ABSTRACT
PURPOSE: We studied the apoptotic index in prostate cancer tissues and investigated the relationship of apoptosis and clusterin expression. MATERIALS AND METHODS: Forty-two archival prostatectomy specimens of varying grades of prostate cancer and 10 of benign prostatic hyperplasia were subjected to immunohistochemical clusterin staining with anti- clusterin antibody. Staining intensities were classified from 0 to 3. Apoptotic index was calculated with TUNEL positive cells under fluorescence microscope. We performed double staining for clusterin and TUNEL using immunofluorescence technique to determine the relationship between apoptosis and clusterin expression. RESULTS: Immunohistochemistry of clusterin showed a weak intensity in all benign tissues. Clusterin was localized mainly in the epithelial cells. Staining intensity was increased according to Gleason grade of cancer. Apoptotic indices of cancer were 0.86+/-0.8%, 0.76+/-1.0%, 0.39+/-0.4% and 0.14+/-0.09% in grades 2, 3, 4 and 5, respectively. In immunofluorescence localization study, apoptosis was not detected in the cancer cells stained with clusterin. Conversely, clusterin was not expressed in the cells showing apoptosis. CONCLUSIONS: These results more clearly show that clusterin acts as a survival protein protecting from apoptosis in prostate cancer. In addition, our findings revealed that the apoptotic index is lower in high grade prostate cancer. These findings have significant clinical implications for identifying the value of apoptotic index and clusterin expression in prostate cancer. Further study is needed to define the role of clusterin in the development and progression of prostate cancer.