| RB1 gene is the first human tumor suppressor gene found and isolated from retinoblastoma. The studies concerned in recent years showed that when the RB1 gene was introduced to the tumor cell lines such as retinoblastoma, lung cancer, and prostatic cancer, especially osteosarcoma, the transfectants with stable RB1 expression lost its abiliby to form colonies in semi-solid medium, their growth rate was significantly decreased, and the tumorigenicity in nude mice markedly weakened or disapeared. These characteristics of the RB1 gene reveals an possibility for the treatment of cancers. Bladder cancer is one of the commonest tumors in human beings. The purpose of this experiment is to study the tumor suppression function of RB1 gene in human bladder carcinoma cells in vitro and to explore a new way for the treatment of this cancer.The cloned RB1 gene which comprises 3546bp was inserted by restriction enzyme BamH1 to a mammalian expression vector plasmid, pCMV-neo, which contains CMV promoter and neomycin-and ampicillin resistant sequences. By electroporation, this RB1 expression vector, pCMV-neo-RB1, was introduced into a bladder cancer cell line, HTB9-5637,and thereafter G418 was used to select the transfectant colonies. The experiment performed on the transfectant cells showed that the growth rate of these cells was significantly slowed, and the properties of anchorage independent growth and tumorigenicity in nude mice was lost. Flowcytometry measurement indicated that the proportion of the transfectants in S phase was distinctly decreased. Northern blot analysis of Ha-ras C-myc oncogenes revealed that the former's expression in transfectants was markedly reduced. These results show that the RB1 gene can work as a tumor suppressor gene in bladder carcinoma cells as in other cancer cells. |
