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ABSTR.40

ABSTR. P131

abstr. P7

Castanea sativa is very common in Italy, and the large amount of waste material generated during chestnut processing has a high environmental impact. Several studies demonstrated that chestnut by-products are a good source of bioactive compounds, mainly endowed with antioxidant properties. This study further investigates the anti-neuroinflammatory effect of chestnut leaf and spiny bur extracts, together with the deepest phytochemical characterisation (by NMR and MS) of active biomolecules contained in leaf extracts, which resulted in being more effective than spiny bur ones. BV-2 microglial cells stimulated with lipopolysaccharide (LPS) were used as a model of neuroinflammation. In BV-2 cells pre-treated with chestnut extracts, LPS signalling is partially blocked via the reduced expression of TLR4 and CD14 as well as the expression of LPS-induced inflammatory markers. Leaf extract fractions revealed the presence of specific flavonoids, such as isorhamnetin glucoside, astragalin, myricitrin, kaempferol 3-rhamnosyl (1-6)(2″-trans-p-coumaroyl)hexoside, tiliroside and unsaturated fatty acids, all of which could be responsible for the observed anti-neuroinflammatory effects. Interestingly, the kaempferol derivative has been identified in chestnut for the first time. In conclusion, the exploitation of chestnut by-products is suitable for the achievement of two goals: satisfaction of consumers’ demand for new, natural bio-active compounds and valorisation of by-products.

Background Although in recent years, the introduction of novel chemotherapy protocols has improved the outcome of T cell acute lymphoblastic leukemia (T-ALL) patients, refractory and/or relapsing disease remains a foremost concern. In this context, a major contribution was provided by the introduction of the nucleoside analog nelarabine, approved for salvage treatment of T-ALL patients with refractory/relapsed disease. However, nelarabine could induce a life-threatening, dose-dependent neurotoxicity. To improve nelarabine efficacy, we have analyzed its molecular targets, testing selective inhibitors of such targets in combination with nelarabine. Methods The effectiveness of nelarabine as single agent or in combination with PI3K, Bcl2, and MEK inhibitors was evaluated on human T-ALL cell lines and primary T-ALL refractory/relapsed lymphoblasts. The efficacy of signal modulators in terms of cytotoxicity, induction of apoptosis, and changes in gene and protein expression was assessed by flow cytometry, western blotting, and quantitative real-time PCR in T-ALL settings. Results Treatment with nelarabine as a single agent identified two groups of T-ALL cell lines, one sensitive and one resistant to the drug. Whereas sensitive T-ALL cells showed a significant increase of apoptosis and a strong down-modulation of PI3K signaling, resistant T-ALL cells showed a hyperactivation of AKT and MEK/ERK1/2 signaling pathways, not caused by differences in the expression of nelarabine transporters or metabolic activators. We then studied the combination of nelarabine with the PI3K inhibitors (both pan and dual γ/δ inhibitors), with the Bcl2 specific inhibitor ABT199, and with the MEK inhibitor trametinib on both T-ALL cell lines and patient samples at relapse, which displayed constitutive activation of PI3K signaling and resistance to nelarabine alone. The combination with the pan PI3K inhibitor ZSTK-474 was the most effective in inhibiting the growth of T-ALL cells and was synergistic in decreasing cell survival and inducing apoptosis in nelarabine-resistant T-ALL cells. The drug combination caused AKT dephosphorylation and a downregulation of Bcl2, while nelarabine alone induced an increase in p-AKT and Bcl2 signaling in the resistant T-ALL cells and relapsed patient samples. Conclusions These findings indicate that nelarabine in combination with PI3K inhibitors may be a promising therapeutic strategy for the treatment of T-ALL relapsed patients. Electronic supplementary material The online version of this article (doi:10.1186/s13045-016-0344-4) contains supplementary material, which is available to authorized users.

