Targeting of tumor associated antigens in renal cell carcinoma using proteome-based analysis and their clinical significance

The suitability of proteome-based strategies for the targeting of tumor-associated markers along with further analysis regarding their clinical significance were investigated in human renal cell carcinoma (RCC). The immunogenic protein expression profile of normal kidney and RCC cell lines was studied by proteome analysis combined with immunoblotting using sera from healthy donors and RCC patients, also termed PROTEOMEX. Employing this approach, a series of proteins reactive with either RCC patient sera and/or reactive with control sera were identified by microanalysis of tryptic peptides. Some of these candidate antigens represent members of the cytoskeletal family, such as cytokeratins, in particular cytokeratin 8, cytoskeletal tropomyosin, F-actin capping protein, gamma-actin, stathmin, tubulin-alpha, tubulin-beta and vimentin. The expression pattern and clinical significance of three of these antigens, namely cytokeratin 8, stathmin and vimentin, were further analyzed in a large series of surgically removed RCC lesions of distinct subtypes. A heterogeneous expression pattern of cytokeratin 8, stathmin and vimentin was demonstrated in the different RCC subtypes. All epithelial cells of the autologous normal kidney showed a strong cytokeratin 8 staining pattern, whereas they totally lack vimentin expression. Stathmin was expressed in 10% of tubule cells. In conclusion, PROTEOMEX could be employed for the identification of tumor-associated antigens of the cytoskeleton which are differentially expressed in RCC of distinct subtypes as well as in normal renal epithelium.