Increased cyclin-dependent kinase 6 expression in bladder cancer.

Cyclin-dependent kinase 6 (Cdk6) controls the cell cycle and aberrant expression of Cdk6 is involved in cancer progression. The aim of this study was to investigate the role of Cdk6 in bladder cancer development. Cdk6 expression was examined in 31 cases of bladder cancer and 29 tissues adjacent to bladder transitional cell carcinoma (TCC) using an immunohistochemistry assay. The correlation between Cdk6 expression and clinical characteristics was also analyzed. Compared with the adjacent tissues, cytoplasmic and nuclear Cdk6 expression levels were significantly increased in the invasive bladder cancer cases (P=0.005 and P<0.001, respectively), but not in the non-invasive superficial cases of bladder cancer (P>0.05 for both). Cytoplasmic and nuclear Cdk6 expression levels were correlated with bladder cancer stage (superficial vs. invasive, P=0.026 and P=0.006, respectively). The results therefore indicate that increased Cdk6 expression contributes to bladder cancer development and may serve as a biomarker for bladder cancer.