Demonstration of human telomerase reverse transcriptase (hTERT) in human parathyroid tumours by in situ hybridization with a new oligonucleotide probe

BACKGROUND AND OBJECTIVE Telomerase activity is present in most malignant tumours and might provide a mechanism for unlimited replication of neoplastic cells. Expression of the gene encoding human telomerase reverse transcriptase (hTERT), the telomerase catalytic subunit gene, is associated with telomerase activity, and it is overexpressed in most parathyroid carcinomas. We have therefore studied hTERT expression in parathyroid tumours. METHODS In the present study, we assayed telomerase activity by the telomeric repeat amplification protocol (TRAP) and used in situ hybridization (ISH) to study hTERT mRNA expression in four parathyroid metastatic cancers, six adenomas and two parathyroid hyperplasia tissue specimens. RESULTS Telomerase activity was detected by the TRAP assay in all of the parathyroid cancers (100%) but in none of the eight parathyroid benign lesions. hTERT gene expression was detected in the nuclei of the parathyroid cancer cells in all of the lesions (100%) but in none of the eight parathyroid benign lesions. CONCLUSIONS Our results demonstrate a correlation between telomerase activity and hTERT gene expression measured by ISH (P < 0.001) in parathyroid tumours. We succeeded in very clearly and sensitively demonstrating hTERT mRNA in parathyroid tissues by using a new probe.