Modulation Of Redox Homeostasis Research Articles

Revealing the Potency of Cinnamon as an Anti-cancer and Chemopreventive Agent

Cinnamon (Cinnamomum spp.), an ancient spice, has been explored as a potential for medicinal purposes. Despite numerous studies about its potency in overcoming of numerous diseases, the potency as anti-cancer would be a challenge. This current article provides a review of the anti-cancer and chemoprevention potency of cinnamon and its major constituents: cinnamaldehyde, cinnamic acid, 2-hydroxycinnamaldehyde, 2-methoxycinnamaldehyde, and eugenol. Comprehensively, cinnamon and its constituents exhibit the anti-cancer and cancer prevention activities through various mechanisms: (1) anti-proliferation, (2) induction of cell death, (3) anti-angiogenesis, (4) anti-metastasis, (5) suppression of tumor-promoted inflammation, (6) immunomodulation, and (7) modulation of redox homeostasis; both in vitro and in vivo. Moreover, cinnamon also shows the synergistic anti-cancer effect with well-known anti-cancer drugs, such as doxorubicin, which support its potency to be used as a combination chemotherapeutic (co-chemotherapeutic) agent. However, further study should be established to determine the exact target molecule(s) of cinnamon in the cancer cells.Keywords: cinnamon, spice, cancer, anti-cancer, chemopreventive

Glutathione reductase mediates drug resistance in glioblastoma cells by regulating redox homeostasis

Glutathione (GSH) and GSH-related enzymes constitute the most important defense system that protects cells from free radical, radiotherapy, and chemotherapy attacks. In this study, we aim to explore the potential role and regulatory mechanism of the GSH redox cycle in drug resistance in glioblastoma multiforme (GBM) cells. We found that temozolomide (TMZ)-resistant glioma cells displayed lower levels of endogenous reactive oxygen species and higher levels of total antioxidant capacity and GSH than sensitive cells. Moreover, the expression of glutathione reductase (GSR), the key enzyme of the GSH redox cycle, was higher in TMZ-resistant cells than in sensitive cells. Furthermore, silencing GSR in drug-resistant cells improved the sensitivity of cells to TMZ or cisplatin. Conversely, the over-expression of GSR in sensitive cells resulted in resistance to chemotherapy. In addition, the GSR enzyme partially prevented the oxidative stress caused by pro-oxidant L-buthionine -sulfoximine. The modulation of redox state by GSH or L-buthionine -sulfoximine regulated GSR-mediated drug resistance, suggesting that the action of GSR in drug resistance is associated with the modulation of redox homeostasis. Intriguingly, a trend toward shorter progress-free survival was observed among GBM patients with high GSR expression. These results indicated that GSR is involved in mediating drug resistance and is a potential target for improving GBM treatment.

Pharmacological and transcriptional inhibition of the G9a histone methyltransferase suppresses proliferation and modulates redox homeostasis in human microvascular endothelial cells

Epigenetic mechanisms, including histone post-translational modifications, are central regulators of cell cycle control. The euchromatic G9a histone methyltransferase (G9a HMT) is a key enzyme catalyzing histone H3 methylation on lysines 9 and 27, and its dysregulation has been linked to uncontrolled proliferation of tumor cells. Here, we have investigated the effect of G9a HMT silencing on cell proliferation of microvascular endothelial cells, a process necessary to sustain tumor growth through the formation of the vascular capillary network.Inhibition of G9a HMT activity in human microvascular endothelial cells (HMEC-1) was performed either pharmacologically, by treatment of cells with BIX-01294 or chaetocin, or transcriptionally, using shRNA. Cell viability and proliferation were examined using the resazurin reduction assay, flow cytometry and immunostaining of phosphorylated checkpoint kinase 1 (pSer317Chk1). Expression of cell cycle- and redox homeostasis-related genes was determined by quantitative PCR. Reactive oxygen species production was measured by oxidation of the fluorescent probe 2′,7′-dichlorodihydrofluorescein diacetate and the cell’s total antioxidant capacity by using the ABTS assay.Inhibition of G9a HMT activity by BIX-01294 treatment or by shRNA attenuated the proliferation of HMEC-1, nuclear localization of phosphorylated Chk1, and induced cell cycle arrest in G1 phase. Transcriptional analysis demonstrated increased gene expression of the cyclin-dependent kinase (CDK) inhibitor p21, and also of Rb1, in BIX-01294 treated cells. Decreased proliferation rate was accompanied by enhanced antioxidant potential of HMEC-1 cells, as demonstrated by reduced production of reactive oxygen species, increased total antioxidant capacity and expression of the antioxidant enzymes catalase and superoxide dismutase 1.Collectively, our results demonstrate of the central role of G9a HMT in the promotion of endothelial cells proliferation, and suggest that endothelial G9a HMT may be a target in the treatment of vascular proliferative disorders and tumor neovascularization.

