Telomerase activation and expression of its catalytic subunits in benign and malignant tumors of the parathyroid

Purpose. Telomerase activity (TA) has been extensively studied in tumors of many organs, but not the parathyroid gland. Therefore, we investigated TA in parathyroid tumors, and examined the mRNA expression of its catalytic subunits. Methods. We examined 17 single adenomas, one hyperplastic parathyroid gland, and one metastatic parathyroid cancer and quantified TA by fluorescence-based TRAP analysis. We also studied the expression of telomerase catalytic subunits in nine adenomas and one cancer by reverse transcription - polymerase chain reaction (RT-PCR) analysis. Results. Telomerase activity was not detected in any of the adenomas or the hyperplastic gland; however, the metastatic cancer was highly positive for TA. Both human telomerase RNA (hTR) and human telomerase-associated pretein (hTEP-1) mRNA were detected universally in every specimen tested. Conversely, human telomerase reverse transcriptase (hTERT) mRNA was not detected by the conventional electrophoresis-based technique. Faint expression of hTERT mRNA was detected by real-time RT-PCR only in the sample of parathyroid cancer. Discussion. We hypothesize that TA plays a role in the malignant transformation of parathyroid disease and suggest that hTERT mRNA expression could be the key step for TA as in other malignancies. Telomerase activity and hTERT may be useful molecular targets of parathyroid cancer.