ObjectiveTo investigate the inhibition of telomerase activity of colorectal cancer by chemotherapeutic drugs.MethodsBy using telomerase repeat amplification protocol (TRAP) combined with PAGE silver staining, we detected the telomerase activity of human colorectal cancer cell line HT-29 under the effect of cisplatin, doxorubicin, pirarubicin, mitomycin C, and 5-FU.ResultsIn high doses,no inhibition of tolemerase activity was found when cells were collected after only 4 hours of drug treatment, but the telomerase activity was completely inhibited by cisplatin when the drug was removed and cells were reculured for 20 hours. However, doxorubicin, pirarubicin, mitomycin C, 5-FU had no such effect. ConclusionCisplatin inhibits telomerase activity of human colon cancer cell HT-29, while other drugs had no such effect.

Objective: To investigate expression of TRAP in human tumors and correlativity between TRAP and hTERT and to explore the role of TRAP in tumorigenesis. Methods: TRAP was expressed in E.coli . and polyclonal antibody was prepared by immunization of New Zealand rabbits. Expressions of TRAP gene and hTERT in human tumors were analyzed by immunohistochemistry. The eukaryotic expression vectors of TRAP were constructed and transferred stably into HeLa cells to be analysed with Northern blot, TRAP PCR ELISA, growth curve, nude mouse transplantation. Results: Polyclonal antibody was obtained from New Zealand rabbits immunized with TRAP fuse protein, which was inducibly expressed in E.coli ., and its specificity was verified in Western blot. TRAP staining was detected in 213 (86.2%)of 247 malignant tumors. On the contrary, TRAP in all tissues adjacent to tumors was negative.There is a obvious difference between borderline,pre cancerous and benign lesion in the expression of TRAP.Furthermore, hTERT staining was conducted and its result was consistent with that of TRAP. Up regulation and down regulation of hTERT expression and telomerase activity were observed respectively in HeLa cells transfected stably with sense and antisence TRAP recombination. Increased proliferation presented in the former and growth inhibition in the latter. Besides, in nude mice, tumorigenecity of sense TRAP transfected HeLa cells was enhanced while tumor growth of antisense TRAP transfected HeLa cells was retarded. Conclusion: The expression of TRAP, which could be detected in most of human cancers and part of pre cancerous lesions, was correlated with expression of hTERT. The status of TRAP expression could regulate telomerase activity and present effects on growth and tumorigeneity of cancer cells. This suggests that TRAP is involved in human tumorigenesis through regulation of telermarase activity.

Objective To investigate the correlation between VEGF-C and COX-2 expression in human rectal cancers and its significance in cancer metastasis. Methods VEGF-C expression was detected with Western blot in LOVO cells treated with NS-398 or PGE2. VEGF-C and COX-2 expression in 45 rectal adenocarcinomas was tested with immunohistochemistry. Results NS-398 inhibited the VEGF-C expression, and PGE2 up-regulated the expression of VEGF-C in a dosage-dependent way in LOVO cells. VEGF-C expression was significantly higher in adenocarcinomas with lymph node metastasis, and was related with the expression of COX-2 in 45 rectal adenocarcinomas. Conclusion COX-2 up-regulates VEGF-C and VEGF-C plays an important role in lymphatic metastasis of rectal cancers.