ABSTRACT
PURPOSE: The clusterin expression has been associated with tumorigenesis of various malignancies, including tumors of the prostate, colon and breast. Furthermore, the expression of clusterin is modulated by many factors that are believed to regulate tumor growth and apoptosis. We studied the clusterin expression in transitional cell carcinoma (TCC) of the bladder and we investigated its correlation with apoptosis. MATERIALS AND METHODS: Eighty five bladder tumor specimens from radical cystectomy or transurethral resection were subjected to immunohistochemical clusterin staining with Ig G clusterin Ab. We examined the immunohistochemical localization of clusterin, and this was followed by TUNEL staining to detect the apoptotic cells. After double-staining with Hoechst 33258, we detected the apoptotic cells under a fluorescence microscope and we calculated the apoptotic index. RESULTS: Invasive TCC showed a stronger positive expression of clusterin as compared with superficial TCC, but the positivity of the clusterin expression was not in proportion to the tumor grade. The apoptotic indices of cancer were 0.52+/-0.28%, 0.30+/-0.16% and 0.17+/-0.11% in Grade I, Grade II and Grade III superficial TCC, respectively, and it was 0.23+/-0.13% in Grade III invasive TCC. Apoptotic cells were not detected in the cancer cells stained with clusterin. Conversely, clusterin was not expressed in the cells showing apoptosis. CONCLUSIONS: These results suggest that clusterin could be used as a marker to provide prognostic information for the TCC patients. The apoptotic index revealed that apoptosis and the clusterin expression have correlation with transitional cell cancer. Further study will be needed to clarify the role of clusterin as a therapeutic target for cancer treatment.