Long non-coding RNA colon cancer-associated transcript 2 may promote esophageal cancer growth and metastasis by regulating the Wnt signaling pathway

The aim of this study was to investigate how long non-coding (lnc)RNA colon cancer-associated transcript 2 (CCAT2) regulates the proliferation, invasion and metastasis of esophageal cancer cells via the Wnt signaling pathway. The expression of lncRNA CCAT2 was quantified by reverse transcription-quantitative PCR in four esophageal cancer cell lines (Eca-109, EC9706, KYSE150 and TE-1) and normal human esophageal epithelial cells (HEECs). The effect of silencing CCAT2 (si-CCAT2) and inhibiting Wnt signaling (using the inhibitor FH535) on the proliferation, migration and invasion of Eca-109 cells was measured by MTT, wound-healing and Transwell invasion assays. Flow cytometry was used to evaluate apoptosis in si-CCAT2 Eca-109 cells. The expression of β-catenin and proliferating cell nuclear antigen (PCNA) proteins was detected by immunohistochemistry. The pro-apoptotic protein Bax, cyclin D1 and Wnt target proteins, including c-Myc and adenomatous polyposis coli (APC), were detected by western blotting. LncRNA CCAT2 was highly expressed in the four esophageal cancer cell lines compared with the HEEC cells. The expression of CCAT2 was significantly decreased in si-CCAT2 Eca-109 cells. Treatment with si-CCAT2 and FH535 alone or in combination significantly inhibited the proliferation, migration and invasion of Eca-109 cells. The treatments also promoted apoptosis, upregulated the expression of Bax and APC proteins, and downregulated β-catenin, PCNA, cyclin D1 and c-Myc proteins. In summary, lncRNA CCAT2 is upregulated in esophageal cancer cells and the knockdown of lncRNA CCAT2 inhibits their proliferation, migration and invasion via the Wnt signaling pathway.