Expression of β-tubulin isotypes in urothelial carcinoma of the bladder

Purpose: Our study aims to investigate the expressions of β-tubulin isotypes and their significances in urothelial carcinoma of the bladder (UCB) as altered expression of a specific β-tubulin isotype is associated with chemoresistance and poor prognosis in other malignancies. Materials and methods: Expression of β-tubulin isotypes was retrospectively examined in 342 UCB samples obtained from 1995 to 2010 by immunohistochemistry. Results: TUBB1 (307/342, 89.8 %) was most frequently overexpressed in the cytoplasm of UCB cases, followed by TUBB4 (101/342, 29.5 %), TUBB2 (85/342, 24.9 %), and TUBB3 (60/342, 17.5 %). TUBB1 overexpression was associated with older age (p = 0.032), high WHO grade (p = 0.001), and advanced TNM stage (p = 0.006). High levels of TUBB2 expression were associated with high WHO grade (p < 0.001), advanced TNM stage (p < 0.001), and non-papillary growth pattern (p = 0.007). TUBB3 overexpression was related to high WHO grade (p = 0.029). In univariate and multivariate survival analyses, TUBB1 overexpression was associated with poor recurrence-free survival (RFS) rates of all cases (hazard ratio 1.98, p = 0.031) and of the patients with transurethral and/or partial resection (hazard ratio 2.12, p = 0.031). TUBB2 overexpression was correlated with a short RFS of the patients with T2-T4 stages (hazard ratio 3.48, p = 0.007). TUBB3 overexpression was related to a poor RFS of the patients undergoing radical cystectomy (hazard ratio 5.90, p = 0.002). Conclusions: High TUBB1, TUBB2, and TUBB3 expressions are associated with unfavorable clinicopathologic factors and are independent prognostic factors for recurrence-free survival of UCB.