Inhibition of lung cancer growth in mice by dietary mixed tocopherols

Abstract

Tocopherols are lipophilic antioxidants found in vegetable oils. Here, we examined the growth inhibitory effect of a γ‐tocopherol‐enriched tocopherol mixture (γTmT) against CL13 murine lung cancer cells grown in culture and as subcutaneous tumors in A/J mice. We found γTmT had no effect after 2 days and weakly inhibited the growth of CL13 in culture after 5 days (28% growth inhibition at 80 μM). Dietary treatment with 0.1 and 0.3% γTmT 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% γTmT, respectively). Dietary treatment with γTmT dose‐dependently increased γ‐ (10.0–37.6‐fold) and δ‐tocopherol (8.9–26.7‐fold) in the tumors of treated mice compared to controls. Dietary treatment with γTmT also increased plasma γ‐ (5.4–6.7‐fold) and δ‐tocopherol (5.5–7‐fold). Whereas others have demonstrated the cancer preventive activity of γTmT 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.