| The telomere is a special structure at the end of human chromosomes, which consist of long tandem arrays of TTAGGG repeats and DNA-binding proteins. In most human somatic tissues, telomeric DNA shortens 50-200 bp after each cell cycle, until critically shortened telomeres act as a signal for replicative senescence. Telomerase is ribonucleoprotein enzymes that synthesize telomeric repeats while telomerase RNA component acts as a template. Telomerase is highly active in most malignant tumors and leukemia, whereas telomerase activity is suppressed in somatic cells. Thus, hTERT may play an important role in cellular senescence and carcinogenesis. However, the mechanism of telomerase activation is unclear.The first telomere binding protein Telomere Repeat Binding Factor (TRF1) was reported in 1995 by Chong's group. Two-hybrid screens using the TRF1 as bait have identified a number of TRF-interacting proteins. Tankyrase(TRF1-interacting, ankyrin-related ADP- ribose polymerase), a 142-kDa protein, with homology to ankyrins and to the catalytic domain of PARPs, was identified as a important component of human telomeric complex.TANK is encoded by a gene (TNKS) on human chromosome 8. Tankyrase contains three domains: 24 ankyrin repeats domain, PARP catalytic domains and asterile alpha module (SAM). Tankyrase binds TRF1 via its ankyrin repeats domain and poly(ADP-ribosyl)ates it and release TRF1 from telomeres. Thus Tankyrase might be a positive regulator of telomerase.Now some studies on the relationship of TRF1 and malignant tumors have obtained. And found TRF1 expression down regulated in gastrointestinal tumors, brain tumors, breast tumors and acute leukemia. And has significantly negative correlation with hTERT expression. But there are few studies on relationship of Tankyrase and tumors. Matsutani's group has found expression of Tankyrase mRNA was higher in gastrointestinal tumors.However, Yamada's group reported it was lower in gastric tumors. No relation on Tankyrase and tumors was reported domestically.In this study, expressions of Tankyrase mRNA and Tankyrase protein were detected and relations of Tankyrase mRNA expression of telomerase reverse transcnptase (hTERT) mRNA were analyzed in order to indicate the possible mechanism of Tankyrase's effects on telomerase in gastric adenocarcinomas.This paper was divided into three parts.Part â… : Construct Tankyrase and hTERT expression plasmid and establish fluorescence quantitative PCR methods for detecting Tankyrase mRNA and hTERT mRNA.Part â…¡: Real-time quantitative RT-PCR with fluorescence probe hybridization was used to detect the expression of Tankyrase mRNA in cancerous and normal adjacent tissues from 16 patients with gastric adenocarcinomas analyze their relation with hTERT mRNA expressions.There were 9males and 7 females with an average age of 55 years.The expression of Tankyrase mRNA in gastric adenocarcinoma(1.44×10-2, 3.88×10-5 0.4847 ) is significantly higher than that in normal adjacent mucosa(1.0134×10-2 04.933×10-2) (P<0.05) . And its expression is no connection to different TNM stages, different dimension of tumors , differentinfiltration and lymph node metastasis (P>0.05).The expression of hTERT mRNA in gastric adenocarcinomas(1.235×10-4, 0 1.33) is also significantly higher than that in normal adjacent mucosa(0 ,0 4.38×10-5) (P<0.01) . But no significant differences were seen between different TNM stages, different dimension of tumors , different infiltration and lymph node metastasis ( P>0.05).The expression of Tankyrase mRNA in gastric adenocarcinoma samples has significant positive correlation with hTERTmRNA expression (r=0.553, P<0.05 ) .Part â…¢: In order to analyse the Tankyrase protein between different TNM stages and different pathological grades, immunohistochemistry was used to detect Tankyrase expressions in 37 gastric adenocarcinoma samples.There were 33 males and 4 females with an average age of 56 years.The expression level of Tankyrase in gastric adenocarcinomas is also significantly higher than that in normal con...
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