Redox-active cerium oxide nanoparticles protect human dermal fibroblasts from PQ-induced damage

AbstractRecently, it has been published that cerium (Ce) oxide nanoparticles (CNP; nanoceria) are able to downregulate tumor invasion in cancer cell lines. Redox-active CNP exhibit both selective pro-oxidative and antioxidative properties, the first being responsible for impairment of tumor growth and invasion. A non-toxic and even protective effect of CNP in human dermal fibroblasts (HDF) has already been observed. However, the effect on important parameters such as cell death, proliferation and redox state of the cells needs further clarification. Here, we present that nanoceria prevent HDF from reactive oxygen species (ROS)-induced cell death and stimulate proliferation due to the antioxidative property of these particles

Singlet oxygen inactivates protein tyrosine phosphatase-1B by oxidation of the active site cysteine

Singlet oxygen (1O2), an electronically excited form of molecular oxygen, is a mediator of biological effects of ultraviolet A radiation, stimulating signaling cascades in human cells. We demonstrate here that 1O2 generated by photosensitization or by thermodecomposition of 3,3′-(1,4-naphthylidene)dipropionate-1,4-endoperoxide inactivates isolated protein tyrosine phosphatases (PTPases). PTPase activities of PTP1B or CD45 were abolished by low concentrations of 1O2, but were largely restored by post-treatment with dithiothreitol. Electrospray ionization mass spectrometry analysis of tryptic digests of PTP1B exposed to 1O2 revealed oxidation of active-site Cys215 as the only cysteine residue oxidized. In summary, 1O2 may activate signaling cascades by interfering with phosphotyrosine dephosphorylation.This study was supported by Deutsche Forschungsgemeinschaft (Bonn, Germany; Sonderforschungsbereich 503, Project B1). H.S. is a Fellow of the National Foundation for Cancer Research, Bethesda, MD, USA

GD3 synthase overexpression sensitizes hepatocarcinoma cells to hypoxia and reduces tumor growth by suppressing the cSrc/NF-κB survival pathway

This is an open-access article distributed under the terms of the Creative Commons Attribution License.[Background]: Hypoxia-mediated HIF-1a stabilization and NF-kB activation play a key role in carcinogenesis by fostering cancer cell survival, angiogenesis and tumor invasion. Gangliosides are integral components of biological membranes with an increasingly recognized role as signaling intermediates. In particular, ganglioside GD3 has been characterized as a proapoptotic lipid effector by promoting cell death signaling and suppression of survival pathways. Thus, our aim was to analyze the role of GD3 in hypoxia susceptibility of epatocarcinoma cells and in vivo tumor growth.[Methodology/Principal Findings]: We generated and characterized a human hepatocarcinoma cell line stably expressing GD3 synthase (Hep3B-GD3), which catalyzes the synthesis of GD3 from GM3. Despite increased GD3 levels (2–3 fold), no significant changes in cell morphology or growth were observed in Hep3B-GD3 cells compared to wild type Hep3B cells under normoxia. However, exposure of Hep3B-GD3 cells to hypoxia (2% O2) enhanced reactive oxygen species (ROS) generation, resulting in decreased cell survival, with similar findings observed in Hep3B cells exposed to increasing doses of exogenous GD3. In addition, hypoxia-induced c-Src phosphorylation at tyrosine residues, NF-kB activation and subsequent expression of Mn-SOD were observed in Hep3B cells but not in Hep3B-GD3 cells. Moreover, MnTBAP, an antioxidant with predominant SOD mimetic activity, reduced ROS generation, protecting Hep3B-GD3 cells from hypoxia-induced death. Finally, lower tumor growth, higher cell death and reduced Mn-SOD expression were observed in Hep3B-GD3 compared to Hep3B tumor xenografts.[Conclusion]: These findings underscore a role for GD3 in hypoxia susceptibility by disabling the c-Src/NF-kB survival pathway resulting in lower Mn-SOD expression, which may be of relevance in hepatocellular carcinoma therapy.Grant support: CIBEREHD and grants FIS06/0395, FIS07/1039, SAF2006-06789 and SAF2008-02199 by Instituto de Salud Carlos III and Ministry of Science and Innovation from Spain, and from the Research Center for Liver and Pancreatic Diseases, P50-AA-11999 funded by the US National Institute on Alcohol Abuse and Alcoholism.Peer reviewe

