Overexpression of Interleukin-6 suppresses cisplatin-induced cytotoxicity in esophageal squamous cell carcinoma cells.

Interleukin-6 (IL-6) expression at local tumor sites or in systemic circulation is associated with disease progression and poor prognosis of esophageal cancer. The aim of this study was to investigate the possible influence of IL-6 on biological activities of esophageal cancer cells in terms of chemosensitivity. Human esophageal cancer cell lines TE13 and KYSE170 were transfected with a plasmid vector expressing IL-6 and stable transfectants overexpressing IL-6 were thus established. The sensitivity of IL-6 transfectants to cisplatin was evaluated using a WST-8 assay and cell-cycle analysis. In addition, the inhibitory effects of IL-6-specific siRNAs were investigated. IL-6 transfectants showed significantly reduced sensitivity to cisplatin compared to control transfectants. In addition, the reduced cisplatin sensitivity of IL-6 transfectants was restored by pretreatment with IL-6-specific siRNA. These results suggest that intracellular IL-6 expression in tumor cells may acts as a resistance factor against cisplatin-based treatments for esophageal cancer.