title: Targeting sphingosine kinase 1 inhibits Akt signaling, induces apoptosis, and suppresses growth of human glioblastoma cells and xenografts.
abstract: Sphingosine-1-phosphate is a potent sphingolipid mediator of diverse processes important for brain tumors, including cell growth, survival, migration, invasion, and angiogenesis. Sphingosine kinase 1 (SphK1), one of the two isoenzymes that produce sphingosine-1-phosphate, is up-regulated in glioblastoma and has been linked to poor prognosis in patients with glioblastoma multiforme (GBM). In the present study, we found that a potent isotype-specific SphK1 inhibitor, SK1-I, suppressed growth of LN229 and U373 glioblastoma cell lines and nonestablished human GBM6 cells. SK1-I also enhanced GBM cell death and inhibited their migration and invasion. SK1-I rapidly reduced phosphorylation of Akt but had no significant effect on activation of extracellular signal-regulated kinase 1/2, another important survival pathway for GBM. Inhibition of the concomitant activation of the c-Jun-NH(2)-kinase pathway induced by SK1-I attenuated death of GBM cells. Importantly, SK1-I markedly reduced the tumor growth rate of glioblastoma xenografts, inducing apoptosis and reducing tumor vascularization, and enhanced the survival of mice harboring LN229 intracranial tumors. Our results support the notion that SphK1 may be an important factor in GBM and suggest that an isozyme-specific inhibitor of SphK1 deserves consideration as a new therapeutic agent for this disease.
authors.affiliation: Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298-0614, USA.
authors.forename: Dmitri
authors.initials: D
authors.lastname: Kapitonov
authors.forename: Jeremy C
authors.initials: JC
authors.lastname: Allegood
authors.forename: Clint
authors.initials: C
authors.lastname: Mitchell
authors.forename: Nitai C
authors.initials: NC
authors.lastname: Hait
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Almenara
authors.forename: Jeffrey K
authors.initials: JK
authors.lastname: Adams
authors.forename: Robert E
authors.initials: RE
authors.lastname: Zipkin
authors.forename: Paul
authors.initials: P
authors.lastname: Dent
authors.forename: Tomasz
authors.initials: T
authors.lastname: Kordula
authors.forename: Sheldon
authors.initials: S
authors.lastname: Milstien
authors.forename: Sarah
authors.initials: S
authors.lastname: Spiegel
mesh_terms: D000605:Amino Alcohols / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D016543:Central Nervous System Neoplasms / Q000098:blood supply / Q000188:drug therapy* / Q000201:enzymology* / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D005909:Glioblastoma / Q000098:blood supply / Q000188:drug therapy* / Q000201:enzymology* / Q000473:pathology; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D008297:Male; D051379:Mice; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000188:drug therapy; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000099157:Sphingosine Kinase
chemical_list: D000605:Amino Alcohols; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D017853:Phosphotransferases (Alcohol Group Acceptor); D051057:Proto-Oncogene Proteins c-akt; D013110:Sphingosine; D000099157:Sphingosine Kinase; C544832:N-methyl-5-(4'-pentylphenyl)-2-aminopent-4-ene-1,3-diol