Telomerase activity in human urothelial tumors.

Telomerase is a ribonucleoprotein that synthesizes telomeric DNA onto chromosomal ends by using an RNA component as a template. Telomerase extends the telomeric repeats, which prevents telomere shortening during cell division, contributes to chromosomal stability, and, possibly, leads to immortalization of the cells. The telomerase activity in 22 urothelial tumors, including 13 bladder cancers, 8 ureter cancers, and 1 renal pelvic cancer, as well as in 12 adjacent normal tissues, was examined with the use of a nonradioisotope polymerase chain reaction (PCR)-based telomeric repeat amplification protocol assay. Different levels of telomerase activity were detected in the urothelial tumors. No significant activity was observed in normal adjacent tissues; however, two cases exhibited weak activity. Nine tumors retained positive telomerase signals after 100-fold dilution of extracts, which suggests that these tumors express high levels of telomerase activity. These findings indicate that telomerase activation may be a critical step in the pathogenesis of urothelial tumors. Unexpectedly, no significant correlation was observed between high levels of telomerase expression and the clinicopathologic features of the tumors, including clinical stage, pathologic grade, tumor multiplicity, and status of recurrence.