Long noncoding RNA CCAT2 promotes hepatocellular carcinoma proliferation and metastasis through up-regulation of NDRG1

Background: Emerging studies demonstrate that long noncoding RNAs (lncRNAs) play crucial roles in hepato-carcinogenesis through various mechanisms. LncRNA CCAT2 was a newly discovered lncRNA and amplified in several cancers. However, the mechanisms involved in function of CCAT2 in hepatocellular carcinoma (HCC) remain to be explored. Methods: CCAT2 expressions in HCC tissues and cell lines were measured by RT-qPCR. MTS assay, colony formation assay, wound-healing assay and transwell assay were used to explore the biological functions of CCAT2 on HCC cells proliferation and metastasis. Experiments in vivo were carried out to confirm these effects. The underlying mechanisms were analyzed by western blot and dual-luciferase reporter assay. Results: In this study, we found that CCAT2 were significantly elevated in HCC tissues and cell lines, and it promoted HCC cells proliferation and metastasis both in vitro and in vivo. Additionally, we identified that NDRG1 was a downstream target of CCAT2. Meanwhile, depletion of CCAT2 inhibited cellular proliferation and metastasis behaviors induced by NDRG1- overexpression. Analysis of mechanism underlying these effects revealed that CCAT2 increased the expression of NDRG1 by enhancing its promoter activity. Furthermore, the active region between CCAT2 and NDRG1 promoter was confirmed by dual-luciferase reporter assay. Conclusions: All these observations demonstrate that CCAT2 acts as an oncogene by up-regulating NDRG1, which may have the potential to be used as a promising prognostic biomarker and therapeutic target for HCC.