The ability of murine tumor cells to metastasize spontaneously from subcutaneous sites is positively correlated with the total sialic acid content of the cells in culture, the degree to which the sialic acid is exposed on the tumor cell surface, and, most strongly, with the degree of sialylation of galactosyl and N-acetylgalactosaminyl residues in cell surface glycoconjugates. These findings suggest that sialic acid on the cell surface may play a role in tumor cell metastasis.

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Several properties of 10 cell lines derived from the polyoma-induced PW20 Wistar-Furth rat renal sarcoma have been examined, including the ability of the tumor cells to metastasize spontaneously from subcutaneous sites in syngeneic hosts, the platelet-aggregating activity of material extracted by urea from the surface of cultured cells, the sialic acid content of the platelet-aggregating material, and the degree of sialylation of cell surface glycoconjugates in cultured cells. A correlation has been observed among all of these parameters. The results suggest a possible link between the degree of cell surface sialylation of tumor cells, their ability to aggregate platelets, and their ability to metastasize. (7,8).In this paper we report the platelet-aggregating activity of the PAM extracted from cells of 10 derivatives of the polyoma-induced PW20 Wistar-Furth rat renal sarcoma cell line, which vary in their ability to metastasize spontaneously from subcutaneous sites of tumor growth (9). The PAM's activity was found to correlate positively with the propensity of the cells to metastasize. In addition, the PAM's activity correlates with the sialic acid content of the PAM and with the degree of cell surface sialylation of the cultured tumor cells. METHODSCell Lines. The PW20 family of tumor cell lines (Table 1) was derived from a culture of the polyoma virus-induced PW20 Wistar-Furth rat renal sarcoma (obtained from H. 0. Sjbgren, Univ. of Lund, Sweden) by varying conditions of passage in tissue culture and passage through syngeneic animals (9). The RO(L) and RO(H) cell lines represent low and high tissue culture passages, respectively, of the original cell culture. The R1 cell line was obtained by reestablishing a subcutaneous RO(L) tumor in tissue culture and maintaining the culture for a large number of passages. The R2 cell line was similarly produced by reculturing a subcutaneous R1 tumor and maintaining the resultant culture for a prolonged period. The RO(L)R1, RO(H)R1, R2R1, and R2R2 cell lines were produced by reculturing subcutaneous RO(L), RO(H), R2, and R2R1 tumors, respectively; the R2L1 and R2N1 cell lines were obtained by culturing explanted lung (L) and lymph node (N) metastases that developed from subcutaneous R2 tumors. These last-named lines were all tested at low passage numbers. In vttro assays were performed with cells within several passages of those listed in The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact.