Objective       To determine the expression of Rap1 and its role in the malignant growth in serous ovarian cancer.       Methods       Rap1 expression was evaluated through Western blot analysis in serous EOC tissues

benign ovarianadenoma tissues and normal ovarian tissues. Three Rapl shRNA eukaryotic expression vectors were constructed with RNA interference technology. Three recombinant plasmids

empty vect

or and negative plasmid were transfected into ovarian cancer cell line SKOV3 respectively through Lipofectamine 2000

then identified by restriction endonuclease digestion and DNA sequencing. The Rap1 siRNA efficiency was determined through monoclonal screening with G418 followed by Western blotting. Two strains of SKOV3-Rap1-RNAi cell lines were established. And malignant proliferation was evaluated by MTT assay.        Results        EOC tissues presented significantly higher Rap1 expression than benign ovarian tumors and normal ovarian tissues (

P

<

0.05). For the 3 recombinant plasmids

pSUPER.retro.neo/GFP-Rap1i-#1

-Rap1i-#2 and -Rap1i-#3

their inhibitory efficiency in transient transfection was 50%

66% and 49%

respectively. So the second one was used to transfect SKOV3 cells

and 2 monoclones of Rap1i cells ( Rap1i-1 and Rap1i-2 with inhibitory rate of Rap1 of 70% and 40% respectively) were established through pSUPER.retro.neo/GFP-Rap1i-#2 transfection followed by G418 screening. Rap1i-1 cells demonstrated enhanced proliferation as compared with control (

P

<

0.05).       Conclusion       Rap1 is highly expressed in serous ovarian cancer

and exerts inhibitory effect on the proliferation of the cancer cells.