Cyclin D1 expression in transitional cell carcinoma of the bladder: Correlation with p53, waf1, pRb and Ki67

Normal cell proliferation is closely regulated by proteins called cyclins. One of these, cyclin D1, in combination with its corresponding cyclin-dependent kinase (cdk), is essential for G₁/S phase transition. Cyclin/cdk complexes are generally inhibited by cyclin-dependent kinase inhibitors(ckis), some of which are induced by wild-type p53. The aims of this study were: to investigate levels of cyclin D1 expression in transitional cell carcinoma (TCC) of the bladder; to correlate these results with data concerning the expression of p53, waf1, pRb and Ki67; and to determine whether cyclin D1 expression could predict clinical outcome. Paraffin-sections from 150 newly diagnosed bladder tumours (Ta/T1 = 97; T2-T4 = 53) were stained for cyclin D1 using immunohistochemistry and a cyclin D1 index assigned. These results were correlated with data relating to the expression of p53 and waf1 by the same tumours. A representative subset of 54 tumours (Ta/T1 = 28; T2-T4 = 26) was also stained for Ki67 and 55 were stained for pRb. The clinical course of each patient was recorded and multivariate analyses of risk factors for tumour recurrence, stage progression and overall survival were performed. Positive staining for cyclin D1 was found in 83% of tumours. The staining pattern varied between tumours with nuclear, cytoplasmic or a combination of the two evident in different tumours. 89% of Ta/T1 and 74% of T2-T4 tumours showed nuclear staining with or without cytoplasmic staining. The median value for cyclin D1 staining was significantly higher in Ta/T1 tumours (41%) compared with T2-T4 tumours (8%, P < 0.005) with 26% of muscle-invasive tumours demonstrating absent staining. In addition, the median value for cyclin D1 staining was significantly higher in G1/G2 tumours (43%) compared with G3 tumours (14%, P < 0.005). There was a significant positive correlation between expression of cyclin D1 and waf1 expression (P < 0.0001) as well as pRb expression but not between cyclin D1 expression and expression of p53. Ki67 expression was significantly associated with increasing tumour stage (P < 0.005) and histological grade (P < 0.05) but did not correlate with cyclin D1 expression. Acyclin D1 index ≥ 8% was associated with significantly better survival in those patients with muscle-invasive disease (T2-T4). In addition, there was a significantly higher progression rate for those patients with Ta/T1 disease whose tumours demonstrated cytoplasmic cyclin D1 staining. These results indicate that cyclin D1 expression is significantly higher in low-stage, well differentiated bladder tumours and strongly correlates with waf1 expression. In a multivariate analysis, cyclin D1 expression is an independent prognostic indicator of survival in those patients with muscle-invasive disease.