Impaired Tissue Content of Iron and Zinc in Mice with Growing Hepatoma 22A and Its Correction with Zinc Sulfate Supplementation

The growth of many tumors is known to induce iron and zincdeficiency in the body. Here, we studied the tissue content of ironand zinc, as well as the specific activity of two antioxidant metalloenzymes, catalase(CAT) and superoxide dismutase (SOD), in three distant organs (thymus,liver and spleen) of mice bearing transplantable hepatoma 22a. Therevealed alterations in the metal content were compared to changesin organ weights. On day 21 of tumor growth, the non-heme iron contentwas decreased in all three organs, while that of zinc in the thymusonly, as compared to controls. CAT and SOD specific activities wereincreased in the thymus, while SOD activity was decreased in theliver. At the same time point, thymic involution and splenomegalywere observed to develop. In an attempt to normalize metal content,hepatoma 22a-bearing mice were supplemented with zinc sulfate (22µg/mL in drinking water) for 3 weeks. Zinc sulfate supplementationpartly compensated for zinc deficiency in the thymus, increasedzinc content in the liver, and restored iron content in all threeorgans. It also normalized SOD activity in the liver, while havingno effect on both enzymes in other organs. Zinc supplementationdid not influence splenic and hepatic weights, but prevented thedevelopment of thymic involution. At the same time, the deficiencyof both metals in the thymus was restored, while the activity ofantioxidant enzymes remained unchanged. It was concluded that thymicinvolution during hepatoma 22a growth in mice was due to iron andzinc deficiency in this organ, but not to the activity of antioxidantenzymes, whereas splenomegaly was not associated with either. Thus,zinc sulphate exerts a positive effect on metabolism of two vitaltrace elements, zinc and iron, in mice bearing hepatoma 22a, preservingthe thymus as a central immune organ and, at the same time, improvingthe antioxidant system of the liver.