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Spassieva SD, Rahmaniyan M, Bielawski J, Clarke CJ, Kraveka JM, Obeid LM. Cell density-dependent reduction of dihydroceramide desaturase activity in neuroblastoma cells. J Lipid Res 2012; 53:918-928. [PMID: 22377532 DOI: 10.1194/jlr.m019075] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We applied a metabolic approach to investigate the role of sphingolipids in cell density-induced growth arrest in neuroblastoma cells. Our data revealed that sphingolipid metabolism in neuroblastoma cells significantly differs depending on the cells' population context. At high cell density, cells exhibited G0/G1 cell-cycle arrest and reduced ceramide, monohexosylceramide, and sphingomyelin, whereas dihydroceramide was significantly increased. In addition, our metabolic-labeling experiments showed that neuroblastoma cells at high cell density preferentially synthesized very long chain (VLC) sphingolipids and dramatically decreased synthesis of sphingosine-1-phosphate (S1P). Moreover, densely populated neuroblastoma cells showed increased message levels of both anabolic and catabolic enzymes of the sphingolipid pathway. Notably, our metabolic-labeling experiments indicated reduced dihydroceramide desaturase activity at confluence, which was confirmed by direct measurement of dihydroceramide desaturase activity in situ and in vitro. Importantly, we could reduce dihydroceramide desaturase activity in low-density cells by applying conditional media from high-density cells, as well as by adding reducing agents, such as DTT and L-cysteine to the media. In conclusion, our data suggest a role of the sphingolipid pathway, dihydroceramides desaturase in particular, in confluence-induced growth arrest in neuroblastoma cells.
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Affiliation(s)
- Stefka D Spassieva
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425
| | - Mehrdad Rahmaniyan
- Department of Pediatrics Division of Hematology/Oncology, Medical University of South Carolina, Charleston, SC 29425; and
| | - Jacek Bielawski
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425; and
| | - Christopher J Clarke
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425; and
| | - Jacqueline M Kraveka
- Department of Pediatrics Division of Hematology/Oncology, Medical University of South Carolina, Charleston, SC 29425; and
| | - Lina M Obeid
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425; Division of General Internal Medicine, Ralph H. Johnson Veterans Affairs Hospital, Charleston, SC 29401.
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102
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Dihydroceramide desaturase and dihydrosphingolipids: debutant players in the sphingolipid arena. Prog Lipid Res 2011; 51:82-94. [PMID: 22200621 DOI: 10.1016/j.plipres.2011.12.002] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
Sphingolipids are a wide family of lipids that share common sphingoid backbones, including (2S,3R)-2-amino-4-octadecane-1,3-diol (dihydrosphingosine) and (2S,3R,4E)-2-amino-4-octadecene-1,3-diol (sphingosine). The metabolism and biological functions of sphingolipids derived from sphingosine have been the subject of many reviews. In contrast, dihydrosphingolipids have received poor attention, mainly due to their supposed lack of biological activity. However, the reported biological effects of active site directed dihydroceramide desaturase inhibitors and the involvement of dihydrosphingolipids in the response of cells to known therapeutic agents support that dihydrosphingolipids are not inert but are in fact biologically active and underscore the importance of elucidating further the metabolic pathways and cell signaling networks involved in the biological activities of dihydrosphingolipids. Dihydroceramide desaturase is the enzyme involved in the conversion of dihydroceramide into ceramide and it is crucial in the regulation of the balance between sphingolipids and dihydrosphingolipids. Furthermore, given the enzyme requirement for O₂ and the NAD(P)H cofactor, the cellular redox balance and dihydroceramide desaturase activity may reciprocally influence each other. In this review both dihydroceramide desaturase and the biological functions of dihydrosphingolipids are addressed and perspectives on this field are discussed.
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103
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Abstract
Ceramides are a class of sphingolipids that are abundant in cell membranes. They are important structural components of the membrane but can also act as second messengers in various signaling pathways. Until recently, ceramides and dihydroceramides were considered as a single functional class of lipids and no distinction was made between molecules with different chain lengths. However, based on the development of high-throughput, structure-specific and quantitative analytical methods to measure ceramides, it has now become clear that in cellular systems the amounts of ceramides differ with respect to their chain length. Further studies have indicated that some functions of ceramides are chain-length dependent. In this review, we discuss the chain length-specific differences of ceramides including their pathological impact on Alzheimer's disease, inflammation, autophagy, apoptosis and cancer.
