Inhibitory Effect of Vitamin E on Cellular Events Related to Lung Tumorigenesis in Mice

Abstract

We estimated the inhibitory effect of vitamin E on pulmonary polyamine biosynthesis and cell proliferation in urethane-induced lung tumorigenesis of mice. The induction of pulmonary ornithine decarboxylase (ODC) and the accumulation of subsequent putrescine (a polyamine) were observed during the initiation and promotion phases of the urethane-induced lung tumorigenesis in mice. Histochemical analysis indicated that the induction of ODC in the lungs of mice treated with urethane was localized in the alveolar type II cell, which is a progenitor cell of lung adenocarcinoma. The urethane-induced increases of ODC activity and putrescine level during both phases were almost inhibited when a high vitamin E diet was provided. In conjunction with these events, an increase in the level of pulmonary proliferating cell nuclear antigen by urethane treatment was not observed with vitamin E feeding. These results suggest that vitamin E controls cell proliferation during the initiation and promotion phases of the urethane-induced lung tumorigenesis due to the inhibition of polyamine biosynthesis.