Detection of Telomerase Activity in Exfoliated Cells in Urine from Patients with Bladder Cancer

Background: Telomeres are specific structures located at the ends of chromosomes that help maintain chromosome stability. In most tissues, telomeres become shorter as cells divide, a phenomenon thought to be associated with limitations on normal cell proliferation. Almost all types of cancer cells, including bladder cancer cells, express the enzyme telomerase, which can maintain or extend telomere length.

Purpose: We examined telomerase activity in tumor specimens from a cohort of patients with bladder cancer and determined whether telomerase could be detected in exfoliated cancer cells present in urine from these patients.

Methods: Spontaneously voided urine specimens and bladder-washing fluids (obtained by propelling normal saline into the bladder through a catheter and then withdrawing the liquid contents) were taken from 45 patients before they underwent surgery. Telomerase activity was examined by means of the TRAP (telomeric repeat amplification protocol) assay on extracts of tumor samples from 42 patients and extracts of exfoliated cells in urine and bladder-washing fluid from 42 and 43 patients, respectively. Standard cytologic examination (Pap staining) of urine specimens was also used to detect exfoliated cancer cells.

Results: Telomerase activity was found in 41 (98%; 95% confidence interval [CI] = 87%-100%) of the 42 tumor samples examined. In contrast, it was not detected in normal bladder tissue from two autopsied individuals who were free of bladder cancer and five of six individuals who had bladder cancer. Telomerase was detected in exfoliated cells in 23 (55%; 95% CI = 39%-70%) of the 42 spontaneously voided urine specimens and in 36 (84%; 95% CI = 69%-93%) of the 43 bladder-washing fluids examined. Considering voided urine specimens and bladder-washing fluids together, telomerase was detected in exfoliated cells from 40 (89%; 95% CI = 76%-96%) of the 45 patients. Telomerase activity was not detected in bladder-washing fluids from 12 cancer-free individuals. Cancer cells were detected by means of standard cytologic examination in the urine of 19 (42%; 95% CI = 28%-58%) of the 45 patients. Urine cytologic examination detected cancer cells in one (8%; 95% CI = 0%-38%) of 12 patients with grade 1 tumors and in 13 (46%; 95% CI = 28%-66%) of 28 patients with grade 2 tumors. In contrast, telomerase activity was detected in exfoliated cells (in voided urine or bladder-washing fluids) from nine (75%; 95% CI = 43%-95%) of 12 patients with grade 1 tumors and from 27 (96%; 95% CI = 82%-100%) of 28 patients with grade 2 tumors.

Conclusion And Implication: Telomerase activity can be detected in exfoliated cells in urine from patients with bladder cancer, and measurement of this activity appears to be more sensitive in detecting the presence of cancer than standard urine cytologic examination. These findings suggest that measuring telomerase activity in exfoliated cells would be useful in the diagnosis and follow-up of patients with bladder cancer, a possibility that warrants further study.