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Suhrland C, Truman JP, Obeid LM, Sitharaman B. Oxidized graphene nanoparticles as a delivery system for the pro-apoptotic sphingolipid C 6 ceramide. J Biomed Mater Res A 2018; 107:25-37. [PMID: 30422374 DOI: 10.1002/jbm.a.36474] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/16/2018] [Accepted: 05/24/2018] [Indexed: 01/22/2023]
Abstract
Sphingolipids such as ceramide have attracted much attention as possible anticancer agents due to their potent pro-apoptotic effects. However, due to their extreme hydrophobicity, there is currently no clinically approved delivery method for in vivo use as a therapeutic agent. To this end, we have developed a novel method for loading the short-chain C6 ceramide onto oxidized graphene nanoribbons (O-GNRs) and graphene nanoplatelets (GNPs). Mass spectrometry revealed loading efficiencies of 57% and 51.5% for C6 ceramide onto O-GNRs and GNPs, respectively. The PrestoBlue viability assay revealed that 100 µg/mL of C6 ceramide-loaded O-GNRs and C6 ceramide-loaded GNPs reduced HeLa cell viability by approximately 93% and approximately 76%, respectively, compared to untreated HeLa cells, while equal concentrations of these nanoparticles without C6 ceramide did not significantly reduce HeLa cell viability. We confirmed that this cytotoxicity was apoptotic in nature via capase-3 activity and Hoechst staining. Using live-cell confocal imaging with the fluorescent NBD-ceramide loaded on O-GNRs, we observed robust uptake into HeLa cells within 30 min while NBD-ceramide on its own was uptaken much more rapidly. Transmission electron microscopy confirmed that C6 ceramide-loaded O-GNRs were actually entering cells. Taken together, these data show that O-GNRs are a promising delivery agent for ceramide. To our knowledge, this study is the first to use such a loading method. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 25-37, 2019.
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Affiliation(s)
- Cassandra Suhrland
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York
| | - Jean-Philip Truman
- Department of Medicine and the Stony Brook Cancer Center, Health Science Center, Stony Brook University, New York, New York
| | - Lina M Obeid
- Department of Medicine and the Stony Brook Cancer Center, Health Science Center, Stony Brook University, New York, New York
| | - Balaji Sitharaman
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York
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Carilho Torrao RBD, Dias IH, Bennett SJ, Dunston CR, Griffiths HR. Healthy ageing and depletion of intracellular glutathione influences T cell membrane thioredoxin-1 levels and cytokine secretion. Chem Cent J 2013; 7:150. [PMID: 24007191 PMCID: PMC3766689 DOI: 10.1186/1752-153x-7-150] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 08/14/2013] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND During ageing an altered redox balance has been observed in both intracellular and extracellular compartments, primarily due to glutathione depletion and metabolic stress. Maintaining redox homeostasis is important for controlling proliferation and apoptosis in response to specific stimuli for a variety of cells. For T cells, the ability to generate specific response to antigen is dependent on the oxidation state of cell surface and cytoplasmic protein-thiols. Intracellular thiols are maintained in their reduced state by a network of redox regulating peptides, proteins and enzymes such as glutathione, thioredoxins and thioredoxin reductase. Here we have investigated whether any relationship exists between age and secreted or cell surface thioredoxin-1, intracellular glutathione concentration and T cell surface thioredoxin 1 (Trx-1) and how this is related to interleukin (IL)-2 production. RESULTS Healthy older adults have reduced lymphocyte surface expression and lower circulating plasma Trx-1 concentrations. Using buthionine sulfoximine to deplete intracellular glutathione in Jurkat T cells we show that cell surface Trx-1 is lowered, secretion of Trx-1 is decreased and the response to the lectin phytohaemagglutinin measured as IL-2 production is also affected. These effects are recapitulated by another glutathione depleting agent, diethylmaleate. CONCLUSION Together these data suggest that a relationship exists between the intracellular redox compartment and Trx-1 proteins. Loss of lymphocyte surface Trx-1 may be a useful biomarker of healthy ageing.
