The Effect Of BCG On The Expression Of B7-H1/PD-1 Pathway In Rat Bladder Cancer Cells

Objective: To establish an orthotopic rat model of bladder cancer,to study the effect of BCG to B7-H1 / PD-1 expression pathway on rat bladder cancer cells,furthermore,to evaluate the action of B7-H1/PD-1 pathway in bladder cancer immune escape and failure mechanism of BCG immunotherapy.Methods:(1)33 SD rats randomly divided into the model group with 30 rats and the control group with 3 rats.Each rat of the model group was treated with 2 mg MNU per dose every other week,totally 4 doses,by per urethra administration.(2)At the 10 th week,,all the rats were evaluated by CT scanning combined with bladder irrigation with iodine contrast agent.To select randomly two rats of cancer to observe the anatomy of bladder cancer and pathological examination.(3)Rats of cancer of the model group were randomly divided into BCG instillation group,intravesical gemcitabine group,epirubicin instillation group,normal saline instillation group,no instillation group of rows,the last four groups as the control group.Intravesical infusion period of each group was four weeks and the frequency of infusion was once a week.(4)At the 4th weeks,all rats of each group were killed and the anatomy of bladder cancer were observed.Then,the tumor tissue was manipulated respectively to single cell suspension and B7-H1 expression of bladder cancer cells were detected by flow cytometry.Resu Its:A rat model of orthotopic bladder cancer can be established by per urethra administration of MNU.At the 10 th weeks,the tumor formation rate of rats of the model group up to 95%,which two rats were diagnosed with bladder cancer by pathology.B7-H1 average expression level of rat bladder cancer cells in BCG infusion group was 9.96%.At the 14 th weeks,the average expression level of B7-H1 molecular of the control group was respectively 1.34%,1.42%,1.39% and 1.43%.B7-H1 expression level of rat bladder cancer cells in BCG infusion group was significantly increased and was statistically significant compared with control group(p <0.05).B7-H1 expression level of rat bladder cancer cells between control groups rats were not significantly increased and the comparison between groups was not statistical significance(p> 0.05).Conclusions:1.A rat model of orthotopic bladder cancer can be established successfully by per urethra administration of N-methyl-nitrosourea(MNU),which the time is short and tumor formation rate is high.2.BCG could induce B7-H1 expression of bladder cancer cells in rats significantly up-regulating.3.The enhanced expression of B7-H1 / PD-1 pathway may be one of the mechanisms of the immune escape of bladder cancer cell in BCG bladder perfusion treatment.