 min (CGB), 231 min (CGSL), and 140 min (CGSL+E). All composite series formed by compression molding were exposed to UV-light radiation using Xenon lamps and subjected to spectroscopic (FTIR) analysis, color assessment, and mechanical testing. LDPE/CGSL+E composites demonstrated the most favorable mechanical properties after UV-light exposure. In their case, an increase in Young modulus of 360 MPa was observed for the 40 wt% sample (PE ∼ 180 MPa) and an acceptable decrease in tensile strength of 6.5 MPa compared to the reference LDPE of 9.8 MPa. The study consists of a screening for future research on the use and simultaneous valorization of the invasive plant into functional composite fillers with increased oxidation resistance.

Identification of the oxidation and hydrolysis products content influence on the rapeseed oil oxidation induction period

The object of the study is the dependence of the induction period of rapeseed oil on the content of oxidation and hydrolysis products. A feature of the work is determining the approximation dependence of the induction period of accelerated oxidation of refined rapeseed oil on the content of primary oxidation products and free fatty acids. This is useful when predicting the shelf life of refined rapeseed oil. It was determined that both factors negatively affect the oxidation stability of refined rapeseed oil. An increase in the peroxide value decreases the induction period of model oil samples by 32.8512 units for each additional mmol ½ O/kg. In turn, increasing the acid value of oil samples reduces the induction period by 19.8424 units for each additional mg KOH/g. Different oxidation dynamics of model samples of refined rapeseed oil with tocopherol were revealed, depending on the concentration of primary oxidation and hydrolysis products. The obtained data are explained by the fact that the primary lipid oxidation products are unstable and quickly decompose to form free radicals. These radicals initiate further lipid oxidation, resulting in reduced oil quality. In addition, free fatty acids are more reactive than triglycerides and are more easily oxidized. A feature of the obtained results is the possibility of modeling processes that affect the oxidation stability of refined rapeseed oil. From a practical point of view, the research results allow initiating measures to maintain the safety of oil-containing food products based on refined rapeseed oil. An applied aspect of using the scientific results is the possibility of rationalizing the storage conditions of refined rapeseed oil to maximize its shelf life and increase competitiveness

Vorinostat Treatment of Gastric Cancer Cells Leads to ROS-Induced Cell Inhibition and a Complex Pattern of Molecular Alterations in Nrf2-Dependent Genes.

Histone deacetylase inhibitors (HDACi) show high antineoplastic potential in preclinical studies in various solid tumors, including gastric carcinoma; however, their use in clinical studies has not yet yielded convincing efficacies. Thus, further studies on cellular/molecular effects of HDACi are needed, for improving clinical efficacy and identifying suitable combination partners. Here, we investigated the role of oxidative stress in gastric cancer cells upon treatment with HDACi. A particular focus was laid on the role of the Nrf2 pathway, which can mediate resistance to cell-inhibitory effects of reactive oxidative species (ROS). Using fluorescence-based ROS sensors, oxidative stress was measured in human gastric cancer cell lines. Activation of the Nrf2 pathway was monitored in luciferase reporter assays as well as by mRNA and proteomic expression analyses of Nrf2 regulators and Nrf2-induced genes. Furthermore, the effects of ROS scavenger N-acetyl-L-cysteine (NAC) and Nrf2-knockdown on HDACi-dependent antiproliferative effects were investigated in colorimetric formazan-based and clonogenic survival assays. HDACi treatment led to increased oxidative stress levels and consequently, treatment with NAC reduced cytotoxicity of HDACi. In addition, vorinostat treatment stimulated expression of a luciferase reporter under the control of an antioxidative response element, indicating activation of the Nrf2 system. This Nrf2 activation was only partially reversible by treatment with NAC, suggesting ROS independent pathways to contribute to HDACi-promoted Nrf2 activation. In line with its cytoprotective role, Nrf2 knockdown led to a sensitization against HDACi. Accordingly, the expression of antioxidant and detoxifying Nrf2 target genes was upregulated upon HDACi treatment. In conclusion, oxidative stress induction upon HDAC inhibition contributes to the antitumor effects of HDAC inhibitors, and activation of Nrf2 represents a potentially important adaptive response of gastric cancer cells in this context.