Redox-dependent modulation of metformin contributes to enhanced sensitivity of esophageal squamous cell carcinoma to cisplatin.

Glutathione is the major intracellular anti-oxidant against reactive oxygen species and serves as a detoxification essential. The anti-diabetic drug metformin has been showed to exert anti-tumor activity via modulation of redox homeostasis. In this study, we provided evidence that metformin inhibits proliferation and induces apoptosis of esophageal squamous cancer cells. Importantly, we found that metformin acts as pro-oxidant via depletion of intracellular glutathione. Co-treatment with metformin reversed the elevated intracellular glutathione induced by cisplatin and therefore enhanced the sensitivity to cisplatin in vitro and in vivo. Taken together, our data indicate that combination of metformin with cisplatin may represent a novel therapeutic strategy for esophageal squamous cell carcinoma treatment.

Mahanine exerts in vitro and in vivo antileishmanial activity by modulation of redox homeostasis

Earlier we have established a carbazole alkaloid (mahanine) isolated from an Indian edible medicinal plant as an anticancer agent with minimal effect on normal cells. Here we report for the first time that mahanine-treated drug resistant and sensitive virulent Leishmania donovani promastigotes underwent apoptosis through phosphatidylserine externalization, DNA fragmentation and cell cycle arrest. An early induction of reactive oxygen species (ROS) suggests that the mahanine-induced apoptosis was mediated by oxidative stress. Additionally, mahanine-treated Leishmania-infected macrophages exhibited anti-amastigote activity by nitric oxide (NO)/ROS generation along with suppression of uncoupling protein 2 and Th1-biased cytokines response through modulating STAT pathway. Moreover, we have demonstrated the interaction of a few antioxidant enzymes present in parasite with mahanine through molecular modeling. Reduced genetic and protein level expression of one such enzyme namely ascorbate peroxidase was also observed in mahanine-treated promastigotes. Furthermore, oral administration of mahanine in acute murine model exhibited almost complete reduction of parasite burden, upregulation of NO/iNOS/ROS/IL-12 and T cell proliferation. Taken together, we have established a new function of mahanine as a potent antileishmanial molecule, capable of inducing ROS and exploit antioxidant enzymes in parasite along with modulation of host’s immune response which could be developed as an inexpensive and nontoxic therapeutics either alone or in combination.

