Artesunate enhances radiosensitivity of esophageal cancer cells by inhibiting the repair of DNA damage.

Radiotherapy plays an important therapeutic role in esophageal cancer (EC). However, acquired radioresistance impairs the efficacy of radiotherapy, often leading to treatment failure. Therefore, it is important to develop novel radiosensitizers to enhance the clinical treatment of EC. The purpose of this study was to investigate the role of artesunate (ART) on radiosensitivity of human EC cell line TE-1. We found that ART inhibited the proliferation of EC cells and enhanced the radiosensitivity of TE-1 cells (SER = 1.24). In vivo tumor growth of xenografts was inhibited markedly by irradiation (IR) combined with ART, with a tumor inhibition rate of 53.76% in IR + ART group vs. 41.13% in IR-alone group. Pretreatment with ART significantly prompted cell apoptosis and reversed the IR-induced G/M arrest. ART treatment could aggravate DNA damage of EC cells and prolong the formation of γ-H2AX foci induced by IR. ART up-regulated P21 and down-regulated the expression of cyclin D1, RAD51, RAD54, Ku70 and Ku86 protein of irradiated TE-1 cells. These findings support that ART induce radiosensitivity of TE-1 cells in vitro and in vivo, and may prove to be a promising radiosensitizer for EC treatment.