LncRNA NALT1 Promotes Colorectal Cancer Progression Via Targeting PEG10 by Sponging MicroRNA-574-5p

Colorectal cancer (CRC) is currently one of the commonest tumors and the main reason for cancer-related deaths worldwide. It has been reported that long non-coding RNAs (lncRNAs) act as important indicators and regulators in various cancers. There is an urgent need to explore new lncRNA biomarkers in CRC, as well as their functions and molecular mechanisms. NALT1 has been implicated in the occurrence of gastric cancer (GC). However, the detailed function and mechanism of NALT1 in CRC progress have not been reported. In this study, RT-qPCR was conducted to detect the expression of NALT1 in 76 CRC patients ranging from stages I through IV. To assess the biological function of NALT1, loss- and gain-of-function experiments were conducted both in vivo and in vitro. Moreover, RNA-seq, bioinformatics analysis, RNA pulldown assay, dual-luciferase reporter, Ago2-RIP, quantitative PCR, Western blot assays, and rescue experiments were performed to reveal the molecular mechanisms of competitive endogenous RNAs (ceRNAs). It was observed that high expression of NALT1 was markedly correlated with advanced cancer stage in the clinic. Functionally, NALT1 downregulation inhibited cell proliferation, migration and invasion, whereas NALT1 overexpression exhibited an opposite trend both in vivo and in vitro. Bioinformatics analysis, RNA pulldown, Ago2-RIP, and luciferase reporter assays showed that miRNA-574-5p was a target of NALT1. Additionally, dual-luciferase reporter assays, Ago2-RIP, and rescue experiments indicated that miRNA-574-5p could target the PEG10 gene directly. Our results suggested that NALT1 promoted CRC proliferation and migration by sponging miRNA-574-5p to upregulate PEG10 expression, and implied that NALT1 might act as a promising biomarker and therapeutic target for CRC.