A novel fine tuning scheme of miR-200c in modulating lung cell redox homeostasis

Oxidative stress induces miR-200c, the predominant microRNA (miRNA) in lung tissues; however, the antioxidant role and biochemistry of such induction have not been clearly defined. Therefore, a lung adenocarcinoma cell line (A549) and a normal lung fibroblast (MRC-5) were used as models to determine the effects of miR-200c expression on lung antioxidant response. Hydrogen peroxide (H2O2) upregulated miR-200c, whose overexpression exacerbated the decrease in cell proliferation, retarded the progression of cells in the G2/M-phase, and increased oxidative stress upon H2O2 stimulation. The expression of three antioxidant proteins, superoxide dismutase (SOD)-2, haem oxygenase (HO)-1, and sirtuin (SIRT) 1, was reduced upon H2O2 stimulation in miR-200c-overexpressed A549 cells. This phenomenon of increased oxidative stress and antioxidant protein downregulation also occurs simultaneously in miR-200c overexpressed MRC-5 cells. Molecular analysis revealed that miR-200c inhibited the gene expression of HO-1 by directly targeting its 3′-untranslated region. The downregulation of SOD2 and SIRT1 by miR-200c was mediated through zinc finger E-box-binding homeobox 2 (ZEB2) and extracellular signal-regulated kinase 5 (ERK5) pathways, respectively, where knockdown of ZEB2 or ERK5 decreased the expression of SOD2 or SIRT1 in A549 cells. LNA anti-miR-200c transfection in A549 cells inhibited the endogenous miR-200c expression, resulting in increased expressions of antioxidant proteins, reduced oxidative stress and recovered cell proliferation upon H2O2 stimulation. These findings indicate that miR-200c fine-tuned the antioxidant response of the lung cells to oxidative stress through several pathways, and thus this study provides novel information concerning the role of miR-200c in modulating redox homeostasis of lung.

Monodora myristica (African nutmeg) modulates redox homeostasis and alters functional chemistry in sickled erythrocytes.

The antioxidative effect of Monodora myristica seed acetone extract and its effect on chemical functional groups were investigated in sickled erythrocytes as well as molecular modeling of the antisickling potentials of its secondary metabolites. The extract was subjected to gas chromatography-mass spectrometry to identify the compounds present, which were then docked into the allosteric-binding site of deoxy-hemoglobin. The extract was incubated with sickled erythrocytes at 37°C for 6, 12, and 24 h and were subjected to antioxidative analysis for reduced glutathione (GSH), superoxide dismutase (SOD), catalase, and lipid peroxidation (LPO). Chemical functional group of the treated cells was analyzed via Fourier transform infrared spectroscopy (FTIR). The predominant compounds identified were 17-octadecynoic acid; oleic acid, androstan-3-one, 17-hydroxy-2-methyl- (2.beta.,5.beta.,17.beta.)-; estran-3-one, 17-(acetyloxy)-2-methyl-, (2.alpha., 5.alpha., 17.beta.), and (+)-3-carene, 10-(acetylmethyl)-. They all fitted well within the active site of Hb with good binding affinity, as evidenced by the negative CDocker interaction energies of their complexes ranging between -54.4 and -26.7 kcal/mol. Treatment with the extract exacerbated SOD and catalase activities as well as GSH level, while LPO was suppressed. This antioxidative activity was time and/or dose dependent, with 6 and 12 h incubation showing the optimum activity. FTIR analysis of the treated cells showed the presence of hydrophobic functional groups. The synergetic molecular interaction of the major compounds of the extract with the α-dimer of Hb depicts an antisickling effect of M. myristica acetone extract. This is accompanied by exacerbation of endogenous antioxidant enzymes activity and modification of the functional chemistry of the cells.

Autophagy supports generation of cells with high CD44 expression via modulation of oxidative stress and Parkin-mediated mitochondrial clearance

