Telomerase activity in bladder carcinoma and its implication for noninvasive diagnosis by detection of exfoliated cancer cells in urine

BACKGROUND: Telomerase is an enzyme that can reconstitute the ends (telomeres) of chromosomes after cell division and thus circumvent the cumulative damage that occurs in normal adult somatic cells during successive mitotic cycles. Recently, it has been proposed that this enzyme should, therefore, be detectable in immortal malignant cells but not in their normal counterparts, which stop dividing and senesce. Accordingly, telomerase activity has been reported in many types of malignant tumors, including those of the gastrointestinal tract, breast, and lung but little information was available regarding its status in bladder carcinoma or in exfoliated cancer cells. METHODS: In the current study, telomerase activity was examined by a polymerase chain reaction-based assay designated TRAP (telomeric repeat amplification protocol) in tissue samples from 56 bladder carcinomas, 17 nonneoplastic bladder lesions, and 2 dysplastic lesions of the urinary tract. The feasibility of identifying cancer patients by the detection of telomerase activity in exfoliated cancer cells in the urine was also investigated. Such activity was assayed in centrifuged urine cell pellets from 26 bladder carcinoma patients and from 83 patients with no evidence of malignant disease. RESULTS: Evidence of telomerase was detected in solid tissue specimens from 48 of the 56 bladder carcinomas (86%) regardless of tumor stage or differentiation, whereas it was not found in any normal bladder tissue specimen. However, it was present in the dysplastic bladder lesions as well as in nearly all Stage I well differentiated carcinomas, suggesting that its activation occurs for the early stages of carcinogenesis and could perhaps be a useful marker for the detection of early primary or recurrent bladder tumors. Telomerase activity was detected with various signal intensities in urine specimens from 16 of the 26 patients with bladder carcinoma (62% sensitivity), whereas only 3 of 83 nonmalignant urine samples showed any activity (96.4% specificity); this was very weak. CONCLUSIONS: These results suggest that telomerase could be a good diagnostic marker for the early noninvasive identification of patients with bladder carcinoma by facilitating the detection of exfoliated immortal cancer cells in their urine.