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1.
Melatonin is a pleiotropic molecule with many cellular and systemic actions, including chronobiotic effects. Beneficial effects are widely documented concerning the treatment of neoplastic diseases in vivo as well as reductions in viability of cultured cells from melanoma, one of the most aggressive cancers in humans. However, studies of its effects on non-tumor cells in vitro have not focused on viability, except for experiments aiming to protect against oxidotoxicity or other toxicological insults. Furthermore, there is no agreement on the range of effective melatonin concentrations in vitro, and the mechanisms that reduce cell viability have remained unclear. Tumor cell-specific increases in the production of reactive oxygen and nitrogen species (ROS/RNS) may provide a possible explanation. Our aim was to analyze the potential inhibition of tumor (B16 melanoma 4A5) and non-tumor cell (3T3 Swiss albino) viability using a wide range of melatonin concentrations (10−11–10−2 M), and to determine whether intracellular ROS enhancement was involved in this process. In the absence of fetal bovine serum (FBS), low melatonin concentrations (10−9–10−5 M) reduced the proliferation of melanoma cells with no effect in fibroblasts, whereas, in the presence of FBS, they had no effect or even increased the proliferation of both fibroblast and melanoma cells. Melatonin concentrations in the upper millimolar range increased ROS levels and reduced the viability of both cell types, but more markedly so in non-tumor cells. Thus, low melatonin concentrations reduce proliferation in this specific melanoma cell line, whereas high concentrations affect the viability of both tumor (B16 4A5 melanoma) and non-tumor (3T3 fibroblasts) cells. Increased ROS levels in both lines indicate a role for ROS production in the reduction of cell viability at high—but not low—melatonin concentrations, although the mechanism of action still remains to be elucidated.  相似文献   

2.
The human body is constantly under attack from free radicals that occur as part of normal cell metabolism, and by exposure to environmental factors such as UV light, cigarette smoke, environmental pollutants and gamma radiation. The resulting “Reactive Oxygen Species” (ROS) circulate freely in the body with access to all organs and tissues, which can have serious repercussions throughout the body. The body possesses a number of mechanisms both to control the production of ROS and to cope with free radicals in order to limit or repair damage to tissues. Overproduction of ROS or insufficient defense mechanisms leads to a dangerous disbalance in the organism. Thereby several pathomechanisms implicated in over 100 human diseases, e.g., cardiovascular disease, cancer, diabetes mellitus, physiological disease, aging, etc., can be induced. Thus, a detailed investigation on the quantity of oxygen radicals, such as hydroxyl radicals (OH) in human serum blood, and its possible correlation with antioxidant therapy effects, is highly topical. The subject of this study was the influence of schizophrenia on the amount of OH in human serum blood. The radicals were detected by fluorimetry, using terephthalic acid as a chemical trap. For all experiments the serum blood of healthy people was used as a control group.  相似文献   

3.
Prostate cancer is a leading cause of cancer-associated deaths in men over 60 years of age. Most patients are killed by tumor metastasis. Recent evidence has implicated a role of the tumor microenvironment and urokinase plasminogen activator (uPA) in cancer cell migration, invasion, and metastasis. Here, we examine the role of the Na+/H+ exchanger isoform 1 (NHE1) and uPA in DU 145 prostate cancer cell migration and colony formation. Knockout of NHE1 reduced cell migration. The effects of a series of novel NHE1/uPA hexamethylene-amiloride-based inhibitors with varying efficacy towards NHE1 and uPA were examined on prostate cancer cells. Inhibition of NHE1—alone, or with inhibitors combining NHE1 or uPA inhibition—generally did not prevent prostate cancer cell migration. However, uPA inhibition—but not NHE1 inhibition—prevented anchorage-dependent colony formation. Application of inhibitors at concentrations that only saturate uPA inhibition decreased tumor invasion in vivo. The results suggest that while knockout of NHE1 affects cell migration, these effects are not due to NHE1-dependent proton translocation. Additionally, while neither NHE1 nor uPA activity was critical in cell migration, only uPA activity appeared to be critical in anchorage-dependent colony formation of DU 145 prostate cancer cells and invasion in vivo.  相似文献   

