CYCLIN D1 PROTEIN OVEREXPRESSION IS RELATED TO TUMOR DIFFERENTIATION,BUT NOT TO TUMOR PROGRESSION OR PROLIFERATIVE ACTIVITY, IN TRANSITIONAL-CELL CARCINOMA OF THE BLADDER

Purpose: We attempted to clarify the significance of cyclin D1 in the development and progression of transitional cell carcinoma of the blad der in humans. Materials and Methods: Immunohistochemical staining of archival tissue specimens of transitional cell bladder carcinoma obtai ned from 163 patients was performed by the labeled streptavidin-biotin -peroxidase method. Results: Cyclin D1 protein overexpression was obse rved in 51 of the 163 specimens (31.3%), Cyclin D1 protein overexpress ion was showed a highly significant inverse correlation with the histo logical grade of malignancy (p <0.01). Grade 3 tumors showed a highly significant low incidence of cyclin D1 protein overexpression as compa red with grade 2 tumors (p <0.01). There was no significant correlatio n between the overexpression of cyclin D1 protein and tumor stage or t he Ki-67 labeling index. Conclusion: Cyclin D1 in transitional cell bl adder carcinoma was closely related to tumor differentiation but not t o tumor progression. Transitional cell carcinoma of the bladder may ut ilize another pathway for proliferation that is independent of cyclin D1.