Abstract: Objective To analyze the effects of silencing micro RNA-26b(miR-26b) on proliferationand apoptosis of placental trophoblastic cells and PI3K/Akt pathway in patients with pregnancy-induced hypertension(PIH). 
Methods Human placental trophoblastic cells were purchased, and induced by 100 μmol/L N-nitro-L-arginine methyl ester to simulate the microenvironment of PIH. The blank group(N-nitro-L-arginine methyl ester induced placental trophoblastic cells), the overexpression group(N-nitro-L-arginine methyl ester induced placental trophoblastic cells which was transfected with miR-26b for overexpressionplasmid transfection), and the silence group(N-nitro-L-arginine methyl ester-induced placental trophoblastic cells that were silenced by miR-26b for plasmid transfection). Cell proliferation, apoptosis and PI3K/Akt pathway protein expression were detected. 
Results Compared with the blank group, the expression of miR-26b was increased in the overexpression group and decreased in the silencing group(P＜0.05), indicating that miR-26b was successfully transfected. The cell proliferation rate at 24 h, 48 h and 72 h in the overexpression group was gradually decreased, while that of the silence group was gradually increased, and the differences between groups, time points and time points between groups were statistically significant in three groups(P＜0.05).Compared with the blank group, the expression of PI3K, p-PI3K, Akt, p-Akt and Bcl-2 protein was decreased and the expression of Bax protein was increased in the overexpression group(P＜0.05). Compared with the blank group, the expression of PI3K, p-PI3K, Akt, p-Akt and Bcl-2 protein was increased and the expression of Bax protein was decreased in the silencing group(P＜0.05). Compared with the overexpression group, the expression of PI3K, p-PI3K, Akt, p-Akt and Bcl-2 protein was increased and the expression of Bax protein was decreased in the silencing group(P＜0.05). 
Conclusion Silencing miR-26b can inhibit apoptosis and promote proliferation of placental trophoblastic cells in patients with PIH, and its underlying mechanism may be related to the activation of PI3K/Akt pathway. 

Key words: hypertension, pregnancy-induced, cell proliferation, apoptosis