Protein Expression and Gene Copy Number Analysis of Topoisomerase 2α, HER2 and P53 in Minimally Invasive Urothelial Carcinoma of the Urinary Bladder - a Multitissue Array Study with Prognostic Implications

Background: Due to their variable clinical course, there is a need for new prognostic parameters in minimally invasive (stage T1) bladder carcinomas. Materials and Methods: Using multitissue arrays, protein expression and gene copy numbers of topoisomerase (TOP2α), HER2 and p53 were investigated by immunohistochemistry and by fluorescence in situ hybridization (FISH) in 73 T1 tumors. The results were compared with tumor recurrence and progression. Results: The median TOP2α and p53 index was 21% (range, 3-59%) and 7% (range, 0-93%), respectively. HER2 overexpression (score 3+) was detected in 9 cases (12%). High TOP2α and p53 indices and HER2 overexpression were significantly associated with earlier tumor recurrence, but not with earlier tumor progression. While TOP2α and p53 gene amplification was detected in no case, 5 cases (8%) showed HER2 gene amplification, which was related to HER2 3+ score in 4 cases. Loss of TOP2α, HER2 and p53 gene was observed in 4 (8%), 8 (13%) and 6 cases (12%), respectively. By univariate analysis, TOP2α index (p=0.0267), HER2 score (p=0.028) and p53 index (p=0.0188) were significantly and loss of TOP2α gene (p=0.0575) tendentially correlated with tumor recurrence, while loss of HER2 gene (p=0.069) and loss of p53 gene (p=0.0587) were tendentially correlated with tumor progression. In a multivariate analysis, which also included tumor grade and T1 substage, TOP2α index (p=0.043) and p53 index (p=0.02) were identified as independent predictors of tumor recurrence and loss of p53 gene (p=0.012) and T1 substage (p=0.029) as independent predictors of tumor progression. Conclusion: Immunohistochemical TOP2α and p53 staining as well as FISH analysis of p53 gene copy numbers and T1 substaging are helpful means of providing additional information on the biological behavior of T1 transitional cell carcinomas.