Foxhead box D1 promotes the partial epithelial-to-mesenchymal transition of laryngeal squamous cell carcinoma cells via transcriptionally activating the expression of zinc finger protein 532

Abstract

The presence of cervical lymph node metastases has been considered as the most important adverse prognostic factor for patients with laryngeal squamous cell carcinoma (LSCC). However, the underlying mechanisms remain to be fully revealed. In this study, we explored the expression profile of Foxhead box D1 (FOXD1), its association with epithelial-to-mesenchymal transition (EMT), and its downstream targets in LSCC. Bioinformatic analysis was performed based on the LSCC subset of The Cancer Genome Atlas-Head and Neck Squamous Cell Carcinoma (TCGA-HSNC) and Chromatin immunoprecipitation (ChIP)-seq data from Cistrome Data Browser. LSCC cell lines AMC-HN-8 and TU212 were used for in vitro studies. Results showed that FOXD1 upregulation was associated with poor prognosis of LSCC. FOXD1 knockdown reduced N-cadherin and Vimentin expression but increased E-cadherin expression in AMC-HN-8 cells. Its overexpression showed opposite effects in TU212 cells. FOXD1 could bind to the promoter of ZNF532 and activate its transcription. ZNF532 overexpression enhanced the invasion of both AMC-HN-8 and TU212 cells. In comparison, its knockdown significantly impaired their invasion. ZNF532 knockdown nearly abrogated the alterations of EMT markers caused by FOXD1 overexpression. Its overexpression largely rescued the phenotypes caused by FOXD1 knockdown. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that ZNF532 correlated genes are largely enriched in extracellular matrix regulations. LSCC patients with high ZNF532 expression (top 50%) had a significantly worse progression-free survival. In summary, this study confirmed that FOXD1 promotes partial-EMT of LSCC cells via transcriptionally activating the expression of ZNF532.