Dietary selenium fails to influence cigarette smoke-induced lung tumorigenesis in A/J mice

The goal of the study was to determine if dietary selenium inhibited the induction of lung tumorigenesis by cigarette smoke in A/J mice. Purified diets containing 0.15, 0.5, or 2.0 mg/kg selenium in the form of sodium selenite were fed to female A/J mice. Half of the mice in each dietary group were exposed to cigarette smoke 6 h/day, 5 days/week for five months followed by a four month recovery period in ambient air, while the other half were used as controls. After the recovery period, the mice were euthanized, and their lungs were removed for further analysis. Mice exposed to smoke had a higher tumor incidence and a higher tumor multiplicity, whereas dietary Se did not affect either the tumor incidence or tumor multiplicity. An increase in dietary selenium led to increased levels of selenium in the lung as well as GPx protein levels, but dietary Se did not affect lung SOD protein levels. In conclusion, these data confirm the carcinogenic activity of cigarette smoke in mice but show that dietary Se provided as sodium selenite does not affect smoke-induced carcinogenesis in this model.