title: Activation of ceramide synthase 6 by celecoxib leads to a selective induction of C16:0-ceramide.
abstract: Ceramides serve as bioactive molecules with important roles in cell proliferation and apoptosis. Ceramides (Cer) with different N-acyl side chains (C(14:0)-Cer-C(26:0)-Cer) possess distinctive roles in cell signaling and are differentially expressed in HCT-116 colon cancer cells. Celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, exhibiting antiproliferative effects, activates the sphingolipid pathway. To elucidate the mechanism, HCT-116 cells were treated with 50μM celecoxib leading to a significant increase of C(16:0)-Cer. Interestingly, 50μM celecoxib resulted in a 2.8-fold increase of ceramide synthase (CerS) activity as measured by a cell-based activity assay. siRNA against several CerSs revealed that CerS6 was predominantly responsible for the increase of C(16:0)-Cer in HCT-116 cells. Moreover, the silencing of CerS6 partially protected HCT-116 cells from the toxic effects induced by celecoxib. Treatment of cells with celecoxib and fumonisin B1 (inhibitor of CerSs) or myriocin (inhibitor of l-serine palmitoyl transferase) or desipramine (inhibitor of acid sphingomyelinase and acid ceramidase) revealed that the increase of C(16:0)-Cer results predominantly from activation of the salvage pathway. Using the nude mouse model we demonstrated that celecoxib induces also in vivo a significant increase of C(16:0)-Cer in stomach, small intestine and tumor tissue. In conclusion, celecoxib causes a specific increase of C(16:0)-Cer by activating CerS6 and the salvage pathway, which contribute to the toxic effects of celecoxib.
authors.affiliation: pharmazentrum frankfurt/ZAFES, Institut für Klinische Pharmakologie, Klinikum der Goethe-Universität Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt/Main, Germany. susanne.schiffmann@med.uni-frankfurt.de
authors.forename: Susanne
authors.initials: S
authors.lastname: Schiffmann
authors.forename: Simone
authors.initials: S
authors.lastname: Ziebell
authors.forename: Jessica
authors.initials: J
authors.lastname: Sandner
authors.forename: Kerstin
authors.initials: K
authors.lastname: Birod
authors.forename: Klaus
authors.initials: K
authors.lastname: Deckmann
authors.forename: Daniela
authors.initials: D
authors.lastname: Hartmann
authors.forename: Sina
authors.initials: S
authors.lastname: Rode
authors.forename: Helmut
authors.initials: H
authors.lastname: Schmidt
authors.forename: Carlo
authors.initials: C
authors.lastname: Angioni
authors.forename: Gerd
authors.initials: G
authors.lastname: Geisslinger
authors.forename: Sabine
authors.initials: S
authors.lastname: Grösch
mesh_terms: D000818:Animals; D000068579:Celecoxib; D049109:Cell Proliferation / Q000187:drug effects; D002518:Ceramides / Q000096:biosynthesis*; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D045325:HCT116 Cells; D006801:Humans; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D008819:Mice, Nude; D011720:Pyrazoles / Q000494:pharmacology* / Q000633:toxicity; D051049:Sphingosine N-Acyltransferase / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D013449:Sulfonamides / Q000494:pharmacology* / Q000633:toxicity; D014018:Tissue Distribution / Q000187:drug effects / Q000502:physiology
chemical_list: D002518:Ceramides; D008565:Membrane Proteins; D011720:Pyrazoles; D013449:Sulfonamides; C097760:N-palmitoylsphingosine; C506123:CERS6 protein, human; D051049:Sphingosine N-Acyltransferase; D000068579:Celecoxib