Suppressive effect of microRNA-449a on the NDRG1/PTEN/AKT axis regulates endometrial cancer growth and metastasis.

Database screening indicated that microRNAs (miRNAs) are involved in pathogenesis of endometrial cancer. Among these miRNAs, miR-449a might be involved in tumorigenesis and lower expression of miR-449a was associated with poor prognosis. However, the role of miR-449a and its underlying molecular mechanism in endometrial cancer (EC) has not been investigated. In this study, our analysis found that miR-449a expression is inversely correlated with the stage of EC. Downregulation of miR-449a was correlated with tumor progression and poor prognosis in the EC patients. Results of functional analyses revealed that overexpression of miR-449a in human EC cells alleviated cell proliferation, invasion and metastasis. Conversely, loss of miR-449a in EC cancer cells facilitated all these cellular activities. Moreover, we identified N-myc downstream-regulated gene 1 (NDRG1) as a direct and functional target gene of miR-449a in EC cells, and the expression of NDRG1 in 87 EC specimens were inversely correlated with that of miR-449a. Additionally, further studies show that the down-regulation of NDRG1 expression inhibited proliferation and metastasis of EC cells through the PTEN/AKT pathway. Therefore, these results suggest that miR-449a suppresses the growth and metastasis of EC by directly targeting the NDRG1 gene and that the activation of miR-449a may represent an effective therapeutic strategy in EC.