| BACKGROUND Bladder cancer is the most frequent malignant tumor of urinarysystem in China, and the incidence rate is ascending recently. High recurrence rate is the significant feature of bladder cancer, even an operation was performed in earlier period and intravesical chemotherapy was used after operation. Over 20~30 percent of superficial transitional cell carcinoma of bladder will eventually progress to muscle invasive carcinoma of bladder, so how to prevent bladder cancer from recurrence become a hot point of research in this field.In the last decade, as a new therapeutic way, there were many research work had perfomed to improve the effect of gene therapy for curing bladder tumor. As a half open organ, bladder can communicate with outside through urethra, it is convenient to infuse drug into bladder; and the recurrence rate of bladder cancer after operation is so high that it is facilitate to evaluate the curative effect of gene therapy promptly through cystoscopy and biopsy. So gene therapy is more useful in the clinical treatment of bladder tumor than other else.One of the strategies developed for bladder tumor gene therapy is immunogene therapy, which involves modulation of immune responses through transfer of cytokines into target cells. Cytokine gene therapy can promote immune cells of host to differentiate proliferate, and strengthen their functions. The cytokines will keep on the immune response between the immune cells and tumor cells, accordingly the tumor cells will be killed directly or will be induced to apoptosis.Interleukin-2 is a cytokine which has a broad spectrum of biological activities, such as stimulating T cell into proliferation in the body; inducing and facilitating the killing activity of NK cell; promoting B cell to differentiate proliferate and produce antibody. Interleukin-2 is one of the immunotherapeutic agents that have been used for the clinical treatment of many tumors.The critical step for the success of gene therapy strategies is not only relevant with selecting the effective therapeutic genes, but also with chosing an efficient vector system that is able to specifically deliver therapeutic genes into target cells and the therapeutic genes can effectively express for a long period. Adenoviruses vector system is a system safe for in vivo gene therapy in human, it is easy to manipulate by classical recombinant DNA techniques, and it has the added advantages that it's infection is efficient, it can be produced in large quantities in cell culture. Since adenovirus has the property of addiction bladder cell and bladder is a half open organ, it is possible that adenovirus be used to transfer to transitional cell through infusing bladder.PURPOSE we successfully construct the model of bladder cancer of rat viainfusing bladder with MNU(N-methyl-N-nitrosourea). Then the recombinant adenovirus carrying IL-2 gene is transfered to bladder transitional cell in vivo in order to make the concentration of IL-2 high enough to strengthen the local immune reactiom reduce the incidence rate of bladder tumor and prevent the recurrence of bladder cancer. This study provide the experiment evidence that recombinant adenovirus carrying IL-2 can be a useful gene therapeutic agent to treat bladder cancer.METHODS (1)A total of 30 female SD rats weighing about 250 gm weredivided randomly into two groups, 20 rats (group 1) were infused intravesically with 2mg MNU 4 times, at 2 weeks interval, 10 rats (group 2) were infused with PBS as control. Ten weeks later all rats were killed and bladder were resected, macroscopic observation and microscope observation after HE staining were performed to study the morphologic change of transitional cells and discriminate the type of tumors. (2) HEK293 cell was cultivated to amplificate AdvIL-2 and AdvLac-Z. A total of 60 female SD rats weighing about 250 gm were divided randomly into four groups, every group had 15 rats, all rats were infused intravesically with 2mg MNU per animal, at 1 3 5 7 week; at 2 4 6 8 week each group of rats' bladders were filled w...
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