Objective: To evaluate the diagnostic role of telomerase in benign and malignant lesion of lung and its biological significance in normal lung tissues.
Methods: Tissues studied consisted of 38 specimens of lung cancer, 35 adjacent non-neoplastic tissue and 7 benign parenchymatous lesion. Telomerase activity was determined using a semiquantitative polymerase chain reaction-based telomeric repeat amplification protocol (TRAP) assay. Localization of telomerase reverse transcriptase (hTERT) expression was examined by in situ hybridization and immunohistochemistry.
Results: Telomerase activity was detected in 31 out of 38 lung cancer, 7 of 35 adjacent non-neoplastic lung tissue and 3 of 7 benign parenchymatous lesions (P < 0.001). Both hTERT protein and mRNA were detected in cancer cells, lymphocytes, fibroblasts, macrophages in benign parenchymatous tissue, epithelial cells of small airways, bronchiole, alveoli as well as lymph nodule germinal center of the adjacent normal tissues. There was no significant difference in the expression intensity of hTERT protein among different kinds of cells. There was a tendency that the expression intensity of hTERT protein was higher in squamous carcinoma than those in adenocarcinoma and stronger at TNM stage III with poorly differentiated than those at TNM stage I-II with well-differentiated squamous carcinomas and adenocarcinomas (P > 0.05).
Conclusions: (1) Telomerase is involved in the pathogenesis of both lung cancer and benign parenchymatous lesion. (2) Telomerase expression may be of biological significance in maintaining the normal function of airway epithelial cells, alveolar macrophage and lymphocytes. (3) It is suggested that telomerase might be used as a proliferative marker, rather than a specific malignant marker. False positive response may occur using telomerase as a diagnostic marker.