NEFL promotes invasion and migration of esophageal squamous carcinoma cells via the EGFR/AKT/S6 pathway.

To explore the expression, the roles and the underlying mechanism of neurofilament light chain (NEFL) in esophageal squamous cell carcinoma (ESCC), we firstly analyzed the NEFL mRNA and protein expression in ESCC and paired normal tissues by using Gene Expression Omnibus (GEO) database, and real-time quantitative reverse transcription PCR (qRT-PCR). The results showed that NEFL mRNA level was significantly upregulated in ESCC tissues compared with that of normal tissues. Western blot analysis revealed that NEFL protein level was also significantly upregulated in ESCC tissues. CCK8 and transwell assays were performed to analyze the effect of NEFL overexpression on the malignant phenotypes of ESCC cells, and the results showed that NEFL knockdown significantly impaired the ESCC cell invasion and migration in vitro. Xenograft assay in nude mice indicated that NEFL silencing suppressed tumor growth in vivo. At the molecular level, NEFL knockdown significantly upregulated E-cadherin and downregulated N-cadherin expression, suggesting that NEFL overexpression might influence the epithelial-mesenchymal transition (EMT) process. Furthermore, we found that NEFL knockdown significantly reduced the mRNA and protein expression of epidermal growth factor receptor (EGFR) and the phosphorylation levels of protein kinase B (PKB; also known as AKT) and ribosomal protein S6 (S6). Ectopic expression of EGFR after NEFL knockdown significantly restored the phosphorylation levels of AKT and S6 as well as the invasion and migration of ESCC cells. These data indicate that NEFL overexpression might promote the EMT process of ESCC cells via the EGFR/AKT/S6 pathway, ultimately enhancing the invasion and migration of ESCC cells.