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Griffiths HR. ROS as signalling molecules in T cells – evidence for abnormal redox signalling in the autoimmune disease, rheumatoid arthritis. Redox Rep 2013; 10:273-80. [PMID: 16438798 DOI: 10.1179/135100005x83680] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Reactive oxygen species are recognised as important signalling molecules within cells of the immune system. This is, at least in part, due to the reversible activation of kinases, phosphatases and transcription factors by modification of critical thiol residues. However, in the chronic inflammatory disease rheumatoid arthritis, cells of the immune system are exposed to increased levels of oxidative stress and the T cell becomes refractory to growth and death stimuli. This contributes to the perpetuation of the immune response. As many of the effective therapies used in the treatment of rheumatoid arthritis modulate intracellular redox state, this raises the question of whether increased oxidative stress is causative of T-cell hyporesponsiveness. To address this hypothesis, this review considers the putative sources of ROS involved in normal intracellular signalling in T cells and the evidence in support of abnormal ROS fluxes contributing to T-cell hyporesponsiveness.
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Affiliation(s)
- Helen R Griffiths
- Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK.
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Gao D, Pararasa C, Dunston CR, Bailey CJ, Griffiths HR. Palmitate promotes monocyte atherogenicity via de novo ceramide synthesis. Free Radic Biol Med 2012; 53:796-806. [PMID: 22640955 DOI: 10.1016/j.freeradbiomed.2012.05.026] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2011] [Revised: 04/30/2012] [Accepted: 05/15/2012] [Indexed: 11/21/2022]
Abstract
Elevated plasma free fatty acids (FAs) are associated with increased risk of cardiovascular disease. This study investigates the effects of the saturated FA palmitate and unsaturated FA oleate on monocyte phenotype and function. Incubation of human U937 and THP-1 monocytes with palmitate for 24h increased cell surface expression of integrin CD11b and scavenger receptor CD36 in a concentration-dependent manner with some decrease in mitochondrial reducing capacity at high concentration (300 μM). Monocytes incubated with palmitate, but not oleate, showed increased uptake of oxidized LDL and increased adhesion to rat aortic endothelium, particularly at bifurcations. The palmitate-induced increase in CD11b and CD36 expression was associated with increased cellular C16 ceramide and sphingomyelin, loss of reduced glutathione, and increased reactive oxygen species (ROS). Increased monocyte surface CD11b and CD36 was inhibited by fumonisin B1, an inhibitor of de novo ceramide synthesis, but not by the superoxide dismutase mimetic MnTBap. In contrast, MnTBap prevented the mitochondrial ROS increase and metabolic inhibition due to 300μM palmitate. This study demonstrates that in viable monocytes, palmitate but not oleate increases expression of surface CD11b and CD36. Palmitate increases monocyte adhesion to the aortic wall and promotes uptake of oxidized LDL and this involves de novo ceramide synthesis.
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Affiliation(s)
- Dan Gao
- School of Life and Health Sciences, Aston University, Birmingham B4 7ET, UK
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Ferreira LF, Moylan JS, Gilliam LAA, Smith JD, Nikolova-Karakashian M, Reid MB. Sphingomyelinase stimulates oxidant signaling to weaken skeletal muscle and promote fatigue. Am J Physiol Cell Physiol 2010; 299:C552-60. [PMID: 20519448 DOI: 10.1152/ajpcell.00065.2010] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Sphingomyelinase (SMase) hydrolyzes membrane sphingomyelin into ceramide, which increases oxidants in nonmuscle cells. Serum SMase activity is elevated in sepsis and heart failure, conditions where muscle oxidants are increased, maximal muscle force is diminished, and fatigue is accelerated. We tested the hypotheses that exogenous SMase and accumulation of ceramide in muscle increases oxidants in muscle cells, depresses specific force of unfatigued muscle, and accelerates the fatigue process. We also anticipated that the antioxidant N-acetylcysteine (NAC) would prevent SMase effects on muscle function. We studied the responses of C2C12 myotubes and mouse diaphragm to SMase treatment in vitro. We observed that SMase caused a 2.8-fold increase in total ceramide levels in myotubes. Exogenous ceramide and SMase elevated oxidant activity in C2C12 myotubes by 15-35% (P < 0.05) and in diaphragm muscle fiber bundles by 58-120% (P < 0.05). The SMase-induced increase in diaphragm oxidant activity was prevented by NAC. Exogenous ceramide depressed diaphragm force by 55% (P < 0.05), while SMase depressed maximal force by 30% (P < 0.05) and accelerated fatigue--effects opposed by treatment with NAC. In conclusion, our findings suggest that SMase stimulates a ceramide-oxidant signaling pathway that results in muscle weakness and fatigue.
