MicroRNA-191 acts as a tumor promoter by modulating the TET1-p53 pathway in intrahepatic cholangiocarcinoma

Current treatment of intrahepatic cholangiocarcinoma (ICC) remains ineffective because knowledge of ICC carcinogenesis is unclear. Increasing evidence suggests that microRNAs (miRNAs), including miR-191, play an important role in tumorigenesis; but expression and biological functions of miR-191 in ICC remain to be established. This study investigated the functions and underlying mechanisms of miR-191 in ICC. ICC miRNA profiles were generated in five pairs of ICC and matched to normal bile duct tissues by next-generation sequencing technology; ICC miRNA profiles were verified in 18 pairs of ICC tissues and normal bile duct tissues by quantitative RT-PCR. The miR-191-associated mechanisms in ICC were investigated in vitro and in vivo, and clinical outcomes associated with miR-191 were correlated in 84 patients. Our results showed that miR-191 expression was significantly increased in ICC compared with the adjacent normal bile duct tissues (P < 0.001). Overexpression of miR-191 promoted proliferation, invasion, and migration of cholangiocarcinoma cells in vitro and in vivo. The elevated miR-191 expression reduced the expression level of ten-eleven translocation 1 (TET1)-a direct target gene of miR-191 in ICC, which catalyzes demethylation. The reduced TET1 expression level allowed the methylated CpG-rich regions at the p53 gene transcription start site stay methylated, leading to reduced p53 expression level, which compromises p53's anticancer vigor. Finally, miR-191 was found to be an independent risk factor for poor prognosis in patients with ICC (overall survival, hazard ratio = 3.742, 95% confidence interval 2.080-6.733, P < 0.001; disease-free survival, hazard ratio = 2.331, 95% confidence interval 1.346-4.037, P = 0.003).

Our results suggest that overexpressed miR-191 is associated with ICC progression through the miR-191/TET1/p53 pathway. (Hepatology 2017;66:136-151).