Placenta specific 8 gene induces epithelial-mesenchymal transition of nasopharyngeal carcinoma cells via the TGF-β/Smad pathway

The present study aimed to investigate the effects and mechanisms of PLAC8 on the epithelial-mesenchymal transition (EMT) of Nasopharyngeal carcinoma (NPC). The expression of PLAC8 in NPC and nasopharyngitis (NPG) tissues from 150 patients was determined using immunohistochemistry. The levels of PLAC8 in five NPC cell lines and nasopharyngeal permanent epithelial cell line were measured using western blotting. We then knocked out or overexpressed PLAC8 in CNE2 cells. Cell proliferation, wound healing, migration, and invasion assays were used to analyze the effects of PLAC8 on the proliferation, migration, and invasion in vivo and vitro. The results showed that the expression of PLAC8 was much higher in NPC tissues than in NPG tissues. The expression of PLAC8 was higher in all the cell lines than in the nasopharyngeal permanent epithelial cells. PLAC8 knockout resulted in significant decreases in cell proliferation, migration, and invasion; associated with lower protein levels of N-cadherin; and increased levels of E-cadherin. Overexpression of PLAC8 had the opposite effect. Furthermore, knockout of PLAC8 inactivated TGF-beta/SMAD signaling pathway and suppressed the growth of NPC xenografts. PLAC8 may promote the carcinogenesis and EMT of NPC via the TGF-beta/Smad pathway, which suggests that PLAC8 may be a potential biomarker for NPC.