Effects of combined selenium and vitamin E administration on DNA in Walker tumor bearing Wistar rat exposed to cytostatic acute treatment.

Previous studies have showed that organic Se and Vitamin E have a significant protective effect when administered in combination with cytostatics. This paper reports the investigation on effects of mixed administration Orgasel 50 and Vitamin E in Wistar rat with experimentally induced Walker tumor under acute cytostatic treatment, with emphasis on two aspects: a) the influence of antioxidants upon liver unscheduled DNA biosynthesis under cytostatic (Lomustin) acute aggression; and b) the potential improvement of cytostatic effects by antioxidants treatment in tumor. Two lots of animals were used: lot 1 - Orgasel 50 and Vitamin E administered 7 days before the initiation of tumor induction and lot 2 - the antioxidants were concomitantly administered with tumor cell inoculation. The Walker tumor (an epithelial carcinoma) cells were subcutaneously injected (5 x 10(6) cells/0.5 ml in isotonic saline solution); the first tumor nodules appeared in 4 days; the tumor has reached the appropriate dimensions in 12 days. The unscheduled DNA biosynthesis caused by Lomustin in rat liver as well as the replicative DNA biosynthesis taking place in Walker tumor cells were assessed radioisotopically by measuring the uptake of 3H-Thymidine (200 microCi / 100 g.b.w.). Our observations regarding the role of antioxidant treatment suggest: 1) a benefic effect on DNA alkylant-induced lesions, expressed by a decrease in the level of 3H-Thymidine uptake in liver and, 2) an increase of the inhibitory activity of cytostatic on DNA replication biosynthesis in tumor cells, suggested by lower 3H-Thymidine incorporation in tumor cells. The most significant results were showed in both analyzed tissues, when the Orgasel 50 + Vitamin E administration begins at the same time with the tumor cell inoculation. These findings clearly show the organic Se salts and Vitamin E constitute a valuable adjuvant in anticancer medication, increasing the interest for the application of these antioxidants in cancer therapy and prevention.