Trichostatin A augments cell migration and epithelial-mesenchymal transition in esophageal squamous cell carcinoma through BRD4/c-Myc endoplasmic reticulum-stress pathway.

BACKGROUND: The causes of death in patients with advanced esophageal cancer are multifactorial, with tumor metastasis being one of the important factors. Histone acetylation promotes the migration of esophageal squamous cell carcinoma (ESCC) cells, while the histone deacetylase inhibitor (HDACi) shows complex effects on tumor functions. AIM: To comprehensively elucidate the impact and molecular mechanisms of trichostatin A (TSA), an HDACi, on cell migration in ESCC through bromodomain-containing protein (BRD4)/cellular myelocytomatosis oncogene (c-Myc)/endoplasmic reticulum (ER)-stress. METHODS: The effects of TSA on ESCC cell lines Eca109 and EC9706 migration were evaluated using Transwell assays, with small interfering transfection and pathway-specific inhibitors to elucidate underlying mechanisms. The mRNA levels involved were examined by quantitative real-time polymerase chain reaction. Protein levels of acetylated histones H3 (acH3) and acetylated histones H4, BRD4, c-Myc, as well as markers of ER stress and epithelial-mesenchymal transition (EMT), were analyzed using western blot. Additionally, this method was also used to examine acH3 levels in esophageal cancer tissues and adjacent tissues. Patient outcomes were subsequently tracked to identify prognostic indicators using Log-Rank tests and Cox multivariate analysis. RESULTS: TSA promoted the migration of ESCC cells by stimulating the EMT process. TSA-mediated histone acetylation facilitated the recruitment of BRD4, a bromodomain-containing protein, triggering the expression of c-Myc. This cascade induced ER stress and enhanced EMT in ESCC cells. To further elucidate the underlying mechanism, we employed various interventions including the ER stress inhibitor 4-phenylbutyric acid, knockdown of c-Myc and BRD4 expression, and utilization of the BRD4 inhibitor carboxylic acid as well as the inhibitor of TSA 1. Mechanistically, these studies revealed that TSA-mediated histone acetylation facilitated the recruitment of BRD4, which in turn triggered the expression of c-Myc. This sequential activation induced ER stress and subsequently enhanced EMT, thereby promoting the migration of ESCC cells. Additionally, we examined histone acetylation levels in specimens from 43 patients with ESCC, including both tumor tissues and paired adjacent tissues. Statistical analysis unveiled a negative correlation between the level of histone acetylation and the long-term prognosis of patients with ESCC. CONCLUSION: TSA promoted ESCC cell migration through the BRD4/c-Myc/ER stress pathway. Moreover, elevated histone acetylation in ESCC tissues correlated with poor ESCC prognosis. These findings enhance our understanding of ESCC migration and HDACi therapy.