| Telomerase is a ribonucleic acid(RNA)-protein complex and a specialized type of reverse transcriptase, which synthesizes telomeric DNA onto chromosomal ends by using its RNA component as a template and contributes to chromosomal stability. Recent advances indicate that the expression of telomerase activity is repressed in most normal human somatic cells but is reactivated during the carcinogenesis of most human cells. This striking observation led to the suggestion that the role of telomerase might be important for the pathogenesis, proliferation and progression of the tumors. Owing to high telomerase activity expression in most human bladder cancers, it might be suggested that telomerase could be used as a specific cancer marker and an ideal cancer target.Bladder tumor is the most commonly malignant tumor of urothelial tumors. The molecular and celluar mechanisms of bladder tumor are poorly understood, A complete understanding of its mechanism, diagnosis and treatment is always-5-important and difficult in the study of urothelial tumors. People had been searching for the new methods of early diagnosis and treatment of bladder tumor. With the development of the theory and technology of molecular biology, gene diagnosis and therapy is becoming realized. Telomerase, which was found and further studied, is becoming a new target for gene therapy of tumor.In the present study, we investigated the expression of human telomerase reverse transcriptase gene (hTERT) in transitional cell carcinoma of the bladder and the effects of antisense oligodeoxynucleotide targeted against human telomerase and transfection with antisense telomerase RNA gene on malignant phenotype of bladder carcinoma cell T24. The major results were reported as follows:1. Using S-P immunohistochemical method, The expression of hTERT gene protein was studied in 56 cases of paraffin-embedded TCC tissues and in 10 cases of normal bladder tissues. Results showed that the positive expression rates of hTERT gene were 64.3% in patients with TCC and 0% in the normal bladder tissues respectively (PO.05). hTERT protein positive staining was detected in the cytonucleus of TCC. Significant difference of hTERT gene expression was observed in TCC with different pathological grades I, II and III, its positive expression rates were 43.8% (7/16), 57.7%(15/26), 100% (14/14) respectively . Statistical significance was found in I and III, II and III, I+II and III respectively (PO.05). hTERT gene expression was related to the clinical stages and its positive expression rates among superficial and invasive tumor were 53.1%(17/32) and 79.2 %(19/24) respectively (PO.05). The expression of hTERT was significantly positively related to the recurrence of the patients (PO.05).2. Using molecular biological technology, bladder carcinoma cell line T24-6-was treated with antisense oligodeoxynucleotide targeted against telomerase (ASODN-t) at different concentrations. The effects of ASODN-t on the growth, cell cycle and apoptosis of T24 cells were detected. Results indicated that ASODN-t acted as a specific growth inhibitor on T24 cells and the effects were in a sequence specific, dose dependent manner. Election microscopy observed the typical cytological feature of apoptosis, the significant apoptotic peak was exhibited with FCM, the apoptotic rate of bladder carcinoma cell treated with ASODN-t at the concentration of 6mol/L for 72 hours was 10.4%. Controlled oligodeoxynudeotide had no inhibitory effect on T24 cells.3. Using lipofectamine-mediated DNA transfection technique, an antisense telomerase RNA gene expression plasmid was introduced into T24 bladder cancinoma cells. The changes of telomerase activity were detected by PCR-ELISA method. MTT method, light and electron microscopy, and flow cytometry (FCM) were used to observe the proliferation and apoptosis of the transfected T24 cells. Results suggested the antisense telomerase RNA gene was successfully introduced into T24 cells, which could remarkably inhibit the telomerase activity and prolifer...
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