HIGH TUMOR-PREVENTIVE EFFECTS OF POLYCLONAL IGG GENERATED AGAINST P53TUMOR-ASSOCIATED PROTEIN OBTAINED FROM BENIGN-TUMOR BEARING RATS

We have shown the different effects of rabbit IgG generated against va rious types of p53 tumor-associated protein on chemically induced colo n cancer in rats. p53 protein was isolated in the form of cytoplasmic, soluble, protein from sera obtained from: a) rats with colon cancer a nd b) rats with benign colon tumors. The isolation was performed using the affinity chromatography columns with,eel fiberglass membranes. An ti-p53 IgG were obtained from rabbits vaccinated with the above mentio ned types of p53. Sprague Dawley rats were vaccinated with anti-p53 Ig G (100 mu g/rat) at two-week intervals for 2 months and then monthly f or 3 months. The induction of colon cancer was caused by weekly inject ions with 1,2-dimethylhydrazine (20 mg/kg) for 7 weeks and was initiat ed 8 weeks after the start of the vaccination. Results of experiments were evaluated 6 months after the start of cancer induction. It was fo und that vaccination of rats with IgG generated against the p53 protei n isolated from cancer-bearing rats did not exhibit significant protec tive effect. Only IgG generated against p53 protein from benign tumor- bearing rats significantly prevented the carcinogenic effect of DMH. T he number of tumor-bearing rats in vaccinated group decreased to 44% a s compared with 93% in the control group. In vaccinated rats, the numb er of tumors/rat was 0.8 as compared to 9.3 in controls. The number of malignant tumors in vaccinated rats was half that in controls: 29% an d 58%, respectively. In the controls, metastases were found in 6 of 45 rats (13%). Anti-p53 IgG not only has an anti-tumor effect but also p revented benign tumors from becoming malignant. We suggest that the an ticancer role of a vaccine generated against p53 protein from benign t umor-bearing rats is related to a wild-type p53 protein. Further studi es will be performed to clarify this hypothesis.