title: 1Alpha,25-dihydroxyvitamin D3 inhibits programmed cell death in HL-60 cells by activation of sphingosine kinase.
abstract: Sphingolipid breakdown products [ceramide, sphingosine, and sphingosine-1-phosphate (SPP)] are emerging as a new class of bioactive molecules. In agreement with previous studies, treatment of human promyelocytic leukemia HL-60 cells with 1-alpha,25-dihydroxyvitamin D3 [1,25-(OH)2D3] induced a transient increase of ceramide levels within 2 h, which then returned to basal levels within 8 h. In contrast, sphingosine kinase activity increased more slowly and reached maximal levels only after 20 h of exposure, leading to a concomitant increase in SPP level. Unlike treatments with cell-permeable ceramide analogues or sphingomyelinase, which induce apoptosis, 1,25-(OH)2D3 did not induce apoptosis, despite the early formation of ceramide. Moreover, prolonged treatment of HL-60 cells with 1,25-(OH)2D3 suppressed ceramide-induced apoptosis. There was a correlation between the time course and dose response of the activation of sphingosine kinase by 1,25-(OH)2D3 and the protection against apoptosis. In contrast, treatment with all-trans-retinoic acid neither stimulated sphingosine kinase activity nor protected cells from ceramide-induced apoptosis. Treatment with SPP protected HL-60 cells from ceramide-induced apoptosis, and N,N-dimethylsphingosine (DMS), a competitive inhibitor of sphingosine kinase, prevented the survival effect of 1,25-(OH)2D3. The effect of DMS was counteracted by SPP, suggesting that SPP is a critical component of the cytoprotective effect of 1,25-(OH)2D3. Chelerythrine chloride, an inhibitor of protein kinase C, markedly reduced sphingosine kinase activity and the apoptosis-sparing effect of 1,25-(OH)2D3, and conversely, the tumor promoter 12-O-tetradecanoylphorhol-13-acetate not only suppressed ceramide-induced apoptosis but also stimulated sphingosine kinase activity. Moreover, the protective effect of 12-O-tetradecanoylphorbol-13-acetate was blocked by DMS. Collectively, our observations indicate that the cytoprotective effect of 1,25-(OH)2D3 is mediated by SPP, which is formed as a consequence of activation of sphingosine kinase.
authors.affiliation: Department of Biochemistry and Molecular Biology, Georgetown University Medical Center, Washington, DC 20007, USA.
authors.forename: B
authors.initials: B
authors.lastname: Kleuser
authors.forename: O
authors.initials: O
authors.lastname: Cuvillier
authors.forename: S
authors.initials: S
authors.lastname: Spiegel
mesh_terms: D000470:Alkaloids; D017209:Apoptosis / Q000187:drug effects*; D053119:Benzophenanthridines; D002117:Calcitriol / Q000494:pharmacology*; D002273:Carcinogens / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002518:Ceramides / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018922:HL-60 Cells / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D006801:Humans; D008246:Lysophospholipids; D010617:Phenanthridines / Q000494:pharmacology; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D000099157:Sphingosine Kinase
chemical_list: D000470:Alkaloids; D053119:Benzophenanthridines; D002117:Calcitriol; D002273:Carcinogens; D002518:Ceramides; D004791:Enzyme Inhibitors; D008246:Lysophospholipids; D010617:Phenanthridines; D017853:Phosphotransferases (Alcohol Group Acceptor); D013110:Sphingosine; D013755:Tetradecanoylphorbol Acetate; D000099157:Sphingosine Kinase; C060506:sphingosine 1-phosphate; C016299:chelerythrine; C061800:N,N-dimethylsphingosine