c-erb-2 amplification and overexpression are currently attracting a great deal of attention because a new adjuvant therapy using an antibody against the c-erbB-2 gene product, trastuzumab (Herceptin; Genentech, Inc., South San Francisco, CA), has proved effective in treating breast cancer with amplification and/or overexpression of c-erbB-2. Aberrations of c-erbB-2 have also been detected in ovarian, endometrial and gastric carcinomas at varied frequencies. Amplification of the c-erbB-2 locus (17q12-q21.32), overexpression of c-erbB-2 protein (p185) and serum levels of soluble c-erbB-2 protein fragments (p105) were examined in gastric cancer patients using fluorescence in situ hybridization (FISH), immunohistochemistry and enzyme-linked immunosorbent assay (ELISA), respectively. Overexpression of c-erbB-2 protein was found in 29 (8.2%) of the 352 gastric carcinomas analyzed. In FISH analysis, all tumors with 3؉ immunostaining and 1 of 5 tumors with 2؉ staining showed high-level amplification of c-erbB-2. Pre-operative serum p105 was quantified in serum specimens from 129 patients with gastric cancer and 28 patients with benign diseases. There were no significant differences in the serum p105 levels among 11 patients with c-erbB-2-overexpressing carcinomas, 118 patients with c-erbB-2 non-overexpressing carcinomas and 28 controls, although a single case of gastric carcinoma overexpressing c-erbB-2 with extensive liver metastasis had a higher level than the cut-off value. The mechanisms of overexpression of p185 and highlevel amplification of c-erbB-2 in gastric adenocarcinomas seem similar to those well-established in breast cancers. Patients having gastric adenocarcinoma with c-erbB-2 amplification are potential candidates for a new adjuvant therapy using humanized monoclonal antibody.

Background: Patients with gastric cancers producing alpha-fetoprotein (AFP) were reported to have a poor prognosis with high rates of liver metastasis. The purpose of the present study was to clarify the clinicopathological features of AFP-producing gastric cancers, in particular characteristics of liver metastasis, and to evaluate treatment of these cancers. Methods: In 27 of the 29 cases with elevated preoperative serum AFP levels among a total of 974 primary gastric cancers, AFP production was confirmed in gastric cancer cells by immunohistochemistry. These cases were included in the AFP-positive gastric cancer group (AFP(+), 2.7%). The remaining 945 cases with normal serum AFP levels were designated the AFP-negative gastric cancer group (AFP(–)). Results: There was a higher incidence of lymph node metastasis, a deeper invasion of the gastric wall, a higher frequency of advanced stage, a more marked lymphatic invasion and a higher rate of liver metastasis in the AFP(+) group than in the AFP(–) group. The patients received curative resection in AFP(+) group had a significantly worse survival rates in comparison to that in AFP(–) group. With respect to liver metastasis (n = 17) in AFP(+) group, of 3 cases who received curative hepatic resection, 1 patient survived more than 3 years, while the remaining 2 died in less than 3 years due to multiple liver recurrence. The patients (n = 5) who received palliative resection for liver metastasis followed by transarterial continuous infusion chemotherapy all died in less than 1 year. Conclusion: AFP-producing gastric cancers had aggressive behavior and their clinical or biological features were quite different from the common AFP-negative gastric cancers. Surgical resection of liver metastasis from AFP-producing gastric cancers was unsatisfactory. The development of a novel multimodal therapy against AFP-producing gastric cancers is needed.

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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.

Gastric cancers producing α-fetoprotein (AFP) have a poor prognosis and a high incidence of liver metastasis. Hepatocyte growth factor (HGF) and its receptor, c-Met, are known to induce mitosis and cell movement and to promote tumor progression. In the present study, c-Met and HGF expression in AFP-producing gastric cancer was compared with those gastric cancers that do not produce AFP. Twenty-six patients with AFP-producing gastric cancers [AFP(+)] and 26 patients stage-matched gastric cancers without AFP production [AFP(–)] were evaluated for c-Met and HGF expression and proliferating cell nuclear antigen-labelling index using immunohistochemical analysis. A higher frequency of c-Met expression was observed in the AFP(+) group than in the AFP(–) group (p < 0.01). A higher expression of c-Met might be one explanation for the poorer prognosis of AFP-producing gastric cancers.

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.

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Serum HER-2/neu (c-erbB-2) levels in patients with gastric cancer were evaluated by an enzyme-linked immunosorbent assay and tissue levels of HER-2/neu in the same cohort were determined by immunohistochemistry. Nine (16%) of 57 gastric carcinomas had an overexpression of HER-2/neu detected immunohistochemically. Of these 9 patients, 6 had elevated serum HER-2/neu levels, while 45 of 48 tissue samples with negative staining exhibited normal serum HER-2/neu levels. These results indicated that overall accuracy, positive predictive value, and negative predictive values of their serum measurements were 89, 67 and 94%, respectively. Serum levels of HER-2/neu were correlated with tissue overexpression of HER-2/neu in patients with gastric cancer.