【Abstract】Objective To investigate the mechanism of endothelin-1 (ET1) activation leading to the peritoneal mesothelial cell proliferation-induced peritoneal angiogenesis. Methods Human peritoneal mesothelial cells (HPMCs) (HMrSV5) were cultured and underwent high glucose stimulation. The secretion of ET1 from HPMCs was assayed. Exogenous ET1 was added in the medium and phosphorylated extracellular signalregulated kinase 1/2 (ERK1/2) and E26 transformation specific- 1 (Ets- 1) were detected by western blot. Knockdown and blockage of Ets-1 were carried out by siRNA interference and anti-Ets-1 antibody, respectively.

The proliferation of HPMCs was determined by BrdU method. Total capillary length of the five randomly selected regions was analyzed by capillary formation experiments and Image J software. Results High glucose stimulation induced the higher expression of ET1 in HMPCs (2.5% glucose, F=5.561, P=0.036; 4.25% glucose, F=4.784, P=0.008). Exogenous ET1 promoted the increases of phosphorylated ERK 1/2 (F=66.347, P=0.026) and Ets-1 (F=110.614, P=0.031), the downstream molecule of ERK1/2, in HPMCs. Blocking MEK-1 in HPMCs could significantly abolish the activation of ERK 1/2 induced by ET1 (F=56.361, P=0.006). After the addition of ETA and ETB receptor inhibitors to HPMCs, ETA receptor inhibitor was found to reduce the expression of Ets- 1 (F=131.191, P=0.039). ET1 was capable of inducing HPMC proliferation (F=4.671,P=0.046), which could be attenuated by ET1 antagonists (F=5.329, P＜0.001; F=5.362, P＜0.001). Knockdown and blockage of Ets- 1 had similar anti- proliferative effects (F=5.638, P<0.001; F=4.611, P=0.007).These findings suggest that ET1 specifically promotes HPMC proliferation through the ERK1/2-Ets-1 signaling pathway. In addition, HPMCs in conditional media and stimulated with ET1 significantly promoted VEGF production (F=11.614, P＜0.001) and endothelial cell angiogenesis. Conclusion ET1 promotes HPMCs proliferation, VEGF production and endothelial cell angiogenesis via the ERK1/2-Ets-1 signaling pathway.