Telomerase activity in diagnosis of bladder cancer

Telomerase is an enzyme that can reconstitute the ends of chromosomes after cell division and thus circumvent the damage that occurs in normal adult somatic cells during successive mitotic cycles. Immortal cells have short but stable chromosomes and increased telomerase activity. Transitional cell carcinoma (TCC) has only a few useful markers of diagnostic or prognostic importance. The objectives of this study were to determine whether there was a correlation between telomerase activities and the grade or stage of TCC and whether the activity of the enzyme could serve as a biochemical marker of this tumor.

Telomerase activity was determined by examining, using a polymerase chain reaction-based assay designed using the telomeric repeat amplification protocol (TRAP), urine cell pellets obtained from 42 bladder cancer patients, 18 patients with primary hematuria, 19 patients with benign urologic disease, 14 patients with urologic malignancies other than TCC and 20 healthy volunteers.

Telomerase activity was found in 24/31 patients with bladder tumors (77.4% sensitivity) and in 5/77 patients without tumors (93.5% specificity). No correlation was found between telomerase activity and the grade or stage of the tumor. Although none of the urine cell pellets obtained from the 20 healthy volunteers demonstrated telomerase activity, positive telomerase activity was found in two subjects in the benign urologic disease group and in three subjects in the other urologic malignancy group. It was demonstrated that gross hematuria was the cause of false-negative results in six of the nine patients (66.7%). but washing the pellets four times and diluting them before the TRAP assay solved this problem.

These results indicate that telomerase activity may be a promising marker for TCC but the technical aspects of the technique must be improved before it is used in routine clinical practice as a standard method. False-negative results obtained using gross hematuric urine should be carefully reevaluated and cell pellets should be washed again and diluted before analysis.