Identification of hsa_circ_0039053 as an up-regulated and oncogenic circRNA in hepatocellular carcinoma via the miR-637-mediated USP21 activation.

Accumulating evidence indicated that circular RNAs (circRNAs) are crucial regulators in tumorigenesis of hepatocellular carcinoma (HCC), but it is still unclear how hsa_circ_0039053 causes HCC. Herein, hsa_circ_0039053 was upregulated in HCC tissues and cell lines. The upregulation of hsa_circ_0039053 was linked to the advanced clinical characteristics of patients. Downregulation of hsa_circ_0039053 decreased the invasion and proliferative ability of tumors in vitro and as well as tumor growth in vivo. Mechanically, hsa_circ_0039053 positively regulated USP21 expression through interacting with miR-637. Moreover, overexpression of USP21 or silencing of miR-637 restored the inhibitory impacts of hsa_circ_0039053 silencing on HCC progression. Collectively, our study confirmed that hsa_circ_0039053 could be regarded as a competing endogenous RNA (ceRNA) to positively modulate the expression of USP21 combining with miR-637, which provided a potential target in HCC treatment.