Abstracts
2000 Digestive Disease Week

# 2250 Telomerase Activity in Barrett’s Esophagus and Esophageal Adenocarcinoma.
Mark S. Diamond, Ziad Younes, Petra H. Nass, Tsung-Tseh Wu, Parviz Nikoomanesh, Mark D. Duncan, Michael D. Crowell, John W. Harmon, Baltimore, MD, Princeton, NJ

Telomerase activity has been detected in the majority of cancer types. There is limited information regarding telomerase activity in either esophageal cancer or the premalignant Barrett’s metaplasia or dysplasia. Aims: To compare telomerase activity in tissue samples from the esophagus of 10 controls, 18 patients with Barrett’s esophagus (9 without dysplasia and 9 with high-grade dysplasia), and 15 patients with esophageal adenocarcinoma. Methods: Telomerase activity was measured using a semiquantitative PCR/ELISA assay (TRAPezeTM, Invitrogen). Protein extracts were incubated in a reaction mix where active telomerase containing samples extended a biotinylated template. The extended products were then amplified via PCR using DNP labeled primers. In a final ELISA step, the PCR products were bound to a streptavidin coated microtiter plate and visualized using a horseradish-peroxidase conjugated anti-DNP antibody. Absorbance was measured at l=450 and mean absorbance values were obtained by subtracting the adjusted (A450 - A630)values from a heat inactivated control. Absorbance values higher than 0.15 were considered positive for telomerase activity. Results: 30% of the controls, 67% of Barrett’s metaplasia (7/9 non-dysplastic, 5/9 dysplasia), and 67% of adenocarcinoma tested positive for telomerase activity. An semi-quantitative analysis of the absorbance values revealed no differences between Barrett’s metaplasia, dysplasia, and adenocarcinoma. The mean values in controls were lower than Barrett’s and adenocarcinoma with p values of 0.035 and 0.085 respectively. Conclusions: We conclude that telomerase activity is induced in patients with Barrett’s metaplasia and esophageal adenocarcinoma. The similarity in activity in non-dysplastic Barrett’s and adenocarcinoma suggests that telomerase is involved early in esophageal carcinogenesis. The positivity of telomerase activity in some control samples may limit the clinical usefulness of this assay as a tumor marker in esophageal carcinogenesis.