Abstract
Currently used clinicopathological parameters are insufficient for a reliable prediction of metastatic risk and disease-free survival (DFS) of patients with clear-cell renal cell carcinoma (ccRCC). To identify prognostic genes, the expression profiles of primary ccRCC obtained from patients with different DFS--eight synchronously, nine metachronously and seven not metastasized tumors--were determined by genome-wide expression analyses. Synchronously and metachronously metastasized primary ccRCC differed in the expression of 167 genes. Thirty-six of these genes were also differentially expressed in synchronously vs. metachronously developed pulmonary metastases analyzed in a previous study. Because of their DFS-associated deregulation that is concordant in metastases and primary ccRCC, these genes are potentially functionally involved in metastatic tumor growth and are also prognostically useful. A prognostic impact was confirmed for the genes CD31, EDNRB and TSPAN7 at the mRNA level (n=86), and for TSPAN7 at the protein level (n=106). Patients with a higher gene expression of EDNRB or TSPAN7, or with TSPAN7-positive vessels in both cores investigated on tissue microarrays had a significantly longer DFS and tumor-specific survival (TSS). Patients with a higher CD31 gene expression showed a significantly longer TSS. EDNRB was an independent prognostic marker for the DFS. CD31, EDNRB and TSPAN7 had an independent impact on the TSS. In summary, comparative analysis of primary tumors and metastases is appropriate to identify independent prognostic markers in ccRCC. Gene expression of CD31 and EDNRB, and endothelial TSPAN7 protein level are potentially useful to improve outcome prediction because of their independent prognostic impact.