4.
Vegetables are widely consumed in Brazil and exported to several countries. This study was performed to evaluate the phenolic content and antioxidant activity of vegetables commonly consumed in Brazil using five different methods, namely DPPH and ABTS free radical, β-carotene bleaching, reduction of Fe3+ (FRAP), oxidative stability in Rancimat, and the chemical composition using gas chromatography-mass spectrometry (GC-MS). The content of phenolic compounds ranged from 1.2 mg GA/g (carrot) to 16.9 mg GA/g (lettuce). Vegetables presenting the highest antioxidant activity were lettuce (77.2 μmol Trolox/g DPPH; 447.1 μmol F2+/g FRAP), turmeric (118.6 μmol Trolox/g ABTS•+; 92.8% β-carotene), watercress and broccoli (protective factor 1.29—Rancimat method). Artichoke, spinach, broccoli, and asparagus also showed considerable antioxidant activity. The most frequent phenolic compounds identified by GC-MS were ferulic, caffeic, p-coumaric, 2-dihydroxybenzoic, 2,5-dihydroxybenzoic acids, and quercetin. We observed antioxidant activity in several vegetables and our results point out their importance in the diet.  相似文献   

5.
The current study was performed to investigate mitochondrial protection and anti-aging activity of Astragalus polysaccharides (APS) and the potential underlying mechanism. Lipid peroxidation of liver and brain mitochondria was induced by Fe2+–Vit C in vitro. Thiobarbituric acid (TBA) colorimetry was used to measure the content of thiobarbituric acid reactive substances (TBARS). Mouse liver mitochondrial permeability transition (PT) was induced by calcium overload in vitro and spectrophotometry was used to measure it. The scavenging activities of APS on superoxide anion (O2•−) and hydroxyl radical (•OH), which were produced by reduced nicotinamide adenine dinucleotide (NADH)—N-Methylphenazonium methyl sulfate (PMS) and hydrogen peroxide (H2O2)–Fe2+ system respectively, were measured by 4-nitrobluetetrazolium chloride (NBT) reduction and Fenton reaction colorimetry respectively. The Na2S2O3 titration method was used to measure the scavenging activities of APS on H2O2. APS could inhibit TBARS production, protect mitochondria from PT, and scavenge O2•−, •OH and H2O2 significantly in a concentration-dependent manner respectively. The back of the neck of mice was injected subcutaneously with D-galactose to induce aging at a dose of 100 mg/kg/d for seven weeks. Moreover, the activities of catalase (CAT), surperoxide dismutase (SOD) and glutathione peroxidase (GPx) and anti-hydroxyl radical which were assayed by using commercial monitoring kits were increased significantly in vivo by APS. According to this research, APS protects mitochondria by scavenging reactive oxygen species (ROS), inhibiting mitochondrial PT and increasing the activities of antioxidases. Therefore, APS has the effect of promoting health.  相似文献   

6.
The levels of methionine sulfoxide (MetO) and the abundances of methionine sulfoxide reductases (Msrs) were reported as important for the desiccation tolerance of Acer seeds. To determine whether the MetO/Msrs system is related to reactive oxygen species (ROS) and involved in the regulation of germination in orthodox and recalcitrant seeds, Norway maple and sycamore were investigated. Changes in water content, MetO content, the abundance of MsrB1 and MsrB2 in relation to ROS content and the activity of reductases depending on nicotinamide adenine dinucleotides were monitored. Acer seeds differed in germination speed—substantially higher in sycamore—hydration dynamics, levels of hydrogen peroxide, superoxide anion radicals (O2•−) and hydroxyl radicals (•OH), which exhibited peaks at different stages of germination. The MetO level dynamically changed, particularly in sycamore embryonic axes, where it was positively correlated with the levels of O2•− and the abundance of MsrB1 and negatively with the levels of •OH and the abundance of MsrB2. The MsrB2 abundance increased upon sycamore germination; in contrast, it markedly decreased in Norway maple. We propose that the ROS–MetO–Msr redox system, allowing balanced Met redox homeostasis, participates in the germination process in sycamore, which is characterized by a much higher speed compared to Norway maple.  相似文献   

