cis-4-Methylsphingosine Phosphate Induces Apoptosis in Neuroblastoma Cells by Opposite Effects on p38 and ERK Mitogen-Activated Protein Kinases

Nätzker, Sven; Heinemann, Thomas; Figueroa‐Pérez, Santiago; Schnieders, Barbara; Schmidt, Richard R.; Sandhoff, Konrad; Echten‐Deckert, Gerhild van

doi:10.1515/bc.2002.212

Cited by 12 publications

(27 citation statements)

References 37 publications

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“…3B) and cell death (Fig. 1B) is also consistent with reports showing that a downregulation in ERK1/2 activation accompanies p38 MAPK-mediated apoptosis in both neuronal and nonneuronal cells [17,20,24].…”

Section: Discussionsupporting

confidence: 91%

p38 MAPK as a negative regulator of VEGF/VEGFR2 signaling pathway in serum deprived human SK-N-SH neuroblastoma cells

Gomes

Rockwell

2008

Neuroscience Letters

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Evidence suggests that vascular endothelial growth factor (VEGF) mediates neuroprotection to prevent an apoptotic cell death. The p38 mitogen activated protein kinase (MAPK) pathway is implicated as an important mediator of neuronal apoptosis but its role in VEGF-mediated neuroprotection is unclear. Herein, we show that treatments with the p38 MAPK inhibitor, SB202190, enhanced VEGF-mediated survival in serum deprived SK-N-SH neuroblastoma cells by decreasing caspase-3/7 activation while increasing the phosphorylation of the extracellular signalregulated kinase (ERK1/2) and Akt signaled through the VEGF receptor, VEGFR2. A blockade of VEGFR2 signaling with a selective inhibitor, SU1498 or gene silencing with VEGFR2 siRNA in SB202190 treated cells abrogated this prosurvival response and induced high activation levels of caspase-3/7. These findings suggested that the protection elicited by p38 MAPK inhibition in serum starved cells was dependent on a functional VEGF/VEGFR2 pathway. However, p38 MAPK inhibition attenuated caspase-3 cleavage in SU1498/SB202190 treated cells, indicating that p38 MAPK and caspase-3 only contributed in part to the total levels of caspase-3/7 induced by VEGFR2 inhibition. Pretreatments with the pan caspase inhibitor, z-VAD-fmk, prevented the apoptosis induced by VEGFR2 inhibition and promoted survival in serum starved cells irrespective of p38 MAPK inhibition. Collectively, our findings suggest that p38 MAPK exerts a negative effect on VEGF-mediated signaling through VEGFR2 in serum starved neuroblastoma cells. Furthermore, VEGF signals protection against a caspase-mediated cell death that is regulated by p38 MAPKdependent and -independent mechanisms.

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Section: Discussionsupporting

confidence: 91%

p38 MAPK as a negative regulator of VEGF/VEGFR2 signaling pathway in serum deprived human SK-N-SH neuroblastoma cells

Gomes

Rockwell

2008

Neuroscience Letters

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“…Because our data clearly show that safingol is only converted into less-bioactive compounds like dihydroceramide and more complex sphingolipids, its antineoplastic activity most probably cannot be explained by the formation of l-threo-ceramide, as suggested before (37). From our results, it appears more likely that the cytotoxic effect of safingol is a result of blocking sphingosine kinase on the one hand (12,39,40) and PKC on the other hand (9,38). However, we cannot exclude that the different cell systems used in different studies might explain the different results.…”

Section: Discussionsupporting

confidence: 48%

“…We have recently shown that in neuroblastoma cells (12) as well as in primary cultured neurons (unpublished observations), the inhibitory effect of safingol (20 M) on sphingosine kinase catalyzed phosphorylation of the synthetic sphingosine analog cis-4-methylsphingosine decreases over time. These findings indicate that, although safingol is a nonnatural stereoisomer, it appears to be efficiently metabolized by neuronal cells.…”

mentioning

confidence: 93%

Metabolism of the unnatural anticancer lipid safingol, l-threo-dihydrosphingosine, in cultured cells

