Antitumor activity of marine bacteria, Vibrio anguillarum, in mice

Antitumor activity of marine bacteria, Vibrio anguillarum P-B-1, against Ehrlich carcinoma cells in ddY mice was investigated. Ehrlich carcinoma cells were inoculated intraperitoneally (ip) into mice and V. anguillarum (1.0 mg/mouse) was administered ip twice before and 4 times after the tumor inoculation. Groups of mice administered V. anguillarum survived 80 approximately 90% and their mean survival was 54.0 approximately 56.0 days (range, 24.0 approximately 60 days) at day 60 after inoculation of 10(4) to 10(6) tumor cells against the mean survival of 16.4 approximately 22.3 days (range, 7 approximately 26) in the control group. When 2 x 10(6) tumor cells were inoculated subcutaneously (sc) mixed with 1.0 mg of V. anguillarum, the bacterial cells markedly suppressed the growth of tumor at the injection site; tumor did not grow in 30% of recipient mice and the inhibition rate of grown tumor in the rest of recipients was 69%. The consistently demonstrable antitumor activity of V. anguillarum was reduced by pretreatment of mice with immunosuppressants such as anti-thymocyte serum, hydrocortisone, or irradiation of X-ray. This fact indicates that the antitumor activity of V. anguillarum is mediated by immune response.