Increased Expression of Cullin 3 in Nasopharyngeal Carcinoma and Knockdown Inhibits Proliferation and Invasion

This study aimed to investigate the clinical significance of cullin 3 expression in nasopharyngeal carcinoma (NPC), as well as to explore the regulatory mechanism of cullin 3 underlying the growth and metastasis of NPC cells. Our findings showed that the expression levels of cullin 3 were significantly increased in both NPC tissues and cell lines. A strong positive correlation was found between cullin 3 expression and the Ki-67-based proliferation index in NPC tissues. Moreover, cullin 3 overexpression was correlated with local relapse and distant metastasis in NPC patients. In vitro experiments showed that knockdown of cullin 3 caused a significant reduction in the proliferation of NPC cells, probably by inducing cell cycle arrest. In addition, downregulation of cullin 3 inhibited colony formation and the migratory and invasive capacities of NPC cells. The expression levels of PCNA and epithelial-to-mesenchymal transition (EMT)-related proteins were also meditated by cullin 3 in NPC cells. Based on these findings, we demonstrated that cullin 3 plays a promoting role in the malignant progression of NPC and suggest that the cullin 3-based ubiquitin proteasome pathway may be used as a promising therapeutic target for NPC.