Metformin Effect on Endocan Biogenesis in Human Endothelial Cells Under Diabetic Condition

Abstract

Endocan is a novel endothelium-derived proteoglycan and may play a role in endothelial cells activity under diabetic conditions. Here, we evaluated the effect of high glucose concentration (30mmol glucose) on endocan level in presence or absence of metformin in human umbilical vein endothelial cells (HUVECs). Cells were incubated with 30mmol glucose for 72h. High glucose content, metformin (2.5 to 500mmol) and compound C (10mmol) effects were assessed on cell viability. HUVECs migration was studied by scratch test. The changes in endocan expression and protein level were evaluated by RT-PCR, ELISA and flow cytometry assays. Griess reaction was used to measure NO levels. Functional activity of endothelial cells was monitored related to lipoprotein lipase activity using Dil-Ac-LDL uptake. p-AMPK/AMPK ratio was assessed by western blotting. Cells viability significantly was reduced under high glucose condition (p<0.05). 30mmol glucose inhibited HUVECs migration, whereas these features were improved by 50mmol metformin (p<0.05). Endocan transcription and protein levels were increased in diabetic HUVECs exposed to metformin (p<0.05). Metformin increased NO production in HUVECs under high glucose condition (p<0.001). Metformin increased LDL uptake capacity under high glucose condition (p<0.05). The addition of compound C blunted these effects. Western blot analysis confirmed the increase of p-AMPK/AMPK ratio in metformin-treated cells. Data demonstrated that metformin could promote angiogenic potential of endothelial cells which its reduction is a main cause in the development of diabetic foot ulcer, probably by the regulation of endocan dynamics under high glucose condition.