miR-124 inhibits progression of hepatocarcinoma by targeting KLF4 and promises a novel diagnostic marker.

Hepatocarcinoma is one of the most lethal malignancy haunting the Chinese population, which is partially due to the difficulties in diagnosis at an early stage. The search for a biomarker that could signify the presence and progress of hepatocarcinoma is never ended. MicroRNAs are 22-nt RNAs that could bind to 3' UTR of target mRNAs, mediating degradation of mRNAs or inhibiting the translation. Although much has been investigated, the role of miR-124 in hepatocarcinoma remained elusive. We first detected aberrant expression level of miR-124 in HCC tissues of 112 patients. By exploring the clinical parameters, we found a significantly inverse correlation between miR-124 level and TNM stages. Consistent with this, the survival analysis indicated the association of low miR-124 with longer survival time. Subsequent forced expression miR-124 resulted in reduced cell viability of Hep3B and SMMC-7221, which cell lines have high and low background expression of miR-124, respectively. TargetScan prediction rendered a subset of target candidates, which were selected for experimental validation, KLF4 was subject to luciferase assay. Ectopic expression of KLF4 increased the sphere formation ability and CD44/133-positive cell numbers, which can be reversed by abundant expression of miR-124, suggesting that KLF4 is a functional target of miR-124 in tumourigenesis and cancer progression of HCC.