[Effects of immunosuppressive acidic protein on 7, 12-dimethylbenzanthracene (DMBA) induced pancreatic cancer in rats].

In order to determine the effect of immunosuppressive acidic protein (IAP) on the formation of pancreatic carcinoma, rats of Sprague-Dawley strain were embedded with 7, 12-dimethylbenzanthracene (DMBA) in the pancreas with and without administration of IAP as a promotor, which was purified from the ascites obtained from cancer bearing patients, to induce pancreatic carcinoma experimentally. In these animals, growth of pancreatic cancer was studied both immunologically and histologically. Out of 60 rats treated with embedding of 1 mg DMBA alone, tumor was induced in 51 animals (85%). Tumors began to appear from the 16th week after the embedding. Among animals in which tumor was induced, tubular adenocarcinoma and pleomorphic carcinoma accounted for 55% of the cases. When administration of IAP was combined, the period required for development of tumor was shortened. It became shorter with an increase in the dosage and frequency of administration of IAP. In animals received IAP at a mean dosage of 75 mg/kg the area showing cancerous changes appeared as early as at 8th week after the embedding of DMBA. The acceleration of carcinogenesis in DMBA induced pancreatic carcinoma may be attributable to the immunosuppressive effect of IAP administered and tend to be dependent on the dosage and frequency of its administration in the early phase of tumor induction.