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

Abstract

Background 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. Methods 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-340–5 p 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. Results 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-340–5 p, which directly targeted HIF1A. Hsa_circ_0,019,054/miR-340–5 p/HIF1A formed a feedback loop. HIF1A was up-regulated, while miR-340–5 p was decreased in ICC tissues and cells. MiR-340–5 p re-expression attenuated ICC cell growth. Besides that, rescue experiments suggested that HIF1A overexpression or miR-340–5 p 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. Conclusion Hsa_circ_0,019,054 deficiency could attenuate the proliferation and glycolysis of ICC cells via miR-340–5 p/HIF1A axis.

Differentially expressed non-coding RNAs and their regulatory networks in liver cancer

“…Several significantly upregulated in ICC patients' blood serum, tissues and cells circRNAs have been attributed to tumor growth, recurrence after treatment, and patients’ survival. These included circACTN4, circHMGCS1-016 and hsa_circ_0,019,054 [ [126] , [127] , [128] ].…”

“…Additionally, circHMGCS1-016 induced ICC cell invasion and reshaped the tumor immune microenvironment via the miR-1236-3p/CD73 and GAL-8 axis [ 127 ]. Also, hsa_circ_0,019,054 has been reported to sponge miR-340-5p, which directly targeted HIF1A to regulate glycolysis and tumor cell apoptosis [ 128 ]. Table 3 summarizes representative DEC-DEM-DEG axes and signaling pathways involved in liver cancer.…”