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Affiliation(s)
- Sabine Grösch
- pharmazentrum frankfurt/ZAFES, Institut für Klinische Pharmakologie, Klinikum der Johann Wolfgang Goethe-Universität Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt/Main, Germany.
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104
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Evaluation of bioactive sphingolipids in 4-HPR-resistant leukemia cells. BMC Cancer 2011; 11:477. [PMID: 22061047 PMCID: PMC3218121 DOI: 10.1186/1471-2407-11-477] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 11/07/2011] [Indexed: 12/27/2022] Open
Abstract
Background N-(4-hydroxyphenyl)retinamide (4-HPR, fenretinide) is a synthetic retinoid with potent pro-apoptotic activity against several types of cancer, but little is known regarding mechanisms leading to chemoresistance. Ceramide and, more recently, other sphingolipid species (e.g., dihydroceramide and dihydrosphingosine) have been implicated in 4-HPR-mediated tumor cell death. Because sphingolipid metabolism has been reported to be altered in drug-resistant tumor cells, we studied the implication of sphingolipids in acquired resistance to 4-HPR based on an acute lymphoblastic leukemia model. Methods CCRF-CEM cell lines resistant to 4-HPR were obtained by gradual selection. Endogenous sphingolipid profiles and in situ enzymatic activities were determined by LC/MS, and resistance to 4-HPR or to alternative treatments was measured using the XTT viability assay and annexin V-FITC/propidium iodide labeling. Results No major crossresistance was observed against other antitumoral compounds (i.e. paclitaxel, cisplatin, doxorubicin hydrochloride) or agents (i.e. ultra violet C, hydrogen peroxide) also described as sphingolipid modulators. CCRF-CEM cell lines resistant to 4-HPR exhibited a distinctive endogenous sphingolipid profile that correlated with inhibition of dihydroceramide desaturase. Cells maintained acquired resistance to 4-HPR after the removal of 4-HPR though the sphingolipid profile returned to control levels. On the other hand, combined treatment with sphingosine kinase inhibitors (unnatural (dihydro)sphingosines ((dh)Sph)) and glucosylceramide synthase inhibitor (PPMP) in the presence or absence of 4-HPR increased cellular (dh)Sph (but not ceramide) levels and were highly toxic for both parental and resistant cells. Conclusions In the leukemia model, acquired resistance to 4-HPR is selective and persists in the absence of sphingolipid profile alteration. Therapeutically, the data demonstrate that alternative sphingolipid-modulating antitumoral strategies are suitable for both 4-HPR-resistant and sensitive leukemia cells. Thus, whereas sphingolipids may not be critical for maintaining resistance to 4-HPR, manipulation of cytotoxic sphingolipids should be considered a viable approach for overcoming resistance.
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105
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Devlin CM, Lahm T, Hubbard WC, Van Demark M, Wang KC, Wu X, Bielawska A, Obeid LM, Ivan M, Petrache I. Dihydroceramide-based response to hypoxia. J Biol Chem 2011; 286:38069-38078. [PMID: 21914808 DOI: 10.1074/jbc.m111.297994] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To understand the mechanisms of ceramide-based responses to hypoxia, we performed a mass spectrometry-based survey of ceramide species elicited by a wide range of hypoxic conditions (0.2-5% oxygen). We describe a rapid, time-dependent, marked up-regulation of dihydroceramides (DHCs) in mammalian cells and in the lungs of hypoxic rats. The increase affected all DHC species and was proportional with the depth and duration of hypoxia, ranging from 2- (1 h) to 10-fold (24 h), with complete return to normal after 1 h of reoxygenation at the expense of increased ceramides. We demonstrate that a DHC-based response to hypoxia occurs in a hypoxia-inducible factor-independent fashion and is catalyzed by the DHC desaturase (DEGS) in the de novo ceramide pathway. Both the impact of hypoxia on DHC molecular species and its inhibitory effect on cell proliferation were reproduced by knockdown of DEGS1 or DEGS2 by siRNA during normoxia. Conversely, overexpression of DEGS1 or DEGS2 attenuated the DHC accumulation and increased cell proliferation during hypoxia. Based on the amplitude and kinetics of DHC accumulation, the enzymatic desaturation of DHCs fulfills the criteria of an oxygen sensor across physiological hypoxic conditions, regulating the balance between biologically active components of ceramide metabolism.
