Abstract
MicroRNAs (miRNAs), which are a class of small RNAs, have been shown to negatively regulate the expression of their target genes by directly binding to the 3'-untranslated region (3'-UTR) of mRNA. miRNA dysregulation has been associated with the pathogenesis of numerous types of human cancer. However, the role of miRNAs in intrahepatic cholangiocarcinoma (ICC) has yet to be fully elucidated. The present study aimed to investigate the role of miR-212 in the growth and metastasis of ICC in vitro, as well as the underlying mechanism. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting were used to examine mRNA and protein expression. An MTT assay and transwell assay were conducted to determine cell proliferation and invasion rates. The results of the RT-qPCR demonstrated that miR-212 was downregulated in the majority of investigated ICC tissues, as compared with their matched adjacent non-tumor tissues. In addition, miR-212 expression was shown to be markedly downregulated in three ICC cell lines, as compared with human intrahepatic biliary epithelial cells. Furthermore, restoration of miR-212 expression significantly suppressed the proliferation and invasion of ICC QBC939 cells. Forkhead box protein A1 (FOXA1) was predicted to be a putative target of miR-212 by bioinformatics analysis with TargetScan. Therefore, a luciferase reporter assay was conducted to confirm that miR-212 was able to directly bind to the 3'-UTR of FOXA1 mRNA. In addition, using western blot analysis, the protein expression of FOXA1 was shown to be negatively regulated by miR-212 in ICC QBC939 cells. In conclusion, it was demonstrated that FOXA1 was frequently upregulated in various ICC tissues and cell lines. The results of the present study suggested that miR-212 inhibits the proliferation and invasion of ICC cells by directly targeting FOXA1, and thus may be considered a potential candidate for the treatment of ICC.