Inhibitory effect of synthetic interferon inductor Cycloferone (R) on 1,2-dimethylhydrazine-induced colon carcinogenesis in rats

The effect of a synthetic interferon inductor Cycloferone(R) on colon carci nogenesis was firstly studied in rats. Seventy-five 2-month-old outbred fem ale LIO rats were subdivided into three groups and were weekly exposed to 1 5 s.c. injections of 1,2-dimethylhydrazine (DMH) at a single dose of 7 mg/k g body wt, From the day of the fist injection of DMH rats from group 2 were given weekly i.p. injections of Cycloferone(R) (62.5 mg/kg) until the end of the experiment. DMH-treated rats (group 3) were exposed to weekly i.p. i njections of Cycloferone(R) (62.5 mg/kg) starting in the week after the las t injection of the carcinogen. Rats from group 1 were exposed to DMH and tr eated weekly with 0.2 ml i.p. of normal saline. Additional groups of rats w ere treated weekly with Cycloferone(R) (62.5 mg/kg) or with 0.2 mi of salin e. The experiment was ended 6 months after the first injection of DMH. In D MH-treated rats (groups 1, 2 and 3) colon adenocarcinomas developed in 87, 61 and 59%, respectively. The number of colon tumors per tumor-bearing rat was 2.5, 1.9 and 1.3 in groups 1, 2 and 3, respectively. Treatment with Cyc loferone(R) significantly inhibits carcinogenesis in ascending and descendi ng colon. The incidence of tumors of the rectum was decreased in the group 2 as compared with the group 1. There were no cases of tumors of rectum in rats from group 3. The treatment with Cycloferone(R) alone as well as with normal saline failed to induce any tumors in rats. Thus, our results demons trated inhibitory effect of Cycloferone(R) on colon carcinogenesis induced by DMH in rats. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.