Supplemental Silk Protein , Sericin in 1 , 2 - Dimethylhydrazine - Treated and Cell Proliferation , Suppresses Colon Tumorigenesis Mice by Reducing Oxidative Stress

This study was done to discover tbe underlying mechanism of the inhibitory effect of sericin against colon tumorigenesis. Mice were fed a diet with 30 g!kg sericin for 115 d, and giyen a weekly iajection of 1,2dimethylhydrazine (10 mglkg body weight) for the initial 10 wk. Dietary supplemental sericin caused a 62% reduction in the incictence of colonic adenoma (P<O.05), but did not affect the incidence of co]onic adenecarcinoma. Sericin intake significantly reduced the number of colon adenornas. Consumption of sericin significantly reduced the BrdU labeling index of colonic proliferating cells and the expression of colenic c-myc and c:fbs. The leye]s of co]enic 8-hydroxydeoxyguanosine, 4-hydroxynonenal, and inducible nihic oxide synthase protein were significantly suppressed by sericin. The results suggest that dietary sericin suppresses the deyelopment ef colon tumors by reducing oxidative stress, cell proliferation, and nitric oxide production.