Effects of cimetidine on tumor growth and immune function in nude mice bearing human ovarian carcinoma.

The effects of cimetidine on the growth of a human ovarian cancer cell line inoculated into BALB/c nude mice were examined. The cell line, designated "KK," was derived from a cystadenocarcinoma of the ovary. The passage number was about 40, and its tumorigenicity in nude mice was 100% even when 10(5) cells were inoculated. About 2 weeks after inoculation, the KK cells formed palpable tumors, and the tumor volume reached 2.29 cm3 on day 36. Conversely, the nude mice given cimetidine (100 mg/kg/day) orally with drinking water had about one-third the tumor volume (0.81 cm3) of that in untreated nude mice on day 36. The natural killer activity against the YAC-1 (a T-cell lymphoma) cell line in spleen cells of the nude mice challenged with human xenogeneic tumor (KK cell line) was not affected by treatment with cimetidine while inhibiting the tumor growth. The capacity to lyse the KK cells did not exist in the spleen cells of nude mice challenged with the KK cell xenograft and not treated with cimetidine. The cimetidine-treated spleen cells acquired the capacity to lyse the KK cells on day 14. Thereafter, the capacity was maintained at the same level as long as cimetidine was administered, whereas that in untreated nude mice remained undetectable.