Hypoxia inducible factor-2 alpha regulating hypoxia-induced angiogenesis via angiopoietin-2 pathway / 中华消化外科杂志

ABSTRACT

Objective To investigate the mechanisms of hypoxia inducible factor-2 alpha (HIF-2a) regulating human umbilical vein endothelial cells (HUVECs) under hypoxic conditions.Methods The experimental study was adopted.(1) HUVECs in logarithmic growth phase were taken:HUVECs without any disposals as control group,HUVECs with shRNA transfection control as shRNA control group,HUVECs with HIF-2α shRNA transfection as HIF-2α shRNA group and HUVECs with HIF-2α shRNA transfection then added rhAng-2 as HIF-2α ± rh-Ang-2 group.(2) Western blot testing:the expressions of Ang-2 and HIF-2α proteins in HUVECs were cultured under hypoxia conditions at 0,2,4,8,12,16,20 hours,and the levels of which were detected in the control group,shRNA control group and HIF-2α shRNA group.(3) Enzyme-linked immunosorbent assay(ELISA):the level of Ang-2 protein in supernatant of HUVECs was detected in the control group,shRNA control group and HIF-2α shRNA group.(4)The amounts of endothelial cell tubes in HUVECs among the 4 groups were detected by tube formation experimental testing.(5) Transwell method was performed to detect the amounts of cells migration in HUVECs and hepatoma cells SMMC-7721 migration intervened by supernatant of HUVECs among the 4 groups.Measurement data with normal distribution were presented as x ± s,repeated measurement data were analyzed by the repeated measures ANOVA,comparison among groups and pairwise comparison were conducted respectively by the one-way ANOVA and Dunnett's test.Results (1) Western blot test:the expression levels of Ang-2 and HIF-2α proteins in HUVECs under hypoxia conditions at 0,2,4,8,12,16,20 hours were 0.110 ±0.011,0.120 ±0.020,0.210 ±0.070,0.410 ±0.100,0.520 ± 0.090,0.790±0.130 1.010 ±0.220 and 0.180 ±0.090,0.410 ±0.070,0.470 ±0.110,0.470 ±0.070,0.580 ± 0.120,0.690 ± 0.140,0.920 ± 0.130,respectively,and which were increased after culturing under hypoxia conditions and had an ascending tendency as the hypoxia time extended,with statistically significant differences (F =403.550,3 265.587,P ＜ 0.05).The expression levels of Ang-2 and HIF-2α proteins in the control group,shRNA control group and HIF-2α shRNA group were 1.030 ±0.180,1.070 ±0.120,0.210 ± 0.070,and 0.940 ± 0.110,0.930 ± 0.190,0.170 ± 0.021,respectively,showing statistically significant differences (F =290.242,26.688,P ＜ 0.05).(2) The results of ELISA:the expression levels of Ang-2 in the control group,shRNA control group and HIF-2α shRNA group were (433.2 ±9.7)ng/L,(438.3 ± 2.6)ng/L,(114.6 ± 4.2) ng/L,with a statistically significant difference (F =2 642.180,P ＜ 0.05).(3) The results of tube formation experiments:the number of endothelial cell tubes in the control group,shRNA control group,HIF-2α shRNA group and HIF-2α ± rh-Ang-2 group were 48.3 ± 2.5,47.4 ± 3.1,19.7 ± 1.5 and 38.3 ± 2.1,respectively,with a statistically significant difference (F =148.196,P ＜ 0.05).(4) The results of Transwell method:① the number of HUVECs migration in the control group,shRNA control group,HIF-2α shRNA group and HIF-2α + rh-Ang-2 group were 140.3-± 3.5,142.7 ± 2.1,42.7 ± 3.1 and 78.1 ± 4.2,respectively,showing a statistically significant differences (F =212.205,P ＜ 0.05).②The results of Transwell method:the number of SMMC-7721 cells migration after intervening using four different supernatant in the control group,shRNA control group,HIF-2α shRNA group and HIF-2α ± rh-Ang-2 group were 106.7 ± 5.5,102.7 ± 6.6,63.0 ± 3.3 and 96.7 ± 2.1,respectively,showing a statistically significant difference (F =55.122,P ＜ 0.05).Conclusion HIF-2a could not only affect HUVECs formation but also promote SMMC-7721 cells migration via regulating Ang-2 expression.