7.
8.
Melanoma is the most aggressive type of skin cancer due to its high capability of developing metastasis and acquiring chemoresistance. Altered redox homeostasis induced by increased reactive oxygen species is associated with melanomagenesis through modulation of redox signaling pathways. Dysfunctional endothelial nitric oxide synthase (eNOS) produces superoxide anion (O2−•) and contributes to the establishment of a pro-oxidant environment in melanoma. Although decreased tetrahydrobiopterin (BH4) bioavailability is associated with eNOS uncoupling in endothelial and human melanoma cells, in the present work we show that eNOS uncoupling in metastatic melanoma cells expressing the genes from de novo biopterin synthesis pathway Gch1, Pts, and Spr, and high BH4 concentration and BH4:BH2 ratio. Western blot analysis showed increased expression of Nos3, altering the stoichiometry balance between eNOS and BH4, contributing to NOS uncoupling. Both treatment with L-sepiapterin and eNOS downregulation induced increased nitric oxide (NO) and decreased O2 levels, triggering NOS coupling and reducing cell growth and resistance to anoikis and dacarbazine chemotherapy. Moreover, restoration of eNOS activity impaired tumor growth in vivo. Finally, NOS3 expression was found to be increased in human metastatic melanoma samples compared with the primary site. eNOS dysfunction may be an important mechanism supporting metastatic melanoma growth and hence a potential target for therapy.  相似文献   

9.
The high plasticity of cancer stem-like cells (CSCs) allows them to differentiate and proliferate, specifically when xenotransplanted subcutaneously into immunocompromised mice. CSCs are highly tumorigenic, even when inoculated in small numbers. Thus, in vivo limiting dilution assays (LDA) in mice are the current gold standard method to evaluate CSC enrichment and activity. The chick embryo chorioallantoic membrane (CAM) is a low cost, naturally immune-incompetent and reproducible model widely used to evaluate the spontaneous growth of human tumor cells. Here, we established a CAM-LDA assay able to rapidly reproduce tumor specificities—in particular, the ability of the small population of CSCs to form tumors. We used a panel of organotropic metastatic breast cancer cells, which show an enrichment in a stem cell gene signature, enhanced CD44+/CD24−/low cell surface expression and increased mammosphere-forming efficiency (MFE). The size of CAM-xenografted tumors correlate with the number of inoculated cancer cells, following mice xenograft growth pattern. CAM and mice tumors are histologically comparable, displaying both breast CSC markers CD44 and CD49f. Therefore, we propose a new tool for studying CSC prevalence and function—the chick CAM-LDA—a model with easy handling, accessibility, rapid growth and the absence of ethical and regulatory constraints.  相似文献   

10.
As a naturally occurring anthraquinone pigment, chrysophanol (MHAQ) has attracted considerable attention in recent years owing to its efficient photosensitivity under the solar spectrum. Considering the successful use of time-dependent density functional theory (TD-DFT) in investigating the photo-physicochemical behaviors of dyes and pigments, we performed a study by means of TD-DFT calculations, which provided us with various excited state properties of chrysophanol, including absorption spectrum, lowest triplet excited-state energy, vertical electron affinity and vertical ionization potential. On the basis of the calculated results, the photosensitive mechanisms of chrysophanol were discussed and some deeper insights were gained. First, we indicated that the experimentally observed chrysophanol’s photo-damage to DNA in oxygen-free media is more likely to arise from MHAQ•+ rather than from T1 state chrysophanol. Second, we revealed that it is the MHAQ•− that is responsible for the O2•− generation in solvents. Based on the photosensitive activities, chrysophanol may be potentially used as the photodynamic medicine for clinical therapy of the diseases occurring on the shallow surface and vascular capillary diseases.  相似文献   

