Abstract: AIM: To investigate the expression of long non-coding RNA (lncRNA) PCAT19 in nasopharyngeal carcinoma tissues and cell lines, and to explore its molecular mechanism of inhibiting proliferation and invasion of nasopharyngeal carcinoma cells. METHODS: Real-time fluorescent quantitative PCR (qRT-PCR) was used to detect the relative expression of PCAT19 in nasopharyngeal carcinoma tissues and five nasopharyngeal carcinoma cell lines. The lowest expressing nasopharyngeal carcinoma cell line was transfected with empty plasmid (control group) or high expression PCAT19 plasmid (experimental group). qRT-PCR was used to detect transfection efficiency. MTS method and Transwell invasion test were used to detect the effect of overexpressing PCAT19 on the proliferation and invasion ability of nasopharyngeal carcinoma cells. Bioinformatics predicts target genes for PCAT19. qRT-PCR and Western blot were used to detect target gene expression at mRNA and protein levels. RESULTS: Compared with adjacent tissues, the expression of PCAT19 in nasopharyngeal carcinoma tissues was decreased (P<0.01). Compared with immortalized nasopharyngeal epithelial cells, the expression of PCAT19 in five nasopharyngeal carcinoma cell lines was significantly reduced (P<0.05), and the expression was the lowest in SUNE-1 cells (P<0.01). Transfection of high-expressing PCAT19 plasmid could significantly promote the expression of PCAT19 (P<0.01). High expression of PCAT19 could inhibit the proliferation ability (P<0.01) and invasive ability (P<0.01) of nasopharyngeal carcinoma SUNE-1 cells. The target gene of PCAT19 was miR-142-5p, the target gene of miR-142-5p was inhibitor of growth gene 3 (ING3). After high expression of PCAT19, miR-142-5p expression was significantly reduced (P<0.01), and the expression of ING3 at both mRNA and protein levels was significantly increased (P<0.01). CONCLUSION: PCAT19 expression is down-regulated in nasopharyngeal carcinoma tissues and cell lines. Up-regulating PCAT19 can inhibit the proliferation and invasion of nasopharyngeal carcinoma SUNE-1 cells. The mechanism may be that PCAT19 promotes the expression of ING3 gene by adsorbing miR-142-5p.

Key words:  long non-coding RNA, nasopharyngeal carcinoma, inhibitor of growth gene 3, cell proliferation, cell invasion