Survivin protein expression positively correlated with proliferative activity of cancer cells in bladder cancer

CONTEXT: Survivin is an inhibitor of apoptosis that is selectively over-expressed in common human cancers, but not in normal tissues, and that correlates with aggressive disease and unfavorable outcomes. AIMS: To identify the role of survivin in bladder carcinogenesis and the correlation between survivin protein expression and the occurrence of spontaneous apoptosis, proliferative activity of cancer cells. SETTINGS AND DESIGN: Retrospective analysis. METHODS AND MATERIAL: Bladder transitional cell cancer (BTCC) tissue samples for 128 patients were investigated, with normal bladder tissues serving as controls. From these tumor samples, 42 (32.8%) were grade I, 59 (46.1%) were grade II, and 27 (21.1%) were grade III; 72 (56.2%) were superficial, 56 (43.8%) were invasive. The survivin protein level was quantified by Western blot analysis. The apoptotic index (AI) using in situ labeling apoptotic DNA fragment kit and the Ki-67 labeling index (Ki-67LI) with an anti-Ki-67 monoclonal antibody were analyzed in these tumors, respectively. STATISTICAL ANALYSIS USED: Differences in the S/beta ratio between tumor grade and stage were evaluated by using unpaired t-test and F-test. The relationships between the S/beta ratios and AIs, Ki-67LIs of tumors were evaluated by Pearson correlation coefficient. RESULTS: High survivin levels were detected by Western blot analysis in tumor tissue extracts. None of the expression of survivin protein was found in normal bladder tissues. Survivin levels were significantly different from different clinical stages and pathological grades of the tumors (P > 0.05, respectively). Spearman rank correlation test revealed a positively correlation between survivin protein level and the proliferative activity (P < 0.001) and failed to find significant correlation between AI and survivin protein level (P > 0.05). CONCLUSIONS: Survivin protein expression played an important role in the malignant progression of BTCC.