A Novel Sphingosine Kinase Inhibitor Induces Autophagy in Tumor CellsS
The sphingolipids ceramide, sphingosine, and sphingosine 1-phosphate (S1P) regulate cell signaling, proliferation, apoptosis, and autophagy. Sphingosine kinase-1 and -2 (SK1 and SK2) phosphorylate sphingosine to form S1P, shifting the balanced activity of these lipids toward cell proliferation. We h...
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Published in | The Journal of pharmacology and experimental therapeutics Vol. 333; no. 2; pp. 454 - 464 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
The American Society for Pharmacology and Experimental Therapeutics
01.05.2010
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Subjects | |
Online Access | Get full text |
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Summary: | The sphingolipids ceramide, sphingosine, and sphingosine 1-phosphate (S1P) regulate
cell signaling, proliferation, apoptosis, and autophagy. Sphingosine kinase-1 and -2
(SK1 and SK2) phosphorylate sphingosine to form S1P, shifting the balanced activity
of these lipids toward cell proliferation. We have previously reported that
pharmacological inhibition of SK activity delays tumor growth in vivo. The present
studies demonstrate that the SK2-selective inhibitor
3-(4-chlorophenyl)-adamantane-1-carboxylic acid (pyridin-4-ylmethyl)amide (ABC294640)
induces nonapoptotic cell death that is preceded by microtubule-associated protein
light chain 3 cleavage, morphological changes in lysosomes, formation of
autophagosomes, and increases in acidic vesicles in A-498 kidney carcinoma cells.
ABC294640 caused similar autophagic responses in PC-3 prostate and MDA-MB-231 breast
adenocarcinoma cells. Simultaneous exposure of A-498 cells to ABC294640 and
3-methyladenine, an inhibitor of autophagy, switched the mechanism of toxicity to
apoptosis, but decreased the potency of the SK2 inhibitor, indicating that autophagy
is a major mechanism for tumor cell killing by this compound. Induction of the
unfolded protein response by the proteasome inhibitor
N-
(benzyloxycarbonyl)leucinylleucinylleucinal
Z
-Leu-Leu-Leu-al (MG-132) or the heat shock protein 90 inhibitor
geldanamycin synergistically increased the cytotoxicity of ABC294640 in vitro. In
severe combined immunodeficient mice bearing A-498 xenografts, daily administration
of ABC294640 delayed tumor growth and elevated autophagy markers, but did not
increase terminal deoxynucleotidyltransferase-mediated dUTP nick end
labeling-positive cells in the tumors. These data suggest that ABC294640 promotes
tumor cell autophagy, which ultimately results in nonapoptotic cell death and a delay
of tumor growth in vivo. Consequently, ABC294640 may effectively complement
anticancer drugs that induce tumor cell apoptosis. |
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ISSN: | 0022-3565 1521-0103 |
DOI: | 10.1124/jpet.109.163337 |