Adrenomedullin(22-52) suppresses high-glucose-induced migration, proliferation, and tube formation of human retinal endothelial cells

PURPOSE: To investigate the roles of an adrenomedullin receptor antagonist (adrenomedullin(22–52)) on high-glucose-induced human retinal endothelial cell (HREC) in vitro cell biology. METHODS: HRECs were cultured with different concentrations of glucose and adrenomedullin(22–52). The proliferation of HRECs was evaluated by a cell counting kit-8 assay. Cell migration was assessed by scratch wound assay, and cell sprouting was detected by tube formation assay. The mRNA levels of adrenomedullin (ADM), vascular endothelial growth factor (VEGF), ADAMTS-1, and TSP-1 were measured by reverse-transcription polymerase chain reaction (RT–PCR). The VEGF and phosphatidylinositol 3′ kinase (PI3K) pathway protein expression levels were assessed by western blot analysis. RESULTS: Compared with 5 mM normal glucose treatment, 30 mM glucose significantly promoted the migration of HRECs, which was attenuated by 1 μg/ml adrenomedullin(22–52). The proliferation of HRECs was also suppressed by 1 μg/ml adrenomedullin(22–52). Furthermore, compared with other groups, 5 μg/ml of adrenomedullin(22–52) was shown to suppress high-glucose-induced tube formation of HRECs. With adrenomedullin(22–52) treatment, the mRNA level of ADAMTS-1 was significantly increased. Moreover, western blot and RT–PCR analyses showed that HRECs treated with 30 mM glucose exhibited increased VEGF and PI3K pathway protein levels, while the expression levels were suppressed by 5 μg/ml of adrenomedullin(22–52). CONCLUSIONS: Our study indicated that adrenomedullin(22–52) mediated the migration, proliferation and tube formation after HRECs were exposed to high levels of glucose, which may be related to its ability to affect the expression of VEGF through the PI3K pathway.