Expression of transcription factors snail, slug, and twist in human bladder carcinoma

Abstract

Background: Slug, snail, and twist are transcription factors that regulate the expression of tumor suppressors such as E-cadherin. In this study, we aimed to examine the expression of these transcription factors in human bladder carcinoma.

Methods: We first investigated expression of slug, snail, twist and E-cadherin in five bladder Carcinoma cell lines by reverse transcription-polymerase chain reaction and western blotting. Furthermore, we investigated slug, snail, and twist and E-cadherin expression by immunohistochemistry with bladder carcinoma (tumor, n = 120; background, n = 42).

Results: Expression of slug mRNA and protein was detected in all cell lines, twist was clearly expressed in two out of five bladder carcinoma cell lines, snail was not expressed, and E-cadherin was detected in 3 cell lines. 44.2% (53/120) of human bladder carcinoma tissues and 38% (16/42) background tissue showed an expression of twist; 62.5% (75/120) of human bladder carcinoma tissues and 40% (17/42) background tissue showed an expression of slug, 15.8% (19/120) of human bladder carcinoma tissues and 76% (32/42) background tissue showed an expression of snail, and 25.8% (31/120) cases were negative for E-cadherin expression in carcinoma tissues. Expression of slug and twist shows increased levels in tumors, whereas snail seems reduced. Statistically significant correlations were found between twist, slug, and E-cadherin expression. Immunohistochemistry analysis showed that twist was elevated with increasing tumor stage (P = 0.001), the grade (P < 0.001), the progression (P = 0.035). Slug was elevated and snail was reduced with increasing nodal involvement (tumor-node-metastasis status) (P = 0.004, P = 0.01). E-cadherin was reduced in expression corresponding with tumor grade (P < 0.01). Positive twist, slug and E-cadherin expression clearly predicted poorer PFS (P = 0.042, P = 0.014, P = 0.001). In the multivariate analysis, only snail and E-cadherin expression were independent prognostic factors for OS (P = 0.002, P < 0.001).

Conclusions: These data demonstrate that twist, snail and slug have inappropriate expression in bladder carcinoma and that this may play a part in the progression of human bladder carcinoma.

Figure 1

Expression of Snail, Slug and Twist in five bladder cancer cell lines T24, HTB-1, HTB-2, HTB-3 and HTB-9. The analysis of the relative mRNA and protein intensity of Slug, Snail and Twist compared with E-cadherin showed that bladder cancer cells with a high Slug and Twist expression had no or only low E-cadherin expression. In contrast, cells with low Slug and Twist expression had high expression levels of E-cadherin.

Figure 2

Expression of Slug, Twist, Snail and E-cadherin in human bladder cancer and bankground tissue was determined by immunohistochemistry. Staining of Snail(A), Slug(B), and Twist(C) was found in the cytoplasm as well as in the nucleus of tumor cells. Magnification, ×200. E-cadherin (D)expression was identified in the cell membrane and intensive in the cytoplasm. Magnification, ×200. No expression of Slug in bankground tissue(E), strong of Twist and Snail expression in bankground tissue (F-G).