High CD44 expression is associated with enhanced malignant potential in esophageal squamous cell carcinoma (ESCC), amongst the deadliest of all human carcinomas. Although alterations in autophagy and CD44 expression are associated with poor patient outcomes in various cancer types, the relationship between autophagy and cells with high CD44 expression remains incompletely understood. In transformed esophageal keratinocytes, CD44Low-CD24High (CD44L) cells give rise to CD44High-CD24−/Low (CD44H) cells via epithelial-mesenchymal transition (EMT) in response to transforming growth factor (TGF)-β. We couple patient samples and xenotransplantation studies with this tractable in vitro system of CD44L to CD44H cell conversion to investigate the functional role of autophagy in generation of cells with high CD44 expression. We report that high expression of the autophagy marker cleaved LC3 expression correlates with poor clinical outcome in ESCC. In ESCC xenograft tumors, pharmacological autophagy inhibition with chloroquine derivatives depletes cells with high CD44 expression while promoting oxidative stress. Autophagic flux impairment during EMT-mediated CD44L to CD44H cell conversion in vitro induces mitochondrial dysfunction, oxidative stress and cell death. During CD44H cell generation, transformed keratinocytes display evidence of mitophagy, including mitochondrial fragmentation, decreased mitochondrial content and mitochondrial translocation of Parkin, essential in mitophagy. RNA interference-mediated Parkin depletion attenuates CD44H cell generation. These data suggest that autophagy facilitates EMT-mediated CD44H generation via modulation of redox homeostasis and Parkin-dependent mitochondrial clearance. This is the first report to implicate mitophagy in regulation of tumor cells with high CD44 expression, representing a potential novel therapeutic avenue in cancers where EMT and CD44H cells have been implicated, including ESCC.

The complex roles of STAT3 and STAT5 in maintaining redox balance: Lessons from STAT-mediated xCT expression in cancer cells

STAT3 and STAT5 mediate diverse cellular processes, transcriptionally regulating gene expression and interacting with cytoplasmic proteins. Their canonical activity is stimulated by cytokines/growth factors through JAK-STAT signaling. As targets of oncogenes with intrinsic tyrosine kinase activity, STAT3 and STAT5 become constitutively active in hematologic neoplasms and solid tumors, promoting cell proliferation and survival and modulating redox homeostasis. This review summarizes reactive oxygen species (ROS)-regulated STAT activation and how STATs influence ROS production. ROS-induced effects on post-translational modifications are presented, and STAT3/5-mediated regulation of xCT, a redox-sensitive target up-regulated in numerous cancers, is discussed with regard to transcriptional cross-talk.

Apigenin Alleviates Endotoxin-Induced Myocardial Toxicity by Modulating Inflammation, Oxidative Stress, and Autophagy.

Apigenin, a component in daily diets, demonstrates antioxidant and anti-inflammatory properties. Here, we intended to explore the mechanism of apigenin-mediated endotoxin-induced myocardial injury and its role in the interplay among inflammation, oxidative stress, and autophagy. In our lipopolysaccharide- (LPS-) induced myocardial injury model, apigenin ameliorated cardiac injury (lactate dehydrogenase (LDH) and creatine kinase (CK)), cell death (TUNEL staining, DNA fragmentation, and PARP activity), and tissue damage (cardiac troponin I (cTnI) and cardiac myosin light chain-1 (cMLC1)) and improved cardiac function (ejection fraction (EF) and end diastolic left ventricular inner dimension (LVID)). Apigenin also alleviated endotoxin-induced myocardial injury by modulating oxidative stress (nitrotyrosine and protein carbonyl) and inflammatory cytokines (TNF-α, IL-1β, MIP-1α, and MIP-2) along with their master regulator NFκB. Apigenin modulated redox homeostasis, and its anti-inflammatory role might be associated with its ability to control autophagy. Autophagy (determined by LAMP1, ATG5, and p62), its transcriptional regulator transcription factor EB (TFEB), and downstream target genes including vacuolar protein sorting-associated protein 11 (Vps11) and microtubule-associated proteins 1A/1B light chain 3B (Map1lc3) were modulated by apigenin. Thus, our study demonstrated that apigenin may lead to potential development of new target in sepsis treatment or other myocardial oxidative and/or inflammation-induced injuries.

Proteome changes in the small intestinal mucosa of growing pigs with dietary supplementation of non-starch polysaccharide enzymes.

