Diana Fiorentini's scientific contributionswhile working at University of Bologna and other institutions
- Abstract: The effect of AD6 (8-monochloro-3-beta-diethylamino-ethyl-4-methyl-7-ethoxycarbonylmeth oxy coumarin), an inhibitor of platelet aggregation, on cyclic nucleotide metabolism was investigated. AD6 inhibited selectively human platelet cyclic GMP phosphodiesterase, which was separated from cyclic AMP phosphodiesterase by DEAE-cellulose chromatography. Addition of AD6 to washed platelets increased cyclic GMP levels significantly in two minutes. These results could be useful in elucidating the... Show More
- Abstract: When model membranes are prepared by ultrasonic irradiation of polyunsaturated phospholipids, radical production can induce a partial degradation of the polyunsaturated fatty acyl chains and the formation of lipid hydroperoxides. A suitable buffer employed during liposome preparation, like Hepes or Tris, is able to exhibit a protective effect against lipid peroxidation. Hepes has been found to be the most effective: a 10 mM concentration provides a 70% protection after 30 min sonication.... Show More
- Abstract: 1. Composition of phospholipids extracted from different organelles of European sea bass liver was determined and compared with that of phospholipids extracted from the same organelles of rat liver. 2. Spermine binding to the vesicles prepared from microsomal and mitochondrial phospholipids and their aggregation was studied: these parameters indicate that only the presence of acidic phospholipids and not their unsaturation was essential for polyamine action. 3. No correlation exists between... Show More
- Abstract: To find experimental conditions to selectively study the propagation phase of lipoperoxidation we studied the lipoperoxidation, catalyzed by FeCl2, of liposomes in a buffering condition where Fe2+ autoxidation and oxygen active species generation does not occur. Liposomes from egg yolk phosphatidylcholine, prepared by vortex mixing, do not oxidize Fe2+; on the contrary they oxidize Fe2+ when prepared by ultrasonic irradiation. Dimyristoyl phosphatidylcholine liposomes prepared by ultrasonic... Show More
- Abstract: The aim of this study was to evaluate both the effect of oxygen free radicals produced by ultrasonic irradiation on ubiquinone-3 incorporated into egg phosphatidylcholine vesicles and lipid peroxidation of the same vesicles. Owing to water sonolysis, degradation of polyunsaturated fatty acid residues occurred when model membranes were sonicated in the absence of ubiquinone. Under these conditions, Hepes buffer, but not formate, was able to protect against HO− damage, probably because access... Show More
- Abstract: Coenzyme Q-3 incorporated into the lipid bilayer at physiological concentration provided an 80% inhibition of the lipid peroxidation induced by ferrous ions. In coenzyme Q-containing vesicles, the fluorescence lifetime and the fluorescence anisotropy decay of the probe, 1,6-diphenyl-1,3,5-hexatriene, were measured in order to find out if the presence of the quinone can cause variations in the membrane organization. Our data show that two distinct populations of the probe were present and... Show More
- Abstract: The aim of this study was to obtain a quantification of the antioxidant activity of ubiquinone. To this purpose the oxidation of egg yolk phosphatidylcholine both in solvent and in liposomes initiated by an azocompound has been studied either in the absence or in the presence of ubiquinone-3, using alpha-tocopherol as a reference antioxidant. The two experimental systems gave similar results. In the presence of ubiquinone-3 the oxidation rate was reduced with respect to control experiments... Show More
- Abstract: The question has been addressed whether the side chain contributes to the antioxidant activity of Ubiquinones. The length, the chemical composition and structure of the chain have been considered. The effect of the actual concentration of the quinone in egg lecithin vesicles has been investigated by means of both UV spectroscopy and time resolved fluorescence quenching experiments of 12-AS. The results indicate that the antioxidant properties of the quinone do not seem to depend on the side... Show More