The modulation of H2O2 production by NADPH oxidase (Nox), on vascular endothelial growth factor (VEGF) stimulation, affects the redox signaling linked to cancer cell proliferation. H2O2 signal transduction involves reversible oxidation of thiol proteins, leading to the formation of cysteine sulfenic acids, responsible for the temporary inactivation of many phosphatases. These events imply that H2O2 reaches its intracellular targets. As Aquaporin-8 (AQP8) has been demonstrated to funnel Nox-produced H2O2 across the plasma membrane, this study aims to elucidate the role of AQP8 in the redox signaling occurring in human leukaemia B1647 cells that constitutively produce VEGF. AQP8 overexpression or silencing resulted in the modulation of VEGF ability of increasing or decreasing respectively, H2O2 intracellular level. Moreover, data obtained by a dimedone-based immunochemical method for sulfenic acid detection demonstrate that the expression of AQP8 can modulate the amplitude of downstream events, altering the activity of redox-sensitive targets. In particular, AQP8 affected VEGF-induced redox signaling by increasing the sulfenation of the tumor suppressor PTEN, which resulted in its inactivation and, in turn, caused Akt activation. Therefore, the dimedone based method for easily monitoring cellular protein sulfenation allowed to demonstrate, for the first time, the role of AQP8 on the fine tune of cysteine oxidation in target proteins involved in leukaemia cell proliferation pathways.

Caveolae/lipid rafts are membrane-rich cholesterol domains endowed with several functions in signal transduction and caveolin-1 (Cav-1) has been reported to be implicated in regulating multiple cancer-associated processes, ranging from tumor growth to multidrug resistance and angiogenesis. Vascular endothelial growth factor receptor-2 (VEGFR-2) and Cav-1 are frequently colocalized, suggesting an important role played by this interaction on cancer cell survival and proliferation. Thus, our attention was directed to a leukemia cell line (B1647) that constitutively produces VEGF and expresses the tyrosine-kinase receptor VEGFR-2. We investigated the presence of VEGFR-2 in caveolae/lipid rafts, focusing on the correlation between reactive oxygen species (ROS) production and glucose transport modulation induced by VEGF, peculiar features of tumor proliferation. In order to better understand the involvement of VEGF/VEGFR-2 in the redox signal transduction, we evaluated the effect of different compounds able to inhibit VEGF interaction with its receptor by different mechanisms, corroborating the obtained results by immunoprecipitation and fluorescence techniques. Results here reported showed that, in B1647 leukemia cells, VEGFR-2 is present in caveolae through association with Cav-1, demonstrating that caveolae/lipid rafts act as platforms for negative modulation of VEGF redox signal transduction cascades leading to glucose uptake and cell proliferation, suggesting therefore novel potential targets.

none 13 no Objectives: Oxidized LDL (oxLDL) or pro-inflammatory stimuli lead to increased oxidative stress linked to endothelial dysfunction and atherosclerosis. The oxLDL receptor-1 (LOX1) is elevated within atheromas and cholesterol-lowering statins also inhibit LOX1 expression. Berberine (BBR), an alkaloid extracted from plants of gender Berberis, has lipid-lowering and anti-inflammatory activity. However, its role in regulating LOX1- mediated signalling is still unknown. The aim of this study was to compare the effects of BBR and lovastatin (LOVA) on oxLDL- and TNFa-induced endothelial dysfunction in human umbilical vein endothelial cells (HUVECs). Methods: Cytotoxicity was determined by LDH assay. Antioxidant capacity was measured with chemiluminescent and ORAC method and intracellular ROS levels in HUVECs through a fluorescent dye. Gene and protein expression levels were assayed by qRT-PCR and western blot, respectively. Results: HUVECs exposure to oxLDL (30mg/ml) or TNFa (10ng/ml) for 24h led to a significant increase in LOX1 expression, effect abrogated by BBR (5mM) and LOVA (1mM). BBR but not LOVA treatment abolished the TNFa induced cytotoxicity and restored the activation of Akt signalling. Although both compounds reduced intracellular ROS levels induced by H2O2 (100mM) or TNFa, only BBR inhibited NOX2 expression, MAPK/Erk signalling and subsequent NF-kB e related genes VCAM and ICAM expression, induced by TNFa. Conclusions: These findings demonstrated for the first time that BBR could prevent the oxLDL and TNFa - induced LOX1 expression and oxidative stress, key events that lead to NOX2, MAPK/Erk and NF-kB activation linked to endothelial dysfunction. Cicero, A; Caliceti, C; Rizzo, P; Ferrari, R; Fortini, F; Aquila, G; Shehu, J; Leoncini, E; Zambonin, L; Rizzo, B; Guardigli, M; Roda, A; Hrelia, S Cicero, A; Caliceti, C; Rizzo, P; Ferrari, R; Fortini, F; Aquila, G; Shehu, J; Leoncini, E; Zambonin, L; Rizzo, B; Guardigli, M; Roda, A; Hrelia, S