BackgroundNon-starch polysaccharide enzymes (NSPEs) have long been used in monogastric animal feed production to degrade non-starch polysaccharides (NSPs) to oligosaccharides in order to promote growth performance and gastrointestinal (GI) tract health. However, the precise molecular mechanism of NSPEs in the improvement of the mammalian small intestine remains unknown.MethodsIn this study, isobaric tags were applied to investigate alterations of the small intestinal mucosa proteome of growing pigs after 50 days of supplementation with 0.6% NSPEs (mixture of xylanase, β-glucanase and cellulose) in the diet. Bioinformatics analysis including gene ontology annotation was performed to determine the differentially expressed proteins. A protein fold-change of ≥ 1.2 and a P-value of < 0.05 were selected as thresholds.ResultsDietary supplementation of NSPEs improved the growth performance of growing pigs. Most importantly, a total of 90 proteins were found to be differentially abundant in the small intestinal mucosa between a control group and the NSPE group. Up-regulated proteins were related to nutrient metabolism (energy, lipids, protein and mineral), immunity, redox homeostasis, detoxification and the cell cytoskeleton. Down-regulated proteins were primarily related to transcriptional and translational regulation. Our results indicate that the effect of NSPEs on the increase of nutrient availability in the intestinal lumen facilitates the efficiency of nutrient absorption and utilization, and the supplementation of NSPEs in growing pigs also modulates redox homeostasis and enhances immune response during simulating energy metabolism due to a higher uptake of nutrients in the small intestine.ConclusionsThese findings have important implications for understanding the mechanisms of NSPEs on the small intestine of pigs, which provides new information for the better utilization of this feed additive in the future.Electronic supplementary materialThe online version of this article (doi:10.1186/s12953-016-0109-6) contains supplementary material, which is available to authorized users.

Naringenin causes ASK1-induced apoptosis via reactive oxygen species in human pancreatic cancer cells

Naringenin, one of the most abundant flavonoids in natural citrus fruits, has been investigated for its ability to inhibit growth of breast, colon, gastric and prostate cancer cells. However, naringenin-induced cell death in pancreatic cancer is not well understood. Therefore, we analyzed the naringenin-induced apoptosis mechanism using human pancreatic cancer SNU-213 cells. Annexin V+/PI + marked cells increased from 5.10% to 8.29%, 25.06% and 35.31% in response to treatment with 200, 400, and 600 μM naringenin, respectively. Two-dimensional electrophoresis to identify possible target-related proteins of naringenin-induced apoptosis revealed seven proteins. Among these, the expression of peroxiredoxin-1 (Prdx-1), which modulates redox homeostasis of cells, was decreased. To obtain a broad understanding of the interactive mechanism of naringenin and Prdx-1, we observed changes in reactive oxygen species (ROS) in naringenin-treated SNU-213 cells. The ROS levels were 130.02 ± 20.21%, 182.04 ± 5.39%, and 237.21 ± 12.71% in response to 200, 400, and 600 μM naringenin treatment, respectively. Increases in ROS were followed by up-regulation of apoptosis signal-regulation kinase 1 (ASK1). Moreover, the JNK, p38 and p53 proteins were upregulated. Overall, the results of this study suggest that naringenin causes ASK1-induced apoptosis mediated by ROS.

66 - Copper Transporter, Antioxidant-1 (Atox-1), Modulates Redox Homeostasis during Phorbol-Ester-Induced THP-1 Cell Differentiation

Copper (Cu), an essential micronutrient, is involved in vascular remodeling, and its bioavailability regulated by Cu transporter proteins, such as ATP7A and antioxidant-1 (Atox-1). Superoxide dismutase 3 (SOD3), which has a Cu ion in the active site, plays a pivotal role in the redox homeostasis, and its loss exacerbates vascular diseases. We have reported that SOD3 expression induces in phorbol ester (TPA)-treated human monocytic THP-1 cells; however, the involvement of Cu ion in its induction is entirely unknown. TPA stimulation in THP-1 cells induced ATP7 expression and Atox-1 nuclear translocation through PKC and MEK/ERK signaling. According to the previous report, which shows that Atox-1 functions as a transcription factor for SOD3, we demonstrated the role of Atox-1 in TPA-elicited SOD3 induction. Overexpression of Atox-1 protein enhanced TPA-elicited SOD3 expression, and knockdown of Atox-1 with siRNA suppressed its expression, suggesting that Atox-1 plays a pivotal role in SOD3 regulation in THP-1 cells. Additionally, knockdown of Atox-1 suppressed mRNA expression of gp91phox, an essential component of NOX2. Overall, we have determined that intracellular Cu modulation via its transporter might regulate redox homeostasis in THP-1 cells by the alteration in expression of SOD3 and gp91phox.

