Telomerase activity in benign and malignant cytologic fluids

BACKGROUND: Telomerase is a ribonucleoprotein that maintains telomeric base pair repeats at the ends of mammalian chromosomes during DNA replication. Telomerase is expressed in various human tumors, some normal tissues, and immortalized cell lines. The assay of telomerase activity has potential as an adjunct for cancer detection in cytologic fluids. METHODS: Twenty-four unfixed cytologic fluids, including 13 ascitic fluids, 7 pleural fluids, 3 pelvic washings, and 1 bronchial washing, were prepared for polymerase chain reaction (PCR)-based telomeric repeat amplification protocol (Oncor, Inc., Gaithersburg, MD). Telomerase activity was determined by PCR. The presence of a ladder of products with 6 base pair increments, separated by polyacrylamide gel electrophoresis and detected by phosphoimaging, was considered a positive result. Results were compared with cytologic evaluation of alcohol fixed, Papanicolaou stained smears. RESULTS: Of the 14 cytologically malignant specimens, 11 (79%) contained detectable telomerase activity. Two cytologically malignant samples could not be evaluated for telomerase activity due to the presence of inhibitory substances of PCR reaction. Of the 10 cytologically negative specimens, 1 (10%) was positive for telomerase activity; this specimen was from a patient with history of both endometrial and lung carcinomas. CONCLUSIONS: Telomerase activity can be detected in malignant cytologic specimens and thus has potential as a diagnostic adjunct in cytopathology.