Stevia rebaudiana Bertoni è una pianta perenne appartenente alla famiglia delle Asteracee (Compositae), nativa delle regioni subtropicali del Brasile e del Paraguay. Fin dai tempi più antichi le sue foglie sono state impiegate dalle popolazioni native in virtù del loro potere dolcificante. Questa caratteristica ha sollevato l’interesse dei nutrizionisti e dell’industria, sempre alla ricerca di nuovi dolcificanti naturali, privi di potere calorico e alternativo al saccarosio. Tale esigenza è da imputarsi al preoccupante aumento di diabete mellito di tipo 2 e obesità, sia nei paesi industrializzati sia in quelli in via di sviluppo, che costituisce attualmente il principale problema di sanità pubblica a livello mondiale. Oltre al potere dolcificante, i glicosidi estratti dalla Stevia rebaudiana Bertoni possiedono diversi effetti benefici sulla salute umana, tra i quali i più interessanti sono quelli anti-iperglicemici, insulinotropici ed insulino-simili, che li rendono potenziali coadiuvanti nel trattamento del diabete mellito e dei dismetabolismi ad esso associati. Studi in vivo sia su animali che su volontari umani hanno dimostrato che i glicosidi della Stevia non sono genotossici né carcinogenici, pertanto la Food and Drug Administration statunitense (FDA) e l’Ente Europeo per la Sicurezza Alimentare (EFSA) hanno autorizzato l’uso dei glicosidi della Stevia come dolcificanti commerciali e additivi alimentari. La dose giornaliera consentita è stata stabilita a 4 mg/Kg di peso. Lo scopo di questa ricerca è stato quello di studiare il meccanismo molecolare sotteso agli effetti esercitati dai glicosidi della Stevia sul metabolismo del glucosio. A tal fine è stato valutato l’effetto di alcuni estratti commerciali di Stevia sull’attività di trasporto di glucosio in diverse linee cellulari, confrontandolo con quello dell’insulina per validarne l’attività come nutraceutico ad azione ipoglicemizzante

Caffeic, syringic, and protocatechuic acids are phenolic acids derived directly from food intake or come from the gut metabolism of polyphenols. In this study, the antioxidant activity of these compounds was at first evaluated in membrane models, where caffeic acid behaved as a very effective chain-breaking antioxidant, whereas syringic and protocatechuic acids were only retardants of lipid peroxidation. However, all three compounds acted as good scavengers of reactive species in cultured cells subjected to exogenous oxidative stress produced by low level of H2O2. Many tumour cells are characterised by increased ROS levels compared with their noncancerous counterparts. Therefore, we investigated whether phenolic acids, at low concentrations, comparable to those present in human plasma, were able to decrease basal reactive species. Results show that phenolic acids reduced ROS in a leukaemia cell line (HEL), whereas no effect was observed in normal cells, such as HUVEC. The compounds exhibited no toxicity to normal cells while they decreased proliferation in leukaemia cells, inducing apoptosis. In the debate on optimal ROS-manipulating strategies in cancer therapy, our work in leukaemia cells supports the antioxidant ROS-depleting approach.

The recently demonstrated reliance of glycolytic cancer cells on trans-plasma membrane electron transport (tPMET) for survival raises the question of its suitability as a target for anticancer drug development. In this study, the effects of several new and known compounds on proliferation, tPMET activity and NAD(P)H intrinsic fluorescence in human myelogenous leukemic cell lines were investigated. The whole data confirm the importance of tPMET in leukemic cell survival and suggest this activity as a new potential anti-leukemic target.

The mechanism involved in the prosurvival effect of interleukin-3 on the human acute myeloid leukaemia cell line M07e is investigated. A decrease in intracellular reactive oxygen species (ROS) content, glucose transport activity and cell survival was observed in the presence of inhibitors of plasma membrane ROS sources, such as diphenylene iodonium and apocynin, and by small interference RNA for Nox2. Moreover, IL-3 incubation stimulated the synthesis of Nox2 cytosolic sub-unit p47phox and glucose transporter Glut1. Thus, the inhibition of ROS generation by Nox inhibitors stimulated apoptosis showing that ROS production, induced by IL-3 via Nox2, protects leukaemic cells from cell death. Also incubation with receptor tyrosine kinase inhibitors, such as anti-leukaemic drugs blocking the stem cell factor receptor (c-kit), showed similar effects, hinting that IL-3 transmodulates c-kit phosphorylation. These mechanisms may play an important role in acute myeloid leukaemia treatment, representing a novel therapeutic target.

