ABSTRACT
Long noncoding RNAs (lncRNAs) play an important role in the progression of hepatocellular carcinoma (HCC). Linc01612 is a novel lncRNA that function remains unknown in the progression of cancers, including HCC. In this study, we discovered that Linc01612 is significantly down-regulated in HCC tissues than in non-tumor tissues and correlated with poor prognosis. Linc01612 mainly localizes in the cytoplasm and functions as a tumor suppressor by repressing the growth and metastasis of hepatoma cells in vitro and in vivo. Mechanistically, in p53-expressing hepatoma cells, Linc01612 acts as a competitive endogenous RNA and promotes the expression of activation transcription factor 3 (ATF3) by sponging microRNA-494 (miR-494), which in turn inhibits MDM2-mediated ubiquitination of p53 and activates the p53 pathway. Furthermore, in p53-null hepatoma cells, Linc01612 exerts its biological functions by physically interacting with Y-box binding protein 1 protein (YBX1) and promoting the ubiquitin-mediated degradation of YBX1. Interestingly, the Linc01612-YBX1 signaling pathway is also present in p53-expressing hepatoma cells. In conclusion, our study indicated that Linc01612 is a functional lncRNA in HCC and Linc01612 may serve as a potential diagnostic biomarker and therapeutic target for HCC.
Subject(s)
Carcinoma, Hepatocellular , Liver Neoplasms , MicroRNAs , RNA, Long Noncoding , Activating Transcription Factor 3/genetics , Activating Transcription Factor 3/metabolism , Carcinoma, Hepatocellular/metabolism , Cell Line, Tumor , Cell Proliferation/genetics , Disease Progression , Gene Expression Regulation, Neoplastic/genetics , Humans , Liver Neoplasms/metabolism , MicroRNAs/genetics , MicroRNAs/metabolism , RNA, Long Noncoding/genetics , RNA, Long Noncoding/metabolism , Transcription Factor 3/genetics , Transcription Factor 3/metabolism , Tumor Suppressor Protein p53/genetics , Tumor Suppressor Protein p53/metabolism , Ubiquitination/genetics , Y-Box-Binding Protein 1/genetics , Y-Box-Binding Protein 1/metabolismABSTRACT
Emerging evidence has shown that aberrant expression of lncRNA-TP53TG1 plays important roles in various malignancies. However, the biological functions of lncRNA-TP53TG1 in hepatocarcinogenesis, as well as the underlying mechanisms, remain largely unknown. Here, we assessed whether lncRNA-TP53TG1 plays a key role in the progression of hepatocellular carcinoma (HCC). The expression of lncRNA-TP53TG1 was significantly decreased in HCC tissues and cells. Decreased expression of lncRNA-TP53TG1 was associated with aggressive clinical phenotypes and a poor prognosis. Ectopic expression of lncRNA-TP53TG1 inhibited hepatoma cell proliferation and migration in vitro and in vivo, whereas lncRNA-TP53TG1 knockdown exerted the opposite effects. Furthermore, lncRNA-TP53TG1 played an important role in slowing the epithelial-mesenchymal transition (EMT) process in HCC. Mechanistically, lncRNA-TP53TG1 physically interacted with PRDX4 and promoted its ubiquitin-mediated degradation, resulting in the inactivation of the WNT/ß-catenin signaling pathway in hepatoma cells. Our findings demonstrate a novel mechanism by which lncRNA-TP53TG1 exerts its tumor-suppressive effects through the WNT/ß-catenin signaling pathway in a PRDX4-mediated manner in HCC. Based on these results, lncRNA-TP53TG1 potentially represents a prognostic indicator and therapeutic target for patients with HCC.
