Targeting Histone Deacetylase-3 Blocked Epithelial-Mesenchymal Plasticity And Metastatic Dissemination In Gastric Cancer

Background and purpose: Histone deacetylase (HDAC) inhibitors (HDIs) were shown to modulate the epithelial-mesenchymal transition (EMT) progression and inhibit the migration and invasion of cancer cells. Emerging as a novel class of anti-cancer drugs, HDIs have attracted much attention in the field of drug discovery. This study aimed to the underlying mechanisms of Honokiol in preventing the metastatic dissemination of gastric cancer cells by inhibiting HDAC3 activity/expression.Experimental Approach: Clinical pathological analysis was performed to determine the relationship between HDAC3 and tumor progression. The effects of Honokiol on pharmacological characterization, functional, transcriptional activities, organelle structure changes, and molecular signalings were analyzed using binding assays, Differential Scanning Calorimetry, luciferase reporter assay, HDAC3 activity, ER stress response element activity, transmission electron microscopy, immune-blotting and Wnt/b-catenin activity assays. The in vivo effects of Honokiol on peritoneal dissemination were determined by a mouse model and detected by the PET/CT tomography.Key Results: HDAC3 over-expression was correlated with poor prognosis. Honokiol significantly abolished HDAC3 activity (Y298) via inhibition of NFκBp65/CEBPb signaling, which was reversed by the over-expression of plasmids of NFκBp65/CEBPb. Honokiol-inhibited NFκBp65/CEBPb activation could be reversed by 4-phenylbutyric acid (a chemical chaperone) and calpain-2 gene silencing. Honokiol increased ER stress markers and inhibited EMT-associated epithelial markers, but decreased Wnt/β-catenin activity. Suppression of HDAC3 by both Honokiol and HDAC3 gene silencing decreased cell migration and invasion in vitro and metastasis in vivo. Conclusions and Implications: Honokiol acts by suppressing HDAC3-mediated EMT and metastatic signaling. By prohibiting HDAC3, metastatic dissemination of gastric cancer may be blocked.