Curcumin-induced apoptosis of hemangioma endothelial cells by downregulating expression of vascular endothelial growth factor and angiogenin 2

Abstract

Objective To investigate the effect of curcumin on vascular endothelial growth factor (VEGF) and angiogenin (Ang)-2 in hemangioma endothelial cells (HemECs) and the apoptosis mechanism. Methods HemECs were separated and cultured by enzyme digestion, and were treated with 0, 6.25, 12.50, 25.00, 50.00 and 100.00 μmol/L of curcumin. Cell counting kit-8 (CCK-8) was used to detect the cell proliferation toxicity of HemECs. TdT-mediated dUTP nick end labeling (TUNEL) method was used to detect the apoptosis of HemECs. Real-time reverse transcriptase-polymerase chain reaction(RT-qPCR) was used to detect the mRNA expression of VEGF, Ang-1, and Ang-2. The cell immunofluorescence was used to detect the protein expression of vascular endothelial growth factor receptor (VEGFR)1, VEGFR2, endothelium-specific tyrosine kinase receptor (Tie)1 and Tie2. Results The survival rate of cells treated with 25.00 or 50.00 μmol/L curcumin for 48 h was significantly lower than that of cells treated with 25.00 or 50.00 μmol/L curcumin for 24 h [(62.34±10.08)% vs. (79.25±8.17)% and (15.23±4.01)% vs. (26.10±6.05)%; t=3.192, P=0.010 and t=3.668, P=0.004]. The number of TUNEL positive cells treated with 25.00 μmol/L curcumin for 48 h (16.00±2.80) was significantly greater than that after treatment with 0 μmol/L curcumin (5.00±1.40; t=8.607, P=0.000). The VEGF mRNA relative expression in HemECs treated with 25.00 μmol/L curcumin for 24 h (0.34±0.09) was significantly lower than that after treatment with 0 μmol/L curcumin (1.00±0.12; t=8.193, P=0.001). The Ang-2 mRNA relative expression in HemECs treated with 25.00 μmol/L curcumin for 24 h (0.45±0.07) was significantly lower than that after treatment with 0 μmol/L curcumin (0.99±0.12; t=8.193, P=0.001). The absorbance values of VEGFR2 and Tie2 protein expression in HemECs treated with 25 μmol/L curcumin for 24 h (0.30±0.05 and 0.30±0.04) were significantly lower than those after treatment with 0 μmol/L curcumin (0.48±0.09, 0.52±0.07; t=4.300, P=0.002; t=6.602, P=0.000). Conclusion Curcumin can inhibit the growth of HemECs by inducing apoptosis. The underlying mechanism may be closely related with down-regulations of VEGF and Ang-2. Key words: Hemangioma endothelial cells; Apoptosis; Vascular endothelial growth factor; Angiogenin 2