PVT1 and hepatocellular carcinoma: The TCGA database has also been analyzed to identify the expression profiles of lncRNAs in HCC tissues, among which two crucial lncRNAs termed “PVT1” and “SNHG7” were found to be involved in the recurrence of the tumor, and lncRNA unigene56159 was found to promote the migration and invasion of HCC cells through the miR-140-5p/SNAI2 axis, where it acted as a competing endogenous RNA (ceRNA) for miR-140-5p and downregulated its expression [80].