Proteasome inhibitor MG132 inhibits the proliferation and promotes the cisplatin-induced apoptosis in EC9706 cells

Abstract

Objective To investigate the antitumor activity of proteasome inhibitor MG132 in human esophageal squamous cancer cells.Methods EC9706 cells were treated with 100 mg/L cisplatin,5 pmol/L MG132 and cisplatin + MG132 for 24 h.Cell viability was measured by using cell counting kit-8(CCK-8) assay.The percentages of apoptotic cells were analyzed by using Annexin V-fluoresceine isothio-cyanate (FITC) apoptosis detection kit.Western blotting assay was used to detect the expression of nuclear factor-κB (NF-κB),Caspase-8 and-3.Results Exposure of cells to cisplatin combined with MG132 re-suited in a marked increase in the cell cytotoxicity of EC9706 cells as compared with the single agent.The combined cisplatin and MG132 treatment induced more apoptosis in tumor cells than in cisplatin treatmentalone (68.45 ±2.58 vs.23.5 ± 1.23％ ;P ＜0.01).MG132 significantly enhanced cisplatin-induced ap-optosis in association with the activation of Caspase-3 and-8.These events were accompanied by the down-regulation of NF-κB.Conclusion These findings demonstrate a novel mechanism by which proteasome inhibitor MG132 potentiates cisplatin-induced apoptosis in human esophageal squamous cell carcinoma. Key words: Proteosome inhibitor; Cisplatin; Apoptosis; Esophageal squamous cell carcinoma