Non-involvement of the K-ras mutation in colon carcinogenesis promoted by dietary deoxycholate in azoxymethane-treated rats

Fisher-344 rats, whose ileum or jejunum had been surgically removed to chan ge the influx of bile acids into the colon, were intraperitoneally: adminis tered with azoxymethane and fed on a diet containing deosycholate for 39 we eks to induce colon cancer, Fetal bile acids in the ileum-resected group we re 1.5-times and serum bile acids were about half of those in the jejunum-r esected group. As a result, the incidence and number of tumors were higher in the ileum-resected group. In tire total of 59 colon tumors (40 were in t he ileum-resected group and 19 in the jejunum-resected group), 56 were carc inomas, including two well-differentiated invasive and two mucinous carcino mas found in the ileum-resected rats, However! only three carcinomas, two i nvasive and one non-invasive, had the K-ras mutation, These results demonst rate that the K-ras mutation was not essentially involved in deoxycholate-p romoted colon carcinogenesis.