SciCombinator

Discover the most talked about and latest scientific content & concepts.

Journal: Free radical research

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The cornerstone of treatment for rheumatoid arthritis is low dose methotrexate (MTX), but its use is limited by concerns regarding its potential for hepatotoxicity. Allylpyrocatechol (APC), a phytoconstituent sourced from leaves of Piper betle demonstrated antioxidant, anti-inflammatory and antiarthritic properties. The present study aimed to evaluate the combined effect of APC and MTX on limiting progression of lipopolysaccharide accelerated collagen-induced arthritis, along with reduction of MTX-induced hepatic damage. A collagen-induced arthritis (CIA) model was established by immunizing Sprague-Dawley rats with bovine collagen type II (CII) and lipopolysaccharide, followed by a booster dose of CII on day 15. Rats from days 11-27 were administered APC (20 mg/kg), methotrexate (1.5 mg/kg) or a combination of MTX and APC. The combinatorial therapy of APC and MTX significantly improved the parameters of arthritis as evident from the reduction in paw edema and arthritic score and was endorsed by radiological and histopathological changes. This combination prevented the rise in levels of proinflammatory cytokines, tumor necrosis factor (TNF-α) and interleukin 6 (IL-6). Furthermore, unlike MTX-monotherapy, the APC-MTX combination decreased the associated cachexia, splenomegaly and oxidative stress. Importantly, the hepatic damage mediated by MTX monotherapy was effectively attenuated by the inclusion of APC. Taken together, antioxidants like APC, when combined with MTX, not only potentiated the antiarthritic effect but importantly, alleviated the MTX-induced hepatic damage, thus endorsing its effectiveness in preventing progression of articular diseases like rheumatoid arthritis.

Concepts: Inflammation, Collagen, Rheumatoid arthritis, Rheumatology, Vitamin C, Arthritis, Tumor necrosis factor-alpha, Ankylosing spondylitis

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Common protocols for chondrogenic differentiation of adipose-derived mesenchymal stem cells (ADSCs) are generally expensive and time-consuming and so far, have not successfully recreated pure chondrocytes. We hypothesize that a low level of H2O2 may induce differentiation of ADSCs into chondrocytes in a shorter incubation time and relatively lower cost. Therefore, this study aimed to comparatively investigate the effectiveness of H2O2-containing or free medium in the induction of ADSCs to chondrocytes. ADSCs were isolated from the lipoaspirate of four healthy females and evaluated by immunophenotyping for their CD90, CD73, CD44, CD34, and CD45 cell surface markers. Chondrogenic differentiation was carried out using differentiation medium in the presence or absence of 10 and 50 µM H2O2 in normal and 3D culture system. The intracellular contents of reactive oxygen species (ROS) were detected by flow cytometry and fluorescence microscopy. The hydroxyproline, was assessed as marker of collagen and the glycosaminoglycans (GAGs) content were both qualitatively detected and quantitatively determined. Real-time PCR was performed to determine the gene expression level of aggrecan, type-II collagen, and transcription factor Sox9. H2O2-treated cells showed prechondrocyte morphology on day-1 and chondrocyte pellets were formed on day-14. H2O2-treated cells induced greater pellet sizes and showed significantly higher content of GAGs and hydroxyproline level compared with untreated cells. The gene expression levels of aggrecan, collagen type-II, and Sox9 were markedly upregulated by H2O2. Our findings showed for the first time that H2O2-containing differentiation medium is potentially more effective than H2O2-free differentiation medium in the induction of chondrogenesis of ADSCs.

Concepts: DNA, Oxygen, Gene, Gene expression, Molecular biology, Stem cell, Reactive oxygen species, Hydrogen peroxide

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Tumour progression involves the establishment of tumour metastases at distant sites. Resistance to anoikis, a form of cell death that occurs when cells lose contact with the extracellular matrix and with neighbouring cells, is essential for metastases. NO has been associated with anoikis. NO treated HeLa cells and murine melanoma cells in suspension triggered a nitric oxide (NO)-Src kinase signalling circuitry that enabled resistance to anoikis. Two NO donors, sodium nitroprusside (SNP) (500 µM) and DETANO (125 µM), protected against cell death derived from detachment of a growth permissive surface (experimental anoikis). Under conditions of NO-mediated Src activation the following were observed: (a) down-regulation of the pro-apoptotic proteins Bim and cleaved caspase-3 and the cell surface protein, E-cadherin, (b) up-regulation of caveolin-1, and © the dissociation of cell aggregates formed when cells are detached from a growth permissive surface. Efficiency of reattachment of tumour cells in suspension and treated with different concentrations of an NO donor, was dependent on the NO concentration. These findings indicate that NO-activated Src kinase triggers a signalling circuitry that provides resistance to anoikis, and allows for metastases.