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Affiliation(s)
- Cecilia M Devlin
- Department of Medicine, Indiana University, Indianapolis, Indiana 46202
| | - Tim Lahm
- Department of Medicine, Indiana University, Indianapolis, Indiana 46202; R. L. Roudebush Veterans Affairs Medical Center, Indianapolis, Indiana 46202
| | - Walter C Hubbard
- Department of Medicine, The Johns Hopkins University, Baltimore, Maryland 21286
| | - Mary Van Demark
- Department of Medicine, Indiana University, Indianapolis, Indiana 46202
| | - Kevin C Wang
- Department of Medicine, Indiana University, Indianapolis, Indiana 46202
| | - Xue Wu
- Department of Microbiology and Immunology, Indiana University, Indianapolis, Indiana 46202
| | - Alicja Bielawska
- Department of Pediatrics, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Lina M Obeid
- Department of Pediatrics, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Mircea Ivan
- Department of Medicine, Indiana University, Indianapolis, Indiana 46202; Department of Microbiology and Immunology, Indiana University, Indianapolis, Indiana 46202.
| | - Irina Petrache
- Department of Medicine, Indiana University, Indianapolis, Indiana 46202; R. L. Roudebush Veterans Affairs Medical Center, Indianapolis, Indiana 46202.
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106
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Kartal M, Saydam G, Sahin F, Baran Y. Resveratrol triggers apoptosis through regulating ceramide metabolizing genes in human K562 chronic myeloid leukemia cells. Nutr Cancer 2011; 63:637-44. [PMID: 21500096 DOI: 10.1080/01635581.2011.538485] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Resveratrol, an important phytoalexin in many plants, has been reported to have cytotoxic effects on various types of cancer. Ceramide is a bioactive sphingolipid that regulates many signaling pathways, including cell growth and proliferation, senescence and quiescence, apoptosis, and cell cycle. Ceramides are generated by longevity assurance genes (LASS). Glucosylceramide synthase (GCS) and sphingosine kinase-1 (SK-1) enzymes can convert ceramides to antiapoptotic molecules, glucosylceramide, and sphingosine-1-phosphate, respectively. C8:ceramide, an important cell-permeable analogue of natural ceramides, increases intracellular ceramide levels significantly, while 1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) and SK-1 inhibitor increase accumulation of ceramides by inhibiting GCS and SK-1, respectively. Chronic myelogenous leukemia (CML) is a hematological disorder resulting from generation of BCR/ABL oncogene. In this study, we examined the roles of ceramide metabolizing genes in resveratrol-induced apoptosis in K562 CML cells. There were synergistic cytotoxic and apoptotic effects of resveratrol with coadministration of C8:ceramide, PDMP, and SK-1 inhibitor. Interestingly, there were also significant increases in expression levels of LASS genes and decreases in expression levels of GCS and SK-1 in K562 cells in response to resveratrol. Our data, in total, showed for the first time that resveratrol might kill CML cells through increasing intracellular generation and accumulation of apoptotic ceramides.
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Affiliation(s)
- Melis Kartal
- Faculty of Science, Department of Molecular Biology and Genetics, Izmir Institute of Technology, Izmir, Turkey
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107
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Abstract
Intensive research over the past 2 decades has implicated ceramide in the regulation of several cell responses. However, emerging evidence points to dramatic complexities in ceramide metabolism and structure that defy the prevailing unifying hypothesis on ceramide function that is based on the understanding of ceramide as a single entity. Here, we develop the concept that "ceramide" constitutes a family of closely related molecules, subject to metabolism by >28 enzymes and with >200 structurally distinct mammalian ceramides distinguished by specific structural modifications. These ceramides are synthesized in a combinatorial fashion with distinct enzymes responsible for the specific modifications. These multiple pathways of ceramide generation led to the hypothesis that individual ceramide molecular species are regulated by specific biochemical pathways in distinct subcellular compartments and execute distinct functions. In this minireview, we describe the "many ceramides" paradigm, along with the rationale, supporting evidence, and implications for our understanding of bioactive sphingolipids and approaches for unraveling these pathways.
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Affiliation(s)
- Yusuf A Hannun
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SouthCarolina 29425, USA.
