Correlation between morphology and telomerase activity in cells from exfoliative lung cytologic specimens

BACKGROUND. Telomerase is a ribonucleoprotein that compensates for the eros ion of telomeres (chromosomal termini). Telomerase activity is detected in more than 85% of cancerous lesions and is therefore considered a novel mark er of cancer. The authors compared cytologic morphology and telomerase acti vity at the cellular level to obtain further insight into their association . METHODS. The authors used bronchial washing and brushing materials obtained from 18 patients with lung carcinomas (6 squamous cell, 8 adenocarcinoma, 2 large cell, 1 small cell, and 1 metastasis from colon carcinoma) and 20 p atients with nonmalignant disease. An in situ telomeric repeat amplificatio n protocol (TRAP) assay was performed, and routine Papanicolaou-stained sli des using the same sample were assessed. RESULTS. Nuclear fluorescent signals at the nuclear area, corresponding to telomerase activity, shown by the in situ TRAP assay were only detected in samples containing morphologically malignant cells. No nuclear fluorescence was seen in the keratinizing component of well-differentiated squamous cel l carcinoma. Nuclear staining was not seen in metaplastic or basal hyperpla stic cells. Cytoplasmic fluorescence was only found in macrophages and poly morphonuclear leukocytes. CONCLUSIONS. Nuclear fluorescence corresponding to telomerase activity was not demonstrated in metaplastic or basal hyperplastic cells, thus indicatin g that detection of telomerase activity is closely associated with the pres ence of malignant cells, but not premalignant lesions, in lung carcinoma pa tients. Moreover, in some samples with cancer, cells failed to show telomer ase activity, suggesting the limitation of this method for the detection of malignant cells in certain lung carcinoma patients. (C) 2000 American Canc er Society.