Background: Cyclin-dependent kinases (CDK) and cyclins constitute the subunits of the maturation-promoting factor that controls the process of cell division. High levels of these proteins have been reported in human malignancies of the stomach, colon, breast, and lung, and have been implicated in aberrant cell division and dysregulated tumor growth.
Methods: p34cdc2 CDK and cyclin D1 (D1) protein expression were evaluated in 140 radical prostatectomy specimens harboring adenocarcinoma (PAC), using the respective monoclonal antibodies on archival tissue sections. In each case, slides stained with hematoxylin and eosin were examined for evaluation of Gleason's grade and pathologic stage. The DNA content of the tumors was determined by the Feulgen method with the CAS200 Image Analyzer (Cell Analysis Systems, Lombard, IL). Nuclear immunoreactivity for the two proteins was semiquantitatively scored, and results were correlated with Gleason's grade, stage, ploidy, metastatic status, and disease recurrence after radical prostatectomy.
Results: p34cdc2 was expressed in 84 of 140 PACs (60%) and correlated with high Gleason's grade (P = 0.0001), advanced pathologic stage (P = 0.01), nondiploid DNA content (P = 0.0001), and metastases (P = 0.04). On multivariate analysis using the Cox proportional hazards model, p34cdc2 immunoreactivity (P = 0.0001) and high Gleason's grade (P = 0.01) each independently predicted disease recurrence. When tumors were of low Gleason's grade and lacked p34cdc2 expression, 4 of 39 PACs (10%) recurred, as compared with 18 of 47 (38%) that recurred when tumors were of high Gleason's grade and expressed p34cdc2 protein. D1 was positive in 31 of 140 PACs (22%) and showed a trend (P = 0.07) of high Gleason's grade, but it did not reach statistical significance with any of the prognostic variables. In the majority of PACs expressing both p34cdc2 and D1 proteins, the adjacent benign prostate acini showed focal, scattered nuclear positivity of the basal and secretory epithelial cells.
Conclusions: p34cdc2 is expressed in a majority of PACs and correlates with high Gleason's grade, advanced pathologic stage, nondiploid DNA content, and metastases. On multivariate analyses high Gleason's grade and p34cdc2 immunoreactivity predict disease recurrence independently of the pathologic stage. Thus, p34cdc2 appears to play a critical role in the evolution, proliferation, and spread of PACs and may be of prognostic value when applied to initial prostate tissue samples taken by needle biopsy.