Decrease of Telomere Length in Thyroid Adenomas without Telomerase Activity

In somatic cells, telomeres shorten with population doubling, thus limiting their capacity to divide. Telomerase, which synthesizes telomeric repeats, can compensate for such shortening. Telomerase activity is known to be absent from most somatic differentiated cells but is present in germline cells, immortal cell lines, or a large majority of malignant tumors. Autonomous thyroid adenomas are benign tumors composed of highly differentiated cells characterized by TSH-independent function and growth. Telomere length and telomerase activity were measured in autonomous and hypofunctioning adenomas and their surrounding tissues. A significant decrease of 3.8 ± 1.0 kilobases (kb) was observed in the length of the terminal restriction fragments (TRF) in 12 autonomous adenomas (8.6 ± 1.1 kb), compared with the TRF length of their surrounding tissues (12.4 ± 1.6 kb). The same kind of decrease, 3.5 ± 1.2 kb, was also observed in 16 hypofunctioning adenomas (12.3 ± 1.7 kb in surrounding tissue and 8.8 ± 1.6 kb in th...