Upregulated microRNA-194 impairs stemness of cholangiocarcinoma cells through the Rho pathway via inhibition of ECT2.

Cholangiocarcinoma (CCA) is devastating for its delayed presence, difficulty in diagnosis, and high mortality. Other studies have supported the important role of microRNAs (miRNAs) in the pathogenesis of CCA, and the role of miR-194 was investigated in several human cancers, though, the molecular mechanism of miR-194 in CCA stem cells remains largely unknown. We aimed to identify the functional significance of miR-194 in CCA. The microarray-based analysis was applied to detect the epithelial cell transforming sequence 2 (ECT2) expression and predict the miRNA-regulated ECT2, followed by the identification of relationship between ECT2 and obtained miRNA by dual-luciferase reporter gene assay. The effects of depletion or ectopic expression of miR-194 on Rho pathway and the biological characteristics of CCA were assessed by reverse transcription quantitative polymerase chain reaction, immunoblotting, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, scratch test, Transwell, and flow cytometry. Lastly, tumor growth was assessed by xenograft tumor in nude mice. ECT2 was highly expressed while miR-194 was poorly expressed in CCA stem cells, and the targeting relation between ECT2 and miR-194 was proved. More important, the elevated expression of miR-194 or ECT2 silencing inhibited the Rho pathway, and further promoted the apoptosis and suppressed the stem cell proliferation, migration, and invasion of CCA in vitro. miR-194 inhibited the tumor growth in vivo. In a word, miR-194 inhibits ECT2 and blocks the activation of Rho signaling pathway, thus promoting apoptosis, inhibiting proliferation and migration of CCA stem cells, and suppressing tumor growth. The mechanism can be regarded as a target for treating CCA.