mdm2 expression as a prognostic indicator in clear cell renal cell carcinoma: comparison with p53 overexpression and clinicopathological parameters.

The present study was designed to analyze the expression of p53 and mdm2 in clear cell renal cell carcinoma with special emphasis on their association with tumor grade and clinical outcome. In particular, the value of individual protein overexpression as well as combined p53/mdm2 positivity was evaluated because both proteins are functionally connected, and their expression is controlled by an autoregulatory feedback loop. A cohort of 97 clear cell renal cell carcinomas was analyzed. The overexpression of mdm2 and p53 proteins was investigated on paraffin-embedded material by using monoclonal antibodies. Eighteen tumors showed mdm2 positivity, whereas 35 of the tumors overexpressed p53. Whereas p53 and mdm2 positivity correlated significantly (P = 0.00004), no correlation could be found between mdm2 protein overexpression and tumor stage, lymph node involvement, and presence of distant metastases. mdm2 positivity was found significantly more frequently in tumors of higher grade. In univariate analysis, there was a statistically significant correlation between p53 and mdm2 overexpression in the same tumor and poor survival (P = 0.00179). Multivariate analysis revealed that coincident mdm2/p53 overexpression, the presence of distant metastases, and tumor grade were independent predictors for tumor progression. Our results indicate that mdm2/p53 co-overexpression, nuclear grade, and preoperative presence of distant metastasis are independent predictors for poor survival.