- Abstract: In this study we investigated whether alpha-tocopherol can be spared by ubiquinol-3 during autoxidation of multilamellar liposome. A lipophilic azocompound, 2,2'-azobis-(2,4-dimethyl-valeronitrile), was chosen to initiate liposome autoxidation. The effect of either alpha-tocopherol, ubiquinol-3, or a mixture of them was compared. Rates of conjugated diene formation and concomitant disappearance of the two antioxidants was measured. Since the inhibition rate constant for the scavenging of... Show More
- Abstract: Coenzyme Q, besides its role in electron transfer reactions, may act as a radical scavenger. The effect of oxygen radicals produced by ultrasonic irradiation on the quinone ring was investigated. Aqueous solutions of a Q homologue, completely lacking the side chain, were irradiated and the modifications were spectrophotometrically followed. The experimental results show that both degradation and reduction of the benzoquinone ring took place when the irradiation was performed in water. Data... Show More
- Abstract: In a buffer (Mes) and at a pH (6.5) where Fe2+ is very stable, we have studied the peroxidation of liposomes catalyzed by FeCl2. The liposomes studied, prepared by sonolysis, contained either phosphatidylcholine or 1:1 molar ratio of phosphatidylcholine and phosphatidic acid. The presence of the negatively charged phospholipid causes: 1) rapid Fe2+ oxidation and oxygen consumption; 2) increased generation of lipid hydroperoxides; 3) decreased generation of thiobarbituric acid-reactive... Show More
- Abstract: With a view to determining the antioxidant effectiveness of ubiquinol, the autoxidation of egg phosphatidylcholine initiated by an azocompound was studied both in homogeneous solution and in liposomes, either in the presence or in the absence of ubiquinol-3. The results show that ubiquinol behaves as a chain-breaking antioxidant by trapping lipid peroxyl radicals, its inhibition rate constant being about one half of that of alpha-tocopherol in both systems under investigation. In organic... Show More
- Abstract: This study was undertaken to compare, on a kinetic basis, the antioxidant efficiency of an ubiquinol homologue having a short isoprenoid side-chain length, such as ubiquinol-3, with that of the long chain ubiquinol-7, by determining their rate constants of inhibition with respect to alpha-tocopherol. To this purpose we incorporated ubiquinol-3, or ubiquinol-7, or alpha-tocopherol into liposomes of egg yolk lecithin, and triggered lipid peroxidation with the thermal decomposition of a... Show More
- Abstract: The antioxidant activity of ubiquinol homologues with different side-chain length such as ubiquinol-3 and ubiquinol-7 was compared with that of α-tocopherol when peroxidation was induced by the water-soluble initiator 2,2′-azobis-(2-amidinopropane hydrochloride). In large unilamellar vesicles containing equal amounts of α-tocopherol, ubiquinol-3 and ubiquinol-7 the rates of inhibition were very similar but the stoichiometric factor of quinols was ≈ 1. To explain this low value, which is... Show More
- Abstract: The aim of this work was to characterize large unilamellar vesicles (LUVETs) prepared by a hand-driven extrusion device in order to use them for studies of lipid peroxidation and antioxidant activity. Vesicle structure and size were examined by electron microscopy. Lipid and antioxidant content was determined before and after the extrusion procedure. Then LUVETs were subjected to autoxidation initiated by both the lipid-soluble 2,2'-azobis(2,4-dimethylvaleronitrile) and the water-soluble... Show More
- Abstract: The aim of this study was to investigate oxidative cell injury in rat thymocytes under conditions of radical generation exterior to the cell utilizing the thermolabile azocompound 2,2'-azobis(2-amidinopropane) dihydrochloride to generate peroxyl radicals at a constant and reproducible rate. This initiator, being water-soluble and endowed with a positive charge, is suitable for studies on oxidative damage of biomembranes induced in the external water environment. The relationship between cell... Show More
