Objective      To investigate the effect of silencing nucleostemin (NS) in EC9706 cells induced by RNAi on the expression of epidermal growth factor (EGF) and its receptor (EGFR).      Methods      Fifteen nude mice were divided into three groups

each group contains five mice. Three different kinds of cells

EC9706 cells transfected by pRNAT-U6-1-siNS2

or by pRNAT-U6.1-siC and normal EC9706 cells were injected into the hypodermis tissues of corresponding mice respectively. Five weeks later after the injection

the sizes of xenograft tumors in these mice were measured

and the protein and mRNA expression of NS

EGF and EGFR in the xenograft tumor were detected by immunohistochemistry and RT-PCR.     Results      Visible tumors were observed in the injected position after 4 d in transfected pRNAT-U6.1-siC and normal EC9706 cells groups

and after 6 d in transfected pRNAT-U6-1-siNS2 EC9706 cells group. In 5th week

the tumorigenesis were 100%. The protein and mRNA levels of NS

EGF and EGFR were lower in transfected pRNAT-U6-1-siNS2 EC9706 cells group than in the other two groups (P0.05).     Conclusion      Silencing NS of EC9706 cells inhibits the growth of exnograft tumor in nude mice and decreases the expression of EGF gene and EGFR gene. Silencing NS gene may be a new strategy for the treatment of esophagus caicinoma.