Hepatocellular Carcinoma

Circ_0072088[Circular RNA]

miR-375[miRNA]

STAT3[mRNA]

HCC cells

Homo sapiens (human)

IUBMB Life. 2021 Jun 20. doi: 10.1002/iub.2520.

Circ_0072088 promotes progression of hepatocellular carcinoma by activating JAK2/STAT3 signaling pathway via miR-375.

qRT-PCR;RNA immunoprecipitation;Western blot;Flow Cytometry assay;RNA immunoprecipitation;

BACKGROUND: Circular RNAs feature prominently in cancer development. Nonetheless, the role of circ_0072088 in hepatocellular carcinoma (HCC) remains unclear. METHODS: GEO databases (GSE97332, GSE108724, GSE36915, and GSE33006) were used to screen out the differentially expressed circRNAs, miRNAs, and mRNA in HCC. The expressions of circ_0072088, miR-375, and Janus Kinase 2 (JAK2) mRNA in HCC tissue and cell lines were determined with quantitative real-time polymerase chain reaction (qRT-PCR). RNase R treatment assay was used to measure the stability of circ_0072088, and subcellular fraction assay was used to detect the localization of circ_0072088. Cell counting kit-8 (CCK-8) assay, flow cytometry, and Transwell assay were used to measure proliferation, apoptosis, migration, and invasion of HCC cells. RNA immunoprecipitation and dual-luciferase reporter gene assay were employed for investigating the binding sequence between circ_0072088 and miR-375, as well as miR-375 and JAK2 3'UTR. Western blot assay was used to detect the expression of JAK2 and p-STAT3 after circ_0072088 and miR-375 were selectively regulated. RESULTS: Circ_0072088 and JAK2 mRNA expressions were highly expressed in HCC tissues and cell lines while miR-375 expression was remarkably downregulated. Circ_0072088 was resistance to RNase R treatment and mainly located in the cytoplasm of HCC cells. The transfection of circ_0072088 overexpression plasmid or miR-375 inhibitors promoted the proliferation, migration, and invasion, and inhibited the apoptosis of HCC cells whereas transfection of circ_0072088 siRNA or miR-375 mimics exerted opposite effects. Besides, miR-375 was confirmed as a target of circ_0072088 and miR-375 could further downregulate the expression of JAK2. MiR-375 mimics could reverse the upregulation of JAK2 and p-STAT3 protein induced by circ_0072088 overexpression. CONCLUSION: Circ_0072088 can enhance the proliferation, migration, and invasion, and impede apoptosis of HCC cells. Mechanistically, circ_0072088 activates JAK2/STAT3 signaling pathway by serving as a molecular sponge of miR-375.