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Affiliation(s)
- Leonardo F Ferreira
- Department of Physiology and Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, USA
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Phillips DC, Hunt JT, Moneypenny CG, Maclean KH, McKenzie PP, Harris LC, Houghton JA. Ceramide-induced G2 arrest in rhabdomyosarcoma (RMS) cells requires p21Cip1/Waf1 induction and is prevented by MDM2 overexpression. Cell Death Differ 2007; 14:1780-91. [PMID: 17627285 DOI: 10.1038/sj.cdd.4402198] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The sphingoplipid ceramide is responsible for a diverse range of biochemical and cellular responses including a putative role in modulating cell cycle progression. Herein, we describe that an accumulation of ceramide, achieved through the exogenous application of C(6)-ceramide or exposure to sphingomyelinase, induces a G(2) arrest in Rhabdomyosarcoma (RMS) cell lines. Utilizing the RMS cell line RD, we show that this G(2) arrest required the rapid induction of p21(Cip1/Waf1) independent of DNA damage. This was followed at later time points (48 h) by the commitment to apoptosis. Apoptosis was prevented by Bcl-2 overexpression, but permitted the maintenance of elevated p21(Cip1/Waf1) protein expression and the stabilization of the G(2) arrest response. Inhibition of p21(Cip1/Waf1) protein synthesis with cyclohexamide (CHX) or silencing of p21(Cip1/Waf1) with siRNA, prevented ceramide-mediated G(2) arrest and the late induction of apoptosis. Further, adopting the recent discovery that murine double minute 2 (MDM2) controls p21(Cip1/Waf1) expression by presenting this CDK inhibitor to the proteasome for degradation, RD cells overexpressing MDM2 abrogated ceramide-mediated p21(Cip1/Waf1) induction, G(2) arrest and the late ensuing apoptosis. Collectively, these data further support the notion that ceramide accumulation can modulate cell cycle progression. Additionally, these observations highlight MDM2 expression and proteasomal activity as key determinants of the cellular response to ceramide accumulation.
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Affiliation(s)
- D C Phillips
- Division of Molecular Therapeutics, Department of Oncology, St. Jude Children's Research Hospital, 332 North Lauderdale, Memphis, TN 38105, USA
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Grant MM, Mistry N, Lunec J, Griffiths HR. Dose-dependent modulation of the T cell proteome by ascorbic acid. Br J Nutr 2007; 97:19-26. [PMID: 17217556 DOI: 10.1017/s0007114507197592] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
To investigate the hypothesis that the micronutrient ascorbic acid can modulate the functional genome, T cells (CCRF-HSB2) were treated with ascorbic acid (up to 150 microM) for up to 24 h. Protein expression changes were assessed by two-dimensional electrophoresis. Forty-one protein spots which showed greater than two-fold expression changes were subject to identification by matrix-assisted laser desorption ionisation time of flight MS. The confirmed protein identifications were clustered into five groups; proteins were associated with signalling, carbohydrate metabolism, apoptosis, transcription and immune function. The increased expression of phosphatidylinositol transfer protein (promotes intracellular signalling) within 5 min of ascorbic acid treatment was confirmed by Western blotting. Together, these observations suggest that ascorbic acid modulates the T cell proteome in a time- and dose-dependent manner and identify molecular targets for study following antioxidant supplementation in vivo.
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Phillips DC, Martin S, Doyle BT, Houghton JA. Sphingosine-induced apoptosis in rhabdomyosarcoma cell lines is dependent on pre-mitochondrial Bax activation and post-mitochondrial caspases. Cancer Res 2007; 67:756-64. [PMID: 17234787 DOI: 10.1158/0008-5472.can-06-2374] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sphingolipids is the collective term ascribed to components of the sphingomyelin cycle. Modulation of the cellular levels of individual sphingolipids can induce a diverse range of cellular responses including apoptosis, proliferation, and cell cycle arrest. We present data showing that rhabdomyosarcoma cell lines, independent of lineage (alveolar rhabdomyosarcoma and embryonal rhabdomyosarcoma), are particularly sensitive to the induction of apoptosis as a result of an elevation in the cellular levels of sphingosine (D-erythro-sphingosine). Sphingosine-mediated apoptosis does not require its metabolism to the related proapoptotic molecule ceramide and is stereospecific because exposure of the rhabdomyosarcoma cell line RD to the L-erythro and DL-threo isoforms of sphingosine did not induce apoptosis. Importantly, for efficient induction of apoptosis, sphingosine required Bax activation and consequential translocation to the mitochondria. This resulted in selective mitochondrial release of cytochrome c and Smac/Diablo but not other mitochondrial related factors (apoptosis-inducing factor, endonuclease G, and HtrA2/Omi). Using small interfering RNA, reduced Bax expression conferred the impaired release of mitochondrial cytochrome c to the cytoplasm following sphingosine exposure, inhibiting the induction of apoptosis. Furthermore, dissipation of the inner mitochondrial membrane potential and enhanced production of reactive oxygen species were not observed. Bax activation and cytochrome c release were independent of caspases; however, caspase-3 and caspase-9 activity distal to the mitochondria was essential for the execution of apoptosis.