Mitochondrial GSH determines the toxic or therapeutic potential of superoxide scavenging in steatohepatitis

BACKGROUND & AIMS: Steatohepatitis (SH) is associated with mitochondrial dysfunction and excessive production of superoxide, which can then be converted into H(2)O(2) by SOD2. Since mitochondrial GSH (mGSH) plays a critical role in H(2)O(2) reduction, we explored the interplay between superoxide, H(2)O(2), and mGSH in nutritional and genetic models of SH, which exhibit mGSH depletion. METHODS: We used isolated mitochondria and primary hepatocytes, as well as in vivo SH models showing mGSH depletion to test the consequences of superoxide scavenging. RESULTS: In isolated mitochondria and primary hepatocytes, superoxide scavenging by SOD mimetics or purified SOD decreased superoxide and peroxynitrite generation but increased H(2)O(2) following mGSH depletion, despite mitochondrial peroxiredoxin/thioredoxin defense. Selective mGSH depletion sensitized hepatocytes to cell death induced by SOD mimetics, and this was prevented by RIP1 kinase inhibition with necrostatin-1 or GSH repletion with GSH ethyl ester (GSHee). Mice fed the methionine-choline deficient (MCD) diet or MAT1A(-/-) mice exhibited reduced SOD2 activity; in vivo treatment with SOD mimetics increased liver damage, inflammation, and fibrosis, despite a decreased superoxide and 3-nitrotyrosine immunoreactivity, effects that were ameliorated by mGSH replenishment with GSHee, but not NAC. As a proof-of-principle of the detrimental role of superoxide scavenging when mGSH was depleted transgenic mice overexpressing SOD2 exhibited enhanced susceptibility to MCD-mediated SH. CONCLUSIONS: These findings underscore a critical role for mGSH in the therapeutic potential of superoxide scavenging in SH, and suggest that the combined approach of superoxide scavenging with mGSH replenishment may be important in SH

Targeting cholesterol at different levels in the mevalonate pathway protects fatty liver against ischemia-reperfusion injury

El pdf del artículo es la versión post-print.Background & Aims: Liver steatosis enhances ischemia/reperfusion (I/R) injury and is considered a primary factor in graft failure after liver transplantation. Although previous reports have shown a role for qualitative steatosis (macrovesicular vs. microvesicular) in hepatic I/R injury, no studies have compared side by side the specific contribution of individual lipids accumulating in fatty liver to I/R damage. Methods: We used nutritional and genetic models of micro and macrovesicular fatty livers exhibiting specific lipid profiles to assess their susceptibility to normothermic I/R injury. Results: Unlike choline-deficient (CD) diet-fed mice, characterized by predominant liver triglycerides/free fatty acids (TG/FFA) accumulation, mice fed a cholesterol-enriched (HC) diet, which exhibited enhanced hepatic cholesterol loading in mitochondria, were highly sensitive to I/R-induced liver injury. In vivo two-photon confocal imaging revealed enhanced mitochondrial depolarization and generation of reactive oxygen species following hepatic I/R in HC-fed but not in CD-fed mice, consistent with decreased mitochondrial GSH (mGSH) observed in HC-fed mice. Moreover, ob/ob mice, characterized by increased hepatic TG, FFA, and cholesterol levels, were as sensitive to I/R-mediated liver injury as mice fed the HC diet. Livers from ob/ob mice displayed increased StAR expression and mitochondrial cholesterol accumulation, resulting in mGSH depletion. Interestingly, atorvastatin therapy or squalene synthase inhibition in vivo attenuated StAR overexpression, mitochondrial cholesterol loading, and mGSH depletion, protecting ob/ob mice from I/R-mediated liver injury. Conclusions: Cholesterol accumulation, particularly in mitochondria, sensitizes to hepatic I/R injury, and thus represents a novel target to prevent the enhanced damage of steatotic livers to I/R-mediated damage. © 2010 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.The work was supported by grants SAF2006-06780, SAF2008-02199, SAF2008-04974 and SAF2009-11417 (Plan Nacional de I+D), PI070193 and PI09/00056 (Institut de Salud Carlos III), by CIBEREHD from the Institut Carlos III, the Fundación Mutua Madrileña and the center grant P50-AA-11999 Research Center for Liver and Pancreatic Diseases, US National Institute on Alcohol Abuse and Alcoholism, USA.Peer Reviewe

