EGFL6 regulates hypoxia-induced angiogenic factors in retinal pigment epithelial cells

Epidermal growth factor like domain 6 (EGFL6), which is a member of the epidermal growth factor repeat superfamily of proteins, has been demonstrated to be important in angiogenesis. However, the expression and role of EGFL6 in the retinal pigment epithelial (RPE) cells remains to be elucidated. The aim of the present study was to investigate the role of EGFL6 in cultured human RPE cells. ARPE-19 cells were pretreated by 200 mu M CoCl2 for 24 h, then transfected with siRNA-EGFL6 or control siRNA. Cell proliferation was measured using the MTT assay. The expression protein levels of EGFL6, VEGF, pigment epithelium-derived factor (PEDF), stromal cell-derived factor (SDF)-1 and IL-1 beta were detected using western blotting. The expression of EGFL6 was significantly elevated under hypoxic conditions. EGFL6 knockdown inhibited hypoxia-induced RPE cell proliferation. In addition, knockdown of EGFL6 inhibited hypoxia-induced pro-angiogenic factor expression and the expression of inflammatory factors in RPE cells. These results suggested that the knockdown of EGFL6 suppressed pro-angiogenic factors induced by hypoxia in RPE cells. Therefore, EGFL6 may be a potential therapeutic target for the treatment of age-related macular degeneration.