29803

REPIN1

replication initiator 1;REPIN1;replication initiator 1

60 kDa origin-specific DNA-binding protein|60 kDa replication initiation region protein|ATT-binding protein|DHFR oribeta-binding protein RIP60|H_DJ0584D14.12|replication initiation region protein (60kD)|zinc finger protein 464 (RIP60)|zinc finger protein

7q36.1

protein-coding

The transcription factor AP4 mediates epithelial-mesenchymal transition (EMT) in colorectal cancer but its control in this setting is not fully understood. Here, we report the definition of a double-negative feedback loop involving AP4 and miR-15a/16-1 that regulates EMT and metastatic progression. In colorectal cancer cells, AP4 was downregulated by DNA damage in a p53-dependent manner. AP4 downregulation by p53 was mediated indirectly by the tumor-suppressive microRNAs miR-15a and miR-16-1, which targeted the 3 untranslated region (3-UTR) of AP4 mRNA, induced mesenchymal-epithelial transition (MET), and inhibited colorectal cancer cell migration and invasion. The downregulation of AP4 was necessary for induction of MET and cell cycle arrest by miR-15a/16-1. In tumor xenoplants, ectopic miR-15a/16-1 suppressed formation of lung metastases. Furthermore, AP4 directly suppressed expression of miR-15a/16-1. In clinical specimens of colorectal cancer, miR-15a levels inversely correlated with AP4 protein levels shown previously to correlate with distant metastasis and poor survival. In summary, our results define a double-negative feedback loop involving miR-15a/16-1 and AP4 that stabilizes epithelial and mesenchymal states, respectively, which may determine metastatic prowess.