LncRNA MEG3 inhibits the development of nasopharyngeal carcinoma by sponging miR-543 targeting KLF4

BACKGROUND: Emerging evidence shows that long non-coding RNAs (lncRNAs) play a crucial role in tumor development by regulating biological behavior in various cancer cells. Several lncRNAs act as miRNA sponges by binding miRNA sequences and thus regulating mRNA expression. The lncRNA maternally expressed gene 3 (MEG3) has decreased expression levels in many cancer cells and acts as a tumor suppressor in different cancers. MEG3 also showed decreased expression in nasopharyngeal carcinoma (NPC) and plays a role in tumor suppression; however, the detailed mechanism of tumor suppression in NPC cells has not been reported. This paper aimed to explore the function and molecular mechanisms of MEG3 in the development of NPC. METHODS: MEG3 and miR-543 levels in NPC cells were detected by quantitative real-time PCR (qRT-PCR). The regulatory role of MEG3 in NPC cells was examined using knockdown and overexpression of MEG3 in C666-1 cells. Cell proliferation was analyzed by the cell counting kit-8 (CCK-8) assay, cell migration and invasion capacities were evaluated using Transwell assay, and cell apoptosis was assessed using flow cytometry. The relationship between MEG3 and miR-543 was investigated by luciferase reporter assay. MEG3- and Krüppel like factor 4 (KLF4)-mediated changes in NPC cell proliferation and apoptosis were analyzed, and KLF4, Bcl-2 and Bax protein expression levels were measured by western blotting. RESULTS: The results showed that MEG3 was decreased and miR-543 was increased in NPC cell lines, and upregulated MEG3 inhibited cell proliferation, migration, and invasion and promoted apoptosis, suggesting that MEG3 acts as a tumor suppressor in NPC cells. Furthermore, a luciferase reporter assay and western blotting indicated that MEG3 regulated KLF4 expression by sponging miR-543. Functionally, overexpression of MEG3 suppressed cell proliferation, promoted cell apoptosis and affected Bcl-2 and Bax protein levels via regulation of KLF4 expression mediated by sponging miR-543. CONCLUSIONS: These findings show that lncRNA MEG3 inhibits the development of NPC by sponging miR-543 targeting KLF4 and that MEG3 can serve as a new novel target for NPC therapeutics.