The effect of dietary carotenoids on lung tumorigenesis induced by intratracheally instillated diesel exhaust particles

The purpose of this study is to examine the carotenoid effects on lung tumo rigenesis induced by intratracheal instillation of diesel exhaust particles (DEP) into mice weekly for 20 wk. It was suggested that active oxygen radi cals might play an important role in DEP-induced lung tumorigenesis. Mice w ere divided to 4 groups of diet containing 0.02% of palm oil carotene, 0.02 % of beta -carotene, or no carotenoid with or without DEP. The BF group (4% fat) and the HF group (16% fat) were prepared for each diet group. The exp erimental period was 12 mo. By the administration of palm oil carotene, nei ther adenocarcinoma nor adenoma was found in the BF group. In the HF group with palm oil carotene, no adenocarcinoma was observed, and adenoma was red uced. Adenoma in the HF group was not greatly reduced by beta -carotene, bu t rather increased in the BF group. No adenocarcinoma was found in either t he BF or the HF groups with beta -carotene. The 8-hydroxydeoxyguanosine/deo xyguanosine ratio in palm carotene groups was lower than in the ether group s, while that in beta -carotene groups was not. From these results, palm oi l carotene was suggested to prevent lung tumorigenesis by its protective ef fect on DNA from active oxygen. Beta-carotene was supposed to have differen t effects from palm oil carotene on lung tumorigenesis. Besides the chemopr eventive effect, the growth of mice was inhibited by the administration of palm oil carotene. Further studies are necessary to elucidate the mechanism s of carotenoid effects.