- Abstract: The experiments reported here were designed to test the hypothesis that the two-electron quinone reductase DT-diaphorase [NAD(P)H:(quinone-acceptor) oxidoreductase, EC 184.108.40.206] functions to maintain membrane-bound coenzyme Q (CoQ) in its reduced antioxidant state, thereby providing protection from free radical damage. DT-diaphorase was isolated and purified from rat liver cytosol, and its ability to reduce several CoQ homologs incorporated into large unilamellar vesicles was demonstrated.... Show More
- Abstract: The experiments reported here were undertaken to test the hypothesis that the antioxidative, reduced form of hydrophobic phase coenzyme Q (CoQ) may be generated and maintained by the two-electron quinone reductase, DT-diaphorase [NAD(P)H:(quinone-acceptor) oxidoreductase, EC 220.127.116.11] by catalyzing formation of the hydroquinone form of CoQ. This enzyme was isolated and purified from rat liver cytosol and its reduction of several CoQ homologs incorporated into large unilamellar vesicles... Show More
- Abstract: The activity of purified DT-diaphorase in the reduction of ubiquinone homologues of different side-chain length incorporated in uni- and multilamellar vesicles was determined. The direct relationship between the reduced state of ubiquinones and the inhibition of lipid autoxidation induced by thermolabile azocompounds was also demonstrated. Results demonstrate that DT-diaphorase is able to generate and to maintain the reduced, antioxidant form of ubiquinones in both types of vesicles.... Show More
- Abstract: The antioxidant activity of reduced menadione was investigated and compared with that of alpha-tocopherol both in solvent solution and in large unilamellar vesicles by using azocompounds as free radical generators. The results show that: i) reduced menadione behaves as a chain-breaking antioxidant; ii) its inhibition rate constant is similar to that of alpha-tocopherol in homogeneous solution, whereas it is 4 times larger in egg yolk lecithin vesicles; iii) the stoichiometric factor is found... Show More
Publications citing this author (1295)
[Show abstract] [Hide abstract] ABSTRACT: Dexmedetomidine (Dex), a highly selective α2-adrenoceptor agonist, attenuates inflammatory responses induced by lipopolysaccharide (LPS) and induces sedative and analgesic effects. Administration of Dex also reduces salivary secretion in human subjects and inhibits osmotic water permeability in rat cortical collecting ducts. However, little is known about the mechanisms underlying the effects of Dex on salivary glands fluid secretion. We demonstrated the α2-adrenoceptor expression in the basolateral membrane of mouse submandibular glands (SMG). To investigate fluid secretion upon treatment with Dex, we studied the effects of Dex on the activity of Na+-K+-2Cl− cotransporter1 (NKCC1) and Cl−/HCO3- exchange (CBE), and on downstream pro-inflammatory cytokine expression in isolated primary mouse SMG cells. Dex acutely increased CBE activity and NKCC1-mediated and independent NH4+ entry in SMG duct cells, and enhanced ductal fluid secretion in a sealed duct system. Dex showed differential effects on cholinergic/adrenergic stimulations and inflammatory mediators, histamine, and LPS, stimulations-induced Ca2+ in mouse SMG cells. Both, histamine- and LPS-induced intracellular Ca2+ increases were inhibited by Dex, whereas carbachol-stimulated Ca2+ signals were not. Long-lasting (2 h) treatment with Dex reduced CBE activity in SMG and in human submandibular glands (HSG) cells. Moreover, when isolated SMG cells were stimulated with Dex for 2 h, phosphodiesterase 4D (PDE4D) expression was enhanced. These results confirm the anti-inflammatory properties of Dex on LPS-mediated signaling. Further, Dex also inhibited mRNA expression of interleukin-6 and NADPH oxidase 4. The present study also showed that α2-adrenoceptor activation by Dex reduces salivary glands fluid secretion by increasing PDE4D expression, and subsequently reducing the concentration of cAMP. These findings reveal an interaction between the α2-adrenoceptor and PDE4D, which should be considered when using α2-adrenoceptor agonists as sedative or analgesics.
