Kana Ogisawa², Tetsuro Ishikawa², Chiemi Takenaka^{1, 2}, Hideki Tahara³, Masaaki Inaba³, Tsutomu Takashima² and Kosei Hirakawa²

(1)           Department of Oncology, Institute of Geriatrics and Medical Science, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585, Japan

 (2)          Department of Surgical Oncology, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585, Japan

(3)           Department of Endocrinology, Metabolism and Molecular Medicine, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585, Japan

Received: 10 April 2003  Accepted: 09 September 2003  

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.

Key words  Parathyroid adenoma - Parathyroid cancer - Primary parathyroidism - Telomerase - Human telomerase reverse transcriptase

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