Objective    To investigate the effect of membrane-cytoskeleton linker Ezrin on tumor formation and pulmonary metastasis of osteosarcoma cell UMR106 in vivo.     Methods    Two small hair RNA targeting Villin2 gene (Ezrin coding

gene) was designed

chemically synthesized and inserted into plasmid pGenSil-1

then transformed into E. coli DH5α. The recombinant plasmid was extracted in middle quantity and transfected into UMR106 cells by Lipofectamine

TM

2000. Ezrin expression in UMR106 cells transfected by shRNA recombinant plasmid was measured by RT-PCR and Western blotting. UMR106 cells were transfected by more effective shRNA1 plasmid and cultured in 1640 media containing G418

then were transplanted into tibial tubercle of Sprague-Dawley rat. The rats transplanted by normal UMR106 cells or transfected by negative control shRNA were used as control. The time of tumor appearance and rat death were noted

the number of metastatic foci on the lung surface was counted

and the cells expressing EGFP were observed under fluorescence microscope.     Results    （1）shRNA1 knocking down 90% Ezrin in UMR106 cells was the most effective. （2）When at transplantation

about 50% cells were stably transfected by shRNA1 plasmid. （3）The tumors were formed in all rats

and the time of tumor formation had no difference among the 3 groups (P0.05). The rats of experimental group survived longer than that of normal control group and negative control group (P0.01). The number of lung metastatic foci in experimental group were much less than that of normal control group and negative control group (P0.01). Cells expressing EGFP were seen in both lung and primary sites in negative control group

but were not be found in lungs of experimental group.     Conclusion    Ezrin is required in metastasis of osteosarcoma cells and potential to be a target for prevention of pulmonary metastasis.