Telomerase activity and human telomerase reverse transcriptase mRNA expression in soft tissue tumors: Correlation with grade, histology, and proliferative activity

Telomerase activity (TA) is detected in most human cancers but, with few ex ceptions, not in normal somatic cells. Little is known about TA in soft tis sue tumors. We have examined a series of benign and malignant soft tissue t umors for TA using the telomerase repeat amplification protocol assay. Anal ysis of the expression of the human telomerase reverse transcriptase was al so carried out using RT-PCR, TA was undetectable in benign lesions (15 of 1 5) and low-grade sarcomas (6 of 6) and was detectable in 50% (19 of 38) of intermediate-/high-grade sarcomas, Although the presence of TA in soft tiss ue tumors is synonymous with malignancy, it is neither a reliable method in making the distinction between reactive/benign and malignant (especially l ow-grade) lesions nor a reliable marker of tumor aggressiveness. Leiomyosar comas and storiform/pleomorphic malignant fibrous histiocytomas rarely show ed TA, irrespective of their grade. A strong correlation between human telo merase reverse transcriptase mRNA expression and TA was observed, supportin g the close relationship between both parameters. No significant relationsh ip was observed between proliferative activity (as assessed by MIB-1 immuno labeling) and TA. We verified that the absence of telomerase expression was not due to the presence of telomerase inhibitors and therefore alternative mechanism(s) for cell immortalization, yet to be determined, seem to be in volved in the development and/or maintenance of some soft tissue sarcomas.