Notch1 inactivation promotes invasion and metastasis of nasopharyngeal carcinoma cells partly through Slug activation.

Nasopharyngeal carcinoma (NPC) is a rare form of the head and neck cancer of the epithelial lining of the nasopharynx and exhibits the highest metastatic rate among head and neck cancers. Underlying mechanisms of metastasis remain largely unknown. Here, we explored whether Notch1 affects the invasion and metastasis of NPC cells. In vitro migration and invasion capacities were evaluated after the knockdown of Notch1 expression in NPC cells. To investigate the role of Notch1 in in vivo metastasis, we examined the metastatic ability to the lungs following administration of cancer cells via mouse tail vein. The expression of epithelial-mesenchymal transition (EMT) markers associated with Notch1-mediated metastasis was investigated, and their roles in metastasis and relationship with Notch1 expression were investigated. Suppression of Notch1 expression increased the ability of NPC cells to invade Matrigel in vitro. Knockdown of Notch1 expression in NPC cells resulted in extensive lung metastasis in a mouse model and increased the mRNA expression of Slug in NPC cells. Slug-specific RNA interference resulted in the loss of the metastatic and invasion capacities in Notch1-suppressed NPC cells. These findings show that Notch1 has a significant suppressive role in the regulation of metastasis in NPCs, suggestive of its prudent use in clinical trials.