Perchloric acid soluble proteins from goat liver inhibit chemical carcinogenesis of Syrian hamster cheek-pouch carcinoma

Chemically induced Syrian hamster cheek-pouch squamous cell carcinoma is ve ry similar to the corresponding human tumour. This paper describes a blind study in which inhibition of dimethylbenzanthracene-induced cheek-pouch tum ours by a goat liver extract denominated UK101 was investigated. Less than 40% of animals treated with UK101 developed tumours compared with 100% of t he controls. Intermediate results (80%) were noted in a positive control gr oup treated with Calmette-Guerin bacillus. Immunocytochemical testing of ch eek-pouch mucosa by Mib5 showed significantly less proliferating cells in U K101 animals than in the controls. The effect of UK101 was completely rever sed when dexamethasone was added in a third control group. A significant di fference in complement-mediated cytotoxicity was noted in the sera of UK101 -tested and control animals. These findings suggest that an immune mechanis m is responsible for the inhibition of hamster cheek-pouch carcinoma by UK1 01.