Purpose: We attempted to clarify the significance of cyclin D1 in the development and progression of transitional cell carcinoma of the bladder in humans.
Materials and methods: Immunohistochemical staining of archival tissue specimens of transitional cell bladder carcinoma obtained from 163 patients was performed by the labeled streptavidin-biotin-peroxidase method.
Results: Cyclin D1 protein overexpression was observed in 51 of the 163 specimens (31.3%). Cyclin D1 protein overexpression was showed a highly significant inverse correlation with the histological grade of malignancy (p < 0.01). Grade 3 tumors showed a highly significant low incidence of cyclin D1 protein overexpression as compared with grade 2 tumors (p < 0.01). There was no significant correlation between the overexpression of cyclin D1 protein and tumor stage or the Ki-67 labeling index.
Conclusion: Cyclin D1 in transitional cell bladder carcinoma was closely related to tumor differentiation but not to tumor progression. Transitional cell carcinoma of the bladder may utilize another pathway for proliferation that is independent of cyclin D1.