Epstein-Barr virus-associated gastric adenocarcinoma in Taiwan

Fifty-five gastric carcinoma tumors from Chinese patients in Taiwan, including 40 tubular type (one lymphoepthelioma-like carcinoma subtype), eight signet ring cell type, one papillary type, and six mucinous type gastric carcinomas, were investigated for the presence of Epstein-Barr virus (EBV) transcripts by in situ hybridization using fluorescein-conjugated EBV oligonucleotides for EBERs (Epstein-Barr virus early RNAs) expression and the polymerase chain reaction for viral DNA. Epstein-Barr virus was detected in six of 55 lesions (11%), a significantly lower proportion than has been observed in a North American series. Epstein-Barr virus involvement was more common among male patients. Epstein-Barr virus DNA and its EBERs were specifically present within gastric carcinoma and adjacent dysplastic cells but were absent in surrounding lymphocytes and normal gastric mucosa. Epstein-Barr virus DNA and EBERs were found in one sample of lymphoepithelioma-like carcinoma (LELC) and five specimens of typical gastric adenocarcinoma. Among the EBV-positive gastric adenocarcinomas, four were tubular type of varied differentiation and one was signet ring cell type. Furthermore, we evaluated the expression of the latent membrane protein (LMP) with monoclonal antibodies. We found that LMP was expressed in two EBV-positive samples. In addition, the presence of the EBV receptor was studied by probing samples with CD21 monoclonal antibody. Epstein-Barr virus receptor was not detected in any sample. Southern blot analysis indicated single clonal proliferation of tumor cells. These findings confirm and extend the results of Shibata et al. They also indicate that EBV infection might be related to oncogenesis not only in rare gastric cancers that resemble nasopharyngeal lymphoepithelioma but also in typical gastric adenocarcinoma.