FSCN1 is upregulated by SNAI2 and promotes epithelial to mesenchymal transition in head and neck squamous cell carcinoma.

In this study, we investigated whether there is any association between the expression of FSCN1 and SNAI2 and the possible underlying mechanisms in head and neck squamous cell carcinoma (HNSC). In addition, we also investigated whether FSCN1 modulates epithelial-to-mesenchymal transition (EMT) in HNSC cells. Microarray data of dysregulated genes in HNSC were searched in GEO datasets. The association between FSCN1 expression and the 5-year/10-year overall survival (OS), as well as the correlation between the expression of FSCN1 and SOX2, MYBL2, SNAI2, STAT1, and SOX4, was analyzed based on data in TCGA HNSC cohort (TCGA-HNSC). The binding site of SNAI2 in FSCN1 promoter was verified using luciferase reporter assay. SCC9 and SCC15 cells were transfected with pCMV-SNAI2 or pCMV-FSCN1 expression vector or the empty control. Alteration of E-cadherin, Claudin 1, Vimentin, and N-cadherin was then quantified. Our results showed that FSCN1 is significantly upregulated in HNSC tissues compared with the normal control tissues. High FSCN1 expression is associated with worse 5-year and 10-year OS among the HNSC patients. Bioinformatic prediction showed a highly possible SNAI2 binding site in FSCN1 promoter and following luciferase reporter assay verified this site. SNAI2 overexpression significantly increased FSCN1 expression at both mRNA and protein level. FSCN1 overexpression reduced the expression of E-cadherin and Claudin 1, but increased the expression of Vimentin and N-cadherin in SCC9 and SCC-15 cells. Therefore, we infer that FSCN1 is a downstream effector of SNAI2 in promoting EMT in HNSC cells.