Abstract
OBJECTIVES: To investigate CEACAM6 expression in nasopharyngeal carcinoma (NPC) and its regulatory effects on tumor cell proliferation, migration, and epithelial-mesenchymal transition (EMT). METHODS: CEACAM6 expression in NPC was analyzed using GEO datasets and validated by immunohistochemistry in NPC tissues and by Western blotting and RT-qPCR in NPC cell lines (HNE1, C666-1, HK1, 5-8F and CNE2Z) and normal nasopharyngeal epithelial NP69 cells. In the NPC cell lines, the effects of lentivirus-mediated CEACAM6 overexpression and knockdown on cell proliferation, migration, invasion and cytoskeletal structures were evaluated using CCK-8 assay, Edu staining, wound healing assay, Transwell assay, and phalloidin staining. Western blotting was performed to determine the expressions of EMT-related proteins (FN1, ITGA5, ITGB1, E-cadherin, N-cadherin and vimentin) in the NPC cells and the effect of FN1 overexpression on ITGA5 and ITGB1 protein expressions. RESULTS: Analysis of the data from the GEO datasets suggested that CEACAM6 was significantly downregulated in NPC, which was associated with poor patient prognosis. Immunohistochemistry also showed low expressions of CEACAM6 in clinical NPC tissues (P<0.05). In NPC cells, CEACAM6 overexpression significantly suppressed cell proliferation, migration and invasion and reduced the fluorescence intensity of actin. CEACAM6 overexpression also resulted in significant downregulation of FN1, ITGA5, ITGB1, N-cadherin and vimentin expressions and upregulation of E-cadherin expression, and FN1 overexpression obviously attenuated the inhibitory effect of CEACAM6 overexpression on ITGA5 and ITGB1 expressions. CONCLUSIONS: CEACAM6 inhibits NPC cell migration and invasion by inhibiting EMT via regulating FN1, ITGA5 and ITGB1 expressions.