Hsa_circ_0019054 up-regulates HIF1A through sequestering miR-340-5p to promote the tumorigenesis of intrahepatic cholangiocarcinoma.

Abstract

Circular RNAs (circRNAs) have been uncovered to play an important regulatory function in the tumorigenesis of intrahepatic cholangiocarcinoma (ICC). Hsa_circ_0,019,054 was found to be increased in ICC. Here, we aimed to explore the action and mechanism of hsa_circ_0,019,054 in ICC carcinogenesis. Quantitative real-time PCR (qRT-PCR) and western blotting were used to detect the levels of genes and proteins. The functional experiments were performed using in vitro 5-ethynyl-2'-deoxyuridine (EdU) assay, cell counting Kit-8 (CCK-8) assay, flow cytometry, and in vivo murine xenograft model. The glycolysis was analyzed by detecting glucose uptake and lactate level. The binding between miR-340-5p and hsa_circ_0,019,054 or HIF1A (Hypoxia-inducible factor 1-alpha) was validated using pull-down, dual-luciferase reporter and RNA immunoprecipitation assays. Hsa_circ_0,019,054 expression was higher in ICC tissues and cells. Functionally, hsa_circ_0,019,054 silencing could suppress ICC cell proliferation and glycolysis active, as well as induce apoptosis. Mechanistically, hsa_circ_0,019,054 was demonstrated to act as a sponge for miR-340-5p, which directly targeted HIF1A. Hsa_circ_0,019,054/miR-340-5p/HIF1A formed a feedback loop. HIF1A was up-regulated, while miR-340-5p was decreased in ICC tissues and cells. MiR-340-5p re-expression attenuated ICC cell growth. Besides that, rescue experiments suggested that HIF1A overexpression or miR-340-5p knockdown reversed the anti-proliferation and glycolysis arrest effects mediated by hsa_circ_0,019,054 silencing. Importantly, hsa_circ_0,019,054 silencing also impeded the growth of ICC in nude mice. Hsa_circ_0,019,054 deficiency could attenuate the proliferation and glycolysis of ICC cells via miR-340-5p/HIF1A axis.