AIM:To directly investigate the relationship betweentelomerase activity and its subunit expression and the inhibitoryeffect of antisense hTR on pancreatic carcinogenesis.METHODS:We examined the telomerase activity and itssubunit expression by cell culture,polymerase chain reaction(PCR),PCR-silver staining,PCR-ELISA,DNA sequencing,MTTand flow cytometry methods.RESULTS:PCR-silver staining and PCR-ELISA methods hadthe same specificity and sensitivity as the TRAP method.Telomerase activity was detected in the extract of the 10~(th),20~(th) and 30~(th)passages of P3 cells,while it was absent infibroblasts.Furthermore,after the 30th generation,theproliferation period of fibroblast cells was significantlyprolonged.Telomerase activity and hTERTmRNA weredetected in two pancreatic carcinoma cell lines.,but werefound to be negative in human fibroblast cells.Telomeraseactivity and hTERTmRNA were tested in pancreaticcarcinoma specimens of 24 cases.The telomerase activitywas positive in 21 of the 24 cases (87.5 %),and thehTERTmRNA in 20 cases (83.3 %).In adjacent normaltissues positive rates were both 12.5 %.There was asignificant difference between the two groups.Thisindicated a significant correlation between the expressionlevel of telomerase activity and histologic differentiation,metastasis and advanced clinical stage of pancreaticcarcinoma.Our findings showed that the expressions ofhTR and TPlmRNA were not correlated with the activity oftelomerase but the expression of hTERTmRNA was.Aftertreatment with PS-ODNs,telomerase activity in P_3 cellsweakened and the inhibiting effect became stronger withan increase in PS-ODNs concentration.There was asignificant difference between different PS-ODN groups(P<0.05).Inhibition of telomerase activity occurred mostsignificant with PS-ODN1.The results of the FCM test ofpancreatic cancer P_3 cells showed an increase in theapoptotic rate with increasing PS-ODN1 and PS-ODN2 concentrations.CONCLUSION: The expression of telomerase activity has a significant relationship to carcinogenesis. A strong correlation exists between telomerase activity and hTERTmRNA expression. The up-regulation of hTERTmRNA expression may play a critical role in human carcinogenesis. The expression of telomerase activity and its subunit level in pancreatic carcinoma significantly correlate with the clinical stage of pancreatic carcinoma and hence, may be helpful in its diagnosis and prognosis. The anti-hTR complementary to the template region of hTR is sufficient to inhibit P3 cell telomerase activity and cell proliferation in vitro, and can lead to a profound induction of programmed cell death. AIM: To directly investigate the relationship betweentelomerase activity and its subunit expression and the inhibitory effect of antisense hTR on pancreatic carcinogenesis. METHODS: We examined the telomerase activity and itssubunit expression by cell culture, polymerase chain reaction (PCR), PCR-silver staining, PCR ELISA, DNA sequencing, MTT and flow cytometry methods .RESULTS: PCR-silver staining and PCR-ELISA methods had the same specificity and sensitivity as the TRAP method. Tectomerase activity was detected in the extract of the 10 ~ (th) th) and 30 ~ (th) passages of P3 cells, while it was absent infibroblasts. Future plus, after the 30th generation, the prololiferation period of fibroblast cells were significantlyproliated.Telomerase activity and hTERT mRNA weredetected in two pancreatic carcinoma cell lines., but werefound to be negative in human fibroblast cells.Telomerase activity and hTERT mRNA were tested in pancreaticcarcinoma specimens of 24 cases. telomerase activity was positive in 21 of the 24 cases (87.5%), and the hTERT mRNA in 20 cases (83.3%). In the adjacent normal mice both positive rates were both 12.5%. There was asignificant difference between the two groups. This induced a significant correlation between the expression level of telomerase activity and histologic differentiation, metastasis and advanced clinical stage of pancreaticcarcinoma. Our findings showed that the expressions of hTR and TPl mRNA were not correlated with the activity oftelomerase but the expression of hTERT mRNA was. Aftertreatment with PS-ODNs, telomerase activity in P_3 cellsweakened and the inhibiting effect caused enhanced withan increase in PS-ODNs concentration. There was asignificant difference between different PS-ODN groups (P <0.05). Inhibition of telomerase activity occurred most with differential PS-ODN1. The results of the FCM test of pancreatic cancer P_3 cells showed an increase in the apoptotic rate with increasing PS-ODN1 and PS-ODN2 concentrations. CONCLUSION: The expression of telomerase activity hasA strong correlation exists between telomerase activity and hTERT mRNA expression. The up-regulation of hTERT mRNA expression may play a critical role in human carcinogenesis. The expression of telomerase activity and its subunit level in pancreatic carcinoma significant correlate with the clinical stage of pancreatic carcinoma and hence, may be helpful in its diagnosis and prognosis. The anti-hTR complementary to the template region of hTR is sufficient to inhibit P3 cell telomerase activity and cell proliferation in vitro, and can lead to a profound induction of programmed cell death.