The mechanism of repressive effects of transthyretitin on the growth of human retinal microvascular endothelial cells under high glucose and hypoxia environment / 中华眼底病杂志

ABSTRACT

Objective To explore repressive effects of transthyretitin (TTR) on the growth of human retinal endothelial cells (hREC) under high glucose and hypoxia environment. Methods hRECs were divided into 8 groups, including normal glucose group (5.5 mmol/L glucose), hypoxia group, high glucose group (25.0 mmol/L glucose), high glucose and hypoxia group, normal glucose group+TTR, normal glucose and hypoxia group+TTR, high glucose group+TTR, high glucose and hypoxia group+TTR. Flow cytometry was used to analyze cellular apoptosis. The expression level of Akt, p-Akt, eNOS, Bcl-2 and Bax protein were measured by Western blot. Results Hypoxia could induce apoptosis as the apoptosis rate of normal and hypoxia group was higher than normal group (χ2=25.360, P<0.05), high glucose and hypoxia group was higher that high glucose group (χ2=17.400, P<0.05). The cell apoptosis rate of high glucose and hypoxia group+TTR were increased significantly as compared with high glucose and hypoxia group (χ2=9.900, P<0.05). There was no statistically significant difference on the cell apoptosis rate between normal group and high glucose group, normal group+TTR and normal group, high glucose group+TTR and high glucose group, normal and hypoxia group+TTR and normal and hypoxia group (P>0.05). Western blot showed that the expression of Akt did not change significantly in all eight groups(F=2.450, P>0.05). Compared to normal group, the expression of p-Akt, eNOS, Bcl-2 in normal and hypoxia group were decreased (t=9.406, 5.306, 4.819), and the expression of Bax (t=-4.503) was increased (P<0.05). Compared to high glucose group, same trend was found in high glucose and hypoxia group (t=8.877, 7.723, 6.500, -14.646; P<0.05). The expression of p-Akt in normal and hypoxia group+TTR was higher than normal and hypoxia group (t=-5.024, P<0.05) ,but there was no difference on the expression of eNOS, Bcl-2, Bax between these two groups (t=-2.235, -2.656, -0.272;P>0.05). Compared to high glucose and hypoxia group, the expression of p-Akt and Bcl-2 in high glucose and hypoxia group+TTR were decreased (t=4.355, 4.308; P<0.05), the expression of Bax was increased (t=-4.311, P<0.05), and there was no difference on the expression of eNOS between these two groups (t=-1.590, P>0.05). There was no statistically significant difference in the expression of p-Akt, eNOS, Bcl-2, Bax between high glucose group and normal group (t=-3.407, -4.228, -4.302, -2.076; P>0.05), normal group+TTR and normal group (t=-4.245, -4.298, -2.816, -1.326; P>0.05), high glucose group+TTR and high glucose group (t=4.016, -0.784, 0.707, -0.328; P>0.05). Conclusion Under high glucose and hypoxia, transthyretitin suppress the growth of hREC through Akt/Bcl-2/Bax, but not Akt/eNOS signaling pathway.