Influence of miR-34a on preeclampsia through the Notch signaling pathway.

OBJECTIVE: The aim of this study was to investigate the influence of micro-ribonucleic acid-34a (miR-34a) on preeclampsia through the Notch signaling pathway.

PATIENTS AND METHODS: The expressions of miR-34a, Notch-1, Notch-2, and Notch-3 in the placenta of 39 preeclampsia patients and 42 normal patients were detected by immunohistochemistry and Reverse Transcription-Polymerase Chain Reaction (RT-PCR). The correlations between miR-34a expression with the expressions of Notch-1, Notch-2 and Notch-3 were analyzed, respectively. Besides, placental trophoblasts were isolated from preeclampsia patients and cultured in vitro. The expressions of miR-34a, Notch-1, Notch-2 and Notch-3 in placental trophoblasts were analyzed. Furthermore, the influences of miR-34a on the protein expressions of Notch-1, Notch-2, Notch-3, and hairy and enhancer of split-1 (Hes-1) in the Notch signaling pathway were analyzed by Luciferase reporter gene assay and Western blotting. The role of Notch in trophoblast invasion was investigated through the Notch inhibitors. In addition, its influence on the expression of urokinase-type plasminogen activator (uPA) was studied by miR-34a overexpression.

RESULTS: The expressions of miR-34a and Notch-1 were correlated with preeclampsia in the placentas of preeclampsia patients and normal patients to a certain degree. The expression of miR-34a in preeclamptic placenta was significantly higher than that of the normal placenta (p<0.05). However, Notch-1 expression was markedly lower in preeclamptic placenta (p<0.05). No significant differences were found in the expressions of Notch-2 and Notch-3 between the two types of placentas (p>0.05). MiR-34a had a remarkable negative correlation with Notch-1 expression in the Notch family (p<0.001, r=-0.5775). RT-PCR results revealed that the mRNA expression of miR-34a in placental trophoblasts of patients with preeclampsia was notably higher than that of normal people (p<0.01). However, Western blotting demonstrated that the protein expressions of Notch-1, Notch-2 and Notch-3 exhibited the opposite results. Additionally, the protein expression of Notch-1, Notch-2, Notch-3 and Hes-1 in trophoblasts transfected with pre-miR-34a was significantly decreased. The treatment with Notch inhibitors markedly reduced the trophoblast invasion. Furthermore, miR-34a overexpression or intracellular domain of Notch (ICN) overexpression regulated uPA expression.

CONCLUSIONS: MiR-34a regulates uPA system through the Notch signal transduction, thereby regulating the invasion of placental trophoblasts in patients with preeclampsia.