Concepts: Protein, Cancer, Oncology, Cell biology, Apoptosis, Cell culture, Tumor, HeLa

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Biologically and chemically useful hydrazinoimidazolines were evaluated as antioxidant and antihaemolytic agents. 1,1-Diphenyl-2-picrylhydrazyl radical (DPPH•), galvinoxyl radical (GOR), nitric oxide (NO) and hydrogen peroxide (H2O2) scavenging assays, ferric ions reducing power assay and ex vivo model of rat erythrocytes exposed to 2,2'-azobis(2-methylpropionamidine)dihydrochloride (AAPH) or H2O2 were used. The most potent DPPH• scavengers proved to be hydrazinoimidazolines 3, 2 and 4, revealing excellent antiradical effects - superior or comparable to that of all antioxidant standards used. Moreover, these molecules showed strong NO neutralizing potencies - better to that of ascorbic acid (AA) (3), 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (trolox) (3 and 2), butylated hydroxytoluene (BHT) (3 and 2) and butylated hydroxyanisole (BHA) (3, 2 and 4). Compound 4 was also effective in GOR scavenging. The excellent scavenger of GOR, NO and H2O2 proved to be structure 5, with the potency superior or comparable to the majority of antioxidant standards used. In turn, compound 9 was effective in H2O2 and GOR neutralization. All hydrazinoimidazolines revealed the reducing power higher than BHT. Moreover, the protective effects of most test compounds on oxidatively stressed erythrocytes were observed. Some structure-activity relationships were disclosed. A significance of the primary hydrazino group on antioxidant effects was confirmed. The most likely DPPH• and GOR scavenging mechanisms for test compounds were propound. Among all the investigated molecules, hydrazinoimidazolines 5, 3, 2, 4 and 9, due to their excellent or good antiradical activities, can represent promising antioxidant candidates with prospective utility for prevention of diseases related to reactive oxygen/nitrogen species.

Concepts: Oxygen, Acid, Antioxidant, Radical, Hydrogen peroxide, Vitamin C, Butylated hydroxytoluene, Butylated hydroxyanisole

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Curcumin is a polyphenol derived from the herb Curcuma longa, which has been extensively studied in terms of its antitumour, antioxidant, and chemopreventive activity as well as various other effects. In the present work we compared curcumin with its synthetic analogue dimethoxycurcumin (dimc) in terms of its antioxidant enzyme-modulating effects in human peripheral blood mononuclear cells (PBMC). We found that these compounds modulate antioxidant enzymes differentially. Both curcumin and dimethoxycurcumin effected a decrease in lipid peroxidation status in PBMC, however, curcumin had better activity in this regard. An increase in the activity of catalase was seen in the case of curcumin-treated PBMC, whereas dimc increased catalase activity significantly to almost twofold level. Real time-polymerase chain reaction (RT-PCR) analysis revealed significant up-regulation of catalase at mRNA level post treatment with curcumin as well as dimc, however, dimc had better activity in this regard. Glutathione reductase (GR) activity and reduced glutathione levels increased in the case of peripheral blood mononuclear cells (PBMC) treated with curcumin, however, the trend was reversed with dimethoxycurcumin where, both glutathione reductase activity and reduced glutathione levels were significantly reduced. RT-PCR analysis of glutathione reductase mRNA levels showed decrease in mRNA levels post treatment with dimethoxycurcumin (dimc) further corroborating GR enzyme assay results, however, we could not obtain significant result post curcumin treatment. NFkB reporter assay and western blot analysis of nuclear as well as cytosolic fractions of NFkB revealed that curcumin inhibits NFkB activation whereas inhibition was much less with dimc. It has been reported that curcumin and dimc exerts differential cytotoxicity in normal and tumour cells and the reason for this had been attributed to the differential uptake of these compounds by normal cells and tumour cells. Based on our results we propose that differential modulation of antioxidant enzymes via NFkB pathway could be the reason behind differential cytotoxicity of dimc as well as curcumin in normal cells and tumour cells in addition to differential uptake of these compounds as reported previously.