11.
12.
RRM1—an important DNA replication/repair enzyme—is the primary molecular gemcitabine (GEM) target. High RRM1-expression associates with gemcitabine-resistance in various cancers and RRM1 inhibition may provide novel cancer treatment approaches. Our study elucidates how RRM1 inhibition affects cancer cell proliferation and influences gemcitabine-resistant bladder cancer cells. Of nine bladder cancer cell lines investigated, two RRM1 highly expressed cells, 253J and RT112, were selected for further experimentation. An RRM1-targeting shRNA was cloned into adenoviral vector, Ad-shRRM1. Gene and protein expression were investigated using real-time PCR and western blotting. Cell proliferation rate and chemotherapeutic sensitivity to GEM were assessed by MTT assay. A human tumor xenograft model was prepared by implanting RRM1 highly expressed tumors, derived from RT112 cells, in nude mice. Infection with Ad-shRRM1 effectively downregulated RRM1 expression, significantly inhibiting cell growth in both RRM1 highly expressed tumor cells. In vivo, Ad-shRRM1 treatment had pronounced antitumor effects against RRM1 highly expressed tumor xenografts (p < 0.05). Moreover, combination of Ad-shRRM1 and GEM inhibited cell proliferation in both cell lines significantly more than either treatment individually. Cancer gene therapy using anti-RRM1 shRNA has pronounced antitumor effects against RRM1 highly expressed tumors, and RRM1 inhibition specifically increases bladder cancer cell GEM-sensitivity. Ad-shRRM1/GEM combination therapy may offer new treatment options for patients with GEM-resistant bladder tumors.  相似文献   

13.
Cancer is one of the main causes of death worldwide, and, among the most frequent cancer types, osteosarcoma accounts for 56% of bone neoplasms observed in children and colorectal cancer for 10.2% of tumors diagnosed in the adult population. A common and frequent hurdle in cancer treatment is the emergence of resistance to chemo- and radiotherapy whose biological causes are largely unknown. In the present work, human osteosarcoma (SAOS) and colorectal adenocarcinoma (HT29) cell lines were γ-irradiated at doses mimicking the sub-lethal irradiation in clinical settings to obtain two radio-resistant cellular sub-populations named SAOS400 and HT500, respectively. Since “therapy-induced senescence” (TIS) is often associated with tumor response to radiotherapy in cancer cells, we measured specific cellular and biochemical markers of senescence in SAOS400 and HT500 cells. In detail, both cell lines were characterized by a higher level of expression of cyclin-dependent kinase inhibitors p16INK4 and p21CIP1 and increased positivity to SAβ-gal (senescence-associated β-galactosidase) with respect to parental cells. Moreover, the intracellular levels of reactive oxygen species in the resistant cells were significantly lower compared to the parental counterparts. Subsequently, we demonstrated that senolytic agents were able to sensitize SAOS400 and HT500 to cell death induced by γ-irradiation. Employing two natural flavonoids, fisetin and quercetin, and a BH3-mimetic, ABT-263/navitoclax, we observed that their association with γ-irradiation significantly reduced the expression of p16INK4, p21CIP1 and synergistically (combination index < 1) increased cell death compared to radiation mono-alone treatments. The present results reinforce the potential role of senolytics as adjuvant agents in cancer therapy.  相似文献   

14.
Tumor microenvironments are often characterized by an increase in oxidative stress levels. We studied the response to oxidative stimulation in human primary (IGR39) or metastatic (IGR37) cell lines obtained from the same patient, performing patch-clamp recordings, intracellular calcium ([Ca2+]i) imaging, and RT-qPCR gene expression analysis. In IGR39 cells, chloramine-T (Chl-T) activated large K+ currents (KROS) that were partially sensitive to tetraethylammonium (TEA). A large fraction of KROS was inhibited by paxilline—a specific inhibitor of large-conductance Ca2+-activated BK channels. The TEA-insensitive component was inhibited by senicapoc—a specific inhibitor of the Ca2+-activated KCa3.1 channel. Both BK and KCa3.1 activation were mediated by an increase in [Ca2+]i induced by Chl-T. Both KROS and [Ca2+]i increase were inhibited by ACA and clotrimazole—two different inhibitors of the calcium-permeable TRPM2 channel. Surprisingly, IGR37 cells did not exhibit current increase upon the application of Chl-T. Expression analysis confirmed that the genes encoding BK, KCa3.1, and TRPM2 are much more expressed in IGR39 than in IGR37. The potassium currents and [Ca2+]i increase observed in response to the oxidizing agent strongly suggest that these three molecular entities play a major role in the progression of melanoma. Pharmacological targeting of either of these ion channels could be a new strategy to reduce the metastatic potential of melanoma cells, and could complement classical radio- or chemotherapeutic treatments.  相似文献   

