Establishment of a human chorionic gonadotropin-producing human gastric carcinoma in nude mice.

A human chorionic gonadotropin (HCG)-producing gastric carcinoma was transplanted into BALB/c nu/nu nude mice. The original tumor tissue had been obtained by gastrectomy from a 55-year-old patient with gastric carcinoma. The tumor was transplanted serially in nude mice, and its doubling time was stable to approximately 12 days. A positive correlation was observed between serum HCG level and tumor weight. The serum HCG level of the mice and the histology of the tumor weight. The serum HCG level of the mice and the histology of the tumor, papillary adenocarcinoma with partial poorly differentiated adenocarcinoma, did not change on serial transfers. HCG was positively stained by an immunochemical technique only in the site of the poorly differentiated adenocarcinoma, while staining was negative in the site of the papillary adenocarcinoma, which constituted most of the tumor. These results indicate that this tumor in nude mice will be useful not only as a therapeutic experimental system but also for studying the potential malignancy of HCG-producing cancer cells.