Concepts: Protein, Enzyme, Antioxidant, Glutathione, Enzyme assay, PBMC, Antioxidants, Glutathione reductase

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K-ras is one of the most common oncogenes in human cancers, and its aberrant activation may lead to malignant transformation associated with oxidative stress and activation of the transcription factor Nrf2 that regulates multiple detoxification enzymes. The purpose of this research was to use gene editing technology to evaluate the role of Nrf2 in affecting tumor growth and drug sensitivity of K-rasG12V-transformed cells. We showed that induction of K-rasG12Vcaused a significant activation of Nrf2 associated with increased expression of its target genes NAD(P)H:quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1). Interestingly, knock-out of Nrf2 by CRISPR/Cas9 in K-rasG12V-expressing cells only impacted the expression of NQO1 but not HO-1. We also found that Nrf2 knock-out caused high reactive oxygen species (ROS) stress, suppression of cell proliferation, increased apoptosis in vitro, and a decrease of tumor growth in vivo. Furthermore, abrogation of Nrf2 significantly increased the sensitivity of K-rasG12Vcells to multiple anticancer agents including phenethyl isothiocyanate (PEITC), doxorubicin, etoposide, and cisplatin. These results show that genetic abrogation of Nrf2 impairs the malignant phenotype of K-RasG12V-transformed cells in vitro and in vivo, and demonstrate the critical role of Nrf2 in promoting cell survival and drug resistance in cells harboring oncogenic K-ras. As such, inhibition of Nrf2 would be an attractive strategy to increase therapeutic effect and overcome drug resistance in cancer with oncogenic K-ras activation.

Concepts: DNA, Gene, Gene expression, Cancer, Oncology, Oxidative phosphorylation, Reactive oxygen species, Cisplatin

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To evaluate the metabolic responses in tumor cells exposed to ionizing radiation, oxygen consumption rate (OCR), cellular lipid peroxidation, cellular energy status (intracellular nucleotide pool and ATP production), and mitochondrial reactive oxygen species (ROS), semiquinone (SQ), and iron-sulfur (Fe-S) cluster levels were evaluated in human cervical carcinoma HeLa cells at 12 and 24 h after X-irradiation. LC/MS/MS analysis showed that levels of 8-iso PGF2αand 5-iPF2α-VI, lipid peroxidation products of membrane arachidonic acids, were not altered significantly in X-irradiated cells, although mitochondrial ROS levels and OCR significantly increased in the cells at 24 h after irradiation. LC/UV analysis revealed that intracellular AMP, ADP, and ATP levels increased significantly after X-irradiation, but adenylate energy charge (adenylate energy charge (AEC) = [ATP + 0.5 × ADP]/[ATP + ADP + AMP]) remained unchanged after X-irradiation. In low-temperature electron spin resonance (ESR) spectra of HeLa cells, the presence of mitochondrial SQ at g = 2.004 and Fe-S cluster at g = 1.941 was observed and X-irradiation enhanced the signal intensity of SQ but not of the Fe-S cluster. Furthermore, this radiation-induced increase in SQ signal intensity disappeared on treatment with rotenone, which inhibits electron transfer from Fe-S cluster to SQ in complex I. From these results, it was suggested that an increase in OCR and imbalance in SQ and Fe-S cluster levels, which play a critical role in the mitochondrial electron transport chain (ETC), occur after X-irradiation, resulting in an increase in ATP production and ROS leakage from the activated mitochondrial ETC.