The discovery of superoxide-generating enzymes homologues of phagocytic NAD(P)H oxidase, the Nox family, has led to the concept that reactive oxygen species (ROS) are “intentionally” generated with biological functions in various cell types. In this study, by treating an acute leukaemic cell line with different antioxidants, ROS generation was shown to be crucially involved in the modulation of glucose transport (mediated by Glut1), which is frequently up-regulated in cancer cells. Then, this study tried to elucidate ROS source(s) and mechanisms by which ROS are involved in Glut1 activity regulation. Results prove that Nox2 and Nox4 are the candidates and that phosphorylation processes are important in the regulation of glucose uptake on which cancer cells rely. On the whole, data suggest that both Glut1 and Nox homologues may be considered new potential targets in the treatment of leukaemia.

In M07e cells, a human megakaryocytic leukaemia line, reactive oxygen species (ROS) are generated in response to cytokines acting as intracellular messengers to modulate glucose transport. The aim of this work was to study the signal cascade involved in the acute glucose transport activation in cells exposed to growth factors, such as granulocyte macrophage-colony stimulation factor (GM-CSF) and thrombopoietin (TPO), to better understand some aspects of the aberrant proliferation in leukaemia. Results confirm ROS involvement in modulation of glucose transport in this cell line. Furthermore, GM-CSF and TPO produced changes in Glut1 phosphorylation and specific inhibitors employed to identify protein kinases involved in Glut activation by these cytokines proved that Akt, PLC gamma, Syk and the Src family take part in signal transduction leading to Glut1 activation.

Our previous report demonstrated that, when vitamin deficiency is associated with high contents of long chain polyunsaturated fatty acids (LCPUFA) n3, lipid peroxidation susceptibility in rat heart and liver increases. In this paper, we evaluated the effect of the same dietary administration on lipid composition and antioxidant defenses of rat kidney. Results showed that vitamin B 6 deficiency, when associated with a fish oil diet, as compared to vegetable oil condition, increased relative kidney weight and decreased pyridoxal-5P contents. The different LCPUFA n3 dietary contents produced, on kidney phospholipids, effects interlaced with those of vitamin B 6 deficiency; in particular fish oil and vitamin B 6 deficient diet caused a significant decrease of arachidonic acid showing that the processes of elongation and desaturation of linoleic acid were slowed. Also, peroxidation susceptibility was higher, as demonstrated both by increased TBARS formation and glutathione peroxidase activity, and by decreased vitamin E contents and reduced glutathione/oxidized glutathione ratio. Keywords: Rat kidney; Lipid peroxidation; LCPUFA n3; Vitamin B6 deficiency

Alzheimer’s disease is the most common and lethal neurodegenerative disorder. The major hallmarks of Alzheimer’s disease are extracellular aggregation of amyloidβpeptides and, the presence of intracellular neurofibrillary tangles formed by precipitation/aggregation of hyperphosphorylated tau protein. The etiology of Alzheimer’s disease is multifactorial and a full understanding of its pathogenesis remains elusive. Some years ago, it has been suggested that glycation may contribute to both extensive protein cross-linking and oxidative stress in Alzheimer’s disease. Glycation is an endogenous process that leads to the production of a class of compounds known as advanced glycation end products (AGEs). Interestingly, increased levels of AGEs have been observed in brains of Alzheimer’s disease patients. Methylglyoxal, a reactive intermediate of cellular metabolism, is the most potent precursor of AGEs and is strictly correlated with an increase of oxidative stress in Alzheimer’s disease. Many studies are showing that methylglyoxal and methylglyoxal-derived AGEs play a key role in the etiopathogenesis of Alzheimer's disease.

In the last decade, the generation and the role of reactive oxygen species (ROS), particularly hydrogen peroxide, in cell signalling transduction pathways have been intensively studied, and it is now clear that an increase of ROS level affects cellular growth and proliferation pathways related to cancer development. Hydrogen peroxide (H2O2) has been long thought to permeate biological membranes by simple diffusion since recent evidence challenged this notion disclosing the role of aquaporin water channels (AQP) in mediating H2O2 transport across plasma membranes. We previously demonstrated that NAD(P)H oxidase (Nox)-generated ROS sustain glucose uptake and cellular proliferation in leukaemia cells. The aim of this study was to assess whether specific AQP isoforms can channel Nox-produced H2O2 across the plasma membrane of leukaemia cells affecting downstream pathways linked to cell proliferation. In this work, we demonstrate that AQP inhibition caused a decrease in intracellular ROS accumulation in leukaemia cells both when H2O2 was produced by Nox enzymes and when it was exogenously added. Furthermore, AQP8 overexpression or silencing resulted to modulate VEGF capacity of triggering an H2O2 intracellular level increase or decrease, respectively. Finally, we report that AQP8 is capable of increasing H2O2-induced phosphorylation of both PI3K and p38 MAPK and that AQP8 expression affected positively cell proliferation. Taken together, the results here reported indicate that AQP8 is able to modulate H2O2 transport through the plasma membrane affecting redox signalling linked to leukaemia cell proliferation.

