Potential carcinogenicity of 5,6-dimethoxysterigmatocystin in rats

The potential carcinogenic activity of 5,6-dimethoxysterigmatocystin (DMSC) was examined by oral administration in rats. In Experiment I, all of eight effective ACI/N rats given DMSC in the diet at a concentration of 50 p.p.m. developed neoplastic nodules of the liver. Five rats developed hepatocellular carcinomas and four rats had hemangioendothelial sarcomas of the liver. Two other rats developed osteosarcomas. In Experiment II, F344 rats were given DMSC by gavage once every 2 weeks at dose of 2 mg/0.15 ml dimethylformamide. Out of 24 effective animals 19 rats developed neoplastic nodules of the liver, and eight rats had hepatocellular carcinomas. Hemangioendothelial sarcoma of the liver was seen in one rat. Two rats developed osteosarcomas in the upper legs. Proliferative fibrous lesions which were considered to be a preneoplastic change of the bone tumors were seen in the thighbones of four rats. Results obtained from these two experiments indicate that DMSC is hepatocarcinogenic, as is sterigmatocystin, and that the compound is probably weakly carcinogenic for the bone.