Artesunate-induced testicular injury: Oil from selected spices blend modulates redox homeostasis and exacerbates steroidogenesis in rat models

Summary The therapeutic potential of oil from blends of selected culinary spices against artesunate-induced testicular injury in albino rats was investigated. Two groups of rats each were pretreated with the oil at 1.5 and 3.00 mL respectively for seven days and after which administered artesunate (100 mg/kg bw) for seven days; two other groups were administered artesunate for seven days and after which post treated with the oil at both doses respectively for another seven days; another groups were co-administered artesunate and the oil for seven days. A group was administered artesunate only for seven days, while another was fed chows only. After sacrifice, the testicular homogenates of the rats were analysed for GSH, Superoxide Dismutase (SOD), Catalase (CAT), Lipid peroxidation (LPO), 3β-HSD and 17β-HSD activities. LPO and GSH levels, SOD and CAT activities were significantly (p

A wheat superoxide dismutase gene TaSOD2 enhances salt resistance through modulating redox homeostasis by promoting NADPH oxidase activity.

Superoxide dismutase (SOD) is believed to enhance abiotic stress resistance by converting superoxide radical (O2 (-)) to H2O2 to lower ROS level and maintain redox homeostasis. ROS level is controlled via biphasic machinery of ROS production and scavenging. However, whether the role of SOD in abiotic stress resistance is achieved through influencing the biophasic machinery is not well documented. Here, we identified a wheat copper-zinc (Cu/Zn) SOD gene, TaSOD2, who was responsive to NaCl and H2O2. TaSOD2 overexpression in wheat and Arabidopsis elevated SOD activities, and enhanced the resistance to salt and oxidative stress. TaSOD2 overexpression reduced H2O2 level but accelerated O2 (-) accumulation. Further, it improved the activities of H2O2 metabolic enzymes, elevated the activity of O2 (-) producer NADPH oxidase (NOX), and promoted the transcription of NOX encoding genes. The inhibition of NOX activity and the mutation of NOX encoding genes both abolished the salt resistance of TaSOD2 overexpression lines. These data indicate that Cu/Zn SOD enhances salt resistance, which is accomplished through modulating redox homeostasis via promoting NOX activity.

Microenvironmental Stromal Cells Rescue CLL Cells from Apoptosis Via Hypoxia That Can be Targeted Therapeutically

