Abstract: ［Abstract］ Background and purpose：Esophageal squamous cell carcinomas (ESCC) chemotherapy drug resistance is very common, the cancer stem cells theory suggested that this was due to existing the esophageal cancer stem cells which is resistant to traditional chemotherapy. This study is testing stem cell gene Nanog expression in ESCC cell lines TE-1 and its Downregulation by RNAi Sensitizes cells to Cisplatin. Methods：In this study, we detected the expression of Nanog in the ESCC cell lines TE-1 by immunofluorescence. Then we used fluorescence labeled small interfering RNA (siRNA) to block Nanog expression while evaluating the effect of Nanog siRNA by RT-PCR and western blot , and the combined effects with Cisplatin in ESCC cell line TE-1. Results：Nanog is Highly Expressed in ESCC Cell-line TE-1and the main expression in the nucleus.The Nanog expression at the protein and mRNA level in Nanog siRNA-transfected group was reduced by 85% as compared with that in the negative control group. The cells exposed to Nanog siRNA in the presence of Cisplatin showed a significant decrease in IC50 （4.03μg /ml）compared with control siRNA (5.17μg /ml)and mock transfection (5.26μg /ml), (p < 0.05). Conclusion：The results showed that Nanog is highly expressed in ESCC cell-line TE-1 and Nanog siRNA efficiently decreased Nanog expression . Treatment with Nanog siRNA in combination with cisplatin enhanced chemosensitivity.

Key words: Esophageal squamous cell carcinomas, Nanog, Cisplatin, resistance to therapy, siRNA