Expression-patterns of the RNA component (hTR)and the catalytic subunit (hTERT) of human telomerase in nonneoplastic prostate tissue, prostatic intraepithelial neoplasia, and prostate cancer

Background Telomerase, a ribonucleoprotein, is composed of a RNA component (hTR) and two protein subunits. One of these subunits, the catalytic subunit (human telomerase reverse transcriptase, hTERT), represents a reverse transcriptase. hTERT‐expression is closely correlated with telomerase activity. The telomerase is thought to be involved in immortalization process. By adding hexamic repeats to the end of chromosomal DNA, the telomeres, the enzyme is able to stop progresssive telomeric DNA loss that occurs during cell division due to the end replication problem that stops the mitotic clock. Methods Expression‐patterns of hTR using radioactive in situ hybridization with 35S‐labelled RNA probes were compared with immunhistochemical staining for hTERT in 14 cases of archival paraffin‐embedded samples of normal prostatic tissue, high‐grade prostatic intraepithelial neoplasia (PIN), prostatic cancer, and one atypical adenomatous hyperplasia (AAH). Beside the expression‐patterns each telomerase component was evaluated semiquantitatively. Results hTERT and hTR can be found in nonneoplstic tissue and are upregulated in premalignant transformated lesions. AAH showed no hTERT‐expression and low hTR‐expression. There is a heterogenous expression within prostatic carcinomas. Conclusions No association was observed between the grade of the tumour differentiation and semiquantitative levels of hTR‐ or hTERT‐expression. Telomerase is of limited value for the diagnostic of malignant or benign lesions in prostate. Prostate 55: 99–104, 2003. © 2003 Wiley‐Liss, Inc.