sphingosine-1-phosphate and Wilms-Tumor

Sphingosine-1-phosphate (S1P) is an important regulator of cellular functions via interaction with its receptors S1P(1-5). To date, nothing is known about the S1P receptor expression and the effects of S1P signaling in Wilms tumor. In this study, we found ubiquitous expression of S1P receptors in Wilms tumor specimens and cell lines. We demonstrated that S1P(1) acted as a promigratory modulator by employing S1P(1) antagonist VPC44116, S1P(1) siRNA and adenoviral transduction in Wilms tumor cells. Further, we clarified that S1P(1)-mediated migration occurred via Gi coupling and activation of PI3K and Rac1. In addition, S1P stimulated WiT49 cell invasion through S1P(1)/Gi signaling pathway. We consider that targeting S1P(1) may be a point of therapeutic intervention in Wilms tumor.

Topics: Cell Line, Tumor; Cell Movement; GTP-Binding Protein alpha Subunits, Gi-Go; Humans; Kidney Neoplasms; Lysophospholipids; Neoplasm Invasiveness; Phosphatidylinositol 3-Kinases; rac1 GTP-Binding Protein; Receptors, Lysosphingolipid; RNA, Small Interfering; Signal Transduction; Sphingosine; Wilms Tumor

Connective tissue growth factor (CTGF), a member of the CCN family of secreted matricellular proteins, regulates fibrosis, angiogenesis, cell proliferation, apoptosis, tumor growth, and metastasis. However, the role of CTGF and its regulation mechanism in Wilms' tumor remains largely unknown. We found that the bioactive lipid sphingosine-1-phosphate (S1P) induced CTGF expression in a concentration- and time-dependent manner in a Wilms' tumor cell line (WiT49), whereas FTY720-phosphate, an S1P analogue that binds all S1P receptors except S1P2, did not. Further, the specific S1P2 antagonist JTE-013 completely inhibited S1P-induced CTGF expression, whereas the S1P1 antagonist VPC44116 did not, indicating that this effect was mediated by S1P2. This was confirmed by adenoviral transduction of S1P2 in WiT49 cells, which showed that overexpression of S1P2 increased the expression of CTGF. Induction of CTGF by S1P was sensitive to ROCK inhibitor Y-27632 and c-Jun NH2-terminal kinase inhibitor SP600125, suggesting the requirement of RhoA/ROCK and c-Jun NH2-terminal kinase pathways for S1P-induced CTGF expression. Interestingly, the expression levels of CTGF were decreased in 8 of 10 Wilms' tumor tissues compared with matched normal tissues by quantitative real-time PCR and Western blot analysis. In vitro, human recombinant CTGF significantly inhibited the proliferation of WiT49 cells. In addition, overexpression of CTGF resulted in significant inhibition of WiT49 cell growth. Taken together, these data suggest that CTGF protein induced by S1P2 might act as a growth inhibitor in Wilms' tumor.

Topics: Cell Line, Tumor; Cell Proliferation; Connective Tissue Growth Factor; Extracellular Signal-Regulated MAP Kinases; Gene Expression Regulation, Neoplastic; Humans; Immediate-Early Proteins; Intercellular Signaling Peptides and Proteins; JNK Mitogen-Activated Protein Kinases; Kidney Neoplasms; Lysophospholipids; p38 Mitogen-Activated Protein Kinases; Receptors, Lysosphingolipid; rho-Associated Kinases; rhoA GTP-Binding Protein; Sphingosine; Suppression, Genetic; Wilms Tumor