title: Differential regulation of cyclooxygenase-2 expression by phytosphingosine derivatives, NAPS and TAPS, and its role in the NAPS or TAPS-mediated apoptosis.
abstract: We investigated the effect of novel phytosphingosine derivatives, N-acetyl phytosphingosine (NAPS) and tetra-acetyl phytosphingosine (TAPS), on induction of apoptosis in HaCaT cells in comparison with C2-ceramide. NAPS/TAPS effectively decreased cell viability in a dose dependent manner mainly due to apoptosis. An apoptosis expression array analysis showed that in the TAPS treated cells 13 genes including COX-2 encoding cyclooxygenase-2, the most induced by TAPS, were up-regulated while 23 others down-regulated. Therefore, we examined the mechanism underlying the altered expression of COX-2. Assays with inhibitors and antibodies against proteins involved in signal transduction demonstrated that NAPS and TAPS elevated COX-2 expression via tyrosine kinase, src, PI-3 kinase and PKC, followed by ERK activation. However, P38 was not involved in the NAPS-mediated COX-2 expression but in the TAPS-mediated. We further demonstrated by FACS analyses that NAPS- or TAPS-mediated apoptosis was greatly increased in cells treated with celecoxib, a selective COX-2 inhibitor. Inhibition of the ERK pathway apparently involved in the NAPS/TAPS-mediated COX-2 expression enhanced the NAPS/TAPS-mediated apoptosis, whereas inhibition of the P38 pathway did not. These results suggest that expression of COX-2 in the TAPS- or NAPS-treated cells may be increased to counteract the effect of those compounds on apoptosis.
authors.affiliation: Department of Dermato-Immunology, The Catholic University of Korea, Seoul, South Korea.
authors.forename: Hye Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: Weonhye
authors.initials: W
authors.lastname: Shin
authors.forename: Chang Seo
authors.initials: CS
authors.lastname: Park
authors.forename: Hyung-Ok
authors.initials: HO
authors.lastname: Kim
authors.forename: Tae-Yoon
authors.initials: TY
authors.lastname: Kim
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D051546:Cyclooxygenase 2; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D008565:Membrane Proteins; D019950:Mitogen-Activated Protein Kinase 1 / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis*; D011493:Protein Kinase C / Q000502:physiology; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases; D019061:src-Family Kinases / Q000502:physiology
chemical_list: D007527:Isoenzymes; D008565:Membrane Proteins; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D019869:Phosphatidylinositol 3-Kinases; D019061:src-Family Kinases; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C012491:phytosphingosine; D013110:Sphingosine