Enhancing Effect of High Fat Diet on 4‐Nitroquinoline 1‐Oxide‐induced Pulmonary Tumorigenesis in ICR Male Mice

The effects of dietary high fat on 4‐nitroquinoline 1‐oxide (4NQO)‐induced lung tumorigenesis were investigated in male ICR mice. Two groups of mice were initially given a single subcutaneous injection of 4NQO at a dose of 15 mg/kg and, thereafter, fed either 20% corn oil‐supplemented diet or a standard basal diet. Two further groups were maintained on the high fat diet or standard diet without administration of 4NQO. Mice were killed at weeks 15, 18 and 25 and the incidence of lung tumors at each time point was found to be significantly increased in the 4NQO/high fat diet group as compared to the 4NQO/standard diet group in terms of both incidence of tumor‐bearing mice and the number of lesions per mouse. The results thus indicate that dietary high fat can enhance 4NQO‐induced lung tumorigenesis in mice.