title: Sphingosine-1-phosphate regulates glioblastoma cell invasiveness through the urokinase plasminogen activator system and CCN1/Cyr61.
abstract: Glioblastoma multiforme (GBM) is an aggressively invasive brain neoplasm with poor patient prognosis. We have previously shown that the bioactive lipid sphingosine-1-phosphate (S1P) stimulates in vitro invasiveness of GBM cells and that high expression levels of the enzyme that forms S1P, sphingosine kinase-1 (SphK1), correlate with shorter survival time of GBM patients. We also recently showed that S1P induces expression of CCN1 (also known as Cyr61), a matricellular protein known to correlate with poor patient prognosis, in GBM cells. In this study, we further explored the role of CCN1 as well as the urokinase plasminogen activator (uPA), a protein known to stimulate GBM cell invasiveness, in S1P-induced invasion using a spheroid invasion assay. We also investigated the roles of various S1P receptors in stimulating invasiveness through these pathways. S1P induced expression of uPA and its receptor, uPAR, in GBM cells. Whereas S1P(1), S1P(2), and S1P(3) receptors all contribute, at least partially, S1P(1) overexpression led to the most dramatic induction of the uPA system and of spheroid invasion, even in the absence of added S1P. Furthermore, neutralizing antibodies directed against uPA or CCN1 significantly decreased both basal and S1P-stimulated GBM cell invasiveness. Inhibition of SphK blocked basal expression of uPA and uPAR, as well as glioma cell invasion; however, overexpression of SphK did not augment S1P receptor-mediated enhancement of uPA activity or invasion. Thus, SphK is necessary for basal activity of the uPA system and glioma cell invasion, whereas S1P receptor signaling enhances invasion, partially through uPA and CCN1.
authors.affiliation: Division of Neuropathology, Department of Pathology, The Ohio State University, 4164 Graves Hall, 333 West 10th Avenue, Columbus, OH 43210, USA.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Young
authors.forename: Dennis K
authors.initials: DK
authors.lastname: Pearl
authors.forename: James R
authors.initials: JR
authors.lastname: Van Brocklyn
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D055515:Cysteine-Rich Protein 61 / Q000502:physiology*; D005909:Glioblastoma / Q000201:enzymology / Q000401:mortality / Q000473:pathology*; D006801:Humans; D008246:Lysophospholipids / Q000494:pharmacology* / Q000502:physiology; D009361:Neoplasm Invasiveness / Q000473:pathology*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D049349:Receptors, Lysosphingolipid / Q000187:drug effects / Q000502:physiology; D055293:Receptors, Urokinase Plasminogen Activator / Q000502:physiology*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000502:physiology; D017741:Survivors; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*; D000099157:Sphingosine Kinase
chemical_list: D055515:Cysteine-Rich Protein 61; D008246:Lysophospholipids; D017853:Phosphotransferases (Alcohol Group Acceptor); D049349:Receptors, Lysosphingolipid; D055293:Receptors, Urokinase Plasminogen Activator; D013110:Sphingosine; D014568:Urokinase-Type Plasminogen Activator; D000099157:Sphingosine Kinase; C501848:CCN1 protein, human; C060506:sphingosine 1-phosphate