Changes in the Serum Protein Composition in Mice with Transplanted Ehrlich’s Carcinoma

Injection of blood serum from mice with Ehrlich's carcinoma stimulates the growth of trans- planted tumor, which proves the presence of tumor-specifi c factors in the serum. Experiments on (CBA×C57Bl/6)F 1 male mice with transplanted Ehrlich's carcinoma demonstrated the appearance of new proteins in the serum, some of them are identifi ed. The authors suggest continuing the search for tumor-associated factor by combining proteomic analytical methods and testing of identifi ed candidate proteins for their effects on tumor growth. Studies of tumor-specifi c factor and methods of its identifi cation are in progress. The hypothesis on the presence of a factor regulating the tumor growth in the blood serum was proposed after analysis of the results of numerous experiments on mice (3). Our studies in- dicate that partial elimination of the tumor stimulates mitotic activity of remaining tumor cells (2). Presum- ably, this factor quantitatively and qualitatively differs in histological variants of tumors at different stages of the tumor process. Hence, the development of methods for laboratory identifi cation of tumor-associated factor is expected to extend the potentialities of diagnosis and improve the results of therapy for cancer. How- ever, despite the use of the most up to date proteomic methods for protein identifi cation, the factor remains not identifi ed. Search for potential protein markers of gastric cancer in human serum has detected tens of potential candidates (6). It seems that search for this factor should be realized by means of a biological test for analysis of specifi c activity of candidate proteins detected by proteomic analysis. This is expected to detect the differences in the serum protein composi- tion in normal animals and animals with tumors and demonstrate the biological signifi cance of the detected differences. We studied the serum protein composition in mice with transplanted Ehrlich's carcinoma and the effect of this serum on primary tumor growth.