Tanshinone IIA Inhibits VEGF Secretion and HIF-1α Expression in Cultured Human Retinal Pigment Epithelial Cells under Hypoxia

Purpose: The current work intends to study the activity of tanshinone IIA on secretion of vascular endothelial growth factor (VEGF) and expression of hypoxia inducible factor 1 alpha (HIF-1 alpha) in human retinal pigment epithelial cells (ARPE-19 cells) under hypoxic condition. Methods: The cytotoxicity of tanshinone IIA was tested in ARPE-19 cells by MTT assay. ARPE-19 cells were incubated with different concentrations of cobalt chloride (100, 150, and 200 mu M) for 12 h, and levels of expressed HIF-1 alpha and secreted VEGF were quantified through Western blot and ELISA, respectively. Further, ARPE-19 cells were pretreated for 1 h with different concentrations of tanshinone IIA (5, 10, 15, and 18 mu M). After 1 h, the cells were subjected to hypoxic condition using 150 mu M cobalt chloride for 12 h in the presence and absence of tanshinone IIA. The cells were then harvested, and the secreted VEGF and expressed HIF-1 alpha was studied. Results: Tanshinone IIA at concentrations of 5, 10, 15, and 18 mu M did not show cytotoxicity in ARPE-19 cells. Chemical hypoxia induced by cobalt chloride caused a significant increase in VEGF level in a dosedependent manner, and HIF-1 alpha expression peaked at 150 mu M. Based on the data, cobalt chloride concentration was maintained at 150 mu M for further studies. Tanshinone IIA decreased the level of HIF-1 alpha and VEGF secretion in a dose-dependent manner under hypoxic condition. Conclusion: Tanshinone IIA could be explored as a new potential candidate for treating wet AMD.