15.
In this study, leaves of three indigenous varieties of Mulberry namely, Morus alba L., Morus nigra L. and Morus rubra L. were investigated for their antioxidant potential and their proximate composition was determined. The yields of 80% methanolic extracts ranged between 8.28–13.89%. The contents of total phenolics (TPC), total flavonoids (TFC) and ascorbic acid (AA) ranged between 16.21–24.37 mg gallic acid equivalent (GAE)/g, 26.41–31.28 mg rutin equivalent (RE)/g and 0.97–1.49 mg/g, respectively. The antioxidant activity of leaf extracts was evaluated by measuring 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging actity, 2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid (ABTS•+) radical cation scavenging capacity and ferric ion reducing power and values ranged between 1.89–2.12, 6.12–9.89 and 0.56–0.97 mM Trolox equivalent/g of dried leaves, respectively. The investigated features reveal good nutritive and antioxidant attributes of all the varieties with mutually significant differences.  相似文献   

16.
Oxidative stress (OS) contributes to the cascade leading to the dysfunction or death of dopaminergic neurons during Parkinson’s disease (PD). A strategy to prevent the OS of dopaminergic neurons may be the use of phytochemicals as inducers of endogenous antioxidants and phase 2 enzymes. In this study, we demonstrated that treatment of the dopaminergic-like neuroblastoma SH-SY5Y cell line with isothiocyanate erucin (ER), a compound of cruciferous vegetables, resulted in significant increases of both total glutathione (GSH) levels and total antioxidant capacity at the cytosolic level. The increase of GSH levels was associated with an increase in the resistance of SH-SY5Y cells to neuronal death, in terms of apoptosis, induced by 6-hydroxydopamine (6-OHDA). The pretreatment of SH-SY5Y cells with ER was also shown to prevent the redox status impairment, in terms of intracellular ROS and O2•− formation, and loss of mitochondrial membrane potential, early events that are initiators of the apoptotic process, induced by 6-OHDA. Last, the antiapoptotic and antioxidant effects of ER were abolished by buthionine sulfoximine, supporting the main role of GSH in the neuroprotective effects recorded by ER. These results suggest that ER may prevent the oxidative damage induced by 6-OHDA.  相似文献   

17.
N-acetylcysteine (NAC), often used as an antioxidant-scavenging reactive oxygen species (ROS) in vitro, was recently shown to increase the cytotoxicity of other compounds through ROS-dependent and ROS-independent mechanisms. In this study, NAC itself was found to induce extensive ROS production in human leukemia HL-60 and U937 cells. The cytotoxicity depends on ROS-modulating enzyme expression. In HL-60 cells, NAC activated NOX2 to produce superoxide (O2). Its subsequent conversion into H2O2 by superoxide dismutase 1 and 3 (SOD1, SOD3) and production of ClO from H2O2 by myeloperoxidase (MPO) was necessary for cell death induction. While the addition of extracellular SOD potentiated NAC-induced cell death, extracellular catalase (CAT) prevented cell death in HL-60 cells. The MPO inhibitor partially reduced the number of dying HL-60 cells. In U937 cells, the weak cytotoxicity of NAC is probably caused by lower expression of NOX2, SOD1, SOD3, and by the absence of MOP expression. However, even here, the addition of extracellular SOD induced cell death in U937 cells, and this effect could be reversed by extracellular CAT. NAC-induced cell death exhibited predominantly apoptotic features in both cell lines. Conclusions: NAC itself can induce extensive production of O2 in HL-60 and U937 cell lines. The fate of the cells then depends on the expression of enzymes that control the formation and conversion of ROS: NOX, SOD, and MPO. The mode of cell death in response to NAC treatment bears apoptotic and apoptotic-like features in both cell lines.  相似文献   

