Expression of Survivin, HSP90, Bcl-2 and Bax Proteins in N-butyl-N-(4-hydroxybutyl)nitrosamine-induced Rat Bladder Carcinogenesis

ABSTRACT

BACKGROUND: Survivin belongs to the inhibitor of apoptosis family, and it has recently been found to be expressed in most solid tumors. Therefore, its expression is suggested to have prognostic significance. However, no data are available concerning the significance of survivin for the carcinogenesis of bladder cancer. METHODS: In order to induce urothelial tumor in the rat urinary bladder, 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) was administered to male Sprague-Dawley rats for 30 weeks. We used immunohistochemistry to investigate the expressions of survivin, HSP90, Bcl-2 and Bax in rat bladder carcinogenesis. RESULTS: Urothelial cell hyperplasia, papilloma, non-invasive urothelial carcinoma and invasive urothelial carcinoma appeared at 5, 10, 20 and 30 weeks, respectively. The expressions of survivin and HSP90 increased sequentially from normal mucosa, hyperplasia, papilloma, non-invasive urothelial carcinoma to invasive urothelial carcinoma. The expressions of Bcl-2 and Bax did not increase, however the number of cases with more than 1 of Bcl-2/Bax expression ratio increased sequentially during the progression of urothelial lesion. The expression of survivin showed a statistically significant correlation with the expression of HSP90 and the Bcl-2/Bax expression ratio. CONCLUSIONS: Our findings suggest that survivin may be involved in the carcinogenesis of rat bladder and its expression is correlated with the expression of HSP90 and the Bcl-2/Bax expression ratio.