Abstract Microenvironmental support protects malignant cells from apoptosis and from the effects of therapy. We hypothesized that in chronic lymphocytic leukemia (CLL) cells, the non-malignant bystander cells induce a transcriptional signature that prevents apoptosis. We aimed to use this transcriptional signature to identify compounds that target this protective microenvironmental effect. If these compounds are effective against protected CLL cells, we assume that understanding the underlying molecular pathways will open novel therapeutic options for therapy-resistant CLL. In primary CD19+ CLL cells cultured without support after isolation from peripheral blood, apoptosis can already be detected after 8 hrs. These cells can however be rescued by coculture with either human or murine bone-marrow derived stromal cell lines HS-5 and M210B4. In order to identify clinically relevant substances that counteract this pro-survival microenvironmental support, we determined the transcriptional signature that is induced in primary CLL cells by protective feeder cells at 8 timepoints before apoptosis could be detected and compared it to the connectivity map database of transcriptomes induced by 1300 compounds (cMAP). We identified 7 compounds with a transcriptome signature that is negatively correlated to the protective signature induced in CLL cells by in-vitro coculture. Of note, 5 of these substances were more potent than fludararabine to induce apoptosis in protected primary CLL cells. In contrast, none of the 10 control compounds with non-correlated signatures had an effect after 48h of coculture. Most potent were the isoquinoline alkaloids emetine and cephaeline and the cardiac glycoside ouabain that displayed IC50s of 34nM, 190nM and 287nM, while a concentration of 5.1µM of fludarabine was required for comparable induction of apoptosis. To test the efficacy of emetine against CLL in vivo, TCL1-induced murine CLL-like tumors were transplanted into immunocompetent syngeneic mice and treated with 3 high doses of emetine (24mg/kg) after CD5+CD19+ CLL cells reached 40% of leukocytes (CD45+ cells). Treated animals displayed a significant reduction in body weight compared to untreated (26.0g vs 29.1g, p&lt;0.0001). However, treatment of leukemic mice with emetine reduced total lymphocyte counts in the peripheral blood compared to untreated mice (19.3 vs 48.1x10^3/mm^3, p&lt;0.0001) and also the proportion of CLL cells in the bone marrow (4.1% vs 13.0%, p=0.0041). Most importantly, treatment increased survival of mice transplanted with syngeneic murine CLL tumors (median not reached in the treatment arm vs 15 days for untreated mice, n=7 and n=9, p=0.0012, censored for different start of treatment, panel A). This shows that emetine effectively targets murine TCL1-driven CLL even if they are microenvironmentally protected in vivo. Next we aimed to understand the molecular mode of action of therapeutic targeting of the microenvironmental support. Comparing transcriptomes of primary CLL cells cocultured with and without murine or human stromal cell support, 6 of the 10 most deregulated pathways involved redox homeostasis. Downregulation of the Von-Hippel-Lindau (VHL) gene led to an increase in hypoxia-inducible factor HIF1a activity (panel B). In fact, hypoxic in-vitro incubation (3% O2) of primary CLL cells significantly prevented apoptosis between 24h and 72h (n=8, p&lt;0.05). Functionally we found in cell lines stably expressing redox reporter fusion proteins that emetine and ouabain impair recovery from mitochondrial but not cytosolic oxidative stress (Figure, panel B). In fact, the observed effect was stronger than for 13 other redox-active compounds. In addition we could show that emetine and ouabain overcome the anti-apoptotic microenvironmental downregulation of VHL in CLL cells by direct reduction of HIF1a protein and also HIF1a activity, shedding light on their molecular mode of action (panel B). In conclusion, we identified modulation of redox homeostasis to play the most important role in microenvironmental protection of CLL cells by bone-marrow stromal cells in-vitro. In addition we could show that this opens a new target of the malignant CLL cells that reside in the stromal niche protecting them from chemotherapy. Even though unexpected for a chronic leukemia, hypoxia-regulated pathways seem to be a novel therapeutic option for resistant CLL. Figure Figure. Figure. Figure. Disclosures No relevant conflicts of interest to declare.

Shifting anaerobic to aerobic metabolism stimulates apoptosis through modulation of redox balance: potential intervention in the pathogenesis of postoperative adhesions