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108
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Jiang Q, Rao X, Kim CY, Freiser H, Zhang Q, Jiang Z, Li G. Gamma-tocotrienol induces apoptosis and autophagy in prostate cancer cells by increasing intracellular dihydrosphingosine and dihydroceramide. Int J Cancer 2011; 130:685-93. [PMID: 21400505 DOI: 10.1002/ijc.26054] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Accepted: 02/14/2011] [Indexed: 02/05/2023]
Abstract
Although cell-based studies have shown that γ-tocotrienol (γTE) exhibits stronger anticancer activities than other forms of vitamin E including γ-tocopherol (γT), the molecular bases underlying γTE-exerted effects remains to be elucidated. Here we showed that γTE treatment promoted apoptosis, necrosis and autophagy in human prostate PC-3 and LNCaP cancer cells. In search of potential mechanisms of γTE-provoked effects, we found that γTE treatment led to marked increase of intracellular dihydroceramide and dihydrosphingosine, the sphingolipid intermediates in de novo sphingolipid synthesis pathway but had no effects on ceramide or sphingosine. The elevation of these sphingolipids by γTE preceded or coincided with biochemical and morphological signs of cell death and was much more pronounced than that induced by γT, which accompanied with much higher cellular uptake of γTE than γT. The importance of sphingolipid accumulation in γTE-caused fatality was underscored by the observation that dihydrosphingosine and dihydroceramide potently reduced the viability of both prostate cell lines and LNCaP cells, respectively. In addition, myriosin, a specific inhibitor of de novo sphingolipid synthesis, counteracted γTE-induced cell death. In agreement with these cell-based studies, γTE inhibited LNCaP xenograft growth by 53% (p < 0.05), compared to 33% (p = 0.07) by γT, in nude mice. These findings provide a molecular basis of γTE-stimulated cancer cell death and support the notion that elevation of intracellular dihydroceramide and dihydrosphingosine is likely a novel anticancer mechanism.
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Affiliation(s)
- Qing Jiang
- Department of Foods and Nutrition, Interdepartmental Nutrition Program, Purdue University, West Lafayette, IN 47907, USA.
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109
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Kolter T. A view on sphingolipids and disease. Chem Phys Lipids 2011; 164:590-606. [PMID: 21570958 DOI: 10.1016/j.chemphyslip.2011.04.013] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 04/26/2011] [Accepted: 04/28/2011] [Indexed: 12/27/2022]
Abstract
Sphingolipid and glycosphingolipid levels and expression of sphingolipid metabolizing enzymes are altered in a variety of diseases or in response to drug treatment. Inherited defects of enzymes and other proteins required for the lysosomal degradation of these lipids lead to human sphingolipidoses. Also genetic defects that affect sphingolipid biosynthesis are known. Although the molecular details are often far from clear, (glyco)sphingolipids have been implicated to play a role in atherosclerosis, insulin resistance, cancer, and infections by pathogens. More general aspects of selected diseases are discussed.
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Affiliation(s)
- Thomas Kolter
- LiMES-Laboratory of Lipid Biochemistry, Kekulé-Institut für Organische Chemie und Biochemie der Universität, Bonn, Germany.
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110
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Rahmaniyan M, Curley RW, Obeid LM, Hannun YA, Kraveka JM. Identification of dihydroceramide desaturase as a direct in vitro target for fenretinide. J Biol Chem 2011; 286:24754-64. [PMID: 21543327 DOI: 10.1074/jbc.m111.250779] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The dihydroceramide desaturase (DES) enzyme is responsible for inserting the 4,5-trans-double bond to the sphingolipid backbone of dihydroceramide. We previously demonstrated that fenretinide (4-HPR) inhibited DES activity in SMS-KCNR neuroblastoma cells. In this study, we investigated whether 4-HPR acted directly on the enzyme in vitro. N-C8:0-d-erythro-dihydroceramide (C(8)-dhCer) was used as a substrate to study the conversion of dihydroceramide into ceramide in vitro using rat liver microsomes, and the formation of tritiated water after the addition of the tritiated substrate was detected and used to measure DES activity. NADH served as a cofactor. The apparent K(m) for C(8)-dhCer and NADH were 1.92 ± 0.36 μm and 43.4 ± 6.47 μm, respectively; and the V(max) was 3.16 ± 0.24 and 4.11 ± 0.18 nmol/min/g protein. Next, the effects of 4-HPR and its metabolites on DES activity were investigated. 4-HPR was found to inhibit DES in a dose-dependent manner. At 20 min, the inhibition was competitive; however, longer incubation times demonstrated the inhibition to be irreversible. Among the major metabolites of 4-HPR, 4-oxo-N-(4-hydroxyphenyl)retinamide (4-oxo-4-HPR) showed the highest inhibitory effect with substrate concentration of 0.5 μm, with an IC(50) of 1.68 μm as compared with an IC(50) of 2.32 μm for 4-HPR. N-(4-Methoxyphenyl)retinamide (4-MPR) and 4-Oxo-N-(4-methoxyphenyl)retinamide (4-oxo-4-MPR) had minimal effects on DES activity. A known competitive inhibitor of DES, C(8)-cyclopropenylceramide was used as a positive control. These studies define for the first time a direct in vitro target for 4-HPR and suggest that inhibitors of DES may be used as therapeutic interventions to regulate ceramide desaturation and consequent function.
