FOXO1 3'UTR functions as a ceRNA in repressing the metastases of breast cancer cells via regulating miRNA activity.

The competitive endogenous RNAs (ceRNAs) are RNA molecules that affect each other's expression through competition for their shared microRNAs (miRNAs). In this study we explored whether FOXO1 3'UTR can function as a ceRNA in repressing epithelial-to-mesenchymal transition (EMT) and metastasis of breast cancer cells via regulating miR-9 activity. We found that miR-9 binds to both the FOXO1- and E-cadherin-3'UTR, indicating that the FOXO1- and E-cadherin-3'UTR can be linked through miR-9. Follow-up analyses showed that there existed a competition of miR-9 between FOXO1 and E-cadherin-3'UTR. Thus FOXO1 3'UTR inhibits the metastases of breast cancer cells via induction of E-cadherin expression. Our results suggest that FOXO1 3'UTR may function as a miRNA-inhibitor in modulating metastasis of breast cancer cells.