- Dex inhibited LPS-induced IL-6 mRNA expression (#p < 0.05), however, cytosolic and secreted IL-6 protein levels showed no statistical difference (p < 0.1; Figures 7A,B). NADPH oxidases (Nox) are a major source of reactive oxygen species (ROS; Vieceli Dalla Sega et al., 2014), and LPS-induced oxidative stress was found to increase production of ROS through Nox4 (Ngkelo et al., 2012). Normal salivary glands cells express Nox2 and Nox4 (Tateishi et al., 2008).
- It has recently been reported that in a human neuronal cell line, SH-SY5Y, GLUT1 translocation in response to insulin-like growth factor (IGF-I) occurs  and, for the first time in a neuronal cell system, also GLUT4 is translocated to the plasma membrane in response to insulin . We have been studying for a long time the glucose transport activity in many leukaemia cell lines expressing mainly GLUT1, demonstrating that, also in these cell types, GLUT1 is recruited on the plasma membrane from intracellular compartments in response to different stimuli, greatly enhancing the rate of glucose uptake [29, 30] . Moreover , it is well known that impaired GLUT4 translocation is causally linked to insulin resistance and consequently to noninsulin-dependent diabetes mellitus [31, 32].
[Show abstract] [Hide abstract] ABSTRACT: Background and aims: 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 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 signaling is still unknown. The aim of this study was to investigate the effect of BBR on oxLDL- and TNFα-induced endothelial dysfunction in human umbilical vein endothelial cells (HUVECs) and to compare it with that of lovastatin (LOVA). Methods and results: Cytotoxicity was determined by lactate dehydrogenase assay. Antioxidant capacity was measured with chemiluminescent and fluorescent method and intracellular ROS levels through a fluorescent dye. Gene and protein expression levels were assayed by qRT-PCR and western blot, respectively. HUVECs exposure to oxLDL (30 μg/ml) or TNFα (10 ng/ml) for 24 h led to a significant increase in LOX1 expression, effect abrogated by BBR (5 μM) and LOVA (5 μM). BBR but not LOVA treatment abolished the TNFα-induced cytotoxicity and restored the activation of Akt signaling. In spite of a low direct antioxidant capacity, both compounds reduced intracellular ROS levels generated by treatment of TNFα but only BBR inhibited NOX2 expression, MAPK/Erk1/2 signaling and subsequent NF-κB target genes VCAM and ICAM expression, induced by TNFα. Conclusions: These findings demonstrated for the first time that BBR could prevent the oxLDL and TNFα - induced LOX1 expression and oxidative stress, key events that lead to NOX, MAPK/Erk1/2 and NF-κB activation linked to endothelial dysfunction. Chemical compounds studied in this article: Berberine (PubChem CID: 2353); Lovastatin (PubChem CID: 53232).
- LDH activity was assayed by a spectrophotometric method based on the reduction of pyruvate to lactic acid coupled to NADH oxidation. The decrease in absorbance at 340 nm was monitored at 37˚C. The cell viability was assessed by WST8 reagent (cell counting kit-8); it was added to each well according to the manufacturer's instructions.
[Show abstract] [Hide abstract] ABSTRACT: Molecules of mitochondrial cardiolipin (CL) get selectively oxidized upon oxidative stress, which triggers the intrinsic apoptotic pathway. In a chemical model most closely resembling the mitochondrial membrane—liposomes of pure bovine heart CL—we compared ubiquinol-10, ubiquinol-6, and alpha-tocopherol, the most widespread naturally occurring antioxidants, with man-made, quinol-based amphiphilic antioxidants. Lipid peroxidation was induced by addition of an azo initiator in the absence and presence of diverse antioxidants, respectively. The kinetics of CL oxidation was monitored via formation of conjugated dienes at 234 nm. We found that natural ubiquinols and ubiquinol-based amphiphilic antioxidants were equally efficient in protecting CL liposomes from peroxidation; the chromanol-based antioxidants, including alpha-tocopherol, were 2-3 times less efficient. Amphiphilic antioxidants, but not natural ubiquinols and alpha-tocopherol, were able, additionally, to protect the CL bilayer from oxidation by acting from the water phase. We suggest that the previously reported therapeutic efficiency of mitochondrially targeted amphiphilic antioxidants is owing to their ability to protect those CL molecules that are inaccessible to natural hydrophobic antioxidants, being trapped within respiratory supercomplexes. The high susceptibility of such occluded CL molecules to oxidation may have prompted their recruitment as apoptotic signaling molecules by nature.