Extracts fromStevia rebaudianaBertoni, a plant native to Central and South America, have been used as a sweetener since ancient times. Currently,Steviaextracts are largely used as a noncaloric high-potency biosweetener alternative to sugar, due to the growing incidence of type 2 diabetes mellitus, obesity, and metabolic disorders worldwide. Despite the large number of studies onSteviaand steviol glycosidesin vivo, little is reported concerning the cellular and molecular mechanisms underpinning the beneficial effects on human health. The effect of four commercialSteviaextracts on glucose transport activity was evaluated in HL-60 human leukaemia and in SH-SY5Y human neuroblastoma cells. The extracts were able to enhance glucose uptake in both cellular lines, as efficiently as insulin. Our data suggest that steviol glycosides could act by modulating GLUT translocation through the PI3K/Akt pathway since treatments with both insulin andSteviaextracts increased the phosphorylation of PI3K and Akt. Furthermore,Steviaextracts were able to revert the effect of the reduction of glucose uptake caused by methylglyoxal, an inhibitor of the insulin receptor/PI3K/Akt pathway. These results corroborate the hypothesis thatSteviaextracts could mimic insulin effects modulating PI3K/Akt pathway.

Reactive oxygen species (ROS) can act as messengers in cellular signalling transduction pathways and it is now firmly established that an increase of ROS (particularly hydrogen peroxide) supports cellular growth and proliferation contributing to cancer development. Hydrogen peroxide has been long thought to be freely diffusible but recent evidence demonstrated that transport of H2O2 across membranes is tightly regulated [1]. Furthermore, it has been recently reported that a specific mammalian aquaporin homologue (AQP8) possess the capacity to channel H2O2 across membranes [2] and that AQP3 expression modulate the intracellular level of H2O2 in human cells and is necessary for Nox-derived H2O2 signalling [3]. The aim of this study was to assess whether specific aquaporin isoforms can channel Nox-produced H2O2 across the plasma membrane affecting downstream pathways linked to cell proliferation in leukaemia cells. The expression of AQP8 was assessed and verified by Western Blot and PCR in HL60 and B1647 cell lines. We showed that aquaporin inhibition caused a decrease in intracellular ROS accumulation both when H2O2 was produced by Nox enzymes and when it was added exogenously to the medium. In addition, intracellular hydrogen peroxide transport was evaluated by using a boronate-based fluorescent probe selective for H2O2 (PF1) and the data obtained confirmed that aquaporin inhibition decreased the intracellular level of H2O2. As we previously demonstrated that Nox-generated ROS sustain glucose uptake and cellular proliferation in leukemic cell lines [4, 5], in this study we report that treatment with aquaporin inhibitor caused a significant decrease in glucose transport in HL60 and B1647 cells. These results suggest that aquaporins are able to transport Nox-generated H2O2 across the plasma membrane and to affect downstream pathways in leukaemia cells.

In a previous paper, we demonstrated that tissue trans fatty acids can not only derive from the diet but also be endogenously formed. The central focus of this study was to prove that the in vivo isomerization occurs via a radical process. Two different models of radical insult were used: CCl(4) and AAPH injection to rats fed a diet completely free of trans isomers. Following this acute radical stress, a significant increase in unnatural trans fatty acid content of erythrocyte, kidney, and heart, but not liver, was observed. These results can be mainly explained by the high content, particularly in the liver, of antioxidant vitamins A and E that exhibit also an "anti-isomerizing" effect. Since during ageing cellular components are exposed to increasing radical insults, the observation of a significant trans fatty acid accumulation in 30-month-old rats could confirm that the in vivo formation of unnatural isomers is due to a radical process. Trans fatty acids can influence the physical characteristics of bilayer microdomains, affecting membrane properties and functions; thus, knowledge of biological radical species responsible for cis/trans isomerization and their possible sources can provide protective systems for preserving lipid geometry.