The Effect of Interferon on Carcinogenesis by N‐Ethyl‐N'‐nitro‐N‐nitrosoguanidine in the Duodenum of Mice

The inhibitory effect of murine interferon α/β (Mu‐IFN) on the induction of adenocarcinoma of the duodenum in C57BL/6 mice given N‐ethyl‐N‐nitro‐N‐nitrosoguanidine (ENNG) was examined. ENNG was given continuously in drinking water for 4 weeks and Mu‐IFN was given intraperitoneally for 12 weeks. Then, the duodenal tumors of mice were examined stereomicroscopically and histologically. The level of IFN activity and natural killer (NK) activity were evaluated after an intraperitoneal single injection of Mu‐IFN, and the level of NK activity was evaluated 2, 5 and 8 weeks after giving ENNG and Mu‐IFN. In the mice given Mu‐IFN, the incidence of duodenal tumors was significantly decreased (P < 0.01), compared with that in mice given ENNG alone. Further, anti‐asialo GM1 was given intraperitoneally every 5 days for 8 weeks to depress NK function and the incidence and size of duodenal tumors were examined. The results indicated that NK cells also have an important effect on the process of carcinogenesis. These data suggest that chemoprevention with IFN may be feasible.