miR-373-3p inhibits epithelial-mesenchymal transition via regulation of TGFβR2 in choriocarcinoma.

Aim: Previous studies have indicated that early metastasis is a major cause of mortality in patients with choriocarcinoma. However, what determines whether early metastasis of choriocarcinoma has occurred is unknown. The emerging role of miRNA in regulating cancer development and progression has been recognized. miR-373 has been shown to play pivotal roles in tumorigenesis and metastasis. However, whether miR-373 functions to promote choriocarcinoma metastasis is not clear. The purpose of this study is to determine the function of miR-373-3p in the progression of this cancer.

Methods: In this study, we first compared epithelial-mesenchymal transition (EMT)-related markers, which were inversely correlated with miR-373-3p expression in trophoblast and choriocarcinoma cell lines. Using PCR and Western blot, upregulation of miR-373-3p was observed to inhibit EMT progression. Similarly, gain- and loss-of-function studies revealed that ectopic miR-373-3p overexpression inhibited the migration by transwell methods of choriocarcinoma cells.

Results: Our results revealed that miR-373-3p acted as an EMT inhibitor in JEG-3 and JAR cells; this was due to its mediation of the transforming growth factor-β (TGFβ) signaling pathway, which was responsible for EMT. miRNA microarray analysis demonstrated that miR-373-3p interacted with the 3' untranslated region of TGFβR2 mRNA, and then Western blot and dual-luciferase reporter gene assays verified this interaction.

Conclusion: Our findings suggest that miR-373-3p upregulation partly accounts for TGFβR2 downregulation and leads to a restraint of EMT and migration. miR-373-3p may therefore serve as a valuable potential target in the treatment of choriocarcinoma.