Telomerase activity is significantly enhanced in malignant adrenocortical tumors in comparison to benign adrenocortical adenomas

Telomerase is an enzyme that causes short repeated sequence addition to the ends of chromosomes, thereby preventing their shortening during cell divis ion and counteracting cell senescence. Telomerase activity is generally abs ent in adult differentiated cells, whereas it has been demonstrated in tumo r cells, suggesting that its presence might be considered an index of malig nancy. To evaluate whether telomerase might be considered a good predictive index of malignancy in adrenocortical tumors, we measured telomerase activ ity in 11 adrenal adenomas and 7 carcinomas obtained at surgery, using an o riginal quantitative method. Telomerase activity was significantly higher ( P < 0.001) in carcinomas than in adenomas (median, 15.2 ng DNA/mu g protein ; range, 9.0 -27.6 vs. 2.0; range, 0 -8.3), and no overlap was observed bet ween the 2 groups. In carcinomas, telomerase activity was significantly cor related with tumor diameter (r = 0.939; P < 0.0001), whereas in adenomas it was not. The results of this study suggest that quantitative telomerase me asurement may represent a useful tool to differentiate malignant from benig n adrenocortical tumors.