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Affiliation(s)
- Darren C Phillips
- Division of Molecular Therapeutics, Department of Hematology-Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA, and UMR 7175-LC1, Pharmacologie et Physicochimie, Faculté de Pharmacie, Université Louis Pasteur, Illkirch, France
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Luan Y, Griffiths HR. Ceramides reduce CD36 cell surface expression and oxidised LDL uptake by monocytes and macrophages. Arch Biochem Biophys 2006; 450:89-99. [PMID: 16620763 DOI: 10.1016/j.abb.2006.03.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2006] [Revised: 02/06/2006] [Accepted: 03/01/2006] [Indexed: 11/18/2022]
Abstract
Oxidised LDL accumulates in macrophages following scavenger receptor (SR) uptake. The expression of the SR, CD36, is increased by oxidised LDL. The signalling molecule, ceramide, can modulate intracellular peroxides and increase lipid peroxidation. Ceramide also accumulates in atherosclerotic plaques. Thus, we have examined whether ceramide can modulate CD36 expression and function in human monocyte/macrophages. Addition of synthetic short chain ceramides or the action of sphingomyelinase to generate physiological long chain ceramides in situ caused significant reductions in CD36 expression by monocytes/macrophages which was not due to inhibition of mRNA expression. Inhibition of proteasomal degradation using lactacystin had no effect on CD36 expression, however, flow cytometric analysis of permeabilised cells suggested an intracellular trafficking blockade. Ceramide treated monocytes/macrophages showed dose dependent reduction in oxidised LDL uptake. Taken together, it is suggested that ceramide blocks the transport of CD36 to the membrane of monocytes/macrophages, thereby preventing uptake of oxidised LDL.
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Affiliation(s)
- Yingjun Luan
- Life and Health Sciences, Aston University, Birmingham B4 7ET, UK
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Kannan R, Jin M, Gamulescu MA, Hinton DR. Ceramide-induced apoptosis: role of catalase and hepatocyte growth factor. Free Radic Biol Med 2004; 37:166-75. [PMID: 15203188 DOI: 10.1016/j.freeradbiomed.2004.04.011] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2003] [Revised: 03/26/2004] [Accepted: 04/08/2004] [Indexed: 11/18/2022]
Abstract
The aim of this study was to elucidate cellular mechanisms involved in ceramide-induced apoptosis and its attenuation by hepatocyte growth factor (HGF). Human retinal pigmented epithelial cells (RPE) incubated with C2 ceramide accumulated reactive oxygen species (ROS) in mitochondria and underwent apoptosis in a dose-dependent manner. Ceramide-treated cells showed increased caspase-3 activation and an increase in mitochondrial membrane permeability transition (MPT). Low doses of H2O2 (100 microM) alone induced negligible apoptosis; however, ceramide-induced apoptosis was significantly enhanced by co-incubation with H2O2 (100 microM). Furthermore, ceramide treatment significantly decreased catalase enzymatic activity and protein expression. HGF pretreatment (20 ng/ml) significantly inhibited ceramide-induced apoptosis and reduced the accumulation of ROS, the activation of caspase-3, and the increase in MPT and prevented the reduction in catalase activity and expression. Together, the data suggest that ceramide induces apoptosis in RPE cells by increasing ROS production, MPT, and caspase-3 activation. The ceramide effect is potentiated by H2O2 and associated with a reduction in catalase activity, suggesting that catalase plays a central role in regulating this apoptotic response. The ability of HGF to attenuate these effects demonstrates its effectiveness as an antioxidant growth factor.
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Affiliation(s)
- Ram Kannan
- The Arnold and Mabel Beckman Macular Research Center, Keck School of Medicine of the University of Southern California, Los Angeles 90033, USA
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