YY1 and eIF4A3 are mediators of the cell proliferation, migration and invasion in cholangiocarcinoma promoted by circ-ZNF609 by targeting miR-432-5p to regulate LRRC1.

Cholangiocarcinoma is a highly aggressive malignant tumor, and its incidence is increasing all over the world. More and more evidences show that the aberrant expression of circular RNAs play important roles in tumorigenesis and progression. Current studies on the expression and function of circRNAs in cholangiocarcinoma are scarce. In this study, circ-ZNF609 was discovered as a novel circRNA highly expressed in cholangiocarcinoma for the first time. The circ-ZNF609 expression is connected with the advanced TNM stage, lymphatic invasion and survival time in cholangiocarcinoma patients, and can be used as an independent prognostic factor for the patients. Circ-ZNF609 can promote the cholangiocarcinoma cells proliferation, migration and invasion in vitro, it can also catalyze the xenograft growth in vivo. The promoting effect of circ-ZNF609 on cholangiocarcinoma is achieved via oncogene LRRC1 up-regulation through targeting miR-432-5p by endogenous competitive RNA mechanism. In addition, transcription factor YY1 can bind to the promoter of ZNF609 to further facilitate the transcription of circ-ZNF609. RNA binding protein eIF4A3 can bind to the pre-mRNA of circ-ZNF609 which promotes the circ-ZNF609 circular formation. Overall, YY1/eIF4A3/circ-ZNF609/miR-432-5p/LRRC1 have a significant role in progression of cholangiocarcinoma, and circ-ZNF609 is expected to become a novel biomarker for targeted therapy and prognosis evaluation of cholangiocarcinoma.

PCAT1 induced by transcription factor YY1 promotes cholangiocarcinoma proliferation, migration and invasion by sponging miR-216a-3p to up-regulate oncogene BCL3.

This study was designed to illustrate the function and role of PCAT1 in CCA. The relative expression was confirmed by RT-qPCR and western blot. The biological function of PCAT1 was evaluated by CCK8, EdU, colony formation, wound healing, transwell, and subcutaneous tumor formation assays. Protein levels of EMT markers were measured by western blot. The binding relationship was predicted by JASPAR and starBase. The binding of YY1 to PCAT1 promoter was assessed by ChIP and luciferase reporter. The binding capacity between miR-216a-3p and PCAT1 as well as BCL3 was assessed by luciferase reporter and AGO2-RIP assays. In this study, we found that PCAT1 was up-regulated in CCA tissues and cells, and the PCAT1 overexpression was associated with poor prognosis. Moreover, PCAT1 was assessed as an independent risk factor of prognosis for CCA patients. Amplified PCAT1 was found to promote tumor proliferation, migration, invasion and EMT process, whereas PCAT1 knockdown inhibited these malignant phenotypes. Mechanistically, PCAT1 was predominantly localized in the cytoplasm and competitively bound miR-216a-3p to increase BCL3 expression. In addition, PCAT1 was activated by transcription factor YY1. This study revealed that PCAT1 acted as an oncogene in CCA, and the YY1/PCAT1/miR-216a-3p/BCL3 axis exhibited critical functions in CCA progression.