Protective effect of curcumin against high glucose‐induced endoplasmic reticulum stress by downregulation of COX‐2 expression in human umbilical vein endothelial cells

Abstract

OBJECTIVE: The aim of this study is to investigate whether curcumin could protect against high glucose‐induced apoptosis by suppressing endoplasmic reticulum (ER) stress pathway in human umbilical vein endothelial cells (HUVECs). METHODS: HUVECs were exposed to low glucose (5.5mmol/L) or high glucose (30mmol/L) for 12~48 h. The expression of ER stress‐related markers (glucose‐regulated protein 78 (GRP78/Bip) and CAAT/enhancer binding protein homologous protein (CHOP)) and cyclooxygenase‐2 (COX‐2) were also evaluated by western blotting analysis. RESULTS: (1) Annexin V‐FITC/PI flow cytometry analysis revealed a time‐dependent increase of apoptotic cells in HUVECs treated with high glucose. Curcumin (10~100 μ mol/L) inhibited the high glucose‐induced apoptosis in a dose‐denpendent manner. (2) High glucose induced a time‐dependent increase in the levels of COX‐2, GRP78 and CHOP proteins expression in HUVECs. (3) Curcumin and NS‐398 (a COX‐2 inhibitor) downregulated high glucose‐induced overexpression of COX‐2 and CHOP expression in HUVECs. CONCLUSION: These data suggest that curcumin can protect the HUVECs against high glucose‐induced apoptosis by downregulation of COX‐2 and inhibition of endoplasmic reticulum stress.(This work was supported by the National Natural Science Foundation of China (No. 30400094))