HCC, one of the most common causes for cancer-related deaths, is responsible for among 830,000 cases death in China in 2020. Although great advances in screening and prevention techniques contribute to both treatment and diagnosis of HCC patients, the patient survival with HCC still remains poor[3, 13]. As a result, urgent needs are required to further investigate the underlying mechanism for HCC progression to support the therapeutic development. MicroRNAs have been reported to play a key role in multiple biological processes and its abnormal expression has been confirmed to associate with development of various types of cancers. Moreover, miR-518a-3p has been illustrated to play an essential role in the development of many kinds of cancers, including colorectal cancer, triple-negative breast cancer and squamous cell carcinoma[7–9]. Qu et al’s research has revealed that its expression level was downregulation in CRC cells in comparison with normal colonic cell line. Also, its expression level was reduced in CRC tissues. Further mechanism studies demonstrated that miR-518a-3p repressed cell growth and promoted cell apoptosis by regulating the NIK-dependent NF-κB pathway. As yet, little is well-known about roles of miR-518a-3p and its underlying mechanism during the development and metastasis of HCC.
In this study, we first found that the expression level of miR-518a-3p was downregulated in HCC tissues in comparison with adjacent normal tissues. Besides, the survival rate of patients with a higher expression of miR-518a-3p was more awful than that of a lower expression. Consistent with above mentioned findings, its expression level was also reduced in HCC cells, suggesting miR-518a-3p may play critical roles in HCC progression. Next, in order to further elucidate its function in HCC progression, HCC cells were transfected to knockdown or overexpress miR-518a-3p. From our data, cell growth, migration and invasion were induced after miR-518a-3p silencing. Similarly, its upregulation led to suppression of cell growth, migration and invasion, suggesting that miR-518a-3p served as a vital tumor suppressor gene during HCC progression.
ZNF281, a zinc-finger transcription factor, has been reported to act as a key regulator in tissue development and cellular stemness[15, 16]. Notably, recent studies have indicated that ZNF281 also served as a novel oncogene, which has a high expression level in many kinds of tumors, including colorectal cancer, breast cancer and pancreatic carcinomas[17–19]. Moreover, recent study has demonstrated that ZNF281 expression level was higher in HCC cells in comparison with immortalized hepatocytes. Furthermore, ZNF281 silencing led to reduced proliferation, DNA synthesis and anchorage-independent growth of HCC cells. Nevertheless, it still remains unknown whether the suppression of HCC progression by miR-518a-3p was mediated by ZNF281. Thus, in order to confirm the hypothesis, the luciferase assay was employed. We found that overexpression of miR-518a-3p gave rise to a reduced level of luciferase activity in WT group, whereas the relative luciferase activity of cells in MUT group displayed no significant change. What’s more, ZNF281 expression was upregulated in HCC tumor samples, thus, revealing miR-518a-3p suppressed HCC progression by regulating ZNF281. Finally, in order to confirm that the inhibition of HCC progression by miR-518a-3p was mediated by ZNF281, silencing of ZNF281 or miR-518a-3p by siRNA or miRNA inhibitor, separately or together, was performed. Our data have shown that the increased migration and invasion induced via knockdown of miR-518a-3p were diminished when ZNF281 silencing.