Circular RNA hsa_circ_0002124 promotes hepatocellular carcinoma cell proliferation through the MAPK pathway

Zhigang Fang, Ruifang Fan, Ying Lu, Yanling Sun, Caihan Zhao, Lingling Liu, Xiangfu Liu


Background: Hsa_circ_0002124, which was first reported in 2013, is derived from NuSAP1. However, its role in hepatocellular carcinoma (HCC) and its regulatory mechanisms remain to be investigated.
Methods: First, hsa_circ_0002124 was structurally validated via specific convergent and divergent primer amplification. The hsa_circ_0002124 expression in the liver cancer tissues and multiple HCC cell lines were determined using qPCR. Further, the cell functions of hsa_circ_0002124 in HCC cells were examined using knockdown and overexpressed hsa_circ_0002124 in 97H cells. The cell proliferation was assessed using MTS assay, cell proliferation and invasion capacities were evaluated using Transwell culture system, and cell cycle progression and apoptosis were analyzed using flow cytometry. Further, GO and KEGG analyses were performed to uncover the key function and pathways in HCC. The interaction networks between hsa_ circ_0002124 and its downstream miRNAs and genes were constructed using Cytoscape software. The key protein expressions (p-JNK, JNK, p-ERK, ERK, p-P38, P38, and c-Myc) of the MAPK pathway in 97H cells with knockdown and overexpressed hsa_circ_0002124 treatments were detected using Western blotting.
Results: Hsa_circ_0002124 was highly expressed in the HCC cells and liver cancer tissues. Moreover, the knockdown hsa_circ_0002124 in 97H cells resulted in the repression of cell proliferation, cell invasion, and migration, with simultaneous promotion of cell apoptosis and cell cycle transformation. The opposing situations of cell function could be detected in overexpressed hsa_circ_0002124 in 97H cells. KEGG and interaction network analysis of hsa_circ_0002124 indicated that hsa_circ_0002124 could be a molecular sponge of miRNAs, which regulates the key protein expressions in the MAPK pathway. The p-JNK/JNK, p-ERK/ERK, p-P38/P38, and c-Myc expressions in knockdown hsa_circ_0002124-treated 97H cells were significantly lower than in normal 97H cells, whereas these expressions in overexpressed hsa_circ_0002124-treated 97H cells were significantly higher than in mock vector-treated 97H cells.
Conclusions: Hsa_circ_0002124 could be a potential biomarker for the early diagnosis and treatment of HCC.