- shown in Figure 3, the lipid peroxidation was initiated by an azo initiator, based on approaches described in [18, 76, 77], similarly as in our previous study . Following Noguchi et al.  , we launched the peroxidation of CL by adding the peroxyl radical azo initiator MeO- AMVN.
- To obtain a more substantial view of the mechanisms of damage accumulation we measured peptidase activities of proteasomes that are known to be involved in the degradation of oxidatively modified proteins . It is well established that quinones and semiquinones play an important role in electron leakage; hence, we measured the activity of DT-diaphorase, that detoxifies quinones and semiquinones and curbs the formation of ROS and oxidative damage . The anti-carcinogenic effects of DT-diaphorase are well documented [18,19].
[Show abstract] [Hide abstract] ABSTRACT: ABSTRACT Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells at various stages of differentiation/maturation that have a role in cancer induction and progression. They function as vasculogenic and immunosuppressive cells, utilizing multiple mechanisms to block both innate and adaptive anti-tumor immunity. Recently, their mechanism of action and clinical importance has been defined, and the cross talk between myeloid cells and cancer cells has been shown to contribute to tumor induction, progression, metastasis, and tolerance. In this review, we focus on the role of MDSCs in hematologic malignancies and the therapeutic approaches targeting MDSCs that are currently in clinical studies.
- The role of ROS in the development of a leukemic phenotype is important as leukemia cells are affected by intracellular and extracellular ROS-related redox disturbances that may support immune evasion and disease progression. Some tumor-derived GFs that expand MDSCs also contribute to leukemic cell growth and protect against apoptosis, including upregulation of ROS. In AML, malignant cells have significantly higher ROS levels than normal cells, thereby providing a mechanism for immune evasion[108,109].
[Show abstract] [Hide abstract] ABSTRACT: Background Chemoprevention represents the possibility to prevent, stop or reverse the cancerogenetic process. In this context the interest towards natural extracts and botanical drugs has constantly grown due to their phytochemical content. Castanea sativa Mill. (CSM) extracts showed to exert positive effect in the prevention/counteraction of chronic/degenerative diseases, therefore, we evaluated the potential chemopreventive effect of CSM bark extract. Methods Flow cytometry (FCM) analyses of Jurkat cells treated with CSM bark extract (0–500 μg·mL⁻¹) for 24–72 h allowed evaluating its cytotoxicity and ability to induce apoptosis through the intrinsic or extrinsic pathways. Moreover, to evaluate CSM bark extract selectivity towards cancer cells, its cytotoxic and pro-apoptotic effect was also evaluated in human peripheral blood lymphocytes (PBL). Results CSM bark extract induced apoptosis in Jurkat cells in a dose- and time- dependent manner activating the extrinsic pathways as evidenced by the increase of activated caspase-8 positive cells. Moreover, IC50 calculated after 24 h treatment resulted 304 and 128 μg·mL⁻¹ in PBL and Jurkat cells respectively. Conclusions Our data suggest that CSM bark extract might be considered an interesting potential anti-cancer agent, since it induces apoptosis in cancer cells without appreciable cytotoxic effects on non-transformed cells. Electronic supplementary material The online version of this article (doi:10.1186/s12906-017-1756-6) contains supplementary material, which is available to authorized users.
