MicroRNA-149 sensitizes colorectal cancer to radiotherapy by downregulating human epididymis protein 4.

Human epididymis protein 4 (HE4) was significantly up-regulated in colorectal cancer (CRC), while the potential relevance to radiation resistance of this phenomenon is still elusive. Relative expressions of target genes were quantified by real-time PCR. The protein level was determined by Western blot. The regulatory effect of miR-149 on WFDC2 (gene encoding HE4 protein) expression was analyzed by luciferase reporter assay. The response to radiation was evaluated by clonogenic assay in vitro and xenograft growth in vivo. WFDC2 was aberrantly up-regulated and miR-149 was down-regulated in CRC. MiR-149 repressed WFDC2 expression via directly targeting its 3'UTR region. The ectopic expression of miR-149 significantly sensitized CRC to radiation both in vitro and in vivo. Likewise, we further demonstrated that WFDC2-deficiency remarkably improved the radiation resistance in CRC. Simultaneously, WFDC2 rescue completely abolished the radiation sensitivity imposed by miR-149. Our data suggested that miR-149 sensitized CRC to radiation via directly inhibiting WFDC2/HE4, which would hold great promise for future therapeutic exploitations.