Concepts: Photosynthesis, Metabolism, Adenosine triphosphate, Mitochondrion, Oxidative phosphorylation, Cellular respiration, Reactive oxygen species, Electron transport chain

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Besides the preventive effect of aspirin on cerebrocardiovascular diseases, aspirin has adverse effects, especially on the gastrointestinal system and kidneys. Especially, a recent advancement in endoscopy revealed that aspirin-induced small intestinal mucosal injury is considerably higher than previously believed. However, the mechanism of this phenomenon is not clear yet. Moreover, effective prophylaxis does not exist. First, we investigated the cytotoxic effect of aspirin on the intestinal epithelial cell line in rats at a high concentration, and found that aspirin significantly decreased heat shock protein 70 expression, increased reactive oxygen species production, and increased epithelial cell apoptosis. These phenomena were prevented by the increment of heat shock protein 70 expression. Next, we investigated the effect of a lower concentration of aspirin on epithelial cell permeability, and found that aspirin significantly increased reactive oxygen species production, decreased tight junction protein expression, and increased epithelial permeability. These phenomena were suppressed by an antioxidant. Finally, we investigated the role of intestinal mucus on aspirin-induced mucosal damage using an in vivo model, and found that mucus prevented a high concentration of aspirin-induced mucosal damage. The investigation of chronic users of aspirin revealed that mucus-increasing therapy might be useful for preventing aspirin-induced small intestinal mucosal injury.

Concepts: Oxygen, Cell, Bacteria, Large intestine, Stomach, Small intestine, Digestion, Intestinal epithelium

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Mitochondria, evolutionally acquired symbionts of eukaryotic cells, are essential cytoplasmic organelles. They are structurally dynamic organelles that continually go through fission and fusion processes in response to various stimuli. Tumor tissue is composed of not just cancer cells but also various cell types like fibroblasts, mesenchymal stem and immune cells. Mitochondrial dynamics of cancer cells has been shown to be significantly affected by features of tumor microenvironment such as hypoxia, inflammation and energy deprivation. The interactions of cancer cells with tumor microenvironment like hypoxia give rise to the inter- and intratumoral heterogeneity, causing chemoresistance. In this review, we will focus on the chemoresistance by tumoral heterogeneity in relation to mitochondrial dynamics of cancer cells. Recent findings in molecular mechanisms involved in the control of mitochondrial dynamics as well as the impact of mitochondrial dynamics on drug sensitivity in cancer are highlighted in the current review.

Concepts: DNA, Cell, Bacteria, Eukaryote, Mitochondrion, Cytosol, Organelle, Cytoplasm

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Over the last decade, a dual character of cell response to oxidative stress, eustress vs. distress, has become increasingly recognized. A growing body of evidence indicates that under physiological conditions, low concentrations of reactive oxygen and nitrogen species (RONS) maintained by the activity of endogenous antioxidant system (AOS) allow reversible oxidative/nitrosative modifications of key redox-sensitive residues in regulatory proteins. The reversibility of redox modifications such as Cys S-sulfenylation/S-glutathionylation/S-nitrosylation/S-persulfidation and disulfide bond formation, or Tyr nitration, which occur through electrophilic attack of RONS to nucleophilic groups in amino acid residues provides redox switches in the activities of signaling proteins. Key requirement for the involvement of the redox modifications in RONS signaling including ROS-MAPK, ROS-PI3K/Akt, and RNS-TNF-α/NF-kB signaling is their specificity provided by a residue microenvironment and reaction kinetics. Glutathione, glutathione peroxidases, peroxiredoxins, thioredoxin, glutathione reductases, and glutaredoxins modulate RONS level and cell signaling, while some of the modulators (glutathione, glutathione peroxidases and peroxiredoxins) are themselves targets for redox modifications. Additionally, gene expression, activities of transcription factors and epigenetic pathways are also under redox regulation. The present review focuses on RONS sources (NADPH-oxidases, mitochondrial electron-transportation chain (ETC), nitric oxide synthase (NOS), etc.) and their cross-talks, which influence reversible redox modifications of proteins as physiological phenomenon attained by living cells during the evolution to control cell signaling in the oxygen-enriched environment. We discussed recent advances in investigation of mechanisms of protein redox modifications and adaptive redox switches such as MAPK/PI3K/PTEN, Nrf2/Keap1, and NF-κB/IκB, powerful regulators of numerous physiological processes, also implicated in various diseases.

Concepts: Protein, Gene, Cell nucleus, Amino acid, Reactive oxygen species, Nitrogen, Disulfide bond, Glutathione