VITAMIN-E ACTS AS A USEFUL CHEMOPREVENTIVE AGENT TO REDUCE SPONTANEOUS LUNG TUMORIGENESIS IN MICE

The present study was designed to evaluate whether vitamin E could be a useful chemopreventive agent to reduce spontaneous lung tumorigenesi s in mice. Starting at 6 weeks of age, groups were divided into three groups, i.e. A/J mice fed a control diet (A/J control), A/J mice fed a vitamin E-supplemented diet (A/J vitamin E) and ddY mice fed a contro l diet (ddY control). At the 28th experimental week, nuclear NADPH-dri ven active oxygen generation, thiobarbituric acid reactive substances (TEARS) and DNA single strand breaks (DNA-SSB) in A/J mice fed a contr ol diet were significantly higher than those in the ddY control group. A/J mice fed Vitamin E for 28 weeks could decrease the levels of TEAR S and DNA-SSB with a significant difference, as compared with those in AN control mice. The nuclear alpha-tocopherol levels in A/J controls were significantly lower than those in ddY controls, on the contrary, the vitamin feeding to A/J mice increased nuclear cu-tocopherol levels more than that in the ddY controls. At the 40th experimental week, lu ng tumor incidence and tumor multiplicity (percentage of mice with tum ors) in A/J controls were reduced and brought close to those in ddY co ntrol mice by vitamin E. Then the rw-tocopherol level in plasma of A/J controls was significantly lower than the level in plasma of ddY cont rols, and the level in tumor-bearing mice of A/J controls also showed a lower level with significant difference as compared to that in non-t umor-bearing mice of A/J controls. These results suggest that the diff erence in susceptibility to spontaneous lung tumorigenesis between A/J and ddY mice partly depends on the difference of oxidative stress on- the pulmonary nuclei, and vitamin E can act as a useful chemopreventiv e agent to reduce spontaneous lung tumorigenesis in mice.