Suppression of miR-16 promotes tumor growth and metastasis through reversely regulating YAP1 in human cholangiocarcinoma

BACKGROUND & AIMS Aberrant expression of microRNAs is associated with many cancers progression. Many studies have shown that miR-16 is down-regulated in many cancers. However, its role in cholangiocarcinoma (CCA) is unknown. METHODS Quantitative real-time PCR (qRT-PCR) was developed to measure miR-16 expression in CCA tissues and cell lines. CCK-8, colony formation and transwell assays were used to reveal the role of miR-16 in CCA cell proliferation and malignant transformation in vitro. The loss-and-gain function was further validated by subcutaneous xenotransplantation and tail vein injection xenotransplantation model in vivo. Dual-luciferase reporter assay was performed to validate the relationship of miR-16 with YAP1. RESULTS MiR-16 was notably downregulated in CCA tissues, which was associated with tumor size, metastasis, and TNM stage. Both in vitro and in vivo studies demonstrated that miR-16 could suppress proliferation, invasion and metastasis throughout the progression of CCA. We further identified YAP1 as a direct target gene of miR-16 and found that miR-16 could regulate CCA cell growth and invasion in a YAP1-dependent manner. In addition, YAP1 was markedly upregulated in CCA tissues, which was reversely correlated with miR-16 level in tissue samples. Besides, Down-regulation of miR-16 was remarkably associated with tumor progression and poor survival in CCA patients through a Kaplan-Meier survival analysis. CONCLUSIONS miR-16, as a novel tumor suppressor in CCA through directly targeting YAP1, might be a promising therapeutic target or prognosis biomarker for CCA.