CircSEC24A promotes tumor progression through sequestering miR-455-3p in hepatocellular carcinoma

Yulin Liao, Dongming Yang, Huaichao Luo, Guishu Yang, Xiaoxia Wen, Kaijiong Zhang, Chang Liu, Ruiling Zu, Lichun Wu, Zuo Wang,  Dongsheng Wang

Abstract:

Hepatocellular carcinoma (HCC) ranks third in the cause of death due to cancer. Circular RNA circSEC24 Homolog A (circSEC24A) has been uncovered to be upregulated in liver cancer. However, the function of circSEC24A in HCC is indistinct. We analyzed the microarray datasets GSE78520 and GSE94508 to search for differentially expressed circRNAs associated with HCC. Expression of circSEC24A, microRNA (miR)-455-3p, and protein phosphatase, Mg2+/Mn2+ dependent 1F (PPM1F) mRNA was detected by quantitative real-time polymerase chain reaction (RT-qPCR). Loss-of-function experiments were conducted to validate the biological function of circSEC24A in HCC cells in vitro and in vivo. Protein levels were evaluated by western blotting and immunohistochemistry (IHC). The relationship between circSEC24A or PPM1F and miR-455-3p was verified by a dual-luciferase reporter and/or RNA immunoprecipitation (RIP) assays. circSEC24A was overexpressed in HCC. circSEC24A silencing decreased xenograft tumor growth in vivo and repressed proliferation, metastasis, invasion, epithelial-to-mesenchymal transition (EMT), induced cell cycle arrest, and apoptosis of HCC cells in vitro. circSEC24A acted as a molecular sponge to sequester miR-455-3p, resulting in elevating the expression of PPM1F. miR-455-3p inhibitor reversed the suppressive impact of circSEC24A silencing on malignant behaviors of HCC cells. PPM1F overexpression offsets the inhibitory effect of miR-455-3p mimic on malignant behaviors of HCC cells. circSEC24A sponged miR-455-3p to elevate the PPM1F expression, resulting in accelerating malignant behaviors of HCC cells. The study provided a potential therapeutic target for patients with HCC.