TRANSMISSIBLE COLON CARCINOMA OF WF-OSAKA STRAIN RATS

A litter of ACI rat strain, foster bred by a female colon cancer-prone WF-Osaka rat, developed colon carcinoma in the ascending colon at the age of 4 months. We assumed that some microbial infection during their suckling might cause colon carcinoma of WF-Osaka rats, and that the high incidence of spontaneous regression of the colon carcinoma might be an immunologic reaction against microbial agent in the cancer cells. In this report, we showed that new born rats of ACI, LE and W/Shi strain developed colon carcinoma by the intraperitoneal injection of the serum from cancer carrying WF-Osaka rat within 2 months after birth, and that this microbial agent was transmissible among rats regardless the strain. The etiology of colon carcinoma of WF-Osaka rat was considered to be virus-like infection as we found FITC positive granular materials in the cytoplasm of tissue culture cells of colon carcinoma (C2) and tissue specimen of transplantable gastric carcinoma (S3). Supernatant of tissue culture medium of colon carcinoma (C2) also induced colon carcinoma. Solid-phase immune electronmicroscopy study revealed round to oval particles, measuring approximately 40-50 nm in diameter, in the sediment of tissue culture medium of the transplantable gastric carcinoma (S3), which explain that oncogenic viral agent is substantially related to the induction of colon carcinoma in WF-Osaka rat strain.