To compare the effect of shifting anaerobic to aerobic metabolism on key regulators of oxidative stress, including extracellular superoxide dismutase (SOD3), inducible nitric oxide synthase (iNOS), and its product, nitric oxide (NO), as well as mitochondrial potential (Δψm) and apoptosis in fibroblasts established from normal peritoneum and adhesion tissues. Prospective, experimental study. University medical center. Fibroblasts established from normal peritoneum and adhesion tissues from the same patients. Treatment with dichloroacetate (0, 20, 40, and 80 μg/mL, 24 hours). The expression of SOD3, iNOS, and NO levels were measured utilizing real-time reverse transcription-polymerase chain reaction and Greiss assay. The Δψm was evaluated by the JC-1 Mitochondrial Membrane Potential Assay. Apoptosis was determined by caspase-3 activity and TUNEL assays. Data were analyzed using SPSS 19.0. Mixed model repeated-measures analysis of variance was used with a Bonferroni correction. Significant interactions were analyzed with independent sample t tests. Dichloroacetate increased apoptosis, SOD3 messenger RNA, iNOS messenger RNA, and NO levels in fibroblasts from peritoneum and adhesions. There was enhanced Δψm adhesion as compared with normal peritoneal fibroblasts. Creating oxidative stress by exposure by hypoxia markedly increased Δψm in fibroblasts from normal peritoneum to levels observed in adhesions; dichloroacetate protected against the effects of hypoxia. Anaerobic metabolism and oxidative stress are associated with the development of the adhesion phenotype, which manifests decreased apoptosis. Dichloroacetate induces adhesion fibroblasts to undergo apoptosis via modulation of redox homeostasis. These findings may provide targets for therapeutic treatment for reduction of profibrotic disorders, including postoperative adhesions.

Glucose-6-phosphate dehydrogenase and alternative oxidase are involved in the cross tolerance of highland barley to salt stress and UV-B radiation

In this study, a new mechanism involving glucose-6-phosphate dehydrogenase (G6PDH) and alternative pathways (AP) in salt pretreatment-induced tolerance of highland barley to UV-B radiation was investigated. When highland barley was exposed to UV-B radiation, the G6PDH activity decreased but the AP capacity increased. In contrast, under UV-B+NaCl treatment, the G6PDH activity was restored to the control level and the maximal AP capacity and antioxidant enzyme activities were reached. Glucosamine (Glucm, an inhibitor of G6PDH) obviously inhibited the G6PDH activity in highland barley under UV-B+NaCl treatment and a similar pattern was observed in reduced glutathione (GSH) and ascorbic acid (Asc) contents. Similarly, salicylhydroxamic acid (SHAM, an inhibitor of AOX) significantly reduced the AP capacity in highland barley under UV-B+NaCl treatment. The UV-B-induced hydrogen peroxide (H2O2) accumulation was also followed. Further studies indicated that non-functioning of G6PDH or AP under UV-B+NaCl+Glucm or UV-B+NaCl+SHAM treatment also caused damages in photosynthesis and stomatal movement. Western blot analysis confirmed that the alternative oxidase (AOX) and G6PDH were dependent each other in cross tolerance to UV-B and salt. The inhibition of AP or G6PDH activity resulted in a significant accumulation or reduction of NADPH content, respectively, under UV-B+NaCl treatment in highland barley leaves. Taken together, our results indicate that AP and G6PDH mutually regulate and maintain photosynthesis and stomata movement in the cross adaptation of highland barley seedlings to UV-B and salt by modulating redox homeostasis and NADPH content.

Polyamines as redox homeostasis regulators during salt stress in plants

The balance between accumulation of stress-induced polyamines and reactive oxygen species (ROS) is arguably a critical factor in plant tolerance to salt stress. Polyamines are compounds, which accumulate in plants under salt stress and help maintain cellular ROS homeostasis. In this review we first outline the role of polyamines in mediating salt stress responses through their modulation of redox homeostasis. The two proposed roles of polyamines in regulating ROS – as antioxidative molecules and source of ROS synthesis – are discussed and exemplified with recent studies. Second, the proposed function of polyamines as modulators of ion transport is discussed in the context of plant salt stress. Finally, we highlight the apparent connection between polyamine accumulation and programmed cell death induction during stress. Thus polyamines have a complex functional role in regulating cellular signaling and metabolism during stress. By focusing future efforts on how polyamine accumulation and turnover is regulated, research in this area may provide novel targets for developing stress tolerance.

Involvement of the modulation of cancer cell redox status in the anti-tumoral effect of phenolic compounds

The association between the anti-tumoral properties of phenolics, the generation of ROS in culture medium and modulation of redox homeostasis was analyzed. In AGS cells, the anti-proliferative effect of quercetin was not reverted by catalase or SOD.