- MTT assay was performed as previously describedCells were incubated in 96-well flat-bottomed plates with 0.5 mg·mL −1 MTT for 4 h at 37 °C. At the end of the incubation, blue-violet formazan salt crystals were formed and dissolved by adding the solubilization solution (10% SDS, 0.01 M HCl), then the plates were incubated overnight in humidified atmosphere (37 °C, 5% CO 2 ) to ensure complete lysis.
[Show abstract] [Hide abstract] ABSTRACT: The aim of this study was to analyse the oxidative and anti-oxidant status in serum samples from dairy cows naturally infected by Dictyocaulus viviparus and its relation with pathological analyses. The diagnosis of the disease was confirmed by necropsy of one dairy cow with heavy infection by the parasite in the lungs and bronchi. Later, blood and faeces were collected from another 22 cows from the same farm to measure reactive oxygen species (ROS) levels, thiobarbituric acid-reactive substances (TBARS), catalase (CAT) and superoxide dismutase (SOD) activities on day 0 (pre-treatment) and day 10 (post-treatment with eprinomectin). Faecal examination confirmed the infection in all lactating cows. However, the number of D. viviparus larvae per gram of faeces varied between animals. Cows showed different degrees of severity according to respiratory clinical signs of the disease (cough and nasal secretion). Further, they were classified and divided into two groups: those with mild (n = 10) and severe disease (n = 12). Increased levels of TBARS (P < 0.001), ROS (P = 0.002) and SOD activity (P < 0.001), as well as reduced CAT activity (P < 0.001) were observed in cows with severe clinical signs of the disease compared to those with mild clinical signs. Eprinomectin treatment (day 10) caused a reduction of ROS levels (P = 0.006) and SOD activity (P < 0.001), and an increase of CAT activity (P = 0.05) compared to day 0 (pre-treatment). TBARS levels did not differ with treatment (P = 0.11). In summary, increased ROS production and lipid peroxidation altered CAT and SOD activities, as an adaptive response against D. viviparus infection, contributing to the occurrence of oxidative stress and severity of the disease. Treatment with eprinomectin eliminated the infection, and thus minimized oxidative stress in dairy cows.
- The literature reports that nematode parasites cause inflammation and generate ROS (Siwela et al., 2010), which induce oxidative damage of macromolecules such as polyunsaturated fatty acids in membrane lipids (Beyer et al., 1996). This study observed an increase in MDA content that caused deleterious effects on cells, followed by cell death (Beyer et al., 1996), which contributed to the severity of the disease. Catalase enzyme is responsible for the removal of hydrogen peroxide; therefore, the reduction in CAT activity in cows infected by D. viviparus (severe compared to mild disease) suggests an increase in Fig. 2. Blood and serum samples from dairy cows naturally infected with Dictyocaulus viviparus, showing mild and severe clinical signs of the disease, regarding their concentrations of (a) serum thiobarbituric acid reactive substances (TBARS: mmol/ml), (b) serum reactive oxygen species (ROS: uf/mg protein), (c) superoxide dismutase in blood (SOD: UI/mg protein), and (d) catalase in blood (CAT: mmol/mg protein).
[Show abstract] [Hide abstract] ABSTRACT: 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.
- Sample radioactivity was measured by liquid scintillation counting. Transported 2-deoxy-D-glucose was less than 20% of the extracellular-sugar concentration; therefore, glucose transport assay could be considered in zero-trans conditions . B1647 cells deprived of medium components and suspended in PBS during glucose transport measurements maintained their viability up to 2 hours at 37 ∘ C; thus, the number of viable cells during time intervals of experiments was considered constant (data not shown).
[Show abstract] [Hide abstract] ABSTRACT: 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.
- The B1647 cell line, deriving from a human erythromegakaryocytic acute leukaemia, was chosen as a cell model naturally expressing AQP8, Nox proteins, tyrosine kinase receptor VEGFR-2, constitutively producing VEGFand possessing the requisite Akt signaling hub. To assess the involvement of AQP8 in facilitating H 2 O 2 diffusion through plasma membrane, cells were transfected by electroporation with plasmid designed for the overexpression of AQP8 or with specific siRNA against AQP8.