18.
The ruthenium-based complex [Ru(η6-p-phenylethacrynate)Cl2(pta)] (pta = 1,3,5-triaza-7-phosphatricyclo-[3.3.1.1]decane), termed ethaRAPTA, is an interesting antitumor compound. The elucidation of the molecular mechanism of drug activity is central to the drug development program. To this end, we have characterized the ethaRAPTA interaction with DNA, including probing the sequence specific modified DNA structural stability and DNA amplification using the breast cancer suppressor gene 1 (BRCA1) of human breast and colon adenocarcinoma cell lines as models. The preference of ethaRAPTA base binding is in the order A > G > T > C. Once modified, the ethaRAPTA-induced BRCA1 structure has higher thermal stability than the modified equivalents of its related compound, RAPTA-C. EthaRAPTA exhibits a higher efficiency than RAPTA-C in inhibiting BRCA1 amplification. With respect to both compounds, the inhibition of BRCA1 amplification is more effective in an isolated system than in cell lines. These data provide evidence that will help to understand the process of elucidating the pathways involved in the response induced by ethaRAPTA.  相似文献   

19.
Chemical examination of the Taiwanese soft coral Sinularia flexibilis led to the isolation of five cembrane-based diterpenoids 1–5, including two new metabolites, 11-acetylsinuflexolide (1) and 11-acetyldihydrosinuflexolide (2). The structures of the new metabolites were determined based on extensive spectroscopic analysis, particularly mass spectrometry and 2D NMR (1H–1H COSY, HMQC, HMBC, and NOESY) spectroscopy. Metabolites 1, 3 and 4 exhibited moderate to weak cytotoxicity to human tumor cell lines, HeLa, HEp-2, MCF-7 and MDA-MB-231.  相似文献   

20.
Macroporous polyacrylamide-grafted-chitosan scaffolds for neural tissue engineering were fabricated with varied synthetic and viscosity profiles. A novel approach and mechanism was utilized for polyacrylamide grafting onto chitosan using potassium persulfate (KPS) mediated degradation of both polymers under a thermally controlled environment. Commercially available high molecular mass polyacrylamide was used instead of the acrylamide monomer for graft copolymerization. This grafting strategy yielded an enhanced grafting efficiency (GE = 92%), grafting ratio (GR = 263%), intrinsic viscosity (IV = 5.231 dL/g) and viscometric average molecular mass (MW = 1.63 × 106 Da) compared with known acrylamide that has a GE = 83%, GR = 178%, IV = 3.901 dL/g and MW = 1.22 × 106 Da. Image processing analysis of SEM images of the newly grafted neurodurable scaffold was undertaken based on the polymer-pore threshold. Attenuated Total Reflectance-FTIR spectral analyses in conjugation with DSC were used for the characterization and comparison of the newly grafted copolymers. Static Lattice Atomistic Simulations were employed to investigate and elucidate the copolymeric assembly and reaction mechanism by exploring the spatial disposition of chitosan and polyacrylamide with respect to the reactional profile of potassium persulfate. Interestingly, potassium persulfate, a peroxide, was found to play a dual role initially degrading the polymers—“polymer slicing”—thereby initiating the formation of free radicals and subsequently leading to synthesis of the high molecular mass polyacrylamide-grafted-chitosan (PAAm-g-CHT)—“polymer complexation”. Furthermore, the applicability of the uniquely grafted scaffold for neural tissue engineering was evaluated via PC12 neuronal cell seeding. The novel PAAm-g-CHT exhibited superior neurocompatibility in terms of cell infiltration owing to the anisotropic porous architecture, high molecular mass mediated robustness, superior hydrophilicity as well as surface charge due to the acrylic chains. Additionally, these results suggested that the porous PAAm-g-CHT scaffold may act as a potential neural cell carrier.  相似文献   

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