Endothelin-1 Activates the Notch Signaling Pathway and Promotes Tumorigenesis in Giant Cell Tumor of the Spine. Issue 17 (1st September 2019) - Yuan, Wei
Abstract : Study Design: Experimental study. Objective: To examine the role of endothelin-1 (ET-1) and the Notch signaling pathway in giant cell tumor (GCT) of the spine. Summary of Background Data: Previously published studies have shown that the Notch signaling pathway has a role in tumor invasion and that ET-1 is involved in tumor invasion and angiogenesis. However, the roles of both Notch signaling and ET-1 in GCT of the spine remain unknown. Methods: Expression of ET-1 in tissue samples from patients with spinal GCT, and adjacent normal tissue, were analyzed by immunohistochemistry and western blot. GCT stromal cells (GCTSCs) were isolated and ET-1 expression was demonstrated by immunofluorescence. Cell viability and cell migration of GCTSCs and human vascular endothelial cells following ET-1 treatment were assessed using the cell counting kit-8 assay and a transwell assay. Receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG) mRNA expression was determined following ET-1 treatment of GCTSCs using quantitative real-time polymerase chain reaction. In GCTSCs treated with ET-1 and the ET-1 signaling antagonist, BQ-123, levels of cyclin D1, vascular endothelial growth factor, matrix metalloproteinase-2 and -9 (MMP-2 and MMP-9), Jagged1, Hes1, Hey2, and Notch intracellular domain were examined by western blot. Results: Compared with normal adjacent tissue, ET-1 was highly expressed in GCT tissue. In GCTSCs studied in vitro, treatment with ET-1 significantly increased GCTSC and human vascular endothelial cells growth and migration and increased the expression of RANKL and OPG, meanwhile the ratio of RANKL/OPG was increased, in GCTSCs, it upregulated the production of cyclin D1, vascular endothelial growth factor, MMP-2, MMP-9, Jagged1, Hes1, Hey2, and Notch intracellular domain expression in a dose-dependent manner. Treatment with BQ-123 reversed these effects. Conclusion: In GCT of the spine, ET-1 showed increased expression. In cultured GCTSCs, ET-1 treatment activated the Notch signaling pathway. Level of Evidence: 2 Abstract : Endothelin-1 (ET-1) is expressed in giant cell tumor (GCT) of the spine. In cultured GCT stromal cells (GCTSCs), treatment with ET-1 activated the Notch signaling pathway. These findings support the need for further studies on the role of ET-1 in tumorigenesis and as a potential therapeutic target in spinal GCT.