[Show abstract] [Hide abstract] ABSTRACT: Myeloid leukemia cells maintain a high intracellular ROS level and use redox signals for survival. The metabolism of ROS also affects cell fate, including cell death and differentiation. Superoxide dismutases (SODs) are major antioxidant enzymes that have high levels of expression in myeloid leukemia cells. However, the role of SODs in the regulation of myeloid leukemia cells' biological function is still unclear. To investigate the function of SODs in myeloid leukemia cell death and differentiation, we used myeloid leukemia cell lines K562, MEG-01, TF-1, and HEL cells for this study. We found that PMA-induced megakaryocytic differentiation in myeloid leukemia cells is accompanied by cell death and SOD1 down-regulation, while SOD2 expression is not affected. The role of SOD1 is verified when ATN-224, a SOD1 specific inhibitor, inhibits cell proliferation and promotes cell death in myeloid leukemia cells without PMA treatment. Moreover, inhibition or silencing of SODs further increases cell death and decreases polyploidization induced by PMA while they were partially reversed by SOD1 overexpression. Thus, SOD1 expression is required for myeloid leukemia cell fate determination. In addition, the knockdown of PKD2 reduces cell death and promotes polyploidization induced by PMA. PMA/PKD2-mediated necrosis via PARP cleavage involves both SOD1-dependent and -independent pathways. Finally, ATN-224 enhanced the inhibition of cell proliferation by Ara-C. Taken together, the results demonstrate that SOD1 regulates cell death and differentiation in myeloid leukemia cells. ATN-224 may be beneficial for myeloid leukemia therapy. Copyright © 2015. Published by Elsevier B.V.
- AML patients with Fms-like tyrosine kinase 3 -internal tandem duplications (FLT3-ITD) mutation constitute about 30% of AML cases and these patients suffer from poor prognosis . FLT3 increase ROS production via the activation of p22 phox that maintains a higher ROS level in AML cells  and it is essential to their survival. Moreover, inhibition of PDK1/AKT and FLT3 signaling induces AML cell death .
[Show abstract] [Hide abstract] ABSTRACT: The antioxidant activity of mitochondria-targeted small molecules, SkQ1 and MitoQ (conjugates of a lipophilic decyltriphenylphosphonium cation with an antioxidant moiety of a plastoquinone and ubiquinone, respectively), was studied in aqueous solution and in a lipid environment, i.e., micelles, liposomes and planar bilayer lipid membranes. Reactive oxygen species (ROS) were generated by azo initiators or ferrous ions with or without tert-butyl-hydroperoxide (t-BOOH). Chemiluminescence, fluorescence, oxygen consumption and inactivation of gramicidin peptide channels were measured to detect antioxidant activity. In all of the systems studied, SkQ1 was shown to effectively scavenge ROS. The scavenging was inherent to the reduced form of the quinone (SkQ1H(2)). In the majority of the above model systems, SkQ1 exhibited higher antioxidant activity than MitoQ. It is concluded that SkQ1H(2) operates as a ROS scavenger in both aqueous and lipid environments, being effective at preventing ROS-induced damage to membrane lipids as well as membrane-embedded peptides.
- Reduced quinones, in particular ubiquinol and plastoquinol, are known to be lipophilic antioxidants, inhibiting lipid peroxidation in both natural (Ernster and Dallner 1995, and refs. therein; Hundal et al. 1995) and artificial (Frei et al. 1990; Landi et al. 1991; Kagan et al. 1990; Shi et al. 1999; Xia et al. 2007) membranes. The fact that MitoQ prevents lipid peroxidation in mitochondrial membranes (Asin-Cayuela et al. 2004) was considered to be an indication that this compound operates as a ROS scavenger.
University of Bologna