Expression of p27Kip1 Protein in Carcinoma of the Urinary Bladder

Kim, Ki Kwon; Kim, Jung Ran

Abstract

The cyclin-dependent kinase (cdk) inhibitor p27Kip1 gene is a powerful molecular determinant of cell cycle progression. Loss of expression of p27Kip1 has recently been shown to be predictive of disease progression in several human malignancies. The prognostic value and expression of p27Kip1 have been incompletely studied in bladder cancer. In this study, we investigated the relationship between p27Kip1 protein expression and clinicopathologic parameters in 50 cases of carcinoma of the urinary bladder by conducting immunohistochemical analysis and DNA flow-cytometry. Malignant bladder tissue demonstrated a heterogeneous pattern of p27Kip1 immunoreactivity. In addition, there was progressive loss of expression with increasing tumor grade. The expression of p27Kip1 protein was unrelated to stage, DNA ploidy and S phase fraction (SPF). SPF was unrelated with tumor grade and DNA ploidy. The results indicate that p27Kip1 is frequently expressed in well differentiated transitional cell carcinomas of the urinary bladder but less often expressed in muscle-invasive transitional cell carcinomas. The expression of p27Kip1 and its prevalence in low-grade tumors may reflect growth regulatory influences and potential inhibiting action in tumor progression and novel predictive markers of the biological potential of bladder tumors.