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Affiliation(s)
- Mehrdad Rahmaniyan
- Division of Hematology/Oncology, Department of Pediatrics, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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111
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Separovic D, Joseph N, Breen P, Bielawski J, Pierce JS, Buren EV, Bhatti G, Saad ZH, Bai A, Bielawska A. Combining anticancer agents photodynamic therapy and LCL85 leads to distinct changes in the sphingolipid profile, autophagy, caspase-3 activation in the absence of cell death, and long-term sensitization. Biochem Biophys Res Commun 2011; 409:372-7. [PMID: 21545791 DOI: 10.1016/j.bbrc.2011.04.091] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2011] [Accepted: 04/19/2011] [Indexed: 11/18/2022]
Abstract
Two anticancer agents, LCL85 and photodynamic therapy (PDT) were combined to test whether the combination PDT/LCL85 evokes changes in the sphingolipid (SL) profile and promotes cell death. Treatment of SCCVII mouse squamous carcinoma cells using the silicone phthalocyanine Pc 4 for PDT induced increases in the prodeath global ceramides/dihydroceramides (DHceramides), and no changes in the prosurvival sphingosine-1-phosphate (S1P). In contrast, after LCL85, the levels of most ceramides and DHceramides were reduced, whereas the levels of S1P were increased. After PDT/LCL85 the levels of global ceramides and DHceramides, and of S1P, were restored to resting levels. PDT/LCL85 also enhanced the levels of C18-, C20-, and C20:1-ceramide, and C18-DHceramide. Treatment with PDT, with or without LCL85, led to substantial reductions in sphingosine levels. PDT/LCL85 induced enhanced autophagy and caspase-3 activation. None of the treatments affected short-term viability of cells. In contrast, long-term clonogenic survival was reduced not only after PDT or LCL85, but even more after PDT/LCL85. Overall, our data show that short-term exposure to PDT/LCL85 led to distinct signature effects on the SL profile, enhanced autophagy, and caspase-3 activation without cell death. Long-term exposure to PDT/LCL85 enhanced overall cell killing, supporting translational potential of PDT/LCL85.
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Affiliation(s)
- Duska Separovic
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, 259 Mack Ave., Detroit, MI 48201, USA.
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112
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Tanaka K, Yamada M, Tamiya-Koizumi K, Kannagi R, Aoyama T, Hara A, Kyogashima M. Systematic analyses of free ceramide species and ceramide species comprising neutral glycosphingolipids by MALDI-TOF MS with high-energy CID. Glycoconj J 2011; 28:67-87. [DOI: 10.1007/s10719-011-9325-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 01/11/2011] [Accepted: 02/01/2011] [Indexed: 10/18/2022]
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113
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Ponnusamy S, Meyers-Needham M, Senkal CE, Saddoughi SA, Sentelle D, Selvam SP, Salas A, Ogretmen B. Sphingolipids and cancer: ceramide and sphingosine-1-phosphate in the regulation of cell death and drug resistance. Future Oncol 2011; 6:1603-24. [PMID: 21062159 DOI: 10.2217/fon.10.116] [Citation(s) in RCA: 234] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Sphingolipids have emerged as bioeffector molecules, controlling various aspects of cell growth and proliferation in cancer, which is becoming the deadliest disease in the world. These lipid molecules have also been implicated in the mechanism of action of cancer chemotherapeutics. Ceramide, the central molecule of sphingolipid metabolism, generally mediates antiproliferative responses, such as cell growth inhibition, apoptosis induction, senescence modulation, endoplasmic reticulum stress responses and/or autophagy. Interestingly, recent studies suggest de novo-generated ceramides may have distinct and opposing roles in the promotion/suppression of tumors, and that these activities are based on their fatty acid chain lengths, subcellular localization and/or direct downstream targets. For example, in head and neck cancer cells, ceramide synthase 6/C(16)-ceramide addiction was revealed, and this was associated with increased tumor growth, whereas downregulation of its synthesis resulted in ER stress-induced apoptosis. By contrast, ceramide synthase 1-generated C(18)-ceramide has been shown to suppress tumor growth in various cancer models, both in situ and in vivo. In addition, ceramide metabolism to generate sphingosine-1-phosphate (S1P) by sphingosine kinases 1 and 2 mediates, with or without the involvement of G-protein-coupled S1P receptor signaling, prosurvival, angiogenesis, metastasis and/or resistance to drug-induced apoptosis. Importantly, recent findings regarding the mechanisms by which sphingolipid metabolism and signaling regulate tumor growth and progression, such as identifying direct intracellular protein targets of sphingolipids, have been key for the development of new chemotherapeutic strategies. Thus, in this article, we will present conclusions of recent studies that describe opposing roles of de novo-generated ceramides by ceramide synthases and/or S1P in the regulation of cancer pathogenesis, as well as the development of sphingolipid-based cancer therapeutics and drug resistance.
