Ceramide in nitric oxide inhibition of glioma cell growth. Evidence for the involvement of ceramide traffic.
The treatment of C6 glioma cells with the nitric oxide donor, PAPANONOate ((Z)-[N-(3-ammoniopropyl)-N-(n-propyl)amino]diazen-1-ium-1,2-diolate), resulted in a dose-dependent inhibition of cell proliferation. This was associated to a rapid and significant increase of ceramide levels and was mimicked by treatments that augment cellular ceramide. Metabolic experiments with radioactive sphingosine, serine, and choline showed that nitric oxide strongly reduced the utilization of ceramide for the biosynthesis of both sphingomyelin and glucosylceramide. Nevertheless, nitric oxide did not modify the activity of different enzymes of ceramide metabolism. The possibility that nitric oxide impairs the availability of ceramide for sphingolipid biosynthesis was then investigated. The metabolism of N-hexanoyl-[(3)H]sphingosine demonstrated that nitric oxide did not affect the biosynthesis of N-hexanoyl-[(3)H]sphingolipids but inhibited the metabolic utilization of long chain [(3)H]ceramide, synthesized in the endoplasmic reticulum (ER) from the recycled [(3)H]sphingosine. Moreover, results obtained with fluorescent ceramides, brefeldin A, ATP depletion, as well as in a ceramide transport assay indicate that nitric oxide impairs the traffic of ceramide from ER to Golgi apparatus. All this supports that, in glioma cells, the modulation of ceramide traffic can contribute to the regulation of its intracellular levels and participate in the nitric oxide-activated signaling pathway involved in the control of cell proliferation.
Viani
Paola
P
Department of Medical Chemistry, Biochemistry and Biotechnology, University of Milan, via Fratelli Cervi 93, Segrate, Milan 20090, Italy. paola.viani@unimi.it
Giussani
Paola
P
Brioschi
Loredana
L
Bassi
Rosaria
R
Anelli
Viviana
V
Tettamanti
Guido
G
Riboni
Laura
L
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D020126:Brefeldin A / Q000494:pharmacology; D002455:Cell Division; D002460:Cell Line; D002518:Ceramides / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D002794:Choline / Q000737:chemistry; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005910:Glioma / Q000201:enzymology*; D006056:Golgi Apparatus / Q000378:metabolism; D007313:Insecta; D008856:Microscopy, Fluorescence; D009569:Nitric Oxide / Q000378:metabolism*; D051381:Rats; D012694:Serine / Q000737:chemistry; D015398:Signal Transduction; D013109:Sphingomyelins / Q000737:chemistry; D013110:Sphingosine / Q000737:chemistry; D013997:Time Factors; D014407:Tumor Cells, Cultured
D002518:Ceramides; D013109:Sphingomyelins; D020126:Brefeldin A; D009569:Nitric Oxide; D012694:Serine; D000255:Adenosine Triphosphate; D002794:Choline; D013110:Sphingosine