Inhibition of lung cancer growth in mice by dietary mixed tocopherols

Tocopherols are lipophilic antioxidants found in vegetable oils. Here, we examined the growth inhibitory effect of a gamma-tocopherol-enriched tocopherol mixture (gamma TmT) against CL 13 murine lung cancer cells grown in Culture and as subcutaneous tumors in A/J mice. We found gamma TmT had no effect after 2 days and weakly inhibited the growth of CL13 in culture after 5 days (28% growth inhibition at 80 mu M). Dietary treatment with 0.1 and 0.3% gamma TmT for 50 days inhibited the growth of CL13 tumors in A/J mice by 53.9 and 80.5%, respectively. Histopathological analysis revealed an increase in tumor necrosis compared to control tumors (80 and 240% increase by 0.1 and 0.3% gamma TmT, respectively). Dietary treatment with gamma TmT dose-dependently increased gamma- (10.0-37.6-fold) and delta-tocopherol (8.9-26.7-fold) in the tumors of treated mice compared to controls. Dietary treatment with gamma TmT also increased plasma gamma- (5.4-6.7-fold) and delta-tocopherol (5.5-7-fold). Whereas others have demonstrated the cancer preventive activity of gamma TmT against mammary and colon cancer, this is the first report of growth inhibitory activity against lung cancer. Further studies are needed to determine the underlying mechanisms for this anticancer activity, and to determine if such activity occurs in other models of cancer.