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Affiliation(s)
- Suriyan Ponnusamy
- Department of Biochemistry & Molecular Biology, Medical University of South Carolina, Charleston, SC, USA
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114
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Soto BL, Hank JA, Van De Voort TJ, Subramanian L, Polans AS, Rakhmilevich AL, Yang RK, Seo S, Kim K, Reisfeld RA, Gillies SD, Sondel PM. The anti-tumor effect of resveratrol alone or in combination with immunotherapy in a neuroblastoma model. Cancer Immunol Immunother 2011; 60:731-8. [PMID: 21340652 DOI: 10.1007/s00262-011-0971-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 12/31/2010] [Indexed: 12/31/2022]
Abstract
We investigated the anti-tumor effect of peritumoral resveratrol in combination with immunotherapy in vivo in neuroblastoma-bearing mice. Subcutaneous NXS2 tumors were induced in A/J mice. On day 10, some mice received 15 mcg of intravenous immunocytokine for 5 days, mice received 20 mg of peritumoral resveratrol twice a week (starting on day 12) for a total of 5 injections, and a separate group received a combination of both regimens. Tumor progression and survival were assessed every 3-4 days. Blood and primary tumor tissue samples were collected on day 20 for Complete Blood Count and CD45 immunohistochemistry and histology, respectively. The primary tumor regressed in all mice receiving peritumoral resveratrol. Most of these mice receiving peritumoral resveratrol alone developed metastatic tumors and recurrence of the primary tumor after cessation of therapy. When resveratrol and immunocytokine regimens were combined, 61% of the mice receiving this combination therapy resolved their primary tumors and survived without developing metastatic tumors, compared to 15 and 13% receiving resveratrol or immunocytokine alone, respectively. None of the therapeutic regimes prevented lymphocyte infiltration or affected the complete blood count. Greater necrosis was observed microscopically in tumors from mice receiving the combination therapy. These results demonstrate that the combination therapy of peritumoral resveratrol plus intravenous immunocytokine provides better anti-tumor effects in this model than either therapy alone.
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Affiliation(s)
- Brenda L Soto
- Department of Human Oncology, University of Wisconsin, Madison, WI 53792, USA
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115
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Dihydroceramide desaturase inhibition by a cyclopropanated dihydroceramide analog in cultured keratinocytes. J Lipids 2010; 2011:724015. [PMID: 21490810 PMCID: PMC3066699 DOI: 10.1155/2011/724015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 09/21/2010] [Accepted: 10/27/2010] [Indexed: 01/27/2023] Open
Abstract
Most mammalian sphingolipids contain a 4,5-(E)-double bond. We report on the chemical synthesis of a dihydroceramide derivative that prevents the introduction of the double bond into sphingolipids. Minimal alteration of the parent structure by formally replacing the hydrogen atoms in the 5- and in the 6-position of the sphinganine backbone by a methylene group leads to an inhibitor of dihydroceramide desaturase in cultured cells. In the presence of 10–50 μM of compound (1), levels of biosynthetically formed dihydroceramide and—surprisingly—also of phytoceramide are elevated at the expense of ceramide. The cells respond to the lack of unsaturated sphingolipids by an elevation of mRNAs of enzymes required for sphingosine formation. At the same time, the analysis of proliferation and differentiation markers indicates that the sphingolipid double bond is required to keep the cells in a differentiated state.
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116
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Liao PC, Ng LT, Lin LT, Richardson CD, Wang GH, Lin CC. Resveratrol arrests cell cycle and induces apoptosis in human hepatocellular carcinoma Huh-7 cells. J Med Food 2010; 13:1415-23. [PMID: 20946021 DOI: 10.1089/jmf.2010.1126] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Resveratrol has been shown to possess anticancer, anti-aging, anti-inflammatory, antimicrobial, and neuroprotective activities. In this study, we examined the antiproliferative properties of resveratrol and its molecular mechanism(s) of action in Huh-7 cells, a new human hepatoma cell line system for hepatitis C virus. Results showed that resveratrol significantly inhibited Huh-7 cell proliferation (50% inhibitory concentration = 22.4 μg/mL) and effectively induced cell cycle arrest and apoptosis. It up-regulated p21/WAF1 expression in a p53-independent manner, but the expressions of cyclin E, cyclin A, and cyclin-dependent kinase 2 were down-regulated. It also caused an increase in the ratio of pro-apoptotic/anti-apoptotic protein, which was associated with the mitochondrial membrane depolarization and the increase in caspase activity. Resveratrol showed no effect on Fas, Fas ligand, extracellular signal regulated kinase (ERK) 1/2, and p38 expression but down-regulated phospho-ERK and phospho-p38 expression. In addition, resveratrol was noted to trigger autophagic cell death through the increased expression of autophagy-related Atg5, Atg7, Atg9, and Atg12 proteins. These results suggest that resveratrol could be an important chemoprevention agent for hepatoma of hepatitis C virus infection.
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Affiliation(s)
- Pei-Chi Liao
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan
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117
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Mao Z, Sun W, Xu R, Novgorodov S, Szulc ZM, Bielawski J, Obeid LM, Mao C. Alkaline ceramidase 2 (ACER2) and its product dihydrosphingosine mediate the cytotoxicity of N-(4-hydroxyphenyl)retinamide in tumor cells. J Biol Chem 2010; 285:29078-90. [PMID: 20628055 PMCID: PMC2937939 DOI: 10.1074/jbc.m110.105296] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 07/09/2010] [Indexed: 11/06/2022] Open
Abstract
Increased generation of dihydrosphingosine (DHS), a bioactive sphingolipid, has been implicated in the cytotoxicity of the synthetic retinoid N-(4-hydroxyphenyl)retinamide (4-HPR) in tumor cells. However, how 4-HPR increases DHS remains unclear. Here we demonstrate that 4-HPR increases the expression of ACER2, which catalyzes the hydrolysis of dihydroceramides to generate DHS, and that ACER2 up-regulation plays a key role in mediating the 4-HPR-induced generation of DHS as well as the cytotoxicity of 4-HPR in tumor cells. Treatment with 4-HPR induced the accumulation of dihydroceramides (DHCs) in tumor cells by inhibiting dihydroceramide desaturase (DES) activity, which catalyzes the conversion of DHCs to ceramides. Treatment with 4-HPR also increased ACER2 expression through a retinoic acid receptor-independent and caspase-dependent manner. Overexpression of ACER2 augmented the 4-HPR-induced generation of DHS as well as 4-HPR cytotoxicity, and 4-HPR-induced death in tumor cells, whereas knocking down ACER2 had the opposite effects. ACER2 overexpression, along with treatment with GT11, another DES inhibitor, markedly increased cellular DHS, leading to tumor cell death, whereas ACER2 overexpression or GT11 treatment alone failed to do so, suggesting that both ACER2 up-regulation and DES inhibition are necessary and sufficient to mediate 4-HPR-induced DHS accumulation, cytotoxicity, and death in tumor cells. Taken together, these results suggest that up-regulation of the ACER2/DHS pathway mediates the cytotoxicity of 4-HPR in tumor cells and that up-regulating or activating ACER2 may improve the anti-cancer activity of 4-HRR and other DHC-inducing agents.
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Affiliation(s)
| | - Wei Sun
- From the Department of Medicine and
| | | | | | - Zdzislaw M. Szulc
- the Department of Biochemistry and Molecular Biology, Medical University of South Carolina and
| | - Jacek Bielawski
- the Department of Biochemistry and Molecular Biology, Medical University of South Carolina and
| | - Lina M. Obeid
- From the Department of Medicine and
- the Department of Biochemistry and Molecular Biology, Medical University of South Carolina and
- the Ralph H. Johnson Veterans Administration Hospital, Charleston, South Carolina 29425
| | - Cungui Mao
- From the Department of Medicine and
- the Department of Biochemistry and Molecular Biology, Medical University of South Carolina and
- the Ralph H. Johnson Veterans Administration Hospital, Charleston, South Carolina 29425
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118
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Ekiz HA, Baran Y. Therapeutic applications of bioactive sphingolipids in hematological malignancies. Int J Cancer 2010; 127:1497-506. [DOI: 10.1002/ijc.25478] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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119
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Abstract
Oxidative stress has been implicated previously in the regulation of ceramide metabolism. In the present study, its effects on dihydroceramide desaturase were investigated. To stimulate oxidative stress, HEK (human embyronic kidney)-293, MCF7, A549 and SMS-KCNR cells were treated with H2O2, menadione or tert-butylhydroperoxide. In all cell lines, an increase in dihydroceramide was observed upon oxidative stress as measured by LC (liquid chromatography)/MS. In contrast, total ceramide levels were relatively unchanged. Mechanistically, dihydroceramide desaturase activity was measured by an in situ assay and decreased in a time- and dose-dependent fashion. Interestingly, no detectable changes in the protein levels were observed, suggesting that oxidative stress does not induce degradation of dihydroceramide desaturase. In summary, oxidative stress leads to potent inhibition of dihydroceramide desaturase resulting in significant elevation in dihydroceramide levels in vivo.
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120
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Separovic D, Kelekar A, Nayak AK, Tarca AL, Hanada K, Pierce JS, Bielawski J. Increased ceramide accumulation correlates with downregulation of the autophagy protein ATG-7 in MCF-7 cells sensitized to photodamage. Arch Biochem Biophys 2010; 494:101-5. [PMID: 19944062 PMCID: PMC2877393 DOI: 10.1016/j.abb.2009.11.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Revised: 11/17/2009] [Accepted: 11/18/2009] [Indexed: 12/11/2022]
Abstract
The purpose of this study was to determine the sphingolipid (SL) profile in cells defective in autophagy protein ATG-7 and overall cell death after photodynamic therapy (PDT) with the photosensitizer Pc 4. MCF-7 human breast cancer cells with downregulated ATG-7 and their scrambled controls (Scr) were used. Exposure of ATG-7 knockdown cells to PDT led to increased cell killing. PDT evoked an early (2h) greater global increase in ceramides in ATG-7 defective cells compared to Scr cells. The total increases in dihydroceramide (DHceramide) were significant at 2 and 24h in both cell types post-PDT. The levels of sphingosine-1-phosphate (S1P) and sphingosine were decreased below resting levels at both time points irrespective of the cell type. The data imply that ceramide might be a marker of ATG-7 deficiency in cells sensitized to PDT.
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Affiliation(s)
- Duska Separovic
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48201, USA.
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121
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Puissant A, Robert G, Fenouille N, Luciano F, Cassuto JP, Raynaud S, Auberger P. Resveratrol promotes autophagic cell death in chronic myelogenous leukemia cells via JNK-mediated p62/SQSTM1 expression and AMPK activation. Cancer Res 2010; 70:1042-52. [PMID: 20103647 DOI: 10.1158/0008-5472.can-09-3537] [Citation(s) in RCA: 293] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Autophagy that is induced by starvation or cellular stress can enable cancer cell survival by sustaining energy homeostasis and eliminating damaged organelles and proteins. In response to stress, cancer cells have been reported to accumulate the protein p62/SQSTM1 (p62), but its role in the regulation of autophagy is controversial. Here, we report that the plant phytoalexin resveratrol (RSV) triggers autophagy in imatinib-sensitive and imatinib-resistant chronic myelogenous leukemia (CML) cells via JNK-dependent accumulation of p62. JNK inhibition or p62 knockdown prevented RSV-mediated autophagy and antileukemic effects. RSV also stimulated AMPK, thereby inhibiting the mTOR pathway. AMPK knockdown or mTOR overexpression impaired RSV-induced autophagy but not JNK activation. Lastly, p62 expression and autophagy in CD34+ progenitors from patients with CML was induced by RSV, and disrupting autophagy protected CD34+ CML cells from RSV-mediated cell death. We concluded that RSV triggered autophagic cell death in CML cells via both JNK-mediated p62 overexpression and AMPK activation. Our findings show that the JNK and AMPK pathways can cooperate to eliminate CML cells via autophagy.
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Affiliation(s)
- Alexandre Puissant
- INSERM 895, Team 2: Cell Death Differentiation and Cancer, Laboratoire d'Oncohématologie, Centre Hospitalier Universitaire de Nice, Nice, France
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