Apoptotic cell death and Smad4 expression in transitional cell carcinoma of the renal pelvis and ureter

Prognostic Impact of Canonical TGF-β Signaling in Urothelial Bladder Cancer

Background and objectives: Dysregulation of TGF-β signaling plays multiple roles in cancer development and progression. In the canonical TGF-β pathway, TGF-β regulates the expression of hundreds of target genes via interaction with Smads, signal transducers and transcriptional modulators. We evaluated the association of TGF-β1, Smad2, and Smad4, the key components of canonical TGFβ pathway, with clinicopathologic characteristics of urothelial bladder cancer, and assessed their prognostic value in prediction of patients’ outcome. Materials and Methods: Immunohistochemical analysis of TGF-β1, Smad2, and Smad4 expression was performed on 404 urothelial bladder cancer samples, incorporated in tissue microarrays. Expression status was correlated with clinicopathological and follow-up data. The median follow-up was 61 months. Results: High expression of TGF-β1, Smad2, and Smad4 was detected in 68.1%, 31.7% and 45.2% of the tumors, respectively. TGF-β1 overexpression was significantly associated with high tumor grade, and advanced pathologic stage (p < 0.001, respectively). Conversely, high Smad2 and Smad4 expression was linked to low tumor grade (p = 0,003, p = 0.048, respectively), and low tumor stage (p < 0.001, p = 0.003, respectively). Smad2 showed an inverse correlation with variant morphology and divergent differentiation of urothelial tumors (p = 0.014). High TGF-β1 correlated directly, while Smad2 and Smad4 correlated inversely to cancer-specific death (p = 0.043, p = 0.003, and p = 0.022, respectively). There was a strong relationship between Smad2 and Smad4 expression (p < 0.001). Survival analyses showed that high Smad2 and Smad4 expression was associated with longer overall survival (p = 0.003, p = 0.034, respectively), while in multivariate regression analysis TGF-β1 manifested as an independent predictor of poor outcome. Conclusions: Unraveling the complex roles and significance of TGF-β signaling in urothelial bladder cancer might have important implications for therapy of this disease. Assessment of TGF-β pathway status in patients with urothelial bladder cancer may provide useful prognostic information, and identify patients that could have the most benefit from therapy targeting TGF-β signaling cascade.

Apoptosis in transitional cell carcinoma of bladder and its relation to proliferation and expression of p53 and bcl-2

Transitional cell carcinoma of bladder (TCC) is a relatively common cancer among men. Tumor progression is associated with expression or modulation of several gene products that control apoptosis and proliferation. Apoptosis is a negative growth regulatory mechanism in tumors. The aim of this study is to examine apoptosis and related regulatory molecular markers in a group of patients with TCC. Paraffinembedded tissues from 49 patients with TCC were examined for the expression of bcl-2, p53 and Ki-67 by immunohistochemistry. Apoptosis was detected by TUNEL method. Correlation between apoptotic index (AI), proliferation index (PI) and bcl-2 and p53 expression with each other and with pathological grade was determined. Apoptosis was observed in 28.1% of TCC cases. The mean AI of all cases was 13.7+/-24. No correlation was found between apoptosis and differentiation status of carcinoma. Bcl-2 expression was weakly detected in only one sample. P53 expression was detected in 26 of cases with mean staining index of 102+/-96. A significant correlation between p53 and Ki-67 staining indices was observed (r=0.521, p=0.001). Both p53 and Ki-67 expression showed a good association with the pathological grade (p=0.0001 and p=0.004, respectively). None of the markers showed significant correlation with AI and no correlation was found between the ratio of AI to PI and other parameters either. In conclusion, the frequency of apoptosis in TCC of bladder appears not to be associated with tumor grade, and with bcl-2, p53 and Ki-67 expression.