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It has been reported that dendritic cells (DCs) play a crucial role in the host’s immune defense against tumors, and there is an inverse correlation between the density of DCs and the expression of vascular endothelial growth factor (VEGF). However, the relationship between the expression of VEGF-C and DC infiltration remained unclear. In the present study, we investigated whether the expression of VEGF-C correlated with the number of DCs in vivo. We immunohistochemically analyzed gastric carcinoma tissue in this study. The survival curves show that the prognosis for patients with a low density of DCs was significantly poorer than that for patients with high DC density (p < 0.01). Further, the survival curves according to the VEGF-C status showed that the survival rate in patients with low VEGF-C expression was higher than that in patients with higher expression (p < 0.01). There was a significant negative correlation between the density of DCs and the expression of VEGF-C (r = –0.26, p < 0.05). We suggest that VEGF-C produced by cancer causes DCs to become dysfunctional. This may be one of the ways that cancers evade immunosurveillance.

Liver metastasis is one of the poor prognostic factors for gastric cancer. Hepatocyte growth factor (HGF) and its receptor, c-Met, have been reported to be related to the proliferation of carcinoma cells. We examined c-Met and HGF expression in stage IV gastric cancers (n = 121) and compared the results in groups with liver metastasis (n = 47, LM group) and without liver metastasis (n = 74, no-LM group). The survival rate for the LM group was significantly poorer than for the no-LM group (p < 0.01). We found a high frequency of c-Met expression in the LM group compared with the no-LM group at protein level detected by immunohistochemistry (p = 0.0005) and at mRNA level detected by semiquantitative reverse transcriptase-polymerase chain reaction (p = 0.0386) in primary gastric tumors. Furthermore, we evaluated HGF expression in both carcinoma cells and stromal cells in gastric cancers. There was no significant difference in the HGF expression between the LM and no-LM groups. The labeling index of proliferating cell nuclear antigen for the carcinomas in the LM group was higher than that in the no-LM group (47.1 ± 24.5 vs. 26.2 ± 24.5%, p < 0.0001). Thus, the high frequency of c-Met overexpression in carcinoma cells may be involved in the mechanism of liver metastasis in gastric cancers. Moreover, the evaluation of c-Met expression might be a useful indicator of liver metastasis in patients with gastric cancer.