Objective:To construct the orthotopic model of bladder tumor in rats and to observe the inhibition effect on bladder tumor after transfected with expression plasmid pcDNA3.1(+)/Mad1.Methods:Bladder tumors were induced in SD rats by intravascular instillation of MNU.The rats bearing tumor were randomly divided into 3 groups:transfected with pcDNA3.1(+)/Mad1(group A)

transfected with empty vector(group B) and transfected with saline(group C).Tumor-bearing rats were transfected using Lipofectamine.Rat body weight(RBW)

Bladder absolute weight(BAW)

bladder relative weight(BRW) and expression levels of mRNA of Mad1 and TERT were assayed and flow cytometer analysis were used to observe the inhibition effect of Mad1 to bladder tumor.Results:Compared with group B and group C

in group A

though there was no diference in RBW(P>0.05)

BAW and BRW were significantly decreased(P<0.01 and P<0.05

respectively).Mad1 mRNA expression levels were markedly improved

while TERT mRNA expression levels were markedly decreased.Flow cytometry showed an increase of G0/G1-phase cells and a decrease of S-phase cells after transfected with Mad1.Conclusions:Over expression of Mad1 can inhibit the proliferation of bladder tumor.