Expression of the RNA component of human telemorase (hTR) in ThinPrep® preparations from bladder washings

BACKGROUND. The enzyme telomerase is associated with cellular immortality and is expressed in the vast majority of human neoplasms. The expression of the RNA component of human telomerase (hTR) shows excellent concordance with enzyme activity. METHODS. In this study, hTR expression was analyzed in a series of 18 perioperative bladder washings and compared with histologic diagnoses from material obtained in the same setting. The hTR expression analysis used an ³⁵S-based in-situ hybridization assay. ThinPrep® preparations fixed in PreservCyt® solution (Cytyc Corporation, Boxborough, MA) were hybridized with sense and antisense hTR probes. A 1-4+ grading scheme was used, with appropriate positive and negative controls. RESULTS. Five of six (83%) lesions with benign histology had hTR expression that was 2+ or less in the exfoliated urothelial cells. In contrast, 11 of 12 (93%) lesions with malignant histology had an hTR expression that was focally 3+ or more, with 7 of 12 (58%) lesions having 4+ hTR expression in at least some urothelial clusters. Although increased hTR expression was present in smears with malignant urothelial cells, a similar trend was not seen with muscularis propria invasion or higher grades of TCC on subsequent histology. CONCLUSIONS. The use of in situ hybridization technique bypasses the need for stringent specimen processing and allows identification of the specific cell type that expresses telomerase