Downregulation of tumor growth and invasion by redox-active nanoparticles

This work is part of the PhD thesis of M.S. at the Heinrich-Heine-University of Düsseldorf.-- et al.[Aims]: Melanoma is the most aggressive type of malignant skin cancer derived from uncontrolled proliferation of melanocytes. Melanoma cells possess a high potential to metastasize, and the prognosis for advanced melanoma is rather poor due to its strong resistance to conventional chemotherapeutics. Nanomaterials are at the cutting edge of the rapidly developing area of nanomedicine. The potential of nanoparticles for use as carrier in cancer drug delivery is infinite with novel applications constantly being tested. The noncarrier use of cerium oxide nanoparticles (CNPs) is a novel and promising approach, as those particles per se show an anticancer activity via their oxygen vacancy-mediated chemical reactivity. [Results]: In this study, the question was addressed of whether the use of CNPs might be a valuable tool to counteract the invasive capacity and metastasis of melanoma cells in the future. Therefore, the effect of those nanoparticles on human melanoma cells was investigated in vitro and in vivo. Concentrations of polymer-coated CNPs being nontoxic for stromal cells showed a cytotoxic, proapoptotic, and anti-invasive capacity on melanoma cells. In vivo xenograft studies with immunodeficient nude mice showed a decrease of tumor weight and volume after treatment with CNPs. [Innovation]: In summary, the redox-active CNPs have selective pro-oxidative and antioxidative properties, and this study is the first to show that CNPs prevent tumor growth in vivo. [Conclusion]: The application of redox-active CNPs may form the basis of new paradigms in the treatment and prevention of cancers. Antioxid. Redox Signal. 19, 765-778. © 2013, Mary Ann Liebert, Inc.S. Seal acknowledges the National Science Foundation (NSF) to partially fund the nanotechnology research under NSF NIRT (CBET-0708172) and NSF (CBET-0930170).Peer Reviewe

Downregulation Of Tumor Growth And Invasion By Redox-Active Nanoparticles

Aims: Melanoma is the most aggressive type of malignant skin cancer derived from uncontrolled proliferation of melanocytes. Melanoma cells possess a high potential to metastasize, and the prognosis for advanced melanoma is rather poor due to its strong resistance to conventional chemotherapeutics. Nanomaterials are at the cutting edge of the rapidly developing area of nanomedicine. The potential of nanoparticles for use as carrier in cancer drug delivery is infinite with novel applications constantly being tested. The noncarrier use of cerium oxide nanoparticles (CNPs) is a novel and promising approach, as those particles per se show an anticancer activity via their oxygen vacancy-mediated chemical reactivity. Results: In this study, the question was addressed of whether the use of CNPs might be a valuable tool to counteract the invasive capacity and metastasis of melanoma cells in the future. Therefore, the effect of those nanoparticles on human melanoma cells was investigated in vitro and in vivo. Concentrations of polymer-coated CNPs being nontoxic for stromal cells showed a cytotoxic, proapoptotic, and anti-invasive capacity on melanoma cells. In vivo xenograft studies with immunodeficient nude mice showed a decrease of tumor weight and volume after treatment with CNPs. Innovation: In summary, the redox-active CNPs have selective pro-oxidative and antioxidative properties, and this study is the first to show that CNPs prevent tumor growth in vivo. Conclusion: The application of redox-active CNPs may form the basis of new paradigms in the treatment and prevention of cancers. Antioxid. Redox Signal. 19, 765-778. © 2013, Mary Ann Liebert, Inc