Dragusin

Gurgui²,

Schwarzmann

et al. 2003

Journal of Lipid Research

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We studied the metabolism of radioactively labeled safingol ( L -threo-dihydrosphingosine) in primary cultured neurons, B104 neuroblastoma cells, and Swiss 3T3 fibroblasts, and compared it to that of its natural stereoisomer D -erythro -dihydrosphingosine. Both sphingoid bases are used as biosynthetic precursors for complex sphingolipids, albeit to different rates. Whereas a considerable amount of the natural sphingoid base is also directed to the catabolic pathway (20-66%, cell type dependent), only a minor amount of the nonnatural safingol is subjected to catabolic cleavage, most of it being N -acylated to the respective stereochemical variant of dihydroceramide. Interestingly, N -acylation of safingol to L -threo -dihydroceramide is less sensitive to fumonisin B1 than the formation of the natural D -erythro -dihydroceramide. In addition, safingol-derived L -threo-dihydroceramide, unlike its physiologic counterpart, is not desaturated. Most of it either accumulates in the cells (up to 50%) or is used as a biosynthetic precursor of the respective dihydrosphingomyelin (up to 45%). About 5% is, however, glucosylated and channeled into the glycosphingolipid biosynthetic pathway. Our results demonstrate that, despite its nonnatural stereochemistry, safingol is recognized and metabolized preferentially by enzymes of the sphingolipid biosynthetic pathway. Furthermore, our data suggest that the cytotoxic potential of safingol is reduced rather than enhanced via its metabolic conversion. -Dragusin, M., C. Gurgui, G. Schwarzmann, J. Hoernschemeyer, and G. van Echten-Deckert. Metabolism of the unnatural anticancer lipid safingol, L -threo -dihydrosphingosine, in cultured cells.

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“…Genomic DNA Analysis-Genomic DNA analysis was performed as described previously (17). In brief, cells were detached with a cell lifter in the respective medium and centrifuged (2000 ϫ g, 10 min, 4°C), thus collecting both adherent and detached cells.…”

Section: Methodsmentioning

confidence: 99%

Subcellular Origin of Sphingosine 1-Phosphate Is Essential for Its Toxic Effect in Lyase-deficient Neurons

Hagen

Veldhoven

Proia

et al. 2009

Journal of Biological Chemistry

110

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Cerebellar granule cells from sphingosine 1-phosphate (S1P) lyase-deficient mice were used to study the toxicity of this potent sphingolipid metabolite in terminally differentiated postmitotic neurons. Based on earlier findings with the lyase-stable, semi-synthetic, cis-4-methylsphingosine phosphate, we hypothesized that accumulation of S1P above a certain threshold induces neuronal apoptosis. The present studies confirmed this conclusion and further revealed that for S1P to induce apoptosis in lyase-deficient neurons it must also be produced by sphingosine-kinase2 (SK2). These conclusions are based on the finding that incubation of lyase-deficient neurons with either sphingosine or S1P results in a similar elevation in cellular S1P; however, only S1P addition to the culture medium induces apoptosis. This was not due to S1P acting on the S1P receptor but to hydrolysis of S1P to sphingosine that was phosphorylated by the cells, as described before for cis-4-methylsphingosine. Although the cells produced S1P from both exogenously added sphingosine as well as sphingosine derived from exogenous S1P, the S1P from these two sources were not equivalent, because the former was primarily produced by SK1, whereas the latter was mainly formed by SK2 (as also was cis-4-methylsphingosine phosphate), based on studies in neurons lacking SK1 or SK2 activity. Thus, these investigations show that, due to the existence of at least two functionally distinct intracellular origins for S1P, exogenous S1P can be neurotoxic. In this model, S1P accumulated due to a defective lyase, however, this cause of toxicity might also be important in other cases, as illustrated by the neurotoxicity of cis-4-methylsphingosine phosphate.Sphingosine 1-phosphate (S1P) 2 is a potent lipid mediator that has been shown to regulate a wide range of physiological processes, including proliferation, differentiation, motility, cytoskeleton rearrangements, and calcium homeostasis (1, 2). There is convincing experimental evidence that this bioactive sphingolipid can act both extracellularly, as a ligand for a family of five specific G protein-coupled receptors, and inside the cells, as a second messenger (3, 4). In most cell types described so far, S1P and its metabolic precursor ceramide exert antagonistic effects on cell survival with S1P being generally regarded as a survival signal, whereas ceramide and sphingosine are generally toxic (5, 6). Interestingly, generation of sphingosine and S1P is generally thought to be dependent on the availability of ceramide (7), however, relatively high amounts of S1P are also present in blood, lymph, and cerebrospinal fluid (8, 9) and may serve as additional sources for some cells.More than a decade ago, we introduced the synthetic sphingosine analog cis-4-methylsphingosine as a tool for studies of sphingoid base metabolism and function (10). When added to the culture medium, this analog is taken up and mainly phosphorylated to the respective cis-4-methylsphingosine phosphate, which accumulates intracellularly, because it ...

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cis-4-Methylsphingosine Phosphate Induces Apoptosis in Neuroblastoma Cells by Opposite Effects on p38 and ERK Mitogen-Activated Protein Kinases

Cited by 12 publications

References 37 publications

p38 MAPK as a negative regulator of VEGF/VEGFR2 signaling pathway in serum deprived human SK-N-SH neuroblastoma cells

p38 MAPK as a negative regulator of VEGF/VEGFR2 signaling pathway in serum deprived human SK-N-SH neuroblastoma cells

Metabolism of the unnatural anticancer lipid safingol, l-threo-dihydrosphingosine, in cultured cells

Subcellular Origin of Sphingosine 1-Phosphate Is Essential for Its Toxic Effect in Lyase-deficient Neurons

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