Decreased expression of microRNA-199b increases protein levels of SET (protein phosphatase 2A inhibitor) in human choriocarcinoma.

We compared microRNA profiles between choriocarcinoma and non-cancerous trophoblasts, and revealed that miR-199b was underexpressed in choriocarcinoma. By computational prediction and microarray studies, SET (protein phosphatase 2A inhibitor) was shown to be one of the target genes regulated by miR-199b. Ectopic expression of miR-199b inhibited endogenous SET protein levels and the activity of the luciferase reporter containing the 3'-UTR of SET. Further comparisons of formalin-fixed paraffin-embedded human choriocarcinoma, mole, and non-cancer trophoblast tissues confirmed the initial findings of low miR-199b expression and SET upregulation in choriocarcinomas, suggesting that microRNA-dysregulated SET protein may account for the rapid growth seen with choriocarcinomas.