Human telomerase reverse transcriptase (hTERT) gene expression in thyroid neoplasms

Ten percent of fine-needle aspirations (FNAs) of the thyroid are deemed "in determinate" or "suspicious" for malignancy by the cytopathologist, but mos t of these lesions are benign. Therefore, additional markers of malignancy may prove to be a useful adjunct. The catalytic component of telomerase, human telomerase reverse transcripta se (hTERT), has been found to be reactivated in immortalized cell lines. Re verse transcription-PCR of the hTERT gene revealed expression in 15 (79%) o f 19 malignant thyroid neoplasms, including 6 of 6 follicular carcinomas an d 9 of 13 papillary carcinomas, In contrast, hTERT gene expression was dete cted in only 5 (28%) of 18 benign thyroid nodules, including 2 of 7 follicu lar adenomas and 3 of 11 hyperplastic nodules, All five benign thyroids exh ibiting hTERT gene expression had lymphocytic thyroiditis. No normal thyroi ds exhibited hTERT gene expression. Telomerase enzyme activity was examined in all 37 nodules and was found to correlate with hTERT gene expression in 35 (95%) nodules, The two cases in which telomerase activity and hTERT exp ression results were discrepant were in two papillary carcinomas that were telomerase activity negative and hTERT positive. Finally, we have demonstra ted that hTERT gene expression can be measured in in vivo FNA samples. Thes e results suggest that hTERT expression may be more accurate than telomeras e activity in distinguishing benign from malignant and may be measured in F NA samples from suspicious thyroid lesions.