SMND-309 promotes angiogenesis in human umbilical vein endothelial cells through activating erythropoietin receptor/STAT3/VEGF pathways

The aim of the study is to investigate the direct angiogenic activities of SMND-309, a novel metabolite of salvianolic acid B, on human umbilical vein endothelial cells (HUVEC) in vitro and its potential molecular mechanisms. Effects of SMND-309 on proliferation and adhesion of HUVEC were measured using sulforhodamine B assay and cell adhesion assay kit, respectively. Effects of SMND-309 on migration and differentiation of HUVEC were examined through wound-healing assay and tube formation on matrigel method, respectively. Expressions of erythropoietin (EPO), EPO receptor, phosphorylated EPO receptor, signal transducer and activator of transcription 3 (STAT3), phosphorylated STAT3 and vascular endothelial growth factor (VEGF) were detected by Western blot. Knocking down EPO receptor gene and blocking the epidermal growth factor (EGF) receptor/Janus kinase 2 (JAK2) pathways were used to explore the potential mechanisms in SMND-309 induced angiogenesis. SMND-309 strongly induced the proliferation of HUVEC in a concentration-dependent manner within the concentrations of 1-30 mu g/ml and significantly promoted the adhesion of HUVEC to different extracellular matrix at 30 mu g/ml. SMND-309 at doses of 3, 10, 30 mu g/ml significantly enhanced the migration, capillary-like structure formation, and the levels of VEGF, phosphorylated EPO receptor and phosphorylated STAT3. Results from further experiments using HUVECEPO (receptor-) and AG-490 showed that SMND-309 activated EPO receptor first, and then stimulated JAK2/STAT3, which up-regulated the expression of VEGF, and resulted in the angiogenesis. These results clearly show that SMND-309 has powerful angiogenic activity on HUVEC, which is mostly correlated with the up-regulation of VEGF through EPO receptor/STAT3 signal pathways. (C) 2012 Elsevier B.V. All rights reserved.