3A and 3C). The expression was maintained in mouse tumor cells for at least 48-72 h (Fig. 3B and 3D). The same result was observed by immunohistochemical staining with 14F7 antibody on in vitro monolayer cultured cells (Fig. 2E and 2F). Figure 3 Detection of NeuGc-GM3 in cell membrane fraction by slot blot assay in B16 (A and B) and F3II (C and D) cells. A and C, tumor cells were preincubated

with different concentrations of NeuGc-rich BSM and selleck processed 24 h later. CA4P mw B and D, tumor cells were preincubated with 250 μg/ml of NeuGc-rich BSM and further processed 24, 48 or 72 h after preincubation. In all cases, densitometric analysis was normalized to the respective control. Means ± SEM of at least 3 determinations

are shown. *p < 0.05, **p < 0.01 (ANOVA contrasted with Dunnet test). Interestingly, incubation of tumor cells with purified NeuGc modulates the in vitro behaviour. Tumor cell adhesion showed a significant increase in both cell lines (Fig 4A); while NeuGc addition impacted differently on proliferation, significantly increasing growth in B16 but not in F3II cells (Fig 4B). Figure 4 A, adhesion assay. B16 or F3II cells were incubated for 1 h in medium with 2% FBS, either with (filled bars) or without (empty bars) 50 μg/ml of purified NeuGc. Data represent mean ± SEM (n = 6). *p < 0.05, **p < 0.01 (t test). B, proliferation assay. SGC-CBP30 supplier B16 (black square) or F3II (black diamond) Pregnenolone cells were grown for 72 h in medium supplemented with 1, 5 or 10% FBS, either with or without 100 μg/ml of purified NeuGc. Dashed line refers to proliferation in control monolayers without addition of NeuGc. Data represent mean of 6 determinations; in all cases SEM was less than 5%. ***p < 0.001 versus the respective control (ANOVA contrasted with Tukey-Kramer multiple comparisons test). Finally, we evaluated tumorigenicity and lung colonization of BSM-preincubated

tumor cells in syngeneic mice. In both mouse models preincubation with NeuGc-rich BSM significantly enhanced the metastatic ability of tumor cells, approximately doubling the number of lung nodules after intravenous cell injection (Table 1). Similar results were obtained after preincubation with purified NeuGc. B16 NeuGc-treated cells showed a 65% increase in lung nodules (Control: 14.5 ± 4.8, NeuGc: 22.3 ± 3.8; p = 0.14, Mann-Whitney U test), while for F3II NeuGc-treated cells the number of lung nodules resulted in a 112% increase (Control: 7.3 ± 1.8, NeuGc: 15.5 ± 2.2; p < 0.05, Mann-Whitney U test). Although all animals challenged in the flank developed subcutaneous tumors, we observed a rapid tumor take with BSM-preincubated B16 cells. Significant differences were obtained for tumor latency and size of melanoma tumors. However, preincubation with BSM did not significantly modify tumor growth rate (Table 2).