The inhibitory effect of vitamin E on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced DNA injury and the fixation of the DNA injury in mouse lungs.

In order to estimate the effect of vitamin E on DNA injury and K-ras point mutation at an early stage of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone(NNK)-induced lung tumorigenesis in mice, the present study was carried out. Presupplement with vitamin E about 15 times more than control for a week significantly inhibited NNK-induced O6-methylguanine formation in the lungs of mice at 4 and 168 h after the injection. At 30 days after the NNK injection. the activation of K-ras oncogene with a 12th codon GC-->AT transition was detected in 56% of lung samples tested by mutant-allele-specific amplification. Vitamin E supplement reduced the frequency of the mutation to 30%. These results suggest that vitamin E suppresses NNK-induced DNA injury and subsequent fixation of the injury during